Service Information

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ATP GRID INDEX TO MANUFACTURER'S PUBLICATION:

TEXTRON LYCOMING RECIP MODELS-FLYER BINS SERVICE INFORMATION

ISSUE TYPE EYE-READABLE CODE

FLYERS FS

k"" END OF INDEX *X~

10/11/93 (RCR2102 AV 0004 SI) PAGE: 1 FS LYCOMIAIG

I Lycoming Textron Lycomlng/Subsldlary of Textron Inc.

652 Oliver Street. Williamsport, PA 1 7701 717/323-6181 Fax 717/327-7022

Gsne~a Pvllion

1999 Trxlran Lvcam np IBDEX

Ihe articles contained herein are not intended to supersede manufacturers service publications, instructions or manuals or any other qtFcial publications, bur are prorided in order to augment or erplain in pilot5 or mechanic's language these publications, as and well as provide other supplemental helpfitl information for our customers operators.

GENERAL

Title Page No.

OPERATION

MAINTENANCE

Mechanic's Creed. 72 The Basics Of Maintenanceln General Aviation. 72 Ask About Reference Publications Before Your Engine Is Taken 73 The Oil And Your Engine. 73 More About Oil And Your Aircraft Engine. 74 Safety Tip--Sealant Use...... 75 Oil Levels Maintaining of Wet Sump Engines...... 76 Multi-Viscosity Oils. 76 For Tips Changing Your Spin-On Oil Filter. 76 Understanding Engine Color 77 Test Procedure For The 77 Test After Engine 77 The Check Compression As A Maintenance 78 Oil and Filter Change Recommendations...... 80 Spark Plugs Key To Smooth Engine Operation, I. 80 Spark Flues Key To Smooth Engine Operation, n. 81 Is Your Spark Plug Connector Overtorqued?...... 82 Rotate Why Spark 8~ Engine 83 Air Filter Maintenance. 83 And Checking Adjusting Dry Tappet Clearance On Textron Lycoming 83 Of The Importance Correct Cylinder Base Nut Tightening 8j Fuel Nozzles Injector Have Been 8j Unauthorized Additions To Your Engine Can Cause 85 A Check Of Simple Internal Engine Timing...... 85 Installation of Counterveight Rollers...... 86 Maintenance Suggestions From The Lycoming Service Hanger, 86 Maintenance Suggestions From The Lycoming Service Hanger, 87 Notes...... Safety 88 For Engine Suggestions 88 Top 89 Recommendation Regarding Use Of Incorrect Fuel. 89 Recommendations For Aircraft Or Engine Struck By 89 Your Direct Keep Drive Engine Starter Clean To Avoid 90 Ground Strike Propeller or Sudden Stoppage Can Be 90 Some On Tips The Lycoming 0-235 g0 Notes on Replacing Connecting Rods or Pistons. 91 Maintenance Tip--Fuel Injector Nozzies. 91 Model Code Lycoming For Reciprocating 9Â· Facts About The Flyer and Key Reprints

Textron Lycoming has been pleased and impressed by the number of requests for copies of the "Key Reprints" pleased by your many favorable comments concemmg it, and impressed by the thirst for knowledge of General Aviation aircraft engines by operators.

Some of our readers may wonder how authentic is the Flyer and Key Repnnrs or are these two publications an official word from Textron Lycoming?

is In answer to the above question, yes, the information in the Flyer and Key Reprints official and supplements our other official service publications.

Some of the articles published are based on information contained in Service Bulletins. Service Instructions, and Service Letters. In addition, other articles are taken from actual field factorÂ· test data carried on by Textron Lycoming personnel. Furthermore, the Texuon Lycomin_g flow of ail is a central collecting agency on its aircraft engines out in the field with a return kinds of experiences and information from all over the world, which is recorded and analyzed, We share this information with our readers in the Flyer and Key Reprints.

During the preparation process of each article, updating of service information is pan of the procedure, After articles are written, each one is carefully screened and checked by manaÂ·e- fd~r ment, engineering, and service personnel to insure accuracy before being released publi~a- tion. Once in awhile isolated cases may arise whereby arficles dealing with service informa- channels. The tion may be published in advance of distribution through normal publication data contained therein is correlated with the responsible departments to insure that all information is accurate and factual.

The Flyer does not have an established publishing date for each issue. Whenever enough items of mutual interest have accumulated we publish the next Flyer: as a result. we have averaged an issue about once or twice per year.

The original concept of the Flyer has not changed since the first issue was published in 1963~ Approximately 85 of the prepared text deals with technical information related to Tex- tron Lvcoming engines, and the remaining 15rr covers general newsworthy items. Distribu- tion oi the Flyer is made to owners and operators of Textron Lycomin_g powered aircraft, authorized distributors, and others who write us and request that we place them on our mailing list, with all costs of printing and mailing absorbed by Textron Lycomin_e.

It is the intention of Textron Lycomin_g to continue to make available service maintenance and operational data in the Flyer and Key Reprints, which will assist the owner and operator to improve engine performance and reliabilitr.

PERhlIssION TO REPRIhT

Permission to reprint material from the Textron Lvcoming "Kee Repnnts" is eranred. so long as the context of information remains tnract and appropnate credit Is given. GENERAL Some Definitions Of Terms How To Get Textron Lycoming Engine Accessory Maintenance Publications If you are not sure of the meaning of such terms as normally aspirated, turbocharged, supercharged or direct All publications may be ordered through authorized T~uon drive engines, then perhaps you'll want to read our simplified Lycoming distributors or direct from Textron Lycoming, definition of them. Williamsport Plant. If ordered direct from Textron Lycominf Williamsport Plant, payment must be submitted with the request The is that is Normally Aspirated Engine one not as outlined in the latest revision of Textron Lycoming Service turbocharged or supercharged. If the airplane has a manifold Letter No. 114. at full takeoff at sea level on a standard pressure gauge, power The available maintenance publications for Textron day it would indicate a MP reading of approximately 29" of Lycoming engines and accessories consist of the followmg: Hg. Takeoff power at 5,000 ft. density altitude airport would read about 24" MP. The normally aspirated engine uses OPERATOR'S MANUAL and is altitude limited. atmospheric pressure thereby The Operator's Manual contains information of use to pilots and maintenance personnel. It contains engine specifications, Direct Drive Engines are those piston powered engines inspection procedures, operational information and is used in where the is bolted-on the end of the crankshaft and propeller conjunction with the Pilots Operating Handbook for the aircraft. the prop turns at the same speed as the crankshaft. OVERHAUL MANUALS Geared Engines are usually the higher powered, more The Overhaul Manual is a guide for major repair of the complex engines using a reduction gear on the nose of the engine. It contains complete disassembly, inspection, repair, aircraft, and_with the prop attached to it. As a result, the prop reassembly and test procedures for the various Textron will turn somewhat slower than the crankshafU, resulting in a Lycoming engines. When used in conjunction with applicable lower prop noise level. When the engine is geared, we precede parts -catalog, this manual provides an authoritative text for the engine designation with a "G". Thus a geared, opposed complete overhaul of the engine. (Or normally aspirated Lycoming engine with a 480 cubic inch displacement of the cylinders would be designated a GO-480 PARTS CATALOGS model. Textron Lycoming Parts Catalogs are illustrated to permit identification of parts; they are kept up-to-date by revision and manufactured Turbocharged Engines as by Lycoming supplemental listings. A referenced numerical list is also simply consist of a turbocharger unit with a small turbine wheel included. attached by a common shaft to a compressor wheel, and utilizes LETTERS the engine exhaust gas by directing it over the turbine wheel SERVICE BULLETINS, INSTRUCTIONS, drive the The loss in the to compressor. horsepower operating These publications are issued as required. Service Bulletins turbocharger is negligible. Turbocharging can provide greater are generally of a mandatory nature and require some utility to the piston engine by providing sea level horsepower, modification to be accomplished on the engine within a specified of nature and in some models. as high as 20,000 feet; or it can be used to time. Service Instructions are not a mandatory of such add horsepower to die engine particularly for takeoff. The faster cover a variety subjects; as repair processes, modification inspection procedures and overhaul the engine runs, the more air the turbocharger can pack into procedures, methods. Service Letters are of an informative nature usually the cylinder to compensate for the thin air of altittde, or to pertaining to service policy or vendor products. increase the horsepower, Although this definition is somewhat over-simplified, it is a basic definition of turbocharging of SPECIAL SERVICE PUBLICATIONS. General Aviation power-plants. These publications are concerned with topics of general interest or that are too for inclusion in Where turbocharging is used with a fuel injected, opposed subjects lengthy maintenance manuals. Textron Lycoming engine with a 540 cubic inch displacement, we designate it as a TIG-540 model. "T" represents the turt~o-charging.

Supercharged Engines as manufactured by Textron Determining Engine Condition Of wheel air into the Lycoming use a compressor to pack cylinders; High Time Piston Powerplants but the compressor is driven by the crankshaft through an intricate gearing system, which takes considerable horsepower As an engine gets considerable time on it and approaches recommended total overhaul the from the engine to operate. In comparison with a turbocharged the manufacturer's hours, arises the decision to either continue engine, it is a medium altitude powerplant. question concerning dying, or top overhaul, major overhaul, or exchange engines. Here below is a quick reference checklist to help make such a The trend in manufactnring is away from supercharging and decision, followed by a brief explanation of the ten paints. definitely to turbocharging because of the several advantages of the latter, i. Oil Consumption-any unusual increase?

Fuel drift lean at than cruise A supercharged. geared, opposed, fuel injected Textron 9. consumption--any higher engine with cylinders of 540 cubic inch displacement power? is designated an 1GSO-540 model. "S" represents 3. General engine history. supercharging. 4. Pilot and maintenance opinions of the engine. checklist. He will have an opinion based on whether it has been 5. How has the a engine been operated? dependable powerplant, and whether or not he has confidence in it. If the lacks 6. Maintenance--wh~at kind has the engine received? pilot confidence in an engine as it approaches the expected overhaul time, this could be a factor in 7. What does the oil filter tell; if no filter, have there been weighty the decision frequent oil changes? to continue flying or overhaul it. He should consull with his maintenance personnel concerning their evaluation of 8. What has been the trend in compression checks? the condition of his powerplant. 9. What do the spark plugs show? V. OPERATION 10. Refer to the engine manufacturer's service letter for engine life and recommended overhaul periods. The basic question here would be how the engine has been with the above operated the majority of its life. Some Along quick reference checklist, as an engine engines operating at or in manufacturer we would like to share our experience with the continuously high power, dusty conditions, could have a reduced life. interested operators by means of the following discussion of Likewise, if the pilot hasn't followed the manufacturer's the basic ten points: recommendations on operation it may cause engine problems and reduce the expected life. This becomes I. OIL CONSUMPTION a more critical influence on a decision in single engine aircraft. The and maintenance should know and also for operator people what has single or twin engine planes flown frequently at been the of oil general history consumption during the life of night or IFR. an engine. VI. MAINTENANCE A possible danger signal concerning engine health is a Good maintenance should aid in definite~-incrcase in oil consumption during the recent 25 to 50 achieving maximum engine life; hours of flight time. The oil screens and filler should be carefully alternately, poor maintenance tends to reduce the expected observed for life. We notice those signs of metal. Maintenance should also take a among powerplants coming back to the for good differential compression check at this time. They should factory remanufacture or other reasons, that the smaller also look in the with a in have had cylinders gooseneck light or a borescope engines general less care and attention, and in a to detect unusual conditions number of instances have any infhe combustion chamber. been run until something goes wrong. The If you haven't looked at your air filter lately, it would be higher powered engines have generally had better a idea maintenance and show evidence that the good to carefully inspect it for wear and proper fit. This operators do not wait is all the until more important when operating in dusty areas, and something goes wrong, but tend to observe the definitely could be a cause of increased oil consumption. manufacturer's recommended overhaul time for change. The engine logbook should properly reflect the kind of maintenance II. FUEL CONSUMPTION provided the engine or engines. If there has been radical change in fuel consumption VII. IS ENGINE on, FILTERED on the lean side of the manufacturer's predicted consumption, OR particularly at takeoff and climb, then damage from detonation FREQUENTLY CHANGED have may been done to the engine which is not easily detected Clean oil has consistently been an important factor in aiding in some cases. A higher time which has been in engine and extending engine life. A good full flow oil filter has been detonation might necessitate an engine change or overhaul. a most desirable application here. When the filter is exchanged ask the mechanic to it III. GENERAL ENGINE HISTORY open and carefully examine for any foreign elements, just as is accomplished at oil when the If a powerplant has been basically healthy throughout its change engine oil screen is also life, this would examined for the same purpose. Since the spark be a favorable factor in continuing to operate plugs also tell a about what is on it as the engine approached high time. Alternately, if it has story going in the engine, so the engine oil screen and the external oil filter tell a about required frequent repairs. the engine may not achieve its story the health of an If the has expected normal life. The engine logbook should contain this engine. engine no oil filter, oil changes accumulative record, should have been accomplished in accordance with the manufacturer's recommendations. These oil changes should Another important aspect of an engine's history would be have been recorded in the engine logbook. its calendar age. Although our discussion is primarily concerned with engine flight time, the calendar age could be equally vm. COMPRESSION CHECKS important to the operator. We have observed that engines What has been the trend in flown compression in at least the last infrequently do tend to age or deteriorate more quickly two differential checks. than those flown compression The differential on a regular basis. Therefore. an operator who compression check is the more reliable and has ten on 2000 type should be taken years a hour overhaul life engine may have on a warm If flown it 600 engine. the differential check reveals loss only hours, yet finds it necessary to top or major 95~ or more, then trouble be overhaul it because of the calendar age deterioration. may developing. Operators are still confused by the check and IV. PILOT AND MAINTENANCE OPINIONS OF compression its application. A compression test can be made any time faulty THE ENGINE compression is suspected. and should be made if the pilot The pilot's of the based on opinion powerplant his observes a loss of power in flight, experiences high oil experience operating it is another important in our or notices sofi point consumption, spots when hand pulling the prop. It is also considered part of the 100 hour engine inspection and there is a problem requiring a top overhaul, this is a needless the annual inspection. Most experienced maintenance men feel cost; likewise, if the engine is healthy and running satisfactorily, that the differential compression check is best used to chart a then leave it alone! trend over a period of flight hours. A gradual deterioration of One other point deserves attention here; there is no charted compression taken during maintenance checks would substitute or cheap route to safety in the proper maintenance he a sound basis for further investigation. or correct overhaul of an engine. IX. SPARKPLUGS CONCLUSION: The when removed and tell spark plugs carefully observed, Apply all of these basic ten points concerning your engine the skilled mechanic what has been the happening~in cylinders or engines and then make a decision whether to top overhaul, and be a factor in what to during flight, can helpful deciding major overhaul, exchange engines, or continue flying. do with a high time engine: i. Copper runout andlor lead fouling means excessive heat. 2. Black carbon and lead bromide indicate low temperatures Questions Most Often Asked By The and possibly excessive richness of fuel metering at idle. Pilots And/Or Mechanics About 3. Oil fouled plugs may indicate that piston rings are failing to seat, or excessive wear is taking place. Textron Lycoming Geared And 4. The normal color of a spark plug deposit is generally Mechanically Supercharged Engines brownish gray. QUESTION--In a couple of sentences, why gear an engine'.' 5. In high compression and supercharged engines, a cracked ANSWER--The easiest and to spark plug porcelain will cause or has been caused by cheapest way get more preignition. horsepower out of an engine is to turn it faster. However, a rather severe restriction is placed on propeller RPM because X. ENGINE MANUFACTURER'S as propeller RPM increases beyond a certain point, propeller RECOMMENDED OVERHAUL LIFE efficiency decreases. So--the increased horsepower we get from increased RPM is not coverted into thrust. The is- The engine manufacturers publish a recommended overhaul answer reduction device between the and the time period for each specific engine model. The amount of total place a gear engine that the turns at less RPM than the time on an engine will be a basic factor in any decision to either propeller so propeller engine. continue flying, change, top, or major overhaul the powerplant. QUESTION--in two parts: Operators should be reminded, however, that the hours of PART I. I hear so much about engine de-tuning--what service life shown in the chart are recommendations for engines is de-tuning? as manufactured and delivered from the factory. These hours ANSWER--Floating weights are placed on the engine can be normally expected provided recommended operation, crankshaft to eliminate, or move out of the periodic inspections, frequent flights, and engine maintenance engine operating harmful undersirable vibration characteristics. Should have been exercised in accordance with respective engine range, or the surface, or the surface of the rollers operator's manuals, counterweight bearing on which they ride become deformed ("detuned") the purpose If an desires to an the operator operate engine beyond for which the weights were installed is defeated. Engine structure recommended time and he is concerned with cost of overhaul, failure may occur. there is the possibility that the overhaul cost will be higher with PART II. Is there much chance of the average pilot de- increased time, or an engine failure is a potential to consider. tuning an engine?

Operators have topped their engine in some cases at some ANSWER--Not really. With one exception a guy has to point in the engine life. Invariably they want to know if this be an "odd-ball" to de-tune an engine. The exception--during extends the life of the engine. As engine manufacturers increase engine out training, should the throttle be abruptly closed at take- the overhaul life of their powerplants, the latter becomes an off or climb powers, there is a good chance of de-tuning. For important question. The chances are that if the operator applies this kind of training the pilot should study our Service Bulletin the checklist we have been discussing and comes up with No. 245. favorable answers to these about his he can questions engine, QUESTION--Do all your GO and GSO engines have the the hours desired--with some But a probably get exceptions. same starting techniques? top overhaul does not increase the official life or TBO of the ANSWER--Definitely not. Here is an excellent opportumty engine. to stress the importance of using the airplane pilot operator's We are surprised from time to time to have owners tell us manuals. It's very important for pilots and mechanics who have they top overhauled their engine at some point less than the to operate various engines. However, there are four different major overhaul life for no reason other than somebody said it fuel metering systems and several different ignition systems used was a good idea. Unless the manufacturer recommends it, or on various aircraft. So, when in doubt, check the manual. QUESTION--I hear the term "Shower of Sparks'' relative to ignition systems. What does this term mean to us pilots? \iP 121 1`) ANSWER--It means that while the engine is cranking during =I ~4 ,33 a start, that a prolonged series of sparks is jumping the spark plug gap as compared to one single spark. This results in improved cold 6 STiL weather starting. 1 I- 2 Su c)llnder Models (QEluave 2 QUESTION--During starts with the shower of sparks ignition 3 of Intc~nl Acrruon Dme ModeLi 4 3 4 system, I get some pretty severe kickbacks. How come? s -L- 6 ANSWER--The common cause here is the retard breaker doesn't close, resulting in a start attempt on the advance points. 2_3 check 3 A simple is to run the engine at about 700 RPM and for a 17 7 fmction of a second hold the staner switch to the stan position. The tachometer will indicate an immediate drop in RPM if the retard Integnl Accnsory Dnve Models Fwr cylinder Models Etght CIIIIIJcr hlnlell points are operating. There will be no drop in RPM with a malfunctioning retard breaker. C~lindcr Nwrbcr Ss~emr

CAUTION--This check not recommended on our direct drive lYiewcdfrom Topl engines using automotive type starters. TBO What QUESTION--At what RPM should I check my mags? Is It- ANSWER--Where the manual airplane says. For example, HOW It Affects You checking at a lower than indicated RPM may give a higher than normal mag drop. How It Affects Your Pocketbook QUESTION--Is the actual mag drop in RPM very important? Textron Lycoming publishes the latest edition of Service ANSWER--No. We are more concerned that the mag drop is Letter No. 201 which sets forth recommendiations for less than 50 RPM between the two mags and smooth, rather than factory time between overhaul whether it's 50-75 or 150. Again, it should be within the limits as (TBO). indicated in the manual. There have always been many questions concerning this I noticed of QUESTION-- some your engines show practically subject. Questions such as: Does this document mean I must no Is this normal? mag drop. overhaul my engine at the recommended time interval although ANSWER--Yes--but it a litle more time and I think give you'll it is operating satisfactorily? What is the penalty, if any, if I note some if in doubt mag drop. However, about any mag drop, do not comply with the factory recommended overhaul interval? be suspicious of a hot mag. Reduce engine RPM to idle and turn How does Texuon Lycoming arrive at the recommended hours switch to off and see if engine dies out. If it keeps running, beware for the various engine models? The questions are many and of hot mag. It's sad but true that we will still have people gening varied and far too often the answers are as variable as the hurt due to hot mags. questions and do not come from a reliable and/or official source. QUESTION--Can I save the engine any by using less than take- It is our objective here to set forth our policy and responsibility off power? concerning this subject. ANSWER--Indeed not. In fact, harm to the engine can be caused by using less than take-off power. SERVICE LETTER NO. 201

First, let us consider the matter of how the factory arnvls at the recommended overhaul time published in Service Letter No. 201. The old timers in flying will remember when TBO's of 300 to 500 hours were considered exceptionally good. As a matter of fact, when Lindberg flew the Atlantic and his engine

performed for over 33 consecutive hours it was considered on extraordinary mechanical achievement. After World War Il. IW-hour TBO's rvere considered not only exceptional but the maximum we could ever hope to receive from a reciprocating engine. All of this not withstanding, our service and engineenng departments continued to seek new methods for extending the TBO on Lycoming reciprocating engines. The methods used would have to be capable of producing conclusive data that would warrant extending overhaul hours. At the same time. the engineerin~ fraternity was looking for improved metals, designs. etc., that would put more reliability in the engine. ~en The best source for observince the wear chancrsrlsrlcs ot THE FOUR STROKE CYCLE the various model engines was n_eht in our own plant where approximately 2,500 engines a are torn down to into these year go engines could be operated satisfactorily to 2000 hours our remanufactured These engine program. are run-out engines TBO. Other model engines were similarly programmed and returned as exchange on either factory new or remanufactured TBO's established in accordance with the inspection findings. time zero engines. It was a matter of setting up a system for this We must next consider the significance of the overhaul compiling data and assigning reliable personnel to the pro- hours set forth is SL201. First, we must understand that the ject to observe and examine each engine part to determine its condition factory does not extablish firm hours for TBO. This can only and further serviceability. Under condition of part, be done by those maintenance personnel for each we were interested in whether or not it was in or out of specifica- responsible particular engine. Our TBO hours are only used so tion, whether it was an obsolete or current production part, guidelines an operator can have some idea of the hours he can from whether the part was damaged, burned, rusty, worn out, scored expect his the criteria are met as forth later or any of the other various conditions which could affect its engine, providing set in this article. He must also consider any federal he serviceability. To make these determinations, it was necessary regulations is operating under as well as restrictions set forth by his to make dimensional measurements, magnaflux inspections, any insurance company. We mentioned that certain zyglo inspections, and all of the other inspections and tests that previously criteria must be met if an operator wishes to reach recom- are required to make a decision on the condition of the part. factory With mended TBO hours. a complete report on every engine torn down in our plant, certain patterns began to take shape, and those areas that weren't "cutting the mustard" began to stand out. GOOD OPERATION AND MAINTENANCE

The two which establish the standards SERVICE INFORMATION RECORD general categories to be met are: (1) good operation in which pilots follow air- The next step was to inaugurate a system farcompiling data frame and engine manufacturer's recommendations, and (2) on field from all over the world. Thus the complaints SIR (Ser- good maintenance practices as set forth by the airframe and vice Information Record) was born. Textron system Every engine manufacturer. Indeed it is conceivable for an operator a on of ~ycdining employee receiving complaint any our engines to run an engine to destruction by 100 hours or less if he was the of one of these forms assigned responsibility completing disregards standards established by the manufacturer. We agree for our All of these were then into com- this factory. complaints put would be an unusual and extreme case, but we are trying and puters tabulated monthly, quarterly and yearly, thereby giv- to point out that the overhaul time for each particular engine us another excellent source of data to tell where ing us our can vary all the way from the low extreme, to the factory recom- weakness existed in each model, engine mended TBO, depending on operating conditions and maintenance practices. For example, if pilots climb at When the data from factory teardown engines was put steep angles, make abrupt throttle lean the together with our field complaint data, our engineers were able changes, improperly engines in climb, exceed maximum allowable manifold to go back to the drawing boa~s and apply the advances made specified pressure and/or RPM, chop the throttles and let down in metallurgy and technologies known to the present "state of abruptly rapidly thereby causing rapid contraction of metals that have the an", and improve or eliminate the trouble areas, thereby been up to operating temperatures, the TBO will be shortened increasing the TBO to as much as 2400 hours on some engine models, accord-ingly. On the other hand, maintenance personnel who do not follow factory recommended inspection procedures and It now became to if we were to increase TBO apparent us, intervals also contribute to premature engine replacement. Those hours: those established, additional data would beyond already operators who use unqualified personnel for maintenance, or be We needed required. a progressive maintenance program stretch inspection periods and oil changes under the illusion thev similar to that used the airlines if we were to the in- by gather are saving money, are operating under a false economy. Im- formation we required. Thus another was system inaugurated, provements in lubricants such as ashless dispersant oils, spark wherein were to live engineering personnel assigned literally plugs, improvements in use of oil filters, etc., have also been with certain where there was a concentration operators heavy vital to our predicting longer periods between engine overhaul: c,f Textron Certain third level air carriers, Lycoming engines. however, if they are not properly utilized, the benefits achiev- air charter and air taxi operators and schools to ed flying agreed by the engineering fraternity cannot be realized. If pilots use with us and allow cooperate our engineering personnel access proper techniques and judgment, and maintenance personnel to their and operation operational records. They also agreed to follow recommended procedures, the factory recommended all set forth our and in addi- inspection procedures by factory; overhaul hours can be reasonably expected. This is not intend- tion to the normal inspections, to differential com- they agreed ed to mean all systems incorporated on the engine will go to checks at recommended intervals, oil pression spectrometric the TBO hours. Indeed it may be necessary to replace certain as a monitor, and other and innova- analysis safety inspections components such as magnetos, harness. governors, and other tions that would allow us to the records we needed to compile engine driven accessories. It may also be necessary to do a top our in this accomplish goal. Engines program were inspected overhaul, depending upon oil consumption, compression leaks. at 100-hour intervals in order to establish a longer but safe TBO. etc. All of this notwithstanding, by increasing the TBO. the For with a 1500-hour TBO were run 1600 example, engines to operator can reap economic rewards not possible heretofore. hours, disassembled and When it had been completely inspected. Economic benefits are gained in two ways. By increasing the determined that 168() hours was a safe time, operating engines overhaul rime. the cost of operation per hour is greatly nduc- were allowed to operate to 1700 hours and the procedure ed and longer engine life expectation increases the resale value repeated. After two years with improvements, it was determined of the aircraft. Too much emphasis cannot be placed on the relationship especially good practice in those areas where lead foulln~ of calendar time of life. The aircraft flown is a Use of engine being every problem. worn out plugs is false economy and day, properly operated~with good maintenance should have no will shorten engine life immeasureably. in recommended TBO's. problem reaching 7. When reaching mid-point of the published overhaul time and at every 100-hour inspection thereafter, a differential EFFECT OF FREQUENCY OF FLIGHT compression check and boroscope inspection should be made. On the other hand, the aircraft which is only flown occa- 8. Remember, it will not be uncommon to be to sionally becomes subject to factors which can and will shorten required overhaul accessories prior to overhaul. We are refrr- TBO's. Why will only occasional flights shorten TBO? There engine ring to such items as propellers, am many reasons. Among them are the extended time between governors, magnetos, harness oil replacement, turbochargers, etc. changes which allow acids in the oil to build up and anack If internal metallic parts of the engine, moisture can enter the the above rules are followed, the engine should reach engine via the breather and exhaust system causing rusting of our published TBO hours. Better filtration products, better cylinders and other steel parts, rings may take a set and stick lubricants, improved metals, improved technology, etc., have in the condensation in all groove, the magnetos will cause shor- contributed to longer engine life. You are the only one who ting of the breaker points, etc. If your aircraft is i_n this category, can control these matters. If you do not follow the recommended you should fly it as often as possible, and a ground-run only rules, let the engine lay around and become rusty from lack of is not considered satisfactory-temperatures must reach flight use, you will be overhauling your engine long before the fac- conditions to evaporate the condensation caused by starting the tory recommended hours. engine. engine oil should be more In_addition, changed frequent- THE NUMBER OF HOURS YOUR ENGINE IS ly to help prevent die acid which attacks the internal build-up OPERATED BEFORE A MAJOR OVERHAUL IS RE- parts of the engine. QUIRED IS STRICTLY DEPENDENT UPON YOU. What is the magic number of hours per month an aircraft must be flown to be classified in the category that will reach recommended TBO's? Again there are variables to be con- many Spectrometric Oil Analysis sidcred, such as geographic location, temperatures, etc.; however, as close as we can calculate at this time, an aircraft Much is heard these about nown days spectrometric oil analysis; a minimum of 15 hours per month, with proper opera- however, little is understood about the subject by the vast mation and maintenance, an owner can reasonably expect to reach jority of the general aviation We will here to the hours set forth in S,L. No. 201. public. attempt set forth our position on the subject and to point out the advantages and disadvantages of the service. SUMMATION Oil analysis is not new to military and commercial airline let's O.K., sum it all up and see where the operator stands operation, but it came to general aviation later. The object is in relation to the latest edition of S.L. No. 201 and TBO. to examine oil samples from an engine, and break down the sample in parts per million in order to determine the internal He can expect longer TBO on his engines if the followin_g health of the This is based on the fact that all criteria are met: engine. lubricated engine parts wear and deposit a certain amount of metallic prir- i. Proper pilot tides in techniques. the oil. The number of particles per million of each 2. Have maintenance personnel follow factory engine inspec- metal determines the wear pattern for the particular engine be- tion procedures using good aircraft maintenance practices ing analyzed. It is of the utmost importance to understand that at all times, the results of the analysis is only pertinent to THE ENGINE BEING ANALYZED, although accumulation of data on any 3. Change oil and oil filter at recommended intervals. Use the specific engine series is a basis for establishing standards for ashless oils after has been broken in dispersant engine that series of engine. The fact that is important is a nsr mineral oil. onstraight sharp of the amount of a particular metal in the oil. It is imperative 4, the air filter clean and do not with carburetor then to build Keep operate a case history of each engine, wherein a sharp nse heat on the for brief check. With in ground except carburetor any one metal will indicate abnormal engine wear. The heat on, the intake air by-passes the filter and unfrltered analysis can also tell you whether the oil contains other liquid air is taken into engine. Remember, in sandy or dusty opera- contaminants such as gasoline or water. Gasoline contarmna- tions it may be necessary to clean the air filter daily. tion of the oil can result from blow-by from the combustion chamber caused by poor combustion, bad fuel 5. Do not attempt to drive any accessory or "hang" anything timing, improper mixture, worn and the like. Water contamination is usuril- on the engine that is not approved by the factory. This will rings, ly restricted to condensed but this combines not only void the warranty, but often shorten overall engine vapor, vapor with life, the fuel combustion products to form harmful metal-attacking acids. Water also helps to form sludge, which is death to a t~lter. h, Use only approved spark plugs. clean them at regular inter- Based on this contamination in the oil, the analysis will be able vals, and above all, do not try to stretch the life of spark to pinpoint improper mixture, poor maintenance, etc. plugs. Some maintenance personnel rotate plugs, bottom There are five basic types of solid contamination In airplane to top and vice versa. between plug cleaning;. This is engines--carbon. gums, tars. sand (dirt). and metal. Carbon contamination is a product of incomplete combus- of silicon) increased rapidly beyond its normal level of 10. tian, high-speed operation, high load, or high temperature. Gum resulting in increased wear to the piston rings and cylinders. in the crankcase is usually a direct result of raw fuel washing This is clearly shown by the sharp rise in the chrome and iron the cylinder walls and getting into the oil, caused by infrequent content. Corrective action by the operator (filter change and and sporadic operation of the engine, improper mixture, and better fit) quickly resulted in normal iron levels with resultant bad rings. Tar is created when the oil itself starts to decom- good health to the engine. If long TBO's are to be achieved, pare, and high engine temperature is the prime cause. Sand or it is MOST IMPORTANT that clean air be provided to the din is perhaps the most common contaminant in aircraft engines engines. and can into the much easier than be get engine might expected. Basically, that is the oil analysis story. It is a good tool The oil is analyzed on an emission-type direct-reading spec- IF PROPERLY USED. Like any other tool. it is only one of trometer. When the machine operator pushes a button, an elec- many things that must be used to determine engine health. trical spark passes through the specimen to be analyzed. This spark vaporizes a sample of all the elements present and causes their atoms and ions in the spark column to emit light of Engine Overhaul-- What Does It Mean? wavelengths characteristic to iron. If the specimen also contains Overhaul is a term which certainly means different things nickel, chromium, or other elements, the emitted light will then to different people. When the aircraft owner has run a factory include these wavelengths also. All this information is instant- new engine to TBO, and then paid for an overhaul, that owner recorded. The or instrument 16 ly machine, measures key usually has expectations of running the engine until the manufac- elements in normal aviation oil, thus im- present lubricating turer's recommended TBO has again been achieved. These ex- mediately indicating excessive traces of any one element or com- pectations may or may not be realistic depending on what the bination of elements, overhauler puts into the overhaul. Textron Service Letter No. entitled Lycoming L171, Perhaps it would be interesting to look at what an overhaul "General of Oil a Aspects Spectrometric Analysis", provides is in the legal terms of the Code of Fede~al Regulations for for the use of oil in health. guide analysis measuring engine Aeronautics and Space usually referred to as FARs. With The information is in terms since the health of each general regard to overhaul, FAR Part 43.2 says that an aircraft, engine, must be determined on its own merits. engine or other component may not be described as overhauled unless Differences in manufacturing processes may cause a varia- "(1) Using methods, techniques, and practices acceptable tion in analysis results for different engine models. The amount to the Administrator, it has been disassembled, cleaned, of tin plating, copper plating, nitriding, etc., performed dur- inspected, repaired as necessary, and reassembled; and (2) ing manufacture has a definite relationship to the oil analysis It has been tested in accordance with approved standard and repons. It is not uncommon, for example, to see what seems technical data, or in accordance with current standards and to be high copper content early in the life of an engine, only technical data acceptable to the Administrator, which have to have this content continually decrease as the engine ac- been developed and documented by the holder of the type cumulates time and then disappear altogether. Poor air filter certificate, supplemental type certificate.

maintenance, running the aircraft on the ground with car- This brief quote from FAR Part 43.2 should tell us that buretorlalternate air on and holes in the air intake system are overhaul is a term open to broad interpretation. The re- all factors which will allow an engine to ingest dirt and foreign quirements stated in part (1) say nothing about replacement of matter. The result of this will show up as high iron (cylinder wo~ out or damaged components although there are engine barrels) and chrome (piston rings) content at the next oil components which are not repairable. Part (2) requires that an analysis. Neither time nor space permits us here to list all of engine be tested to designated standards. Certainly this re- the variables involved (indeed we do not profess to know them quirements is meant to assure that an engine is airworthy at the

all) but it should be obvious to everyone that a history of each conclusion of an overhaul.

is the criteria which its health can be determin- engine only by Let us assume for a moment that the overhauler has followed. Remember that several must be taken to determine samples ed the FAR to the letter in overhauling. All parts of the of also the characteristics an engine, and remember that the first disassembled engine have been cleaned and inspected. Those few on factory fresh engines will read high as new parts samples parts which are worn beyond service limits are replaced while are: in and to each other. wearing conforming those which meet service limits are reused. Then the engine is These traces show up in parts per million on the spec- installed in the airframe for the test of performance. After a trograph long before detrimental flaking or scoring takes place thorough inspection of the installation to insure it is airworthy, and almost always before any outward indication of trouble. the engine is run up and static RPM falls within the limits Such an example is illustrated by a curve showing a plot of specified for this engine and propeller. This engine now meets pans/million of siiicone, copper. aluminum, iron, etc., as ob- the FAR overhaul standard and is judged to be ainvorthy. Is tlined on a Lycoming IO-540-D4A5 installation in a Piper Com- the engine actually producing at the certiticated power level and ;(nche airplane operating at a flying school. At 270 and 300 how long will it be until the service limit parts wear beyond hours, the dirt ingested by the engine las shown by parts/million those limits? These are questions we cannot answer. There are some things we can do to help make sure that NEW ENGINE "engine overhaul" has the meaning we expect. First, refer to A new engine is a product manufactured Textron the latest revision of Tutron Lycoming Service Bulletin No. by 240. The Lycoming-Williamspon containing all new parts and ac- subject of this bulletin is replacement of parts at nor- cessories, and meeting all production test mal overhaul, The list has about 25 items (times the number specifications, quality control tests, and regulations to hold and maintain of each in the engine) which Lycoming recommends be replac- necessary a production certificate issued by the FAA. When this finally ed at each overhaul regardless of their apparent condition. The accepted engine is shipped to an airframe manufacturer, it will use of this list to establish the ''must items at overhaul replace" be subject to further testing during flight test of the aircraft for will help to insure the quality of the overhaul. its certification acceptance. When the ultimate purchaser To meet when receives your expectations your Lycoming piston the aircraft, it may have also been subjected to ferry is there is engine overhauled, one last consideration. No one time. However, all flight testing and ferry time will be logged. knows an better than engine its manufacturer, and therefore if The user then receives the engine with the full Textron choose to overhaul, Textron would you Lycoming be a logical Lycoming-Williamspor new engine warranty, accompanied by choice, In addition to new and remanufactured engines direct an Engine Logbook. from the factory, Lycoming also overhauls engines at the fac- REMANUFACTURE tory. To produce a first-class, quality overhaul, all parts listed in Service Bulletin 240 are replaced with genuineLycoming To the aircraft engine purchaser, the "remanufactured" pans, The Lycoming overhaul does not stop with the S.B. 240 engine, as provided by Textron Lycoming-Williamspon, offers list. New limits on are assured the to engine cylinders by installing opportunity obtain some of the benefits of a new engine, all factory new cylinder heads, cylinder barrels, valve guides, but at a price savings. valve seats and exhaust valves. The overhaul includes updating The general term "remanuEdcture" has no specific defini- to comply with all ADs, all Textron Lycoming bulletins and tion in FAA Regulations. We have observad it to be considered instructions, and all product improvements. generally the same in the industry as a major overhaul. However, To summarize, all overhauls are not the the Textron engine same. The Lycoming Factory Remanufactured Engine is in a Textron Lycoming overhauled engine is a QUALITY product somewhat different category. The specifications for the factory which assures to remanufacture of long-term reliability meet your expectations. our engines are carefUlly written and made an It carries a one year parts and labor warranty and can be ordered integral part of our Repair Station Manual, which specifies from all Textron Lycoming distributors. precisely what must be done to an engine. The factory rcmanufac- ture specifications their from Part 43. And f~nally, remember that the term "engine overhaul" get authority FAR, can have more than one meaning. Be sure you and the overhauler A Textron Lycoming Factory Remanufactured Engine is defined as an aircraft agree completely on the exact meaning before placing your engine originally designed and manufac- order, tured by Textron Lycoming that has been disassembled, repaired or altered, and inspected in accordance with Lycoming Service Bulletins and/or Instructions, incorporating applicable mandatory engineering changes, and any Airworthiness Directives, at the Some Definitions Applicable To Lycoming factory. Tolerances and limits established and published by Lycoming, and those approved applicable rework Textron Lycoming-Williamsport Engines applications, are used during the remanufacturing of the engine and the In the manufacture, sale, operation and maintenance ofair- engine is brought back to zero time. Such engines retain their serial craft engines, terms such as new, rebuilt, remanufactured, original number, but will add the letter "R" preceding the letter "L" on the data which overhaul. major overhaul, top overhaul, etc., are used plate designates remanufactured throughout the aviation industry. by Lycoming. While Thus, a factory remanufactured we all have a general understanding of most or all engine, by Lycoming's of these definition, has all the the fact that it is done terms, there is no industry dictionary to which we can foregoing, plus by at its refer for a commonly accepted definition of all of them. The Lycoming factory, by factory personnel with manufacturing and This Federal Air Regulations, which would have to be the starting engineering expertise. factory remanufactured engine must also meet the same point for definitions. refers only to new, rebuilt and alterations production test specifications used for a new With each Textron when referencing engines; but the term "rebuilt" is not used engine. Lycoming factory remanuf8c- ~pecifically by Textron Lycoming-Williamsport. tured engine an Engine Logbook is fUrnished with Form No. 776 attached on the inside of the fiist each The page. Additionally, engine purpose of this article is to define the terms new, as released through the remanufacturing system is accompanied remanufactured and overhaul, as used by Textron Lycoming- by a maintenance release that refers to the factory order to which with its and Williamspon, Pennsylvania engines, to offer com- all work was performed, and showing that it was inspected by ment on some of the other related terms. We do add this point-- FAA authorized personnel. these definitions and explanations have been reviewed by WARRANTY Management, Engineering, and Service personnel at our fac- ON TEXTRON LYCOMING FACTORY tory and they are accurate as far as Textron Lycoming- REMANUFACTURED ENGINES Williamspan Plant is concerned. However, are nor offered they "En~ines are remanufactured under Textron Lycoming'~ in contradiction to any authorized manual or publication regar- Repair Station Certificate No. 1108 and afford the same Tex- ding our engines. or to any FAR or FAA authorized publication. tron Lycoming Standard Warranty as new engines." Our factory remanufactured specification lists engine parts OVERHAUL which must be 100% replaced. The major reuse parts of the Although there is no specific defmition of the term overhaul used engine. such as crankcase, crankshafts, housing, gears, in the FAR's, Pan 43, Section 43.13 of the Federal Aviation gearshafts, are thoroughly reconditioned, generally in the same Regulations apply--and it states the following: manufacturing areas in which they were formerly made. These time-tested parts, upon completion of their re-conditioning pro- MAINTENANCE, PREVENTIVE cesscs, are then inspected the same as new pans and returned MAINTENANCE, REBUILDING AND ALTERATION to holding areas for re-assembly into an engine, now designated as remanufactured. These factory reconditioned parts, for all (a) Each person maintaining or altering, or performing practical purposes have become zero time parts from which preventive maintenance, shall use methods, techniques, and evolved the general phrase--''zero time since remanufacture". practices acceptable to the Administrator. He shall use the tools, and Wherever new pans are used, they may be described as new equipment, test apparatus necessary to assure completion and unused except for normal testing. of the work in accordance with accepted industry practices. If special equipment or test is recommended the Any discussion of parts reused in the factory remanufac- apparatus 4v manufacturer involved, he must use that equipment acceptable tured engine should include an explanation of the reuse limita- to the Administrator. tions of parts. Our engine paRs have specific limits and are identified recommended as replacement parts by an enti'iely different (b) Each person maintaining or altering, or performing but effective method. For example, when a part becomes worn preventive maintenance, shall do that work in such a manner to a certain size, it is no longer usable in our engines in accor- and use materials of such quality, that the condition of the air dance with and our publications our practices. Therefore, it has craft, airframe, aircraft engine, propeller, or appliance work- life its a equarto wear dimensions, or otherphysical proper- ed on will be at least equal to its original or properly altered ties, which are spelled out in our manuals,service bulletins, conditions (with regard to aerodnamic function, structural service letters and service instructions. strength, resistance to vibration and deterioration, and other

The term "zero time" might very well be misunderstood, qualities affecting airworthiness). but the fact is that the historical time on the parts has no real The Textron Lycoming overhaul manuals clearly stipulate meaning since the parts have been and completely inspected the work to be done to accomplish an overhaul. We, at Tex- found to meet This allows the Lycoming's specifications. engine tron Lycoming, do not distinguish between major overhaul and the same amount of time between overhauls as a new engine, overhaul. We prefer to use the one word-overhaul-because and the factory remanufactured is considered powerplant capable we want it to be as broad as possible. Overhaul means the en- of being overhauled another and at least by agency attaining tire engine must be considered part by part as per the applicable one additional time between overhaul run. overhaul manuals. To accomplish this, there must be complete While we are on the subject, time between overhauls in the teardown so that all parts can be examined. In overhaul, there United States is nothing more or less than a recommended are certain parts that must be replaced, regardless of condition number of use hours by the engine manufacturer. There are as per the overhaul manuals, and Textron Lycoming Service some operators who never get to the recommended time of Bulletin No. 240. The remaining parts must then be examined overhaul because of improper operation and poor maintenance. as required by one or more of the following: (1) visual examina- There are many more who go beyond it with no problems. It tion for discrepancy, (2) non-destructive testing or other is strictly a function of how the engine is operated and main- mechanical examination, and (3) dimensional checking. At this tained. Furthermore, since time between overhauls is not a re- point, parts must conform to the fits and limits specifications quirement of law in the United States, it is the responsibility listed as part of the Textron Lycoming Overhaul Manual. and of the pilot and his qualified mechanic concerning the condi- the Table of Limits. tion of the engine and whether or not to continue it in service. By means of overhaul manuals for the various engine Please note that to certain special FAA certified aircraft opera- models, Textron Lycoming makes available all maintenance data tions, the above may not apply, i. e., air taxi, commuter airlines, and information necessary to maintain, repair, or overhaul etc, engines which are in service. In addition, Service Bulletin 230 lists the parts that are recommended for replacement at overhaul. REMANUFACTURE A SUMMARY Service Letter No. L201 lists the recommended overhaul periods The Textron remanufac- Lycoming-Williamsport factory for the various engine models. However, the FAA has no tured is an aircraft and engine engine originally designed specific requirements that the repair agency must comply with manufactured and later remanufactured under the by Lycoming, the Lycoming manual, or with the applicable service bulletins of the Federal Air authority Regulations by factory personnel and instructions. The final decision on the type of maintenance with and is time manufacturing engineering expertise. It a zero or repair accomplished is left to the mechanic doing the work. with the same The powerplant warranty as a new engine. key When the mechanic signs for the overhaul of an aircraft eneine. benefit for the owner is price he saves money by purchasing he certifies that he has performed the work using metl;ods. a factory remanufactured engine instead of a new one. In addi- techniques, and practices acceptable to the FAA Administrator. the remanufactured reduces aircraft tion, factory engine greatly The previous time on an overhauled engine is carried forward down time in with an overhaul. The comparison factory engine in the en_ei?e logbook: whereas, a factory remanufactured engine from the latest and also benefits improvements engineering goes back to zero time. changes. In addition to manufacturing and aircraft limited aerobatic remanufacturing capability, only positive G maneuvers and ven~ engines, Textron also overhauls at the brief Lycoming engines periods of invened flight are possible. Lycoming factory. These overhauled engines exceed industry To operate correctly, an engine must have fuel which is standards for quality through the use of genuine Textron Lycom- properly metered in proportion to the air entering the engine ing pans and full factory support. Although these engines do induction system. The fuel injector measures air flow and meters not become zero time as when remanufactured, a policy of ex- fuel to the inlet ports of each cylinder. Unlike the carburetor, tensive parts replacement insures a quality product which has a fuel injector is not affected by unusual aircraft attitudes. a full year parts and labor warranty against defects in material Therefore, all which and workmanship. Lycoming engines are designed for aerobatic flight are equipped with a fuel injector. TOP OVERHAUL VS. MAJOR OVERHAUL Delivery of metered fuel to the combustion chamber is not The industry the terms Overhaul and Ma- originated Top the only challenge addressed in designing an aerobatic aircraft jor Overhaul years ago to identify and make a distinction be- engine. It is also necessary to provide lubricating oil to many tween the degrees of work done on an Textron engine. points in an operating engine regardless of the aircraft attitude. Lycoming-Williamsport defines a top overhaul as the repair or Two different methods have been used to provide oil for overhaul of those parts on the outside of the crankcase without aerobatic engines manufactured by Textron Lycoming. completely disassembling the entire engine._It includes the The flat, opposed cylinder aerobatic first offered removal of the cylinders and degiazing the cylinder walls, in- engines by Lycoming were designated AIO-320 or AIO-360. spcction of the pistons, valve operating mechanism, valve These the guides, and replacing piston rings. A major overhaul consists engines were dry sump type with appropriate oil inlet and outlet connections as well as two crankcase breather of the co_mplete disassembly of an engine, its repair, reassembly connections. lines and an external oil tank with and testing to assure proper operation. Nevertheless, whether Necessary a revolving pickup capable of oil in almost aircraft attitude the work accomplished is a top or major overhaul, Federal Avia- reaching any were then the aircraft manufacturer. This tion Regulations require that it meet regulations, which were supplied by type of installation -quoted at the very beginning of this discussion of overhaul. provided aerobatic capability but it was complicated enough to be very expensive. A simpler, more universally usable OVERHAUL A SUMMARY system was needed. Textron Lycoming does overhaul engines at the factory. Most Lycoming engines are termed "wet sump" engines An overhauled engine carries forward all time in the previous because oil is stored internally in a sump at the bottom of the a remanufactured back engine logbook; factory engine goes to crankcase. When the engine is inverted, the oil will be in the zero time. The cheapest overhaul may not be the best. There of top the crankcase rather than in the oil sump. To maintain should be no compromise with safety. A good overhaul has a a continuous flow of oil during inverted flight, an oil pick-up disadvantage for the owner in that unless he has a spare line be engine, must provided near the top of the engine as well as in down time of the airplane is often undesirable. First overhauls the oil sump. Lycoming aerobatic engines carrying an AEIO on a well-maintained and properly operated are engine generally designation use inverted oil system hardware to adapt oil pick- economical in cost. Subsequent overhauls tend to be more ex- up lines at the top and bottom of the wet sump engine. pensive. Lycoming provides overhaul manuals and related ser- This inverted vice oil system is comprised of two major com- publications to aid operators in the field accomplish a top ponents, the oil valve and the oil separator. Several other items overhaul or the more complete major overhaul; but the overhaul- of hardware adapt the system to the Lycoming so that ing agency must comply with the performance rules set forth engine oil is available to the oil in either the inverted in Section 43.13 of the Federal Aviation Regulations. pump upright or These position. hardware items include a standpipe in the sump which acts as the engine breather during inverted flight, a special adapter or plug at the oil sump suction screen, and other hoses What Is An Aerobatic Engine? and fittings.

In addition to the inverted oil makes other A Fiver reader wrote to express interest in a Lycoming system Lycoming modifications to standard 10-360 engine. He went on to say that the engine would be engine adapt engine models to aerobatic used in an aircraft capable of unlimited aerobatics. A statement use. Some models of the AEIO-540 engine have a bat`- fle in like this indicates a need for explanation of the differences be- added the oil sump to eliminate oil loss through the oil tween the standard Lycoming engine and the aerobatic Lycom- separator. Also the flow ofoii to the oil pickup in the accessory case is limited in the ing engine. Unlimited aerobatic flight with a non-aerobatic inverted position. To improve this oil flow. holes are machined in the engine could result in engine stoppage from either fuel or oil upper rear wall of the crankcase. starvation. With these changes completed, the engine is capable of It should first be explained that unlimited aerobatic flight unlimited periods of inverted flight in addition to normal upright Because the oil implies that the aircraft may be flown in any attitude with no flight. pick up points are at the top and bottom of the knife limitations. For this reason, any engine which employs a float engine, edge flight or flight at very high up or down type carburetor for fuel metering is immediately eliminated from pitch angles have some limitations; the limitations do not pre- use in a fully aerobatic aircraft. Inverted flight would quickly vent engines from being used in aircraft which perform all the cause the carburetor to stop metering fuel and the engine to stop maneuvers required for international aerobatic competition. While running. carbureted engines are used in some aircraft with Engines built with the inverted oil system and incorporating the RULES other modifications discussed earlier are cenified by the FAA A. GENERAL as acrobatic engines. i. Never lean the mixture from full rich dunng take-off, climb The meanings of the letters and numbers in the Lycoming or high performance cruise operation unless the airplane owners manual advises othenvrse. However, during take- engine designation are fully explained elsewhere in this publica- off from elevation or climb at higher tion, but the AE part of the AEIO indicates "aerobatic engine." high airports during of occur at Lycoming is currently producing AEIO-320, AEIO-360 and altitudes, roughness or reduction power may full rich mixture. In such a case the mixture be AEIO-540 acrobatic engines which range from 150 to 300 may obtain smooth horsepower. One of these models should be installed in a general adjusted only enough to engine operaaon. should be aviation aircraft which is designed for acrobatic flight. Careful observation of temperaturt instruments practiced. 2. Operate the engine at maximum power nurture for perfor The Use of Higher Octane Aviation Fuel, formance cruise powers and at best eronomv mixture cruise unless otherwise specified m the 100 ]LL Blue Or 100 Green, For Engines economy power; airplane owners manual. Rated For 80/87 Octane Fuel 3. Always return the mixture to full rich before increaslnp power settings. (A Reprint of Texuon Lycoming Service Lener No. L185) 4. During let-down and reduced power flight operations n may be necessary to manually lean or leave mixture set- We have received many inquiries from the field express- at cruise to landing. During the land- of 80/87 fuel, ting position prior ing concern over the limited availability grade ing sequence the mixture control should then be placed and associated questions about use of higher leaded fuel in in the full rich position, unless landing at high elevation engines rated for grade 80/87 fuel. The leading fuel suppliers fields where may be necessary. fuel is not leaning indicate that in some areas 80/87 grade aviation maximum or best available. It is further indicated that the vend is toward phase 5. Methods for manually setting power 100 LL mixture. out of 80/87 aviation grade fuel. The low lead Avgas, economy lead The blue color, which is limited to 2ml tetraethyl per gallon a. Engine Tachometer--Airspeed indicator Method: will gradually become the only fuel available for piston engines. tachometer andlor the airspeed indicator may be used lead Whenever 80/87 is not available you should use the lowest to locate, approximately, maximum power and best should never be us- 100 grade fuel available. Automotive fuels economy mixture ranges. When a fixed pitch propeller ed as a substitute for aviation fuel in aircraft engines. is used, either or both insvuments are useful m- dicators. If the uses a constant The continuous use, more than 25R of the operating time, airplane speed propeller, indicator is useful. of the with the higher leaded fuels in engines certified for 80 octane the airspeed Regardless pro- the set the controls for the desired cruise power fuel can result in increased engine deposits both in com- peller type, the manual. lean the bustion chamber and in the engine oil. It may require increas- as shown in owners Gradually mixture from full rich until either the tachometer or ed spark plug maintenance and more frequent oil changes. The the indicator are At peak indica- frequency of spark plug maintenance and oil drain periods will airspeed reading peaks. tion the is in the maximum be governed by the amount of lead per gallon and the type of engine operating power operation. Operation at full rich mixture requires more frequent range. maintenance periods; therefore it is important to use properly b. For Cruise Power: Where best economy operation is approved mixture leaning procedures, allowed by the manufacturer, the mixture is first lean- then a when used from full rich to maximum power, leaning To reduce or keep engine deposits at a minimum becomes rouph blue 100 LL or 100 slowly continued until engine operation ing the higher leaded fuels, Avgas green noted conditions or until is rapidly diminishing as grade Avgas, it is essential that the following four engine power an undesirable decrease in airspeed. When either of operation and maintenance are applied. by condition occurs, enricfi the mixture sufficiently to ob- in all modes of A. Fuel management required flight opera- the tain an evenly firing engine or to regain most of tion. (See A, General Rules). lost ah-speed or engine RPM. Some slight engine power B. Prior to shutdown run up to 1800 RPM for 15 engine and airspeed must be sacrificed to gain a best econom)Â· clean out unburned fuel after in. to 20 seconds to any taxlmg mixture setting. (See B, Engine Shut-Down). Refer to c. Exhaust Gas Temperature Method (EGT): C. lubricating oil and filters each 50 hours of Replace, Service Instruction No. 1094 for procedure. operation, under normal environmental conditions. (See C, will not Lubrication Recommendations). Recommended fuel management-manual leaning, only result in less engine deposits and reduced maintenance cost. D~ Proper selection of spark plug types and good but will provide more economic operation and fuel saving. maintenance are necessary. (See D, Spark Plugs). of cruise whenever The use economy engine leaning possi- B. ENGINE SHUT-DOWN ble will keep deposits to a minimum. Pertinent portions of the The deposit formation rate can be greatly retarded by con- manual leaning procedures as recommended in Textron Lycom- the wlling ground operation to minimize sepatation of non- ing Service Instruction No. 1094 are reprinted here for volatile of the higher leaded aviation fuels. This reference. components rate can be accelerated by (1) Low mixture temperatures and detonation. "Knock" is much more obvious in an automobile (2) Excessively rich fuel/air mixtures associated with idling and engine when a lower octane fuel than that specified by the Therefore, it is that taxiing operations. important engine idling manufacturer is used, and the engine has a load or pull on it. should be set at their 600 to 650 RPM with speeds proper range there is a definite knocking sound as a result. This is a type the idle mixture to smooth adjusted properly provide idling of detonation. The proper fuel will burn smoothly from the spark Shut down recommends setting RPM at operation. procedure plug outward, exerting a similar smooth pressure downward 1800 for 15-20 seconds prior to shut down. on the piston. Detonation or "knock'', instead of smooth burning ofthe fuel, results in an explosion or shock, producing very C. LUBRICATION RECOMMENDATIONS high heat and an abrupt hammer-like explosion to the piston. Many of the engine deposits formed by combustion of all In aircraft engines, detonation is almost impossible to hear leaded fuels are in suspension within the engine oil and are not until it has reached proportions where it is frequently too late. removed by a full flow frlter. When sufficient amounts of these The rush of air, sound of the engine and prop, and sound- contaminants in the oil reach high temperature areas of the proofing of modern aircraft cabins all tend to muffle the early engine they can be baked out, resulting in possible malfunc- stages of detonation. Similarly, in most cases, by the time the tions such as in exhaust valve guides, causing sticking valves, cylinder head temperature shoots upward indicating detonation. The recommended periods of 50-hour interval oil change and it be too late because these obvious tend to in- filter replacement for all engines using full-flow fiitration system may symptoms dicate detonation or "knock" has reached serious levels, often and 25-hour intervals for oil change and screen cleaning for progressing into preignition,with pressure screen systems must be followed. If valve sticking is subsequent piston damage. noted, all guides should be reamed using the procedures as stated Lead in aviation fuel has an additional role of preventing in latest editions of Service Instruction No. 1116 and/or Ser- small welds that can form between the hot valve and its seat. vice Instruction No. and time between oil and oil 1425, drain, The experts tell us that with no lead at all, valve action would filter should be reduced. replacement gradually erode the valve seat, resulting in a loss of compression. Lead provides a thin layer of protective material which D. SPARKPLUGS prevents the undesirable erosion.

should be rotated from to bottom on a 50 Spark plugs top Although we have seen that lead is extremely helpful in hour basis, and serviced on a 100 hour basis. If excessive spark the fuel, it can create problems in the cylinder if the fuel did plug lead fouling occurs, the selection of a hotter plug from not have a scavenging agent in it to cope with this problem aspect the approved list in Service instruction No. 1042 may be of TEL. Without the scavenging agent, the resulting lead ox- necessary. However, depending on the of lead deposit type ide deposits from combustion would collect in the cylinder in formed, a colder plug from the approved list may better resolve large amounts, resulting in glowing horspots, preignition and the problem. Depending on the lead content of the fuel and the early engine failure. Bromides are added to the fuel to com- type of operation, more frequent cleaning of the spark plugs bine with the lead so that most of the lead is carried off with may be necessary. Where the majority of operation is at low the exhaust gases as lead bromide. power, such as patrol, a hotter plug would be advantageous. Fuel are added to the fuel to show that the If the majority of operation is at high cruise power, a colder dyes commer- plug is recommended, cial aviation fuel contains lead, and to easily identify its octane raring. They are colored as follows:

80 Octane Low Lead Red 100 Octane Low Lead Blue What is Avgas~ 100 Octane High Lead Green

Aviation Grade 80 octane has 0.5 mi. TEL/U.S. gallon: Avgas (aviation gasoline) is energy that we have tended to 100 octane low lead has 2 mi. TEL/U.S. gallon; and 100 oc- take for granted. Aviation gasoline is really an excellent fuei. tane high lead have anywhere from 3.0 to 4.0 mi. It is easily stored in routine containers. Furthermore, its freez- may TEL/U.S. gallon. ing point (below-760 Fl and boiling point (3380 Fl are separ-dted colors are also used in the of aviation fuel by a wide temperature range, which make it quite a practical Dye coding fuel, storage tanks and transfer lines, and are standard throughout 'he world. The dyes burn Eomp]etely during combustion oirhe The layman pilot or mechanic need only know that fi~ei. technically, Avgas is a careful blending of paraffins, aromatics, napthenes and olefins, to which the refinery adds tetraethyl lead By knowing more about the fuel used in his or her engine. (TEL). It also has dyes added to indicate the fuel has lead, and the pilot or mechanic is better informed to cope with any fuel related that in the to distinguish octane ratings by color. Stabilizers are included problems might occur engine. to aid during long storage periods, and a scavenging agent to help eliminate the combustion products of lead.

The oil companies tell us that addition of lead to the fuel is the best, most economical way to a higher octane fuel. In the petroleum industry jargon, a higher octane rating would make the fuel more "knock" resistant--or more resistant to 80 ~ctane Engine-- carrying Lycoming parr number 75068 and operated more than 25~'0 Grade 100 Aviation Fuel of the time with fuels graded higher than 80. It also recommended that these valves be replaced at overhaul with Lycoming part number Many aircraft owners still ask questions about the effect 74541, an exhaust valve which is identical to the 75068 valve ex- of using a higher grade fuel in engines which were originally for the highly corrosion resistant material in the valve head. certified for 80Â·octane aviation gasoline. Since this question cept remanufactured from revolves around the gasoline usedin aircraft, it is appropriate Since early 1976, new and engines shipped have had this in them. to first discuss the subject of aviation fuel grades, octane levels the factory change incorporated and designations before getting to the central question of the If you are the owner of an aircraft with a low-compression it engine and the fuel used it. engine which still has the 75068 exhaust valves, there may still be Most individuals associated ;vith aviation for a number of no reason for concern. Higher leaded fuel is defined for purposes in of the years tend to recall four aviation fuel grades terms of this discussion as fuel with more than two mi of lead per gallon. lean/rich octane used the American for ratings by Society This includes only the grade 100 green fuel. The blue, grade 100LL and Materials and the These fuel Testing (ASTM) by military. fuel which is found in most areas of the United States contains a grades are listed in the second column of the table under "Old maximum of two mi of lead per gallon and is approved for use in Designation." Two things have happened over the years which all Lycoming engines. Several years of experience with grade 100LL require explanation. First, the oil companies indicated an in- fuel in engines rated for use of grade 80 aviation gasoline has shown tention to produce only a single grade, 100 low lead fuel, which would be used for all aircraft piston engines. Second, the ASTM that use of grade 100LL does not cause measurable erosion of the valve. specification for aviation gasoline was recently updated and new 75068 exhaust each level of "Grade Number" desi~nations were assigned to It is true that use of fuel with a lead content higher than that aviation fuel which is available from commercial presently of grade 80 is more likely to cause lead fouling of the spark plugs sources. The new have a number, but the designations single and combustion chamber. Them are basic operational and octane level requirements for lean and rich mixture still exist. maintenance procedures which can be used to help cope with the The table shown here applies to fuel standards in the United higher lead content of grade 100 or grade 100LL. Textron Lycom- States and will allow easy comparison of the old and new fuel issued Service Lener L185 to provide guidance. designations when the term "grade" is referred to throughout ing the remainder of this article. The advice in Service Letter L185 touches four areas. First. general rules for proper leaning since an over-rich fuel/air mixture Octane or Maximum contributes to lead deposits in the combustion chamber and on the Nevj Performance Milliliters ASTM Old Number of Lead spark plugs. The second item was an excess fuel "clearing pro- Designation Designation LeanlRich Color per U.S. Gallon cedure" to be used before engine shutdown. Third, because the Grade 80 80/87 80/87 Red .5 mi higher leaded fuels also cause more lead to be suspended in the Grade 100LL 1001130 Blue 2.0 mi oil, a maximum time between oil changes of 50 hours was recom- Grade 100 1001130 1001130 Green 4.0 mi mended. The final point suggested rotation of spark plugs from top to boaom at 50 hour intervals and change to a different None 91196 91/96 Blue No longer possible heat if the of made this change 'None 115/145 115/145 Purple available range spark plug type operation appropriate. The annduncement of a single grade aviation fuel for all Whenever the subject of using higher octane fuels in engines reciprocating aircraft engines created a furor which gradually fad- certified for grade 80 comes up, someone is sure to ask if this will ed away as pilots and mechanics became more knowledgeable of cause these engines to run hotter. Tests were run in the Lycoming 'the actual effects of using gradd 100LL fuel. To respond to those test cells using a low-compression 0-320, 4 cylinder engine. In- questions which are still asked, a brief summary of the policies ad- itially, the engine was run with grade 80 fuel at 55 power. 65 ro vocated and instructions issued by Textron Lycoming during the power, and 75% power. At each power sening, the fuel flows were past 10 years may clear up the fuel issue for readers who own adjusted from rich to lean and a curve of cylinder head temperature engines certified for grade 80. was pioned against the fuel flow. This test was repeated using grade Service Instruction 1246 dated 14, Textron Lycoming January 100 aviation gasoline. The results essentially showed no differences. information on conversion of0-235 and 0-290 1972, provided engine The temperature curves in the drawing below show the pioned points low models to the use of grade 100 fuel. These smaller, compres- for the two fuels. sion engines were manufactured with solid stem exhaust valves and 0-320 (150 HP) TEMPS. bronze valve guides. They were certified with grade 80 fuel. Valve CIL HEAD erosion and accelerated valve guide wear occurred when operators FUE;SROW were forced to use highly leaded fuels instead of the grade 80 cn Ha TD1PS designated for the engines. The erosion problem could be alleviated b replacing the original parts with sodium cooled exhaust valves by I 2450 RPN and valve guides made of ni-resist alloy. E 1 ~07 6sX ato RP~ As grade 80 f~el was eliminated from the inventory at many d 55X it became necessary for some owners of low-compression airports, B engines to utilize the highly leaded green fuel extensively. The most g apparent result associated with continuous use of this fuel in low- engines was the possible erosion of the exhaust valve compression NEL FLOW-LB./HR. head. Textron Lycoming Service Bulletin 404 required inspection of those low-compression engines manufactured with exhaust valves o-O 80/87 D(XON GdSOLI~JE-OUce PB/GOL. x-x 100/130 EXXON G1ISOUNE-~.OSes PB/CIIIL. To summarize the contents of this low article, compres- 3. During descents to the traffic pattern, we recommended sion engines which are rated for use with grade 80 fuel should be maintaining the mixture at the leaned cruise condition with with the available aviation in this order a operated gasoline of gradual richening of the mixture, carrying some power. Grade priority: (1) 80, (2) Grade 100LL, (3) Grade 100. Only and at a sensible air-speed to maintain the most efficient the third choice, grade 100 "high lead'' aviation gasoline could engine temperatures possible. Avoid low power--high cause Even this fuel is any problem. only a problem in engines speed descents which cause sudden cooling, severe lead which have the 75068 exhaust valves and only then if high lead fouling, cracked cylinder heads and warped exhaust valves. fuel is used more than 25% of the time. The recommendations 4. If the magneto check before or after flight reveals any in Service Letter L185 will aid in reducing lead induced prob- roughness caused by a fouled spark plug, open the throttle lems. Considering all possibilities, there should be few very slowly and smoothly to cruise RPM and lean the mixture owners who have any reason for concern with the aviation fuel as far as possible, Olet with a smooth engine). After several available to them. If only grade 100 fuel is used, then the ex- seconds leaned, return to the proper mixture position for haust valves should be checked. If either grade 80 or grade takeoff and recheck the magneto. if two such attempts do 100Li is used, these low compression engines should reach not clear the fouled plug, then return to the line and report TBO without difficulty, the problem to maintenance.

RECOMMENDATIONS ON MAINTENANCE TO Minimizing The Spark Plug MINIMIZE SPARK PLUG FOULING Fouling Problem I. Rotate spark plugs from top to bottom on a 50rhour basis. and service plugs every 100 hours, particularly in an engine certified for 80 octane aviation fuel, but using a higher lead- Perhaps it's tbo cliche to say that using proper operating ed fuel such 100 LL. and maintenance procedures will minimize spark plug fouling, as according to engineers at Textron Lycoming and the spark plug 2. Make sure the correct heat range spark plug is being used in if manufacturers. However, this is the best known method of cop your engine you are experiencing plug problems. ing with the problem. Textron Lycoming Service Instruction No. 1042 is the basic reference source concerning the proper spark plug for the RECOMMENDATIONS ON OPERATION TO specific engine. Do not simply replace plugs with same MINIMIZE SPARK PLUG FOULING model number that were in the engine. The previous in- staller may have used the wrong plug. Don't be trapped! i. Use helpful ground operating techniques such as: Use the chart. a. Idle engines in the 1000-1200 RPM range so that the 3. Oil should be at a maximum of 50 lead scavenger in the fuel can operate. land filter) changed when the leaded fuels. b. Avoid closed throttle idle. hours, particularly using higher Oil filters do not filter the lead sludge which accumulates from c. After flight, before shutdown, run engine one minute combustion. Controlled programs have revealed that the at 1200 RPM, increase to 1800 RPM for 15 to 20 higher leaded fuels build an accumulation of lead in the oil seconds, reduce to 1200 RPM and cut engine with mix- from combustion. If the oil is continued in use beyond 50 ture control. hours time, it has caused sticking exhaust valves. d. Check magnetos on fixed pitch direct drive engines at 4. If idle mixture is too rich on the ground, have maintenance 1800 RPM to help prevent lead fouling, and generally adjust it properly. at 2200 RPM with a constant speed prop. t e. Avoid abrupt throttle movements on the ground as it uM, invites LEAD EOULlNG spark plug fouling. CM*x 2. Use efficient fuel management (good leaning techniques) I DEPOSITSLEAST "00 at cruise power: ADYERSE TO GOOD cuma Ilw *ND a. Lean at any altitude at the manufacturers' recornmend- SPARK PLUG cnuaE ed cruise power. OPERATION lax, I HOLD b. Lean as close to best economy mixture as the engine 900 will permit by rulining smoothly, it will help prevent LEAD BROMIDE AHD soo spark plug fouling and save fuel: CARBON FOULING 700 (1) WithanEGTsystem, thismeansoperateatpeak EGT at cruise power of75% or less on the small I ~oo direct drive engine. IDLE CONOUCINE P~TH K)PMED (2) With a float-type carburetor, it means leaning BI COMBVnlON PPODVCIS

to roughness at cruise power, then enriching just TEMP P 'B' enough to remove the roughness.

(3) With a fuel injection engine, it means leaning to Combustion deposit fouling fundamentals the bottom of the percent of power point on the 5. Low ambient temperatures can be a cause of spark plug foul- fuel flow gage, with a smooth engine result. ing. Lead from the fuel should become vaporized during Use Automotive Gasoline In cdmbustion and converted into a powder form which is nor- Do Not achieve the m8lly blown out the -haust. In order to Textron Lycoming Aircraft Engines proper vaporization, suitable engine operating temperatures should be maintained. Note in the chart that Which are Certified for Aviation Gasoline the most desirable range to avoid spark plug fouling is the temperature range 9000 -Â·13000 F. (AUTOMOTIVE GASOLINE COULD BE DANGEROUS TO YOUR HEALTH REWRITTEN MAY 1986) Oil temperature is also an'important factor in preventing desirable oil plug foiling. It has been our experience that a In the issue of Flyer No. 25, dated February 1976. we told should be in the of 1650 F to temperature during flight range operators not to use automotive gasoline in our aircraft engines. outside one 2000 F. For low ambient temperature operations, and listed seven reasons against its use. Service Leaer No. L199, method to keep oil libt is by closing off at least some of the dated January 1983, reiterated that policy by stating: "Textron manufacturers make available air flow to the oil cooler. Airftrlme Lycoming does not approve the use of any fuel other than those be used raise oil to a winterization kit that can to temperatures ...specified in our latest edition of Service Instruction No. 1070. the desired If a kit is not available, use any accepted range. Although Supplemental Type'Certificates (STC) now make means the cooler such as with a good grade of tape, bf~locking the use of automotive fuel, which meets minimum specified stan- kit or tape in spring or you'll be calling for help ap-Remove dards, legal for use in some aircraft, reciprocating engine to oil in-~egards high temperature. manufacturers and most major oil companies do not approve. While it is true that octane levels appear adequate, these SUMMARY: organizations are of the opinion that the varying quality con- Spark plug fouling is not limited to engines that were cer- trol standards applicable to automobile gasoline produce undue tiffed for 80 octane aviation fuel, but which aI~using the higher risk when it is used in aircraft. Several specific reasons are given leaded 100 octane as well. ~herefore, the techniques recom- for the non-approval of automobile fuel: and maintenance to all our mcndea herein for operation apply I. Its use reduces safety. Although an operator may find that the 80 octane 100 engines, but with emphasis on engine using the engine runs wellon a specific grade of auto fuel, there octane fuel. is no assurance that fuel from the same tank will be of the

same quality when purchased the next time. Risk is increased.

2. Its use can void warranty, or result in cancellation of the Fuel Contamination owner's insurance.

3. The storage characteristics of automotive fuel are less With the increase in recent years of the number of fuel in- desirable in comparison with the good storage on our has been a number of complaints about jectors engines, characteristics of aviation After several months, been gasoline. a mysterious occasional engme "miss" in flight. We have stored automotive fuel may suffer loss of octane rating, and able to verify that the majority of these complaints on fuel intends to deteriorate into hard starting, along with forming jected powerplants are from contamination in the fuel-- gum deposits that cause sticking exhaust and intake valves. principally water. We have bekn telling operators for many years and fuel metering problems, resulting in rough running that fuel injectors and their systems are more vulnerable to con- engines. The turnover of automotive fuel is so fast that tamination than are carburetors. Since water and other con- longlasting storage characteristics are not required. taminants collect on the bottom of the airplane fuel tank, it also 4. The additives in automotive fuels are chemically different makes good sense not to make a practice of running a fuel tank from those designed for aviation, and contain auxiliary dry. scavengers which are very corrosive, and under continued Careful of fuel for water will help alleviate draining sumps use can lead to exhaust valve failures. They also cause rust "miss" A sufficient amount of fuel must be drained the problem. and corrosion in the internal parts of the engine. The ensure the water. indicates that draining to getting Experience allowable additives for aviation gasoline are rigidly tested should be before because fuel servic- accomplished refueling and controlled. There is no uniform control of additives mixes the water and fuel, and the water not have set- ing may in automotive gasoline. Many different additives are used, tied to the bottom of the tank until the airplane is airborne. Learn depending on the fuel manufacturer. For example, one fuel to suspended water droplets in the fuel which causes identify company adds a detergent to clean carburetors. This ad_ the fuel to have a or the clear separation cloudy appearance; ditive creates a significant increase in the affinity of the of water from the colored fuel after the water has sealed to the gasoline for water which can cause fuel Nter icing problems bottom of the fuel tank, in flight if outside temperatures are cold enough. 5. Automotive fuels have higher vapor pressures than aviation fuel. This can lead to vapor lock during flight because the fuel companies advise that automotive fuels can have FUEL CONTAMINATIbN--Water (says the FAA) is the double the vapor lock pressures of aviation gasoline. principal contamination of aviation fuel. For a safe flight, depending on the seasons of the year, and the location drain fuel sumps at each preflight. carefully because of climatic conditions. In addition, automotive fuel also increases the possibility of vapor lock on the ground with a warm engine on a hot day. 6. the fuel octane numbers shown the of Although on pump ing on the engine, and why an engine must be designed for a automotive and aircraft gasolines may be similar, the turbocharger; also the operation of turbocharged engines, and actual octane ratingsare not comparable due to the different the maintenance and trouble shooting procedures for turbocharg- methods used to rate the two types of fuels. Furthermore, ed powerplants. aviation gasolines have a lean and rich rating i.e. 1001130, The advent of the lightweight turbocharger has been call- whereas motor gas is not tested for a rich rating. ed the shot of adrenalin which the piston engine needed to re- 7. Automotive fuel used in aircraft an engine may lead to main the prime method of powering general aviation type air- desiructive deionation or and pre-iginition potential engine craft. Although in some respects this may be an overstatement, failure at high power conditions. it does have much merit, and it is the lightweight turbocharger 8. The actual Mo-Gas fuel requirements range from meeting that has enabled general aviation aircraft to operate above ASTM or government specifications only in six states, to adverse weather in the smooth air of the higher altitudes, and few or no minimum requirements in the remaining 44 states, to realize the increased true air speed not possible with nor- as opposed to the uniform strict requirements for aviation mally aspirated engines. So this is the "why" of turbocharg- fuel, ing, and since it is possible that there is a turbocharged Lycom- in or review SUMMARY: ing engine your present future, we are going to the very basics of turbocharging and bring the reader up to the Auto fuel is now beiiig used as a substitute for Grade 80 present "state of the art" of it. aviation gasoline under STC's issued by the FAA. Most major The aircraft as is a heat oil companies and engine manufacturers continue to recommend engine, any reciprocating engine, engine which derives its power from the burning of a mixture that aircraft piston engines be operated only on aviation gasoline. of air and fUel, which has been mixed in the Deterioration of engine and fuel system parts have been reported proper proportions a fuel device. The amount of the in auto fuel. Operators shduld consider the add- by metering power engine will be directly to the total mass of air ed risk of using auto fuel in aircraft. Remember--a pilot can't develops proportional pumped through the engine, providing the fuel/air ratio is kept pull over to the side of the road when fuel creates a problem with the engine. constant. This can be varied in a normally aspirated (un- turbocharged) engine by changing the throttle setting and/or changing the RPM. Let us go over that again. Changing the Understanding The AD throttle will vary the manifold pressure available to the cylinder during the intake stroke. As a result the cylinder will develop a given amount of power on each power stroke. So if we in- The Federal Air~Regulations state that no person may crease manifold pressure to the cylinder. we will in turn receive operate a product to which an Airworthiness Directive applies more from the Now if we the manifold except in accordance with~ the requirements of that airworthiness power engine. keep directive, pressure constant, but increase the number of power strokes by increasing the RPM, we will also receive more power from the The custom on Airworthiness Directives (AD) for Lycom- engine. We see that changing either the throttle setting (manifold ing engines involves a close'working relationship between us pressure) or the number of power strokes per minute (RPM). and the FAA. The AD is usually preceded by a Service Bulletin, will result in varying the total air mass flow through the engine but the AD insuie the broadest circulation. helps possible and will determine the horsepower the engine will develop. So The AD should be carefully followed because it is the best in essence, a reciprocating engine is also an air pump, and if information available: It has been reviewed by the manufac- the fuel/air ratio is kept constant the power developed will vary turer, both from an engineering and service standpoint, and will directly with the mass of air consumed. allow the owner to the from the with gain most utility product We are limited in the speed at which we can operate the the least rimount of and down time. expense An AD should not engine because of engine and prop mechanical limitations. So reaction where cause a panic by oper~tors it insists on immediate the only other way to change the mass flow is to increase the if read in- compliance. Many AD's, carefully, merely require manifold pressure. We all know, however, that as we ascend spection from time to time, and the actual change only at in altitude the air becomes less dense which reduces the mass overhaul, flow through the engine with the result of a power loss that is to the reduced mass air flow the Always check your engine serial number when concerned proportional through engine. You have noted that in climb with a about an AD. Similarly, any contact concerning an engine with normally aspirated engine. it is to the throttle if are to an PEG, Textron Lycoming Distributor, or the factory, should necessary keep opening you keep include the engine serial number, the air speed and the rate of climb constant. So we see that if there was a way we could put the engine into a container so it could be kept at sea level conditions, we could maintain the same performance regardless of ambient conditions and altitude.

A long time ago, a smart engineer who was thinking along Let's Talk Turbocharging these same lines reasoned that if he built an air pump into the engine that could pump the less dense air at altitude up to the Editor's Note: This is the first in a series of articles on tur- same pressure he had at sea level. he would be able to maintain t!ocharging in which we will try to cover the general spectrum sea level horsepower. So he designed a centrifural air com- of this improvement in the lightweight piston engine. We will presser and placed it between the fuel metering system and the deal with the theory of turbochar_eing, the effects of turbocharg- intake pipes. The pump consisted of an impeller, diffuser and collector. The impeller was driven at about twelve times is complete and automatic and except in cases of poor or abrupt cnnkshaft speed and this high rotational speed imparted a large throttle management, it does not overboost. of to the air Now the fuel/air velocity energy passing through. as The automatic control system just described is basic, but leaves the it to the diffuser where vanes charge impeller, goes it is the basis for most control systems used on Lycoming smooth out the air flow while the mixture to slow down allowing engines. In another article we will also talk about the changes so that the from the rapid rotational velocity pressure acquired required in an engine to make it suitable for Nrbocharging. and of the is transformed into static This speed impeller pressure. the difference between an engine designed for turbocharging air mass is then stored and in the col- momentarily equalized and the one that has just had a turbocharger added. We will lector and is then drawn into the Our now cylinders. engineer also discuss turbocharging to increase power at sea level in- has his air but how was he to drive it? Well he could pump, stead of only using it to maintain sea level pressure at altitude. train from the rear of the drive it from the accessory gear or (See "The Pilot and Turbocharging"). crankshaft, but both of these methods robbed the engine of horsepower it could deliver to the propeller. Although super- chargers for many years have been driven mechanically off the crankshaft, our engineer realized he had not reached the ultimate inlhe "state of the an" of supercharging, so he began looking The Dual Magneto for another means of driving his air. pump. Our hypothetical engineer realized that the largest percent Several models of Lycoming engines use the Bendix dual Products Divi- of energy released by burning the fuellair mixture was going magneto now produced by the Ignition Systems out of the exhaust pipe in the form of heat. Realizing if he could sion of Teledyne Continental Motors. This single unit magneto with no in some way7larness this wasted energy to drive his air pump, design had as its first goal, reliability, simplification, the horsepower normally robbed from the engine to drive the increase in cost, and weight reduction as other desirable design impeller could be used by the propeller. features. As a result, the magneto system itself is five to six Ibs. lighter than other present day mags. There is an additional -We have all noted a windmill turning in the breeze, so our weight saving by eliminating one magneto drive and its engineer rightfully reasoned if he put a turbine wheel in the ex- associated hardware from the engine. As an alternative, this haust stream he could take the hot exhaust gas under pressure drive can be.retained and used for another accessory or com- and expand it as it passed through the wheel to extract energy. ponent without the weight penalty of an added drive. New design He took an impeller, connected it by a commdn shaft to the tur- features and simplification of the combined magnetos and engine bine and he had a means of driving his air pump by energy which accessory case should prevent any cost increase for the new was formerly going to waste. Supercharging by means of us- system. ing exhaust gases to drive the air pump is called turbocharg- the ing. Now our engineer hadqrogressed to the point where he Some less obvious advantages whichjustified design are: of his As he climb- required a means contrdlling turbocharger. 1. A considerable saving in installation time. Only one ed in altitude the must out a pump constantly put higher pressure magneto has to be mounted and timed to the engine: the ratio in order to maintain sea level conditions. He reasoned that synchronization of the two magnetos has already been done if he can dump the exhaust gas at sea level through a butterfly within the unit itself. valve in a leg off the exhaust pipe and ahead of the trrbine wheel, 2. Improved maintainability because of fewer pans and the he will be able to control the amount of energy being used to ease of setting internal timing in the unit. drive the turbine and thus control the speed of the compressor, 'The butterfly valve (wastegate) can be positioned by means of 3. Reduced inventory with one integral ignition system replac- mechanical linkage, but the disadvantage in this system is that ing two magnetos. the can be overboosted, causing detonation and severe engine 4. Better synchronization of the two sparks in each cylinder if someone "forgets" and leaves the wastegate engine damage because the two main breakers are operated by a common in the' closed position. So dur engineer was looking for an cam rather than being separated by two engine drive trains automatic means for control which would eliminate someone incorporating gear backlash and "float". putting "Murphy's Law" into practice. (Murphy's Law states 5. If it sh~uld become necessary for reasons of engine per- that if something can be done incorrectly, someone is bound formance or exhaust emission reduction, an automatic to do it.) So he came up with an automatic system that sensed advance can be used. compressor discharge pressure and positioned the wastegate to maintain the correct manifold pressure. The system contains 6. The dual magneto has altitude capabilities of better than two basic components. The controller, which senses the com- 20,000 feet and can withstand high temperatures. presser discharge pressure and regulates engine oil pressure used 7. The dual magnetos have been FAA approved for either as the muscle for the actuator on the wastegate. When the con- retard or impulse coupling. troller calls for more compressor discharge pressure, it closes The most obvious difference between dual and the oil bleed line from the w~stegate so ihe wastegate actuator single is that the dual units contain two each of several pans sees higher engine oil pressure and thus closes the butterfly. magnetos such as coils, distributor breakers, and When the compressor dischaI'ge pressure comes up to the desired gears, capacitors, distributor electrode sets. Insofar as the electrical and major control pressure, the controller will bleed oil from the wastegate portions of the circuit are concerned, a dual is to maintain the correct butterfly position which in rum will main- magneto ma_eneto two units in a common housing. rain the correct compressor discharge pressure. Now the system actually separate Use of the dual magneto does, of course, require a newly "can opener'' service tool for the aviation mechanic. The tool designed engine accessory housing. This new housing require- easily cuts open the filter without contaminating it so the element has made it possible for Lycoming engineers to make some ment can be examined for any signs of engine deterioration. worthwhile new improvements in the accessory housing. Before discarding the filter elements of the AC or the Cham- Although the dual magneto is an innovation with opposed pion filters, an examination of the filter element should be made powerplants, it has an eaily successful history of use with the by unfolding the pleated element and examining the material old Lycoming R-680 engines, and also was used with P W trapped for evidence of internal engine damage. In new or newly R-2800 powerplants as well as the Wright R 3350 BA series overhauled engines, some small particles of metallic shaving engines. might be found; these are generally caused during manufacture and should not be cause for alarm. However, positive evidence of internal engine damage found in the filter element justifies further examination to determine the cause. Information About Lycoming To examine the AC filter element, remove the outer per- Approved Full-Flow Oil Filters forated paper cover, and using a sharp knife, cut through the folds of the element at both ends close to the metal caps. For Although Textron LXcoming publication SSP-885-1 covers examination of the Champion spin-on filter, Tool CT-470 must -.the latest information concerning full-flow oi~filters for our be used to cut top of can. engines, we feel it is also important to emphasize and explain Clean oil is essential life. key aspects of the publication in the "Flyer" to help people engine to long engine Consequent- in the field. SSP-885-1 is concerned with full-flow oil filters ly, the quest for better ways to keep the lubricating oil free from contaminants is endless. in our direct drive engines, but does include one exception the geared TIGO-541 which powers tk4Â· Piper Pressurized Navajo. Detonation And Pre-Ignition Operators and meclianics must carefully read SSP-885-1 before handling the various types of Lycoming approved filters. Although knowledge of detonation and pre-ignition may be Special note should be made of the differences of installing the "old hat" to the old timers in aviation, lots of people in our AC vs. Champion filters. The AC is installed with the housing industry are still somewhat confused over the difference bet- not turned, but with an attaching bolt through the center of the ween the two, and what causeseither of them. housing, torqued to 20-25 foot pounds. DETONATION The Champion spin-on filter calls for a different installation in that the filter housing itself is turned to a torque of 18-20 There is a limit to the amount of compression and the foot pounds. Never exceed the maximum torque limit. degree of temperature rise that can be tolerated within an engine Maintenance people in tke field using both types of filters must cylinder and still permit normal conbustion. When this limit be very careful during installation of this part. is exceeded, detonation can take place. Piston engines are vulnerable to detonation at high power output because combus- SSP-885-1 includes the new Champion Full-flow Spin-On tion temperature and pressure are, of course, higher than they Filter. The latter is an added improvement over older methods are at low or medium powers. Leaning the mixture at high power of filtration, and is installed as optional equipment on all direct it. drive Textron Lycoming aircraft engines. Some of the advan- can cause tages of the. Champion Spin-On Filter include a resin- Unless detonation is heavy, there is no cockpit evidence impregnated paper that constitutes the filter element, which is of its presence. Light to medium detonation may not cause heat cured, acid resistant, and capable of removing contaminants noticeable roughness, observable cylinder head or oil that would be injurious to the engine. The spin-on was design- temperature increase, or loss of power. However, when an ed to save weight and also shorten maintenance time, and is engine has experienced detonation we see evidence of it at tear- available in long and short sizes. There is no need to replace down as indicated by dished piston heads, collapsed valve heads. elements, O-rings, and various nuts and bolts and washers, or broken ring lands, or eroded portions of valves, pistons and to clean the filtering units. cylinder heads. Severe detonation can cause a rough running engine and high cylinder head temperature. All models of Textron Lycoming direct dhve engines can be converted to use the Lycoming approved full-flow filter ele- PRE-IGNITION ment or full-flow spin-on oil filter; however, before installing, Pre-ignition, as the name implies, means that combustion check the distance between the firewall and the mounting pad takes place within the cylinder before the timed spark jumps on the accessory housing. Do not over-torque the filter at in- across the spark plug terminals. This condition can often be stallation. After installation of the full-flow filter, always ground traced to excessive combustion deposits or other deposits (such run the engine before flight and get oil temperature into the bot- as lead) which cause local hot spots. Detonation often leads to tom of the green are on the gage. After a good runup, shut engine pre-ignition. However, pre-ignition may also be caused by high down and inspect the frlter area for oil leaks. Also check engine power operation at excessively leaned mixtures. Pre-ignition oil level; addition of the filter assembly will require adding ap- is usually indicated in the cockpit by engine roughness, backfir- proximately one quart of oil. ing, and by a sudden increase in cylinder head temperature. It with the filter and converter converter kit Along (a simple may also be caused by a cracked valve or piston, or a broken is with some has a new required engines), Champion developed spark plug insulator which creates a hot point and serves as a glow spot. Specifically, preignition is a condition similar to early These worthwhile features in the powerplants have meant of the is a serious condition in the timing spark. Pre-ignition even longer operating life than standard steel barrels, and they combustion chamber and will cause burnt and tuiiped pistons mean dependability and economy. intake valves. The identification for chrome plated cylinders has been the The best methods for correcting pre- color temporary in-flight orange band around the cylinder base, or the equivalent and detonation are to reduce the valve ignitibn cylinder temperature on the edges of the top cylinder head fins between the two cowl by retarding the throttle, enriching the mixture, opening push rod shroud tubes. The color coding for the nitrided if or a combination of all of these, loca- flaps available, cylinders is azure blue and will appear in either of the two tions indicated above. The band around the cylinder base is used when cylinders are painted black as a separate operation prior The Pilots' Operating Handbook is the final authority to engine assembly. The color coding on the top edges of the all regarding operation of your Lycoming engine. cylinder head fins has been used on engines painted gray Study~it thoroughly. after assembly. From the service standpoint on nitrided cylinders, there are three methods of handling a full time engine at overhaul.

i. The barrels can simply be reworked and returned to Nitriding 1 What Is It? service if they are not beyond service limits. be and then chrome Lycoming Engineering, in their continuing effort to improve 2. The barrel can reground plated. our engines, developed a better method of manufacturing 3. The old cylinder may be discarded and replaced with a new hardened alloy steel cylinder barrels a number of years ago by one as in the Lycoming factory overhaul and remanufac- the means of a method known as nitriding. Simply described, rum programs. addition of nitrogen to the surface of an alloy steel produced CHROME vs. NITRIDING a hard, wear resistant surface. Commercially, the introduction of nitrogen into the surface layers of alloy steel is brought about Either method provides a satisfactory hard wearing surface. nitride hardened barrels have a by subjecting the practically finished parts to an atmosphere of Engines with chrome or good and are more than standard steel ammonia gas. The process requires special heat treating fur- wear characteristic, rugged barrels. In of hardened barrels, main- naces which are air tight and capable of holding the parts at spite a'good, properly the ammonia rained air filter is still a must. Pistons are moving up and down a high temperature. At this heat level (9750 Fl, elements at a rate of more than two thousand times minute, and when gas flowing into the furnace is broken down into its per abrasive is introduced into the combustion chambers. of hydrogen and nitrogen, and this is the source of the nitrogen dirt or any which wears metal which penetrates the surfaces of the steel. In order to produce it causes a lapping process rapidly away. for No can dirt and a satisfactory service life. a satisfactory nitrid~d surface, the process must be operated engine digest provide an extended period of time, generally from 25 to 80 hours. Along with cylinder barrels, Lycoming nitrides all its crankshafts and some gears. The nitriding process applied to cylinder barrels has been Compression Ratio An Explanation thoroughly service tested in military as well as commercial ser- AS It Relates To Textron Engines vice. After having been FAA type tested, we began production Lycoming of engines using nitrided cylinders in 1960. The service record We aren't to make mechanics out of pilots by of these cylinders has been excellent. In fact, our Management attempting the nitrid- about compression ratio in aircraft engines, but we desire was so impressed with the favorable service record of writing to both a description as it ed cylinder that they changed from chrome to nitrided cylinders help groups by providing simplified relates to our in all our higher powered turbocharged and supercharged engines. in- engines. Some favorable 'characteristics of nitrided barrels are In order to gain a reasonable amount of work from an mix- as follows: ternal combustion engine, we must compress the fuel/air ture each stroke. The fuel/air charge in the I. Reduced cylinder wall wear--the harder a surface the more during power can be to a coil in that the more it difficult to wear down, cylinder compared spring is compressed, (within limits), the more work it is potentially 2. Natural choked barrels providing improved piston ring life capable of doing. due to a resulting straight cylinder wall when engine is hot tells us that the compression ratio of an engine or operating, and a better job of sealing. Engineering when the is a comparison of the volume of space in a cylinder 3. Nitriding permits use of chrome plated piston rings which piston is at the bottom of the stroke to the volume of space when are more wear resistant and quite compatible with hard- the piston is at the top of the stroke. For example, if there are ened sttel. 140 cubic inches of space in the cylinder when the piston is at hardened surface with an increased 4. Nitriding provides a the bottom and 20 cubic inches of space when the piston is at fatigue strength, the top of the stroke, the compression ratio would be 140 to 5. It also has the ability to resist softening when excessively 20 or usually represented at 7:1. heated during engine operation. Low Compression High Compression recommended cruise power. We have observed too many pilots who consistently operate at full rich mixture at cruise power. It is a needless waste of money and fuel to routinely operate at full rich at cruise. Rich running engines tend to be on the rough side, thereby creating vibration, which causes a deterioration of engine accessories and engine mounts--another controllable cost factor. Proper leaning at cruise and during descent means less spark plug fouling, longer life for the plugs. and reduced maintenance cost as a result. Good leaning techniques likewise result in cleaner combustion chambers with fewer '~Zt f lead salt deposits on the piston and exhaust valve heads. Under certain conditions these deposits invite pre-ignition and higher maintenance costs. Proper leaning at cruise during cool or cold weather, aids in raising engine and oil temperatures to desirable minimums in order to boil the water and acids out of the oil. Water and acids attack the insides of an engine, causing rust and corrosion, another controllable maintenance cost.

Although we can create a more efficient engine by increas- An additional oppormnity for the licensed pilot to help with ing the compression ratio, there are limits and a compromise the cost of flying is in the area of preventive maintenance. The is needed. If the pressure is too high, premature ignition will FAA defines the term in FAR Part I as follows: occur and prodlice overheating. Compression ratio is a con- "Preventive Maintenance' means simple or minor preser- factor in the maximum an trolling horsepower developed by vation operations and the replacement of small standard pans but it is limited fuel and the engine, by present day grades high not involving complex assembly operations." engine speeds and manifold pressures required for takeoff. Then in Part 43.3 paragraph 01), it defines persons authoriz- Our normally aspirated engines are generally categorized ed to perform preventive maintenance: as either low or compression high compression powerplants. "The holder of a pilot certificate issued under Part 61 may In the of all surveying complete range Lycoming engine models, perform preventive maintenance on any aircraft owned or that all the from low 6.5:1 to we note they vary way a a high operated by him (or her) that is not used in air carrier service." of 10:1. Engineering has generally established the low com- Just a reminder that FAR No. 43.9 requires that you make pression group as those with a compression ratio of 6.5:1 to an envy in the engine logbook or maintenance record of 7.9:1; and the high compression from 8:1 and higher. group whatever preventive maintenance, the pilot accomplished. Along All Lycoming engines in the high compression category with these responsibilities. FAR 43.13-1A reminds the pilot that of Grade require a minimum 100LL (blue) or 100/130 (green) after completion of preventive maintenance, he or she should aviation octane, FAA approved fuel, and nothing less. We are do a good complete ground run, and then shut the engine down with the of the stressing high compression engines importance to inspect the engine for proper condition. If everything is nor- manufacturer's recommendations as outlined in the Engine mal, the engine should have a preflight runup and test flight. Operator's Manual or in the Airframe Owner's Manual. With Appendix A of Part 43 of the FAR's, lists examples of work high compression engines, not only do we require the correct defined as preventive maintenance (a few were selected by your fuel, but the proper oil, precise timing and a good air filter. Editor as representative). All are very important in order to protect this high performance powerplant. i. Replacing defective safety wiring or cotter keys. 2. Replacing any cowling not requiring removal of the prop, or disconnection of flight controls.

3. Replacing or cleaning spark plugs and setting spark plug gap clearances. How To Keep Engine Costs Down 4. Replacing any hose connection except hydraulic Through Do-It-Yourself Preventive connections. Maintenance And Sound Operation 5. Replacing prefabricated fuel lines. 6. Cleaning fuel and oil strainers. Some owners and operators of engines certified for 80/87 Now there is more to properly accomplishing preventive octane aviation fuel faced with having to use aviation grade maintenance on your engine than meets the eye in a quick 100LL fuel have about the added maintenance ex- complained reading here. Apparently, other organizations have had similar pense, and cost of operation with the higher leaded (higher than concern for this aspect of the situation. The National Pilots 80/87) fuel. However,there are some the owner or things Association and the Aviation Maintenance Foundation have operator can dd to hold down expenses where they are iorced coordinated their efforts in a program of new series of preven- to use grade 100LL. tive maintenance.meetings "to teach general aviation pilots and A very imponant economy measure penaining to opera- aircraft owners the rudiments of basic aircraft care." If vou can't tion is that of proper leaning ofthe mixture at the manufacturer's attend this kind of instruction before you jump into preventive horses maintenance on the simpler general aviation airplanes as a pilot. The methodical physicist experimenting with draft found a horse we recommend consulting a licensed A and P intially. There used to operate mine pumps that, on an average, of 150 walked are important items to know about, such as specific service pulling with a force equal to a weight pounds work is force exerted a manuals, availability of tools, torque limits on spark plugs and 2'h miles per hour. Since through given measured in terms of feet on an oil screens, etc. It's your responsibility when you do preven- distance, it is pounds. Thus, horse could do work at the rate of feet tive maintenance on your aircraft engine, so use care. average, one 33,000 minute or 550 feet second. In summing it all.up, the best approach to keeping cost down pounds per pounds per Watt's definition for one which has now on your aircraft engine is by means of good operation and sound horsepower, the of work at the rate maintenance. We have outlined how the pilot can personally become univeral, was, therefore, doing accomplish important aspects of both operation and of 33,000 feet~pounds per minute. Today, all conventional power maintenance. producing units are rated on this basis. The modern light plane 250 horsepower engine is capable horses. "Watts" Horsepower of doing work at the same rate as that of 250 average From an interested engineer's point of view, it is capable of by: F. G. Rohm moving 137,500 pounds of weight one foot in one second. Yet, Chief Qualification Engineer ~et.) what a difference there is in its size and weight (approximately 400 when to the horses it This interesting article was written for us by Fred Rohm, pounds) compared replaces! who was our Chief Qualification Engineer when he retired. Fred had a career of 44 in the industry, with a years Cut-Away Of A Four Cylinder majo~y of those years spent at Textyon Lycoming. Most of his career at Lycoming was as ~bief Experimental Powerplant which establishes his to author this Engineer, qualifications FRONT VIEW OF A FOUR CYLINDER kind of article. TEXTRON LYCOMING POWER PLANT. James Watt, Scottish physicist, had an engine problem even in 1769. Although steam engines had been invented before he was born, they were crude, inefficient machines and only a few were in use. So he had, after much experimental work, developed a relatively efficient condensing steam engine, the forerunner of the present day type. Being a good business man, Watt tried to sell his engine to coal mine operators whb were then using draft horses to supply power to drive the pumps which kept the mines free of water. But the mine owners had sales resistance! They insisted on knowing exactly how many horses each engine would replace, or, in other words, the horsepower of the engine. How much work would his steam engine do? This, then, was James Watt's problem. PY Although simple machines such as sailing vessels, wind- mills and waterwheels had been used for centuries, Watt realized that for the most part, the majority of work in the world had SIDE VIEW OF THE been done by man and his domesticated animals. Work was CYLINDER ENGINE. measured and paid for by the day, from "sun to sun". With FOUR the advent of reliable clocks, work was then accounted and paid for by the hour. Evaluating work by this time method, it was r~l oYuun assumed that all nien and animals could and did perform the naoucnl

same amount of work. This was far from being true. Watt realized that in older to have his steam engine used by the coal mine operators he would have to answer their questions "how much work will it do, and how many men and horses will it rei~lace?" Since the "power" of one horse was he would have to a generally known and a constant quantity, determine the "power" of his engine in order to compare it with the horses which it was to replace. His problem then was to define "power".

Power did not mean force. The mine owners cared nothing about the force Watt)s engine might exert. They wanted to know m turow w~m. how fast the engine would pump water out of the mine: in other words, how fast will the engine do the work? Simply, that was the definition of "power". Your And The mathematics to arrive Engine at this fuel usage are simple:

Fixed,Pitch Propeller 180 HP X 75% of power 135 HP

135 HP X .435 BSFC 58.7 Ibs. of fuel The effect the propeller has on engine operation and on air- 58.7 Ibs. of fuel s 6 Ibs. 9.8 hour craft performance is quite significant. Based on questions which per gal. gal. per have been asked aircraft and by owners from experience gain- Having made some assessments about what can happen with ed at the Textron service Lycoming hangar, there are several a standard propeller, now we will try to see what happens when areas of propeller related information which may be of interest. a cruise propeller is installed in place of the original. The first we must know about the cruise is that it has Aircraft equipped with a fixed pitch propeller will usually thing propeller more have static RPM (full throttle with aircraft standing still) limita- pitch than the standard propeller. This means it will take a big- "bite" of air than the with each revolutions and full power in flight RPM limitations spelled out in ger original propeller tion. This the Pilot's Operating Handbook. If static RPM is below the bigger bite of air will have an effect on aircraft performance and on how the be minimum specified, the engine could be low in power. engine may operated. has shown that However, experience this is not always true. Taking a bigger bite of air increases the resistance to the induction air and/or exhaust Faulty systems faulty systems have turning propeller. Perhaps it may be easiest to imagine what -been shown to contribute to indications of low power. A pro- happens by considering your hand when held in the airstream which is ever so less than the peller slightly perfect may cause outside a moving automobile with the palm forward as com- static RPM to be outside the designated full throttle static RPM pared to having the side of the hand forward. Because of this zone. In addition to these other factors, it is not unusual to find increased resistance, the static RPM will be lower than with a tachometer which is inaccurate. If an incorrect static RPM the original propeller. The same thing will be true when full is observed the one or all of reading during engine che~k, any throttle, in flight RPM, is compared to that of the standard pro- these could be fault. components at The tachometer may be the peller at a similar altitude and temperature. This will reduce easiest to check if a reed tachometer is in the aircraft. placed takeoff performance of any aircraft. Using the earlier exam- This "little box" is not attached permanently to the aircraft, pie, the engine was rated at 180 horsepower at full throttle and but it can quickly verify the accuracy of the standard aircraft 2700 RPM. Now, in spite of applying full throttle, the increas- instrument. the Knowing accuracy limits of the aircraft ed resistance reduces the maximum attainable RPM to something tachometer eliminate the need for further may examination of less than 2700. As a result of not developing the rated 2700 the and or it confirm the need for further engine propeller may RPM, the engine also will not develop the power for which it In consider each troubleshooting. any case, component of the was rated. Since maximum power is less than full rated, air- system before blaming a_low static RPM reading on any one craft performance will suffer. This should be considered before of them, a fixed pitch propeller is chosen or exchanged for a different model. Another aspect of op~ration with a fixed pitch propeller came in the form of a from question a Lycoming engine owner. At this point we must return to the original question. Why He indicated that the the propeller provided by airframe does the engine require more fuel with the cruise propeller? It manufacturer had been for a cruise exchanged propeller. (This is an accepted fact that the cruise propeller is more efficient should be done with exchange only FAA approval.) With the for cruise operation, so it would not be unusual to follow this new cruise is an increase in fuel propeller use, usage was soon line of thinking. Seventy-five percent of rated power using the costs increased and apparent. Operating an explanation was original propeller at sea level and standard temperature required requested. a throttle setting to achieve 2450 RPM. Therefore. without more

it seems that It is well known that the amount of horsepower taken from thoughtful consideration, logical the cruise pro- also be set for 2450 RPM when 75% an engine will have a direct relationship to the amount of fuel peller might power is desired. Of course there is an increase in but this used. Therefore, it can be deduced that use of the cruise pro- performance, peller increased the horsepower requirement. This deduction can be attributed to~the more efficient cruise propeller. Next comes the realization that the cruise deserves some additional explanation, improved performance isn't all efficiency. Instead of 9.8 gallons of fuel, the engine is now As an example, the standard propeller supplied with an air- using a greater amount of fuel per hour. For purposes of this craft may allow the engine to develop 180 horsepower at 2700 illustration, let us assume that the number is 11 GPH. By rever- RPM at full throttle, in flight at sea level, with a standard sing the mathematics used earlier, it is possible to estimate the temperature. The Lycoming 0-360-A Series normally aspirated horsepower and percentage of power actually being used as a engine illustrates this example, result of operating the cruise prop at 2450 RPM with a best Next, let us assume that this same engine/propeller com- economy fuel air mixture. bination is operated at 75 power with a "best economy'' fuel 11 GPH X 6 Ibs. per gallon 66 pounds air mixture setting. Again, assume sea level and standard temperature to simplify and standardize the discussion. Seventy- 66 pounds t .435 BSFC 151.7 horsepower five will about 2450 RPM with a brake percent power require 151.7 HP s 180 rated HP 84.3% of power specific fuel consumption of.435 pounds per brake horsepower Assuming a fuel usage of 11 gallons per hour for this pro- hour. Also, 75% of the 180 rated horsepower is equal to 135 blem provides a reasonably realistic example of the change horsepower. Fuel usagcat this power and mixture setting will which a different fixed pitch propeller might create. It also il- be 58.7 hour or 9.8 hour. The pounds per gallons per lustrates the need for pilots to change their habits when a propeller is changed. In addition to the change of habits, the discus- combustion engine like the Textron Lycoming aircraft piston detonation indicates abnormal combustion. Essential- sion shows a real need tore-evaluate the take-off, climb, and engines, ly, detonation is an uncontrolled explosion of the unburned gases cruise performance of an aircraft if the fixed pitch propeller is in the engine combustion chamber. Some engines are more changed for a different model. susceptible to detonation than others. For example, Nrbocharged Another concerns Remember very important point leaning. engines are more susceptible than similar non-turbocharged that Lycoming recommends leaning to best economy only at models and engines with higher compression ratios are more 75% of rated horsepower or less. It is very possible that lean- likely to exhibit detonation than engines with lower compres- ing to roughness or to peak on the EGT gage could cause serious sion ratios. than 75% of damage ifthe engine is actually producing more Detonation may occur in an aircraft engine as a result of rated horsepower as shown in this illustration. maintaining a manifold pressure which is too high for the and mixture setting being used. The engine With this information as background, it is easy to see that specific engine speed power (i. e. speed and manifold pressure) and mixture settings setting a desired'p;jwer with a fixed pitch propeller can only recommended in the Pilots' Operating Handbook (POH) for a be accomplished if the`pilot has a chart which applies to the particular aircraft model have been determined by a detonation specific aircraftlengine/propeller ~combination. Although the survey. These surveys use special instrumentation to detect and chart for a new aircraft come from data obtained power may record detonation as it occurs. Based on these surveys, the with a accurate by test flying torque meter, fairly detonation limiting conditions are defined. Data from the surveys fixed and chart can be derived for any pitch propeller engine indicate that detonation occurs in varying degrees; it is combination. Briefly, this is done by finding the maximum sometimes possible to operate an engine for relatively long available RPM at any particular altitude and applying data from periods in the first minor phase of detonation without inducing does not recommend or condone the propeller load curve. damage. Textron Lycoming engine operation which even approaches conditions which might To conclude, the purpose of this article is to make readers cause detonation. The laboratory quality equipment used for the more aware of some operational aspects of the fixed pitch pro- detonation survey is not practical for use in an aircraft engaged it is to the material peller. Usually only necessary accept pro- in normal flight operations. Without this equipment, the pilot vidcd the airframe manufacturer and to use the engine/pro- by may not know that detonation is occurring, and it is impossible is or on those pcller as directed. If a propeller change made, to establish the fine line between the first phase of minor detona- rare occasions when we question the power available to the pro- tion and the detonation magnitude which induces preignition pe!ler, the material presented here could prove to be helpful. and/or engine damage. For this reason it is imperative that power and mixture recommendations of the POH be carefully observed.

Preignition is a circumstance which causes destructive engine damage and will be examined here briefly. Most Lycom- Induced Engine Damage ing engines are designed for ignition of the fuel/air mixture at 20 crankshaft angle degrees before the piston reaches top dead From time to time a field service report states that an engine center during the compression stroke. Some engine models has~ damage. After further examination of the engine, this specify ignition at 180, 230 or 250 before top dead center. If damage may be classified as ''induced damage''. To clarify what ignition of the fueyair mixture occurs before the scheduled point is meant by this term, induced engine damage is a failure or in the operational sequence of events, preignition exists and the unsatisfactory condition which results from operational or compression stroke continues as the burning fuel/air mixture maintenance practices employed after the engine is placed in is trying to expand. This subjects the combustion chamber and service. Although there are a variety of conditions which may pistons to temperatures and pressures far in excess of those ex- fall into the induced damage category, this article will discuss perienced during normal combustion. These excessive two panitular types of failure and the circumstances which can temperatures and pressures cause damage to pistons and valves. induce them. In some cases both burned pistons and stretched valves will be

found in an which has been to Examination' of an engine which is reported to have low engine subjected preignition. compression, loss of power, errati~ operation, metal.contamina- Considering the millions of hours flown each year in piston tion, or even complete engine stoppage may result in a deter- powered aircraft, engine damage from detonation and preigni- mination that pistons are burned or valves stretched. (Stretch- tion is quite rare. The infrequency of the happening means lit- ed valves are sometimes sai'h to be tuliped.) These two types tie if your engine is the one affected. Therefore it seems ap- chain of damage can be initiated in a number of ways, but the propriate to look more closely at some of the factors which lead of events is often the same; detonation is followed by preigni- to detonation and preignition. tion and the has To burned engine damage begun. prevent The possibility of overboost is a characteristic of all super- valves, action must be taken pistons and tuli~ed,(or stretched) charged and turbocharged engines. Generally, overboost means the of detonation and to eliminate possibility preignition. the application of manifold pressure which exceeds the limit of the manually Detonation is a phenomena which can occur in any inter- specified by the manufacturer. Early versions nal combustion engine. The possibility of detonation cannot be controlled turbocharger allowed quite a few pilots to inadvenent- completely eliminated. By definition, detonation is a violent ex- ly induce damage by overboost. With this system. the tur- plosion. When used with reference to a spark ignition internal bochar_per wastegate was normally left full open for takeoff: full throttle would 28 to 30 inches of manifold produce pressure. or at a power setting in the high cruise range need a relatively at After takeoff full throttle, gradual closing of the wastegate rich fuel/air mixture to help cool the engine and reduce would slowly increase speed and manifold pressure possibilites of detonation. Since lean fueYair mixtures and high to maintain climb power.to cruise altitude or to the critical power settings promote detonation, it is recommended that altitude of the The worked fine engine. system until the Lycoming engines not be leaned at power settings which pro- was left in the closed wastegate inadvertently position. If the duce more than 75% of rated engine power unless this opera- pilot then applied full throttle for takeoff or a go-round, it could tion is approved in the POH. The pilot, by simply leaning the produce 60 inches or more of manifold pressure and failure of mixture excessively at power settings above the cruise ranges, the engine, may be responsible for inducing the detonation and preignition which leads valves and More recent turbocharger installations usually include a to tuliped burned pistons. relief valve and/or an automatic control pressure wastegate And finally, a small amount of dirt in the fuel system may to avoid the of overboost. Even with which helps possibility be responsible for clogging a fuel injector nozzle or nozzles. these prqtective devices, it is still possible to overboost by rapid A partially clogged fuel injection nozzle will reduce fuel flow throttle and/or inattention operation to limiting manifold to that cylinder and will cause a lean fuel/air mixture. A noule low pressures at engine speeds. which is partially clogged in an aircraft which has a pressure Automatic controllers may not be capable of preventing operated fuel flow indicator will cause that indicator to display overboost if full throttle operation is attempted before engine a higher than normal fuel flow. Leaning in an attempt to cor- oil is warmed up sufficiently. Textron Lycoming Service In- rect the high indicated fuel flow will result in an even leaner struction 369F addresses the problem of overboost and recom- mixture in the affected cylinder. Again it is possible that a burn- mends, depending on the severity and duration of the overboost, ed piston or Nliped valve will be the final result. a book overhaul log entry, engine inspection, or complete engine Understanding and avoiding those factors which lead to in- of the crankshaft. including replacement duced engine damage is certainly preferable to the discovery As stated earlier, ignition of the fueyair mixture must take of tuliped valves or burned pistons in your engine. This entire place at precisely the right time. A spark plug which has been discussion is aimed at promoting an understanding which will dropped, or damaged in some other way, may induce preigni- allow pilots and maintenance personnel to direct their efforts tion by causing a ''hot spot" in the combustion chamber which to those elements which will reduce the possibility of induced self ignites the fuel/air mixture. This could also occur from use engine damage. Observing the refueling of the aircraft and of unapproved spark plugs. Flight with defective magnetos or checking the fuel system for indications of contamination are flight in excess of certified aircraft limits may allow cross fir- tasks expected of the pilot. Meticulous management of power ing within the magneto, improperly sequenced ignition of the and fuel/air mixture as recommended by the POH is also a pilot fuellair mixture, and engine damage. Proper magneto to engine activity which will enhance the possibility of avoiding induced timing is also an important factor. The timing is affected by damage. wear and therefore should be checked and reset at specified in- Maintenance personnel play an equally important role. tervals. Regular, meticulous spark plug and magneto Troubleshooting a fuel injected engine for rough idle may lead maintenance will help to avoid preignition and possible engine to the cleaning or changing of partially clogged fuel injector damage from these sources, nozzles. Damage could result if the engine were operated at overboost and incorrect Although ignition timing are causes takeoff or climb power with reduced fuel flow to one or more of induced this can often be attributed engine damage, damage cylinders. A close check of magneto timing and magneto con- to fuel and the fuel/air mixture. The frrst related problem to dition at regular inspection intentals will help to insure the con- fuel is fuel in the aircraft tanks. simply having improper A piston tinued satisfactory operation of any engine. powered aircraft refueled with jet fuel would have a fuel blend There are some "after the damage" factors that with greatly reduced octane level. A piston engine should not maintenance personnel should consider. Suppose that a power be started when even small amounts ofjet fuel have been add- loss has been reported. A compression check reveals low com- ed to aviation gasoline because engine contamination and detona- pression; a stretched or tuliped valve may be found. This is an tion are likely; attempted flight under these conditions will cer- indication that the engine has experienced detonation and tainly result in destructive detonation and preignition. The use preignition. A borescope examination should be conducted to of 80 octane aviation fuel in an engine certified for 100 octane see if a piston has been burned. A burned piston often results aviation fuel will produce similar results. in damage to cylinder walls and piston skirts; it also may con- The oil be a source of octane fuel lubricating may reducing taminate the engine with metal particles. There is no healing contamination. worn allow Excessively piston rings may enough process for this damage. In some cases it is possible to repair oil into the combustion chamber to dilute the fuel/air mixture. the engine by removing the metal contamination from the engine The dilution will reduce the octane of the fuel and rating can and oil system, including the oil cooler, and by replacing all lead to detonation and While this scenario is engine damage. damaged parts, but often it is necessary to replace the entire not of the which uses amounts of entirely typical engine large engine. If an engine is to be repaired, it must be remembered oil because of worn or broken it is for piston rings, possible that repairing the damage is not enough; the cause of the this situation to occur. r~glfunction which induced detonation and preignition must also Even the use of 100 octane fuel in an engine in good be found and corrected. Did a magneto malfunction produce mechanical condition`ddes not eliminate all the possibilities of ignition outside the normal firing sequence'! Were manufacturer induced engine damage. Most engines operated at takeoff power approved spark plugs installed in the engine? Did a cracked spark plug induce preignition? Was an approved fuel used, and The Flyer may have carried information on this subject in if so, is there evidence of fuel contamination? Whatever the the past, but the reminder from someone who had an unfor- malfunction, it musi be coiiected along with the damage or the tunate incident prompted this story. Preventing possible freez- same problem could reoccur, ing of the crankcase breather tube by use of a whistle slot or other means is an little detail which all of our readers To conclude, induiced damage in the form of tuliped valves important should be aware of. Many may benefit from the knowledge. and burned pistons can usually be avoided by understanding the sequence of events which lead to this form of engine damage. CarefUl attention to detail is required of pilots and maintenance personnkl. Compared the expense of repairing or replacing tp Welding Is Wasteful a damaged engine, it is worth the time and effort necessary to avoid induced engine damage. If you are told that your crankcase or a cylinder head should be welded because of a crack, think long and hard about the step you are about to take. The argument is that it is less ex- The Whistle Slot pensive to have your old case welded than to buy a new one. This is true when the only consideration is getting your aircraft We often tend to believe--what we knows. know, everyone back in the air as cheaply as possible. For the long run, welding While in a instructor refresher a participating flight recently, the aluminum parts of an aircraft engine to repair cracks may from Maine a reminder that this is often young lady provided cause you so many headaches that you will wish you had decided not the case. on replacement as recommended by Textron Lycoming. and her husband in Maine the This-lady fly throughout The recommendation to replace rather than weld is based During the winter, they and their aireraft are frequently year. on years of experience and thousands of examinations in the to cold During the past winter, exposed extremely temperatures. Williamsport Plant Metallurgical Laboratory. Based on this ex- had an unfortunate The end of the engine th_ey experience. perience, the vast Icnowledge of the individuals who work in breather tube froze a build occurred in the over, pressure up this Met Lab should not be ignored. The brief explanation which crankcase, and the crankshaft nose seal The oil leak reptured. follows will attempt to relate some of this experience and to with oil-from to tail. For- that resulted covered the aircraft nose explain why welding is wasteful. yunately, a safe landing was made before all oil was lost. Starting with two very basic but critical items in the welding As she related her story, another flight instructor quickly process, we look at the material to be welded and the welder. indicated that he had also experienced the same problem several The material is an aluminum alloy. Exactly which alloy is very earlier. The safe both cases are good news. years landingsin important, and since this is proprietary information, the welder The bad news is the expense incurred to repair the engine. in the field may ormay not know exactly which alloy a crankcase it An incident like this and for that reason is made of. Also, it takes more than just a very good welder is important that we repeat ourselves from time to time. We to successfully weld aluminum. The experience in qualifying should not assume that everyone knows about the ''whistle slot'' welders at the factory shows that only the most outstanding can of crankcase or other methods insuring adequate venting. pass the annual FAA qualifying examination for Aircraft Cer- tified Welder. Even a welder leave in the First, the cause of this incident. Moisture is expelled from good may tungsten it be the engine crankcase through the breather Nbe which often ex- weld which causes to unsatisfactory. the air tends through the bottom of the engine cowling into A complete knowledge of the material and the expert welder Under cold this moisture freeze stream. very conditions, may cannot assure a satisfactory weld in a cracked crankcase or and continue a of ice until the tube is buildup completely cylinder head because there are many other inherent pitfalls over blocked. which the welder has no control. A new crankcase is heat treated It is normal practice for the airframe manufacturer to pro- to give it strength and is then machined to the exact tolerances match of the two halves and vide some means of.preventing freeze-up of the crankcase needed for a perfect appropriate distor- breather tube. The breather tube may be insulated, it may be crush on the bearings. Welding a crankcase may cause will weaken it. heat designed so the end is located in a hot area, it may be equipped tion and most certainly Unformanately, is a solution because with an electric heater, or it may incorporate a hole, notch or treating to regain this strength not practical and surfaces will slot which is often called a ''whistle slot." The operator of any thl'heat treating will distort the case mating aircraft should know which method is used for preventing freez- not fit as designed. This is why welded crankcases are often ing of the breather tube, and should insure that the configura- plagued with oil leaks. tion is maintained as the airframe manufacturer. specified by A welded case which is weak and slightly distorted from Because of its simplicity, the "whistle slot" is often used. the welding may not be the worst of the problems created. We Although the end of the tube may extend into the airstream, should keep in mind that a crankcase cracks in the first place a notch or hole in the tube is located in a warm area near the from fatigue, and lack of strength in a critical area. After welding engine where freezing is extremely unlikely. When a breather there may be porosity at the weld or subsurface cracks which tube with whistle slot is changed, the n'ew tube must be of the are not visible. Even a dye penetrant inspection will not reveal tube be same design. Replacing a slotted tube with a non-slotted these defects. The welded part should inspected by X-ray. could result in an incident like the one described by the lady but many shops that weld do not have this capability. So now from Maine. we have a crankcase which cracked in a critical area because of overstress and fatigue. The crack has been welded, but con- Before getting to specifics, it would be well to establish ditions~ leading to fatigue may still be there, and the subsurface a background for this discussion. Think for a moment about defects which go undetected will act as stress concentrators. how heavily you rely on that Lycoming engine every time you Many times a new failure occurs in the critical area near the fly. How can you be so comfortable, and so sure the engine weld. For the aircraft owner, this creates a new headache, and will continue to give you power for flight--hour after hour? Isn't for the matallurgists who have seen the problem many times it the excellent reputation of the company, and the solid engine before, it is one more reason to continue saying, "We don't that you place your confidence in? This does not mean that ab- recommend the welding of cracked crankcases." solute perfection has been achieved. Any mechanical device may malfunction, wear out, or at some time cause a problem for its Cylinder heads are also made of aluminum alloy. Cracks owner. All of these things may occasionally apply to a Lycom- sometimes occur inside the dome area and there are individuals but we know that we ex- who recommend welding. The metallurgists consider repair by ing reciprac~iting engine, any problem perience with a factory engine will probably not be life welding to be absolutely foolish and their experience provides threatening. them with good reasons. The surface area in the dome is affected by a thermo-chemical attack--to put it simply--corrosion. Did this reputation for reliability just happen? No, it is the This corrosion is a form of oxidation which will not fuse pro- result of 60 years of experience with aircraft engines. That does perly during weldingi It is not practical to remove all of the not mean that the same individuals who engineered the Lycom- _ -corrosion because this would entail remachining the entire in- ing engines of the 1930s and 1940s are still at Lycoming. It terior surface which would change the designed compression does mean that their experience has been passed on. What has ratio of the engine, in an effort to weld this area, those who been learned from thousands and thousands of hours of test stand do it make an effort to clean the crack thoroughly. Unformnate- running and engineering flight tests over all of those years pro- ly, this isaflittle help because the area adjacent to the cleaned vides a solid data base of knowledge which is used to insure out clack will still' be affected by thermo-chemical attack. that a certified Lycoming engine is a safe and reliable device Because this corrosion will not allow the weld to fuse complete- when opeI-dted and maintained as recommended by the ~y, new cracks are almost certain to occur. manufacturer.

Thermo-chemical attack is not something we can see. To With this background, take a look at some of the modifica- the novice, a welded crack in a cylind_er head may look great. tions being advocated today: for example, "Change pistons and It may not even be possible to identify the weld. But when the increase the compression ratio of the engine." This does in- pan is dissected by a metallurgist for examination under a high- crease the horsepower an engine is capable of producing. It is powered microscope, the weld and the poor fusion and cracks a tactic Lycoming engineers have used for years. Any Lycom- around the weld are immediately identified. ing engine with a compression ratio of 8.00:1 or higher requires 100 octane aviation gasoline and has undergone extensive flight Based on this explanation, readers should now understand testing to establish an adequate detonation margin. why Textron Lycoming does not recommend the welding of cracks in aluminum crankcases and cylinder heads. These cracks An individual or company who proposes to make your usually occur as the result of fatigue over long hours of use, engine more powerful, by whatever means, will usually con- and the odds of achieving long term satisfaction by welding are centrate on selling the benefits the modification will bring. You extremely remote. If you are buying an aircraft, watch out for have an airplane powered by a Lycoming 0-235-K, L, or M the engine which has been repaired by welding, and if you own engine, for example, and are told that by simply changing the an engine which has experienced cracks, remember that you pistons it will be possible to get your aircraft off the ground probably are wasting money by having those cracks welded.Ex- more quickly, to climb faster, and to cruise faster. This sounds perience has shown that replacement of these parts is likely to wonderful, and it is true. You ask, why didn't Lycoming make be most economical and is likely to cause fewer headaches over the engine like this to start with? Well remember this, it ,vas the long run, made that way, but it proved to be less than satisfactory.

By looking at the engine model certification sequence, we find that the 0-235-engine started as a low compression engine. Look What They Are Doing To Our Engines The C and E models had a compression ratio (CR) of 6.75:1 and used 80 octane aviation gasoline. Knowing that higher com- Modification of and the that them, aircraft, engines power pression ratios (CR) increase engine efficiency and that 100 oc- is articles a very popular activiiy today. Magazine frequently tane fuel would help to prevent detonation at the higher CR. tell us of the wonderful changes which occur when a modifica- Lycoming certified the 0-235-F and G models in 1971. The tion has been these articles and incorporated; unfortunately, 9.70:1 CR gained 10 horsepower which allowed the new models those who and sell modifications often do not touch develop to be certified at 125 HP. It did not take long to find that although the detrimental side effects which result from the on may these engines ran well in the test cell, installing them in air- modification. Without there are modifications which question, craft and turning them over to pilots in the field produced poor well and which a benefit. The are engineered provide positive results. Failure to follow critical fuel management procedures is that when we excited about the of the problem get prospects resulted, in some cases, in detonation, preignition, and burned benefit side, we tend to that there is no free lunch--we forget pistons. Not many of these engines were installed in airplanes. don't get the benefit for nothing. The purpose of this discus- The next step for Lycoming was to find a compromise bet- sion.is.to.point r,ut.some Df.the. hidden problems and.costs~of ween a 6.75: i and a 9.70:1 CR which provided acceptable engine modification. performance and increased detonation margin. The testing which followed led to cenif~cation of the O-235-K, L, and M series detonation characteristics of that engine are carefully checked. in engines with a CR of 8.50:1. When the recommended 100 oc- This detonation survey insures that power settings specified tane aviation gasoline isused in these engine models, burned the Pilots Operating Handbook provide an adequate margin so pistons are rarely ever encountered. that detonation and associated engine damage will not occur under any normal operating circumstances. The 0-235 is just one example of an engine being modified to something Lycoming engineers already know will demand When a Supplemental Type Certificate (STC) is issued to the much closer attention to proper operating technique than the allow addition of a turbocharger to a Lycoming engine, high original. An individual called the factory recently and said that compression pistons usually stay in the engine and oil squirts for On the it seem he intended to modify a 290 horsepower 10-540 engine by are often not available cooling. surface, may replacing the 8.70:1 CR pistons with 10.00:1 CR pistons. This that maintaining a manifold pressure of 30 inches or less should about a engine would certainly produce more horsepower, but there are cause the engine to operate the same as normally because at least three problems. First, the modified engine would not aspirated engine. In fact, the engine runs much hotter the air it it. Because the be a certified model and therefore could only be used in an the turbocharger heats as compresses airplane which is operated in the EXPERIMENTAL category. turbocharger must work harder and harder as the air becomes in the run Second, the engine would require a full rich mixture setting over less dense with an increase altitude, engine may very much of its operating envelope in order to avoid detonation. hot during climb and during cruise at altitude. The hot running And third, Lycoming models certified for more than 290 engine with high compression pistons must depend heavily on for this makes correct a critical horsepower are designed with a heavier crankshaft. Both the excess fuel cooling; leaning pilot higher horsepower with the lighter crankshaft and the increas- task. Over the years, Lycoming has received numerous reports in which have field installed tured exposure to detonation make the engine less reliable. This of burned pistons engines and for the stated it has is a modification which is unacceptable in view of Lycoming bochargers. From this, reasons earlier, experience. been concluded that in many cases there has been no detonation survey or the survey did not provide enough data to establish The point of this discussion is to show our readers that reliable power setting and leaning procedures. It can be very Lycoming, as a company, has expended a great deal of effort, expensive to learn about the detrimental effects a turbocharger and has gained a great deal of experience. The result is engine may have on an engine afterthe installation is already in your models which generally can be expected to operate reliably-- airplane. as they are certified. When it is suggested that one of these engines shduld be modified by installing high compression If you are considering the addition of a turbocharger to your be to ask a lot of hard pistons, remember that it was done years ago with poor results. Lycoming engine, prepared questions this before When a modifier with much less experience than Lycoming pro- (a list is printed with article) putting your money and on the line. You can obtain- poses a change which is almost certain to produce the same poor your engine help yourself by The results, Lycoming is concerned for the engine owner who may ing a copy of FAA Advisory Circular 23.909-1. subject in Small believe that this simple change can have no harmful effect. of this AC is "Installation ofTurbochargers Airplanes with Reciprocating Engines." This circular reinforces previous Another favorite modification is the add-on turbocharger. paragraphs of this article when it states that "induction air Are there benefits whichbecome available when this is done? temperature may become ciritical at altitude because of the in- Of course, and anyone who might consider adding a tur- creased compression of air required'' and ''the addition of the bocharger will be well aware of those benefits as well as the turbocharger to an engine not specifically designed for it may price of the installation. But will they be aware of hidden costs affect carburetor inlet and induction air temperature to AP- such as the possibility that a turbocharger may cause problems PRECIABLY REDUCE THE I)ETONATION MARGIN." which will void the engine warranty, or that modifications to Several other related items in the AC include such statements any engine invalidate manufacturer TBO recommendations. At as detonation characteristics may be unsatisfactory, a new first glance, these policies may s'eem somewhat unfair to the recommended overhaul period should be established, the stan- engine owner who wants to add a turbocharger. But again, the dard diaphragm type fuel pump is not adequate to supply a tur- engine manufacturer must rely on the lessons learned from many bocharged engine with fuel under all operating conditions, and years of experience. the change in the engine power to altitude realationship should model be was The first Textron Lycoming to turbocharged be evaluated to determine if propeller certification is valid. FAA certificated in 1961. Since that time, about 60 additional Advisory Circular 23.909-1 also mentions the installation turbocharged engine models have been certificated. The fac- of an intercooler which is another popular addition to the tur- tory turbocharged engine has a number of design features not bocharged engine installation. The AC warns of several items usually included on factory built normally aspirated engines. which must be considered when an intercooler is installed. It These features are incorporated to help the engine withstand recommends careful evaluation of changes to engine power, the additionalheat and pressure generated by the turbocharger cooling characteristics, operating limits, and operating pro- and to reduce the possibility of detonation. Low compression cedures. It also states that addition of an intercooler is likely pistons help to deal with detonation. Valves and valve guides to significantly affect engine horsepower. are made of materials which are more heat resistant. Heat is controlled an intercooler in- also carried away from the pistons by oil which is delivered If engineered and properly, cooler to the back of the piston by oil squirts which are placed in the stallation can provide benefits such as a running engine should be engine especially for this purpose. And finally, before an air- and higher altitude capability. Engine owners wary from which take- frame is certified with any factory engine, the fuel flow and of an add-on intercooler installation improved off and climb performance are claimed. Only increased power Questions To Ask The Engine Modifier can improve take-off and climb performance, and this would As stated in the companion article "Look What They Are indicate that rated engini power is being exceeded as a result Doing To Our Engines," a Lycoming engine owner should ask of the power which cgn be generated from cooler induction air. questions before agreeing to an modification. The To stay within the FAA certified limits for the engine, manifold engine purpose of this brief discussion is to provide and pressure and/or RPM settings may need to be reduced when background specific questions. The various modifications have one item in an intercooler is installed. The exact power settings to be used common they generally propose to some or all of can only be determined by extensive in-flight testing and carefi~l improve the aircraft performance envelope. This generally translates to torque meter measurement of the power being produced. If this getting more power from the engine than it was for. is not done, the reliability of the engine becomes questionable. designed As a result, there are similar questions to be asked about each This is the reason that Textron Lycoming Service Letter No. of the various types of modifications. These may help you: L201B states, "Reliability and average service life cannot be GENERQL predicted when an engine has undergone any modification not Textron approved by Lycoming." I. Will the modification cause the engine to produce more Polishing and porting is yet another fad which is receiving horsepower? How much? a great deal of attention these days. If you are sold on the idea that this type of engine modifying is done in automobile racing 2, If the answer is No. 1 is no, why modify? circles all the time, consider that the TBO on an automobile 3. If the answer to No. 1 is yes, is the modified engine legal be less than 100 would be satisfied racing engine may hours; you for the aircraft in which it was originally certified? if that were all you could expect from your aircraft engine? 4. Has the modification been tested thoroughly enough so that Magazine advertisements have claimed that will cylinder porting the modifier can define a reduced TBO? Has the new TBO add five horsepower per cylinder. If the added five horsepower been stated in writing? per cylinder is a fact, this engtne is outside its certified limits 5. Will the modifier pick up warranty on the engine after it is and would be illegal except in an experimental category aircraft. modified? What are the terms of that warranty and are they What modifications can be made to a cylinder to achieve stated in written form? the increases which are claimed? alone power Polishing might COMPRESSION R4TIO INCREASE improve airflow and efficiency slightly, but it is not likely that I. Ask to see all data from the detonation this improvement would change the power of the engine enough survey. a. Are detonation characteristics to be noticeable in the aircraft performance. To go a step fur- satisfactory? b. How do fuel flow schedules with those for the ther, if the cylinder head ports were ground out just a bit, a compare unmodified engine? larger charge of fuel and air wi~uld generate additional power, Again, this kind of change would affect the legal certification 2. Since torsional vibration levels will be affected, was a survey of the engine. It would also affect reliability because less material done to insure that new characteristics are acceptable? in the cylinder head results in reduced strength. A recent report a. If no survey was done why? in the aviation press indicates that at least two sets of cylinders b. If survey was done, are the results acceptable? to this were found to be when subjected procedure unairworthy 3. Was a survey done to determine the cooling margin during inBpectea by A P mechanics and FAA inspectors. One of these climb? Is the margin still sufficient? sets of cylinders had been flown at least through a normal engine 4. Will a new power setting chart be provided? break-in period. Cracks were found in the port areas of these TURBOCHARGER ADD-ON cylinders when they were inspected. To conclude, this article is not intended to discourage in- I. Has a detonation survey been done for your aircraft model? novation. It is meant to educate readers who and can easily see 2. Has a cooling climb survey been done for your aircraft understand the benefits of an engine modification, but who may model? not be aware of the effect a modification can have on reliabili- 3. What does the data from surveys in question 1 2 show? ty and life expectancy of the engine. Years of experimentation Ask to see the data and have it explained. and thousands of engines in the freld have given Lycoming 4. If engine power changes at any altitude, is the propeller cer- engineers and~service representatives an excellent knowledge tification still valid? of what will work, and what will not work. This knowledge 5. the comes from problems and failures as well as sudcesses. It is Does modification replace the low pressure fuel pump with a fuel of from this experience thit reliable engine models are developed. pump capable delivering the higher fuel The information shared in this article is provided to help engine pressure needed for a turbocharged installation? owners. If own a and you Lycoming engine are contemplating 6. if your engine has a compression ratio higher than 8.5: i, a modification of use the list of any kind, questions provided do leaning instructions reflect the critical fuel management to all the facts. Be help get sure you are completely satisfied procedures necessary to avoid detonation? that the modification will leave you with an engine which is INTERCOOLER ADD-ON legal, safe, and reliable. i. Are new power setting charts available?

DO these charts recommend lower power settings to compensate for the additional power generated by cooler intake air? If you are an engine owner contemplating an engine matched sets, by weight, before installation in a Lycoming modification, thes~ questions should be answered to your engine. Should it be necessary to replace one of these matched satisfaction since the reliability and longevity of your engine parts during the service life of the engine, there is a system to may be affected. Should you desire assistance or have ques- keep the balance within specified tolerances. (See "Notes tions about engine modifications, call Lycoming. We will be on Replacing Rods or Pistons" in the Maintenance Section.) happy to provide assistance if possible. Lycoming engineering Perbaps the engineering answer to other questions may be 717-327-7119. enlightening or to the non-engineers, confusing. The point is, Lycoming engineers are well aware of what is needed to make a Lycoming engine safe and reliable for the long TBO times Engine Balance which are recommended for these engines. Thousands of hours of engine testing followed by days and weeks of data analysis After certifying hundreds of flat, opposed cylinder aircraft provide the basis for the Lycoming engine design. engines, and after building more than a quarter million engines for general aviation, is it possible that Lycoming engineers have The engineering answer as to why there is a need for mat- and of in this: "As a matter of not learned what it takes to produce an engine which is proper- ching balancing engine parts sound and will ly balanced? Many engines have been tested over the years and design practice, matching balancing components load crankshaft in a manner and reduce the ~agreat deal of data is availabre to support the building of engines bearings predictable reaction loads at the mounts." Just as we to factory specifications. To put it simply, the subject of engine engihe suspected balance is well understood by Lycoming and is a consideration right! in the design and manufacturer of all Lycoming engines. Since those engineers did such a good job on that last question, another was ventured, "Is there or problem These~Ltatements are contray to what has been implied by any danger with additional activities?" Those of several advertisements and magazine article~Cilowing reports balancing by non-factory who will understand some of the but it have appeared in several industry publications; they say your us are pilots response, will take those who the of to com- Lycoming engine would be so much better if you would just sepak language engineering the rest. Here it is: "There are occasions when dynamic take the time and spend the money to have it "custom balanc- prehend reduced ed". The implication is that the manufacturer knows noti~ing balance of the prop/engine combination can provide first order vibration, but additional internal balancing of Lycom- about balancing an engine and simply throws the parts together and without consideration of the importance of balancing. This is ing engines-is not required nor recommended. The rotating masses of the six and cylinder opposed absolutely false. Lycoming engines are very carefully balanc- reciprocating eight balanced. The masses of the four ed to the degree which is necessary. They are not balanced to engines are inherently rotating are balanced. The reciprocating masses a point of absolute perfection because they rnn at relatively low cylinder opposed design of the four are not balanced as a vibratory in- speeds (compared to some automobile engines) and therefore cylinder engine enia at second order exists in the of the do not require the degree ofbalancing being advocated by shops moment plane cylinder closer will which deal in this specialty, center lines. Matching the weights of components not reduce the second order moments. A redesign incorporating To justify this excessive emphasis on balancing, the counterrotating layshafts rotating at twice engine speed could automobile racing engine is often cited as another place where be implemented. However, the magnitude of the second order balancing is important. This is like comparing apples to oranges; moments is insignificant with respect to other harmonics of the the two types of engines are not the same. A typical Lycoming engine mount reactions. In light of the contribution of the se- direct drive engine is redlined at 2700 or 2800 RPM while an cond order moment, redesign is not practical. In fact, all iner- auto racing engine may operate at more than three times this tia loads due to slight unbalances from matched weight speed. any groups are a very small portion of the total reaction at the engine In order to delve into the subject a little deeper, several mounts. The largest contributor is due to the engine firing. questions were directed to the Senior Analytical Engineer at Additional internal balancing contributes little to engine Lycoming. His responses may help those who have doubts about smoothness, and it may even be harmful when material is the of balancing done at the factory. quality engine removed from highly stressed parts of the engine. Several Lycoming engine components are dynamically To summarize, these are the points we have attempted to ballinced. For that means that the balance non-engineers, proper communicate by providing information about the balancing of is determined while the is in motion; it is spinning as it part Lycoming reciprocating engines. First, Lycoming engineers would be during operation. These parts are the supercharger have acquired vast amounts of data through years of engine starter slpports, and the crankshaft. In addition, iinpellers, testing. This knowledge is used to insure that Lycoming engines counterweights are statically balanced to control the dynamic are carefully balanced during manufacture. It is also used to location of the very critical center of gravity, formulate a system which allows satisfactory engine balance to the control of for a number Balance also includes weights be maintained when weight matched parts are replaced during of moving engine components. Items such as piston pins, piston the operational life of the engine. The engine balancing done and are 100% machined to close tolerances plugs, piston rings by Lycoming is part of an organized system which is intended consistent The of which provide weights. weight dynamic to provide a quality product. is also carefully controlled. counterweights The second point is that additional internal custom balanc- of is A second aspect engine balancing accomplished by ing is not recommended by Lycoming. It simply is not Pistons and matching some engine pans by weight. connecting necessary, and therefore engine owners would be well advised Both of these are in rods are in this category. parts organized to save their money. Low Time Engine May Not Mean deterioration as a result of not being used. When the engine does Quality and Value not achieve flight operating temperatures on a regular basis, the moisture and acids which form as a result of combustion Reading the ''Aircraft for Sale'' advertisements can be in- and condensation are not vaporized and eliminated through the teresting and misleading. As aviation-oriented people, we are exhaust and crankcase breather. As moisture and acids collect conditioned'to look for certain bits of information which we in the engine, they contribute to the formation of rust on the believe will allow us to evaluate the product offered for sale, cylinder walls,.camshaft, and tappets. In the of this information be case airplanes, can generally As the engine is run after rust has formed, the rust becomes in three and segregated categories-airframe, avionics, engine. a very fine abrasive causing internal engine wear, particularly For purposes of this article, you are on your own with respect to the camshaft and tappets. As these components wear, they to airframe and avionics. There does seem to-be information make more metal which attacks the softer metals in the engine. which be on engines cannot emphasized too strongly. Piston pin plugs are examples of parts which may wear rapidly Engine information is usually provided as hours of opera- when rust becomes an abrasive inside the engine. This wear tion since new or from some major maintenance event. For ex- could eventually lead to failure. 700 TTSN would indicate that this aircraft and ample, engine The infrequently flown engine is just one example of a low have been flown for hours since the 700 new from factory. time engine not meeting the expectations of a buyer or new related -Other, but not all, engine abbreviations include SMOH owner. The term zero SMOH is always enticing since it indicates Thours since major overhaul, SPOH Olours since prop overhaul), the engine has been overhauled, has zero hours since overhaul. STOH since and SFRM fac- (hours top overhaul), (hours since and now may be expected to fly happily on through a full that the recommended TBO of tory remanufacture). Assuming manufacturer recommended TBO. This will happen in some the considered is 1800 or 2000 it would engine being hours, cases, but in others, there will not be a chance of this happen- that hours of in the 400 to 800 hour would appear use range ing. It depends on the quality of the overhaul. make this valua~e Un- automatically engine a very commodity. Textron Lycoming Service Bulletin No. 240 recommends fortunately this is not always true, and therefore an advertise- parts to be replaced at overhaul regardless of the apparent con- ment like those discussed earlier may state numbers and facts dition of the old parts. The number of these new parts used in which are absolutely correct, but still misleading, the engine at overhaul will probably determine the possibilities Consider a situation which occurred A recently. Lycom- of achieving a full TBO. Consider that most overhaulers install 10-360 with less than 700 hours since new was ing engine reconditioned cylinders on the engines they overhaul. These to be oil at the rate of two-thirds hour reponed using quart per cylinders are not traceable. There is no requirement to main- and oil On closer losing pressure during flight. examination, tain a record of their previous histoIy. They may have only 2000 it was determined that deterioration and wear had caused metal hours of operation, but they could just as easily have 5000, 7000, contamination throughout-the engine. An engine overhaul was or more hours of operation. Those cylinders may have been and it included of items such as the cam- necessary replacement cracked and repaired by welding--a procedure which Lycom- shaft, oil pump gears, and-pistons. Why should an engine with ing metallurgists do not recommend because the strength of a less than 700 hours since new be in this sad state? repaired cylinder head may be significantly less than that of a It should be that the number of hours the apparent engine new head. There is no requirement to let a prospective engine has is of the We need to know all the operated only pan story. buyer know if cylinders have been welded and this cannot be facts if we are to understand what have to this may happened determined even by close examination. The possibility of find- reliable and also if we are to determine the value normally engine ing a reconditioned cylinder with cracks after a few hundred of low time in a engine a pre-owned airplane, hours of operation is very real. Should this happen, it will be The engine with metal contamination and less than 700 a costly experience. hours of had been installed brand new from the operation The lesson to be learned here is a very old one-"Buyer THAN 12 YEARS before. The factory--MORE engine log Beware''. Whether you are looking at those ''Aircraft for Sale'' book shows that the first 10 of service this during years engine advertisements or looking for a replacement engine for an air- had less than four hours of time each month. averaged flight craft you already own, consider carefUlly what you are about Chances are excellent that there were some months when the to buy. What do you really know about the engine other than engine was not flown at all, the low time number? How much validity does that number real- Textron Serj~ice Letter No. L201B that Lycoming states ly have? What questions can you ask which may help you to the recommended TBO is based on the use of genuine Lycom- insure that this engine will meet your expectations? in and continuous ing pans,~ average experience operation, ser- Perhaps simply re-reading the paragraphs you have just read vice, Continuous service assumes that the aircraft will not be may help you to formulate questions you want answered before out of service for extended of time. If an is any period engine taking the plunge. In the case of a low time engine with a history to be out of service for longer than 30 days, it should be preserv- of infrequent flight, borescope examination of thecylinders and ed as in Textron Service Letter No. L180. specified Lycoming an inspection of cam and tappet surfaces by a competent and Service Letter No. 201B also states that because of the varia- knowledgeable A P mechanic would be a very wise move. tions in operation and maintenance, there can be no assurance Always remember that low numbers in the hours of operation that an individual operator will achieve the recommended TBO. records do not guarantee reaching TBO with many long hours The point of this discussion is simple. A low time engine of trouble free operation. The buyer must investigate every detail may not add value to an aircraft. and the buver should be aware of engine history as closely as possible, and be satisfied that of all frictors which ii~ay affect the condition and value of the the product does have the value which the low hours of open- engine. An engine which is not flown frequently is subject to tion number suggests. OPERATIOI\T Hard Ffacts About Break-In Engine slightly and allow some wear to occur. This wear, or seating of the with ring the cylinder wall will only occur when pressures Most people seem to-operate on the philosophy that they inside the cylinder are great enough to cause expansion of the can best get their money's worth from any mechanical device piston rings. Pressures in the cylinder only become great enough by treating it with great care. This is probably true, but in many for a good break-in when power settings above 65% are used. cases it is necessary to interpret what great care really means. Full power for take-off and climb during the break-in period This is particularly applicable when considering the break-in is not harmful; it is beneficial, although engine temperatures ofa modern, reciprocating aircraft engine. Aircraft owners fre- should be monitored closely to insure that overheating does not quently ask about the proper procedures for run-in of a new occur. Cruise power settings of 70% to 75% of rated power or remanufactured engine so they can carefully complete the should be used for a good engine break-in. required steps. Many of these recommended break-in procedures It should be remembered that if the new or remanufactured also apply to engines which have been overhauled or had a engine is normally aspirated (non-turbocharged), it will be cylinder replaced. necessary to cruise at the lower altitudes to obtain the required The first careful consideration for engine run-in is the oil cruise power levels. Density altitudes in excess of 8000 feet to be used. The latest revision of Textron Lycoming Service will not allow the engine to develop sufficient cruise power for instruction Number 1014 should be consulted for this informa- a good break-in. tion. The basic rule which applies to most Lycoming piston For those who still think that running the engine hard dur- engines is simple; use straight mineral oil of the proper viscosity ing break-in falls into the category of cruel and unusual punish- for the first fifty hours or until oil consumption stabilizes. Then ment, there is one more argument for high power settings dur- switch to ashless dispersant (AD) oil. But don't stop reading ing engine break-in. As stated earlier, the use of low power set- now because there may be an exception or note of caution which tings does not expand the piston rings enough to break down applies to your particular situation. the film of oil on the cylinder walls. The high temperatures in The exception to the basic rule on break-in oil applies to the combustion chamber will oxidize small amounts of the oil these engine models: TO-360-C, TO-360-F, TIO-360C, film which often creates a condition commonly known as glaz- TIO-541- and TIGO-541-. These engine models are to be ser- ing of the cylinder walls.When this happens, the ring break-in viced with ashless dispersant oil for the entire life of the engine, process stops, and excessive oil consumption frequently occurs. including the break-in period. The bad news is that extensive glazing can only be corrected Textron "76" Series fall into a Lycoming engines category by removing the cylinders and rehoning the walls. This is ex- different from all others. These models include the 0-320-11, pensive and it is an expense that can be avoided by proper break- the O/LO-360-E and the TO/LTO-360-E. Although these in procedures. engines should be run in with straight mineral oil, Textron To summarize, there are just a few items to remember about Lycoming oil additive LW-16702 must be added to the oil for engine break-in. (1) If a preservative oil has been added by the break-in, and every 50 hours thereafter or at every oil change. aircraft manufacturer, drain it after the first 25 hours of opera- After engine break-in, AD oil with LW-16702 is recommended. tion. (2) Follow the engine manufacturers recommendation When of there is another taking delivery a new aircraft, regarding the oil to be used for break-in and the period be- which must be Some aircraft manufacturers point emphasized. tween changes. (3) Run the engine at high cruise power levels add approved preservative lubricating oil to protect new engines for best piston ring/cylinder wall mating. (4) Continue break- from rust and corrosion at the time the aircraft leaves the fac- in operation for 50 hours or until oil consumption stabilizes. This oil be tory. preservative mrcst removed at the end of the These simple procedures should eliminate the possibility of first 25 hours of operation. cylinder wall glazing and should prepare the engine for a long Each new or remanufactured engine is given a production and satisfactory service life. test run at the factory before the engine is delivered to an aircraft manufacturer or other customer. After installation in the aircraft, the engine is run again during the test flights. These Leaning Textron Lycoming Engines test runs will insure that the engine is operating normally and (How to use this outline All should will provide an opportunity to locate small oil leaks or other presentation: operators read the General Introduction and Recommendations, minor discrepancies, in addition, these test runs do the initial Summary but should carefully study the section that to his or her seating of the piston rings. The rest of the break-in is the respon- applies sibility of the pilot who flies the aircraft during the next 50 hours. specific powerpiant.) GENERAL INTRODUCTION A new or remanufactured engine should receive the same start, warm-up, and preflight checks as any other engine. There The information outlined in this presentation has been are some aircraft owners and pilots who would prefer to use reduced to minimum essential facts, and is based on leaning low power settings for cruise during the break-in period. This as described in the various Lycoming "Engine Operator's is not recommended. A good break-in requires that the oil film Manuals", and Service Instruction No. 1094. "Fuel Mixture which lubricates the piston rings and cyiinder walls break down Leaning Procedures". Although the above documents are authentic basic 8. Proper leaning at cruise power results in more normal references 6n leaning, and including the related write-ups in engine temperatures in cool weather or at the cooler pist issues of the'"Flyer", we see the need to review all of temperatures of altitude. Rich mixtures cause undesirable these and outline the basic combined information in one article cool engine temperatures in cool or cold weather. for the following reasons: a. Oil temperatures should be at least 1650 F minimum I. The basic leaning information needs to be repeated from in order to reduce moisture forming vapors and time to time. undesirable acids in the engine oil.

2. We need ib update our information on new engine models, The Three Basic Types of Fuel Metering Devices Used with or concerning new and i;nproved engine instrumentation. Lycoming Engines In General Aviation; and the General Pro- cedures for Leaning at Manufacturers' Recommended Cruise 3. Operators in the field have stated that some of the Pilot's Power: Operating Handbooks lack sufficient information on leaning. 1. Floattype carburetor. 4. The manufacturer with the of the FAA and engine approval a. Fixed pitch propeller lean to a maximum increase in with the airframe is the cooperation manufacturer, in RPM and airspeed or just before engine authority on the operation of his product. roughness. 5. Small aircraft, such as the typi'cal General Aviation trainer, (1) Engineroughness isnotdetonationat cruisepower, have limited instrumentation. we engine Therefore, pro- but is caused by the leanest cylinder not firing due vide the with certain basic rules to operator leaning pro- to a very lean fuel-air mixture which will not the and it teet powerplant yet operate efficiently. Damage support combustion in that cylinder. to this type of engine results from i~ing at higher than b. Controllable propeller lean the mixture until the manufacturer's recommended cruise power. roughness encountered, and then enrich slightly until 6. The more complex powerplants of higher horsepower or roughness is eliminated and engine is smooth. There ratios HP and are higher compression (200 higher), general- may be a slight increase of airspeed noted in smooth sufficient instrumentation to ly accompanied by engine pro- air when properly leaned at cruise when compared to teet the powerplants while operating at approved higher than full rich. routine power settings. However, the engine manufacturer c. The EGT offers little improvement in leaning the float- helps protect these engines by establishing certain re- type carburetor over the procedures outlined above quirements for leaning at higher than average cruise power because of the problem of imperfect distribution. by reference to.fuel flow, exhaust gas temperature, or tur- However, if the EGT is installed, a good rule of thumb bine inlet temperature, cylinder head temperature, oil is lean the mixture plus 500 on the rich side of peak EGT temperatures and pressures. The airplane pilot's manual will with this type of fuel metering device. specify this information for these more complex high performance powerplants. d. With the application of carburetor heat, the mixture is richer; check and adjust mixture leaner. WHY LEAN THE ENGINES? 2. Fuel Injection. In spite of a number of variations in the different models a. Becauseofthevaried modelsoffuelinjectorsused with of our there are some general recommendations powerplants, Lycoming engines, the operator must consult the dffer for all on leaning'we can Lycoming piston engines. specific Pilot's Operating Handbook for specific i. Most carburetors or fuel injectors are set slightly on the leaning instructions. rich side--this calls for leaning at any altitude at the b. However, as a basic technique, at the manufacturer's manufacturer's recommended cruise power. recommended cruise power limitation, with a manual 2. Proper leaning means economy of fuel, which results in mixture control, lean initially by reference to the fuel lower cost of operation. flow (if available) for the percent of cruise power without manufacterer's recommended limits. 3. Rich running engines cause roughness proper leaning exceeding Then for if an exhaust makes them smooth, which protects engine mounts and more precise leaning, gas engine accessories from undesirable vibration and possi- temperature is available, find peak EGT without ex- ble failure. ceeding limits, and operate there, or by the rule of thumb of plus 500 F on the rich side of peak EGT. 4. An engine properly leaned is a more efficient powerplant. (1) Monitor cylinder head temperatures. 5. Leaning at cruise can exiend the range of the aircraft-- The EGT is a instrument for lean- a safety factor. (2) helpful precise ing with fuel injection. 6, Proper leaning means less spark plug fouling and longer fuel flow are not then lean life for plugs also a safety factor, as well as lower (3) If EGT and available, maintenance cost. to just outside roughness, or to a slight airspeed the 7. Correct leaning means cleaner combustion chambers and loss, then as desired by pilot. less likelihead of pre-ignition from undesirable combustion deposits. LEANING RECOMMENDATIONS FOR TYPES full rich mixture regardless of the airport elevation. The OF TEXTRON LYCOMING ENGINES supercharged engine needs the extra fuel for cooling i. Direct drive normalljr aspirated engines, (carbureted or because of the high induction air temperatures created fuel injection): by supercharging, and because it is operating at sea level a. May beleanedatany altitude, atmanufacturer's recom- horsepower. mended cruise 75% or power iusually less), provided b. If leaning by means of manual mixture is permitted at there is a manual mixture control. climb power, it will be specified in the Pilot's Operating b. In climb from sea level through 5,000 ft. density Handbook, and will list required ranges for fuel flow. altitude, mixture must be full rich. Continued climb power settings, and temperature limitations. above 5,000 ft., mixture may be leaned for smooth c. The exhaust is a helpful instru- engine operation. DO NOT confuse the 5,000 ft. gas temperature gage for the at cruise reference for climb with the cruise configuration. ment leaning supercharged engine power with a manual mixture control. c. Operation at higherthan 75% power withoutreference d. Recommended standard cruise for the to fuel flow, cylinder head temperatures, and without power super- is 65 At 65 less this knowledge of specific powef, requires full rich mixture. charged engine power or type of engine may be leaned as desired as long as the engine (1) Leaning at recommended cruise power does not and and are damage a normally healthy engine, but leaning at operates smoothly, temperatures pressures within manufacturer's limits. higher than 75 cruise power in this type of engine prescribed can cause engine damage when complete engine in- SUMMARY RECOMMENDATIONS -strumentation is not available(CHT and fuel flow 1. This presentation has merely covered the minimum basics minimum), and'limitations ffet spelled out in of the various of Textron For airplane pilot's operating handbook, types Lycoming powerplants. a more detailed description of the leaning procedures, par- 2. Leaning the turi~ocharged Lycpming powerplant, ticularly the higher powered more complex engines, refer The turbine inlet is a a. temperature gage (TIT) required to the Pilot's Operating Handbook. If the manual is in- instrument with turbochargingby Lycoming. complete, refer to Textron Lycoming Service Instruction b. During manual leaning, the maximum allowable TIT No. 1094. for the particular engine and installation must not be 2. For maximum service life, where there is a cylinder head exceeded. Check the Pilots' Operating Handbook (POH) temperature installed, maintain cylinder head temperature or The Engine Operator's Manual to determine this (for continuous operation), below recommended 4350 F temperature limit. (2240 C). If cylinder head temperature is higher than recom- c. At cruise power wken leaning the mixture, if m reach- mended during flight, in order to complete the flight as safe- es the maximum allowable limit before peaking, do ly as possible, reduce head temperature to within recom- not exceed the limit to find peak. mended operating range by enriching the mixture, or by d. Operation may be at peak during.cruise provided TIT adjusting cowl flaps if available, or by reducing power, or does not exceed red line maximum and cylinder head by use of any combinations of these methods. should not exceed 4350 F (2240 C), for continuous traffic be in operation. Mixture may be operated anywhere on the 3. Some leaning during descent to pattern may rich side of peak. CHT, fuel flow, and TIT will decide order to prevent roughness or sudden engine cooling. The where the pilot will operate his mixture control as before-landing check should prevent overlooking the mix- specified in the Pilot's Operating Handbook. ture for landing.

e, Very high altitudes may result in high temperatures 4. Always return mixture to rich before increasing power. which will require adequate fuel, cowl flaps, or air 5. Leaning the mixture in accordance with the engine manufac- speed for cooling. turer's recommendations is practical and economical. f. All takeoffs with turbocharged powerplants (where tur- 6. Normally aspirati~d, direct drive Lycoming engines operated bo is operating) must be at full rich mixture regardless at manufacturer's cruise (usually 75% or less) of airport elevation. The turbocharged engine needs the power power be leaned at altitude. Do not confuse the 5.000 extra fuel for cooling because of the high induction air may any for climb with this If cruise temperatures created by turbocharging, and because the ft. reference type. (for exam- less is then engine is operating at sea level horsepower. pie) is 2500 ft., and 75% power or used, the mixture should be leaned for all routine cruise operations g. Always consult the Pilot's Operating Handbook for any outside the traffic pattern. variations for the specific aircraft. If leaning by means of manual mixture is permitted at climb power, it will 7. Leaning techniques vary because of differences in fuel be in the Pilot's Handbook and will specified Operating metering devices (carburetor or fuel injector), turbocharg- list for fuel flow, and required ranges power settings, ing or supercharging, fixed pitch or constant speed prop, limitations. temperature _etc. Read the airplane Pilot's Operating Handbook and the 3. Leaning supercharged Lycoming powerplants. determine the proper operating technique. Get a proper check-out in the aircraft. a. All takeoffs with supercharged powerplants must be at Proper Leaning At Cruise Aids Safe vs. lean at cruise. in the illustration of the 180 HP engine there is one additional hour of flight when properly leaned. This Is Flight And Saves Dollars a very real safety of flight fact. These are some of the more important facts that illustrate In issues of our we have previous Lycoming Flyer, always how proper leaning at cruise power aids safe flight--and saves emphasized proper leaning at the manufacturer's recommend- dollars. ed cruise power at any altitude; however, in this article we will expand our continuing discussion of leaning and explain (1) how it saves dollars, and (2) how it aids safe flight. In a practical approach to our subject, let's look closely at the chart listed Operating The Direct Drive below: Fixed Pitch Lycoming Engine Leaning the normally.aspirated, direct drive Lycoming engine at cruise vs, full rich There is an area of confusion concerned with operating the at 4,000 feet density altitude, 75% power. direct drive fu~ed pitch normally aspirated powerplants among Engine Airplane will indicate some pilots. If there is a power chart provided, it Model Model that as the airplane is flown at different altitudes above sea level, 300 HP Piper Cherokee 300 it is necessary to use a higher RPM for adequate cruise perfor- Full Best Hours Hours Economy mance with an increase in altitude. A typical example might Rich (Peak EGT) Rich Lean be the 0-360, 180 HP Lycoming powerplant. The power chart 15.6 4.2 hrs. 5.1 hrs. 19$ gals. gals. by the airfnune manufacmrer for this fixed landing gear air- Engine Airplane craft lists 75% power at 7500 feet at 2675 RPM (00 manifold Model Model pressure gage in their airplane). The confused pilot observes 250 HP Piper Aztec that red line takeoff RPM is 2700 RPM, and is afraid to lean the altitude because he is Full Best Economy Hours Hours either for cruise or climb despite pull- Rich (Peak EGT) Rich Lean ing almost takeoff RPM. 5.1 hrs. 16.2gals. 13.6gals. 4.3 hrs. However, he can and should lean the engine at these Engine Airplane altitudes despite the high RPM, for the horsepower is down to Model Model 75% because of the thinner air. On the other hand, with any 180 HP Cessna Cardinal direct drive normally aspirated Lycoming engine, he can and should lean the mixnre at altitude as as he is in cruise Full Best Economy Hours Hours any long Rich (peak EGT) Rich Lean configuration at 75% power or less.

11.9 gals. 9.7 gals. 4.1 hrs. 5.1 hrs. Let's take a look at the airframe manufacturer's power chart for the 180 HP and observe the increase Observe the fuel flows at "Full Rich" vs. "Best economy", 0-360, engine gradual in RPM with the increase in altitude, but maintaining and note that the higher horsepowered engine uses almost 3'h required 75% for cruise at each altitude. What the chart will not show gallons per hour more fuel at full rich cruise power. Now multip here is that for above 7500 feet, it is not possible to achieve ly 3 H, times the cost of aviation gasoline per gallon, and con- flight 754~ with a (meaning not tur- ciude how much unnecessary additional cost per hour of flight power normally aspirated engine or time you are incurring by operating at full iich mixture at cruise bocharged supercharged). power. POWER CHART

While we are on a discussion of unne~essary cost of opera- Percent Endurance on tion, another important factor is the damage often done to engine Altitude RPM of H. P. 59 gals. fuel 4.8 hours accessories by operating at full rich at cruise power. Engines 2500 2550 75% 75C/o 4.8 hours operating at full rich in cruise tend to be rough, resulting in 3500 2575 4.8 hours shaking engine accessories and engine mounts. thereby con- 4500 2600 75X siderably reducing their life and often resulting in expensive 5500 2625 75% 4.8 hours 4.8 hours early replacement. A properly leaned engine at cruise power 6500 2650 75~ 2675 752 4.8 hours is a smooth engine and will save money. 7500 We have been telling all concerned about the benefits to the spark plug by proper leaning at cruise power in earlier issues of the Flyer, and it can be repeated in this discussion because Operating Your Lycoming Engines it well illustrates our point on saving dollars. Proper leaning at cruise helps prevent spark plug fouling. The maintenance cost At Takeoff And Climb to remove and clean spark plugs can be reduced by good lean- of reduces their ing techniques. Frequent cleaning spark plugs In reviewing a number of the airframe manuals, it reveal- fouled life and requires early replacement. Furthermore, badly ed that there is a certain amount of implied operation concern- spark plugs could also become a safety of flight problem too. ing rakeoff and climb. Therefore, from an engine point of view, would like to discuss the take-off and climb in detail For a very interesting safety of flight item, let's look at the we greater chart again. Notice the difference in hours of flight at full rich herein. DIRECT DRIVE ENGINES NORMALLY ASPIRATED

Most normally aspirated engines are rated at full power for The normally aspirated and reacts to den- takeoff and climb indtfinirely, provided engine temperatures engine performs sity altitude. As an this at takeoff from and pressures are within the green are area of the engine in- example, type powerplant an with struments. Extra fuel, sensible airspeed, and cowi flaps, if airport a 3,000 ft. indicated altitude, but with an ambient at would available, are all helpful in keeping cylinder head temperatures temperature 850F, have a density altitude of more than within desired limits during takeoff or climb, 5,000 ft. The engine would lack some 20 to 25Lic of us power and also probably run rough because of a nch mixture Climb requirements may vary as an example on a on the ground at full rich. Therefore, the typical normally warm day with the airplane close to gross weight. and a direct aspirated direct drive engine requires the mixture be leaned on drive engine with a fixed pitch prop, the pilot will need full the ground for efficient takeoff performance where are throttle all the way to cruise altitude. The same airplane on a arrports 5.000 ft. or cold day and lightly loadtd, after full throttle at takeoff the pilot (density altitude) higher. The over rich condition is the may want to reduce power 100 or 200 RPM and still not see something pilot can compensate by leaning. However. performance suffer. the higher density altitude with its thinner air cannot be com-

pensated for with a normally aspirated engine unless a super- Those direct drive normally aspirated engines with a prop charger or mrbocharger unit is added to the Thus, governor are also rated indefinitely at full power, and the powerplant. at altitudes of 5,000 6,000 the of a normal- manuals all recommend full power for takeoff, but specify a density feet, pilot small reduction in power, generally to 8596 power climb. Study ly aspirated engine has available to him approximately 75k of the specific airplane Pilot's Operating Handbook for detailed the engine power, and must plan his takeoff accordingly after power settings. setting the mixture.

GEARED, TURBOCHARGED AND SUPERCHARGED ENGINES PROCEDURE FOR LEANING

Turning to the more complex powerplants such as the geared, turbocharged and supercharged models, the manuals i. The fixed pitch propeller lean to maximum RPM at full are quite specific in their description of takeoff and climb rech- throttle prior to takeoff where airports are 5.000 ft. densl- altitude niqucs. Our geared and supercharged powerplants have a limit ty or higher. Limit operation at full throttle on the of five minutes at takeoff power. However, it is advisable to ground to a minimum rime. throttle power to the recommended climb power as stipulated 2. The direct drive normally aspirated engine with a prop in the manual as soon as rakeoff obstructions have been cleared governor but without fuel flow or EGT, set throttle at full and proper airspeed attmed. power and lean mixture at maximum RPM with smooth The turbocharged Lycoming's (including the TIGO-541-E operation of the engine as a deciding factor. series) do not have a five minute limit at takeoff power. 3. With fuel injection, if the powerpiant has a marked fuel flow However. the manual clearly stipulates a reduction to a proper gage, then set mixture in accordance with instructions on climb power when citar of obstaclts, and when climb speed the fuel flow and/or in accordance with the has been established, and cylinder head, oil and turbine inlet gage airplane Pilot's Operating Handbook. tcmperamns art within limits. Due to the more complete engine instrumentation in the the manuals allow lean- airplane, some 4. With an EGT gage, at full throttle, lean mixture to plus at climb. but with the insruments within ing engine indicating 1000 on the rich side of peak of a normally aspirated engine. specified limits listed in the airplane manual. 5. Pressure carburetor Ail Lycoming engines have an The more complex and powerplants (geared, supercharged, automatic mixture controi which does not require leaning turbocharged) demand smooth, careful operation of the throt- for takeoff. tie at all times, particularly at high power, but especially when 6. and engines and oil are not up to normal operating temperatures such Turbocharged supercharged engines All takeoffs must be at full rich mixture because the is as for the initial takeoff. Overboost or erratic engine operation engine brought back to sea level which does will result from abrupt movements of the throttle. All super- horsepower not permit leamng. charged and turbocharged engines must use full rich mixture for all takeoffs regardless of field elevation. DESCENT Landings And Takeoffs From Regardless of the field elevation where the pilot intends to land, the descent from cruise altitude to traffic pattern altitude High EIevation Airports should include some leaning for smooth engine operation. LOW elevation fields @elow 5,000 ft. density altidude) will require Pilots frequently ask us for information and guidance con- that the mixture be moved to full rich in the "before landing ccming landings and takeoffs from high elevation airports. Our checklist". Landing at airports above 5,000 ft. density altitude, reference point in this discussion will be based on density the mixture must be leaned to smooth engine operation during altitude. The discussion also requires that we treat separately traffic pattern flight and landing; otherwise, the engine may stall operation of normally aspirated, supercharged on the runway because-of excessive richness. engines at high elevation airports. The Need For Good Fuel Management

One phase of Textron Lycoming's interest in safety is a constant review of accidents involving our engines. It appears that one of the advantages in reviewing these accidents in five year divisions, is that some patterns emerge. After a recent review, the pattern of poor fuel management was obviously a serious problem.

These accident reports list such poor fuel management techniques as switching to another fuel tank after the before takeoff Nnup was completed, and then experiencing engine problems on takeoff. There are other reports of pilots switching "EGT Probe and Gage" fuel tanks at a critical point on the approach to a landing, with the result that the pilot turned the fuel valve to an empty tank but couldn't in time and crashed. It is also compensate painful INSTALLATION INFORMATION -ta read about pilots flying low on day cross-country, or The mechanic must carefUlly follow the installation instruc- moderately low at night, and running a tank dry. By the time tions concerning placing the probe in the exhaust stack. If it they realized what caused the engine stoppage and attempted is closer than I'h inches to the cylinder head, probe life will to see the correct fuel selector position, the aircraft had lost too be limited, or if too far down toward the end of the exhaust much altitude and made contact with the ground. stack, the response on the gage will be slow. Should there be There several other of fuel are examples po~ management doubt concerning in which stack a single probe is to be in- in this particular five year study, but those listed herein should stalled, that information is available from the airframe dealer's make a with Be familiar with point pilots. thoroughly your service department. The operator might desire the more expen- fuel and tank airplane system switching procedure. Furthermore, sive installation of probes in ail cylinders, therefore the accom- it is unsafe to run a tank as a routine pilot technique dry pro- panying gage will generally have a selector switch for individual cedure. We realize there is the occasional but to exception, readings on all cylinder exhaust stacks. Again, it is mast im- a fuel tank asks for trouble. Our records show routinely run dry portant that the installation instructions are carefully followed of accidents where the fuel selector broke a number off, or was In order to get reliable readings. frozen or jammed into one position, or caused sediment in the INTERPRETING THE SYSTEM bottom of the fuel tank to be sucked into the fuel system. Fuel Most of the EGT manufacturers have standardized on injection is more difficult to restart in the air than most car- gage increment of 250 F (see illustration). A few EGT buretion because of its vulnerability to vapor lock. markings manufacturers will go further and show the temperature range Good judgment and sound fuel management go on the gage as 12000 F to 1750" F. Lycoming engines normal- hand-in-hand. ly operate within an EGT range of 12000 F 16000 F. The simple gage shown in the illustration is quite satisfactory for the less complex engines. An advantage of the EGT over the cylinder head temperature gage is one of an almost The Exhaust Gas Temperature (EGT) immediate response to manual movement of the mixture control. as as it is not a movement of the control. And Fuel Management long rapid Remember that the peak or point of maximum needle detlec- tion of the EGT gage is the basic reference for fuel manage- Since so many operators of our engines frequently ask us ment. If an operator has experimented with the EGT at the about the use of an exhaust gas temperature with our engine manufacturer's recommended cruise power, he observes powerplants, perhaps we should examine the system, and also that gradual leaning does result in peak EGT. The location of set how it relates to fuel management. peak EGT on the gage will also vary with different power set- One of the better publications describing the EGT that we tings, changes in altitude, and change in ambient temperature. have seen was put out by Alcor Aviation, Inc., P. O. Box 32516 From peak EGT, either increasing or decreasing the fuel of San Antonio, Texas 78284. This excellent booklet is titled, flow causes a decrease in EGT. When richer than peak EGT "EGT and Combustion Analysis In A Nutshell", and is there is excess fuel, and when leaner than peak, there is excess available free to interested operators. air. An EGT system is not a complex or expensive item to in- Peak EGT with a float-type carbureted engine is frequent- htall. The more economical kit consists basically of the gage, ly a vague point because of less efficient distribution (than fuel wiring, and probe (see illustration). The system generates its injection) to the individual cylinders by this type of metenng own electricity to operate the instn~ment. device. As a result, float-type carbureted engines tend to operate smoother at +250 to +500 F on the rich side of peak EGT. Whereas, the fuel injected engines at 250 H.P, and higher will provide a precise peak, and theretbre the EGT system is likewise a more precise method of fuel management with fuel injection DEFINITION OF PEAK EGT the pilot attempts to go leaner than peak EGT, (with fuel InJt~c- A tion the simple definition of peak EGT is given us by engineer- only), power decreases rapidly as fuel flow decreases. ing as the chemically correct mixture of fuel and airwhich BEST POWER MIXTURE gives 100% utilization of all the fuel and all the air. Remember, Best Power Mixture, or sometimes we said earlier that at mixtures leaner than peak EGT there is termed Maximum Power Range, as depicted on the EGT is in the nn4e of excess air, and at richer mixtures, excess fuel. Operation at peak gage, plus 1000 F to 1500 F on the rich side of Best Powlrhlix- EGT, particularly on long flights, can be an advantage not on- peak. ture will provide fastest indicated for a cruise ly for purposes of increased range, but there is less likelihood airspeed power it is not considered a of spark plug fouling as well, setting, although generally practical economic mixture for cruise purposes. However, Best Power Don't be surprised to see variations in temperature between Mixture generally provides a safe amount of fuel for a power individual cylinders where there is a probe for every cylinder. setting higher than the engine manufacturers recommended It is fairly typical to see an average 1000 F variation with fuel cruise, except that needed for takeoff Satisfactory ''Nle and power. injection, as much as 2000 F variation with a float-type car- of thumb" compromise between Best Economy and Best Power buretor, The latter (carburetor) variation tends to be greater Mixtures has been at plus 500 F on the rich side of peak EGT. because fuel/air distribution is not as good as with fuel injec- Again we that maximum EGT) does tion, In cold outside air temperature flight conditions, the mix- repeat leaning (peak not damage an engine at the manufacturers recommended tTure distribution is poorer for both fuel injected and carbureted engine cruise is caused maximum engines. However, with the float-type carburetor operating in power. Damage by leaning at higher than recommended cruise where the manuals do below freezing ambient temperatures, the fuel/air distribution power not spell it out or allow it, and when the aircraft does not have 3 com- is definitely worsened, resulting in noticeable variations in set of reliable temperature between individual exhaust stacks. plete engine instruments to protect the powerplants. Excessive leaning under the latter high power con- It is also important to understand that leaning to roughness ditions can cause detonation and/or preignition and possible at the engine manufacturers recommended cruise is not power engine failure. an indication of detonation, but indicates normal characteristics The exhaust can be a valuable aid of distribution to the individual cylinders. The roughness in- gas temperature system in proper leaning at cruise power, with fuel dicates that the leanest cylinder has become so lean it is begin- particularly injection powerplants. It is hoped that this write-up will help the ning to miss. This is typical of an engine with a float-type car- operators of Lycoming engines achieve the best effi- buretor. Damage to an engine from leaning does not occur at possible cient use of the EGT system. the manufacturers recommended cruise power, but takes place at higher than cruise power. If we were to sum up the major advantages of an EGT to the operator, they are as follows: As far as the pilot is concerned, operating on the lean side ofpeak EGT can only be accomplished with fuel injected engines I. Saves fuel an economy aid. of at least 250 HP or higherbecause the fuel flows in the lower 2. Aids proper mixture control more precise fuel are so small. It isn't horsepower engines possible with float- management. type carburetors because of the fuel/air distribution problem. 3. Helps increase range. Leaning past the peak is not recommended. 4. Detects some types of engine troubles. LIMITATIONS OF POWER AT PEAK EGT 5. Aids peak engine performance at cruise. Textron Lycoming allows leaning to peak EGT at 75% 6. Helps prevent spark plug fouling. power and below on our direct drive normally aspirated engines. 7. Fits any General Aviation piston aircraft We limit operation at peak EGT on our geared, supercharged engine. powerplants at 65% power or below. With Lycoming tur- 8. Can be used with carbureted or fuel injected engines. bocharged engines, where the EGT gage is used to interpret turbine inlet temperature (TIT), the maximum allowable TTT specified in the POH should not be exceeded when attempting An to find a peak temperature by manual leaning. Where a cylinder Explanation Of Power Settings head temperature is also available, the operator ought always A recent letter received here at the asked a to cross-check the head temperature as a routine procedure when factory question we are hearing more often in recent months: leaning, and remember that whenever CHT reaches the maximum before reaching peak EGT, then CHT rather than EGT "Is it a fact, or is it fiction, that engines with constant speed should dictate the leaning. props should not use power settings where inches of mercury exceed RPM in hundreds? I am referring of course to non- BEST ECONOMY MIXTURE turbocharged engines in general--". Best Mixture Economy as it relates to the EGT system The this answer to question is easily found in cruise power begins at peak. For all with practical purposes Lycoming charts of the airframe Pilot's Operating Handbook. Whatever EGT is at the of Best mix- engines, peak right edge Economy the combinations of RPM and MP listed in the charts thev ture, and is our of reference in the Best only practical point have been flight tested and approved by the airframe anh Economy Mixture range. At the manufacturers recommended powerplant engineers. Therefore, if there are power settings cruise power. peak EGT causes a slight loss of horsepower such as 2100 RPM and 24" MP in the power chart, they are usually reflected in two or three miles hour of If per airspeed. approved for use. The confusion over so-called "squared" power settings Then, follow with the appropriate manifold pressure now (i. e. 2400 x 24" MP), to have been a from appears carry-over that the mixture and RPM have been correctly set to accom- some models of the old iadial engines which were vulnerable modate the increased throttle. to excessive bearing wear where a MP higher than "squared" DECREASING POWER--Most models of our engines re- was used. More pressure on the bearings with the higher than quire the basic procedure for decrease of power by retarding "squared" MP was the cause of their problem. However, throttle, followed by RPM. However, we do have an excep- changes in design, metals and lubricants permit changes in tion in several older models of our geared normally aspirated operation in the more modern flat opposed powerplants. powerplants such as the GO-480 and GO-435 series. In the climb Let's look at the power charts in a couple of the Pilot's configuration, we recommended full throttle throughout the Handbooks of two different aircraft Operating manufacturers, climb for internal fuel cooling with RPM reductions initially but where both are using the four cylinder 200 HP Lycoming to 3000 RPM and then 2750 RPM for prolonged climb. engine, Turbocharged and Supercharged engines require careful ap Cessna's Model 177 RG, using the Lycoming plication of the basic power sequences as outlined in the begin- 1O-360-A1B6D, in the cruise range at 6,000 feet lists a cruise ning. It is also possible to create a "like" overboost on these power setting range at that altitude of anywhere from 2100 RPM engines by going to takeoff manifold pressure at cruise RPM. to 2500 RPM with variations all the way from 18" MP to 24" such as might take place in an unexpected go-around. The MP. They list a recommended Power setting for 664% power stresses and pressures on prop and engine would create a threat at 2100 RPM at 24 n MP. to both. The Piper Arrow, powered by the Lycoming 1O-360-C series engine, lists the following cruise power settings at 6,000 feet in their chart at 65% at full throttle (about 23 MP) power Considerations For Low Power x 2100 RPM. Low RPM Cruise The complete chart for 65% power is shown as follows:

Altitude 2100 RPM 2400 RPM The high price of aviation fuel is causing aircraft owners SL 25.9 MP 22.9 MP and pilots to review their operations in search of ways to keep 1,000 25.6 MP 22.7 MP operating costs down. Those operating aircraft with controllable 2,000 25.4 MP 22.5 MP propellers have been requesting information on cruise opera- 3,000 25.1 MP 22.2 MP tion in the low RPM range 1800 or 1900 RPM for example. 4,000 24.8 MP 22.0 MP The number of queries received indicates a great deal of interest 5,000 F. T. MP 21.7 MP and, therefore, it seems appropriate to share the information 6,000 F. T. MP 21.5 MP on this subject with all of our readers. The Textron Lycoming Engine Operator's Manual has per- After studying the power chart, the pilot would undoubtedly formance curves applicable to each engine series. The curve then ask what combination of RPM and MP would be best to for the 1O-540-K series, 300 horsepower engine is printed here use at cruise. We recommend the pilot try the various combina- as a reference for this article. The curve does provide data on tions offered by the power chart over a five-minute period when the maximum manifold pressure (MP) which may be used with flying in smooth air, and use the listed RPM and MP Combina- any particular RPM at sea level and at altitude. The limiting tion which gave the least vibration and the lowest noise level. manifold pressure line clearly restricts high manifold pressures The Pilot's Operating Handbook is the basic reference for with low RPM settings. There is a good reason for this; high the pilot as this subject illustrates. manifold pressure and low RPM is similar to allowing your automobile to lug up hill in fourth gear. The pinging you hear in your automobile tells you that detonation is occurring and you should shift down to a lower gear. In an aircraft, detonation is not likely to be heard, damage occurs in the engine and Basic Power Sequence it is then too late for preventive measures. For this reason. should be within the limitations established (Governed Engines) engine operation in the Pilot's Operating Handbook (POH).

TQ INCREASE POWER first, enrich mixture, increase Although there are restrictions, it is quite apparent that RPM, then follow with throale. operation is possible in the 1800 to 1900 RPM range. The real is whether there is actual benefit. TO DECREASE POWER first, reduce throttle, reduce question any RPM, and then adjust mixture. One of the first considerations of low RPM cruise is that this low should not be used the INCREASING POWER enrich mixture first to ensure power settings during engine break-in period. During the break-in period, power settings of protecting the engine against damage from higher power when at least 7546 or more should be used for climb and cruise. Low previously leaned out for a lower power setting. power for break-in may result in glazed cylinder walls and high Next, increase RPM because the engine and propeller would oil consumption which can only be cured by cylinder removal have undesirable and stresses with a high manifold pressure and rehoning. pressure and lower RPM in some models. CUIM Y) 1YJ3 moving vertically down the curve to 1900 I~ltFmR Y1 UI[C mrMICTWC TrrY Pr*au~ R*Os~I I I I I I LMYI)K 1(4 au RPM while URCRIFT UWIE maintaining 24 inches of MP will PERFORY"WCE DLTI lamor i ruru*mi feSUlf i, a ur~ra o*l* rru loss of about 30 and v*roo nm YUYUI P(I~R YXIICIE horsepower I i I I_l.uraru*rao I II IllunmonrmarnorPo therefore arevised IW(IIÂ·'n~rUUrll(YOÂ· Inllm~l\a powerof5546. Because fC sauFÂ·* ~4 MCm cap~Essw amo this power is near the *UL(I1IHLlw tllY NELIIXtTWI setting limiting rUUm~ r~ rRDn~l %nax RU-IOW manifold pressure line, it would be inap- 3 NawoE.uuu 10 mrrauL urmRE N1ID propriate to increase the manifold WED pressure MlulIUI* amnD* rOI ru* lo'r uu~a rru 5 setting at 1900 RPM since the limiting 1~'" manifold pressure might be exceeded. *w Quite frequently, someone will ask if the t engine will last longer if it is run at a slower RPM setting. The answer is "No". Open- tion at the recommended cruise RPM settings should allow the engine to reach TBO if it has regular oil changes, is operated within normal temperature ranges, and is well cared fo' and KI I ;I I r hll~n 1 I IIl I I by pilots maintenance personnel. In rulromr summary, it is possible to run an g engine at cruise using 1800 or 1~00 RPM. A curve from the Engine Operator's Manual should be consulted to insure that manifold pressure limits are not exceeded. In ~P*oaumur hÂ· reality, at these low I, n Ic ,I I~ tJ 2) n n n t( n lad i r I II b IJ u ii Â·saoiiiinii operation RPM settings is not s11594 ILllr(IY H1 r*aa~*or nÂ·n I very practical because the very low power operation may induce drag and inefficiency. Sea Level and Altitude Performance Curve IOÂ·540-K, -L, Â·M, -S The recommendations of the Pilot's Operating Handbook provide the best There are some other considerations of low cruise power opera- guidance for operation of an aircraftlengine tion. Low manifold pressures, below an arbitrary point of perhaps combination and therefore the limitations of 18 inches for continuous cruise, may cause excessive oil usage, the POH should be observed. and oil build-up in the valve guides which could lead to sticking valves.

Particularly during cold weather operation, low power operation may allow both the oil and cylinder head temperatures to fall below the normal range. This is detrimental to good engine health. Oil temperature in POWER TABLE SETTING particular must be maintained at a minimum LYCOMING ;MODEL IO-540-K, -L, -M SERIES, 300 HP ENGINE of 1650 F. At lower temperatures, the P"". ~dÂ· moisture which gathers as a result of com- HP jj~ Riled 19j HP 6SL~ R~cd 225 HP ~j4 RÂ·lcd Air. fcmp RPY end MAN. PeI* RPM end MAN. Pm.. RPM end M4N RcÂ·r bustion will not vaporize and be F,,I I Â·F expelled. 2100 2200 u00 2400 2100 poe 2300 2~00 2200 uno 2~00 This can cause dilution of the oil which SL detracts from the lubricating properties. 39 22..3 21.8 21.2 20.; 25.6 21.7 23.8 23.2 27.6 26.6 25.8 1.000 33 22.3 21.6 21.0 20.5 2.5Â·.3 2Â·1.1 23..5 22.9 27.3 26.3 23.~ The Pilot's Handbook for Operating 2.000 32 22.1 21.-1 20.7 20.2 25.1 21.2 23.3 22.7 27. 1 26. 1 .,.i.2 each aircraft a of provides variety power set- 3.000 21.9 21.2 20.5 20.0 21.8 23.9 23.0 22..5 26.8 23.8 ?j.9 which most often show 2100 tings or 2200 aooo 33 21.; 21.0 20.3 19.8 21.6 23.7 22.8 22.2 26.3 23.6 9-1.6 RPM as the minimum for cruise. The table ~I 21.3 20.8 20.1 lc).6 2Â·2.3 23.3 22..5Â· 22.0 25.3 21.Â·1 shown here is for the IO-540-K series engine 6.000 38 21.3 20.6 19.8 19.3 21.0 23.2 22.3 21.7 23.0 "1.1 which was illustrated in the curve shown 7.000 3-1 21.0 20.1 19.6 19.1 23.7 22.9 22.0 21.3 23.8 earlier. The power which may be obtained 8.000 31 20.8-20.2 19.1 18.9 22.i 21.8 21.2 when using 1800 or 1900 RPM is generally 9.000 27 20.6 20.0 19.2 18.6 21.3 21.0 not for continuous cruise practical because Io.ooo 23 20.1 19.8 19.0 18.4 21.2 20.7 the aircraft must be flown at a high angle of Il.ooo 19 20.2 19.6 18.7 18.2 20.-1 attack which may have a detrimental effect 12~000 16 20.0 19.1 18.5 18.0 on air flow and which also induces cooling 13.000 12 19.2 l8.J 1;.7 more drag and, therefore, inefficiency. 14.000 9 18.0 17.3 1.'.000 As an example, the power setting table I 16.9 shows 2100 RPM and 24 inches of MP to To maintain constant power, correct manifold pressure approumately 0.18" HR for each be 65~ power at cSOIW) feet on a standard day. 10"F variation In induction air temperature from standard altitude temperature. Add this same on the altitude Picking point per- manifold for air pressure temperature above standard: subtract for temperature below fbrmance curve, it is possible to see that standard. Engine Operational Tip and himself.

We will emphasize here again, as we have in the past, that Lycoming does not recommend running a fuel tank dry as these normally aspirated (not supercharged or turbocharged) routine procedure. Operators have related to us many of their direct drive engines with a manual mixture control should be experiences where using this undesirable technique has resulted leaned at cruise powers of 7546 or less at any altitude while in forced landings when the fuel selector broke and a tank with cruising. With this type of power plant, the 5,000 feet reference fuel could not be selected, and in another instance where the was only for climb purposes. The recommendation during climb fuel selector was frozen in one position. was to maintain full rich in the climb from sea level through However, a flight instructor recently recounted to us a "hair 5,000 ft. density altitude. If the climb was to continue higher raiser" during a flight in a borrowed single engine turbo- than 5,000 ft., mixture should be leaned for engine efficiency charged aircraft over the Rockies. Fortnnately, he was aware and smoothness. of his friend's habit of running a tank dry. When the instructor Damage to a direct drive normally aspirated engine from refueled the aircraft before flight, he observed that both out- excessive leaning is done at higher than cruise power, or above board tanks were completely empty. After filling them, he 7596 on the direct drive engines we have been discussine, and climbed the aircraft eastbound to 22,000 feet in order to top above 6596 power on the geared and supercharged engines. a heavy overcast which had dangerous icing. Part on this way Therefore, the principal consideration in leaning is the percent trip the instructor switched to one of the ouf60ard tanks--at of power at cruise, and secondly altitude. Even though the pilot which point the engine temporarily quit. After all the necessary of a direct drive nounally aspirated powerplant is only flying moves under this emergency, he was finally able to restart his 1,000 feet above sea level (for example), if he is at 75 Z power but in the meantime he had lost altitude down engine; precious or less he should lean the mixture. to 19,00~feet which put him in the overcast. The aircraft began Leaning is not the easiest subject to write about when a to ice up, and gain weight, and the wastegate had manufacturer has as many varieties of engines and fuel meter- warped in a slightly open position due to sudden cooling, which ing devices as Lycoming offers. Our Service Instruction 1093 created a reduced power condition. These two factors made it covers most aspects of leaning our engines across the board. impossible for him to climb out of the icing in the clouds. This discussion has been largely limited to the misunderstood With high mountains below him the declared an pilot 5,000 ft. reference with normally aspirated direct drive engines emergency, and fortunately received a radar steer to an airport with a manual mixture control, and limited engine instrumen- above minimums. A later test showed he had a vapor lock in tation, in order to help prevent any similar accidents in this type the lengthy fuel line from the outboard tank to the engine. Fuel of equipment. The more complex engines and aircraft are pro- injection, particularly, is vulnerable to vapor lock from empty vided with more complete engine instrumentation to protect the fuel tanks. So don't fuel tank runa dry as routine procedure. powerplants.

A Special On Fuel Management Fuel Starvation Accidents

While reading the report of a recent accident that could have Pilots interested been prevented, it occurred to us that despite all our efforts and are generally in reading about the causes and of aircraft accidents because there is basic those of others to inform people who operate our engines, peo- prevention a sur- vival instinct characteristic in pie are still confused or they misunderstand some basic aspects most people. As a result, pilots are curious to learn what caused of leaning. In this particular accident, it was caused either by accidents so they can avoid lack of understanding, or confusion over the 5,000 ft. reference a similar experience. There is much to be learned from the in leaning. We will attempt to clarify this area ofmisunderstan- unhappy experiences of other pilots in a special National ding; but first let's review the facts concerning the accident to Transportation Safety Board study ofU. S. general aviation accidents fuel starvation. The is observe how it happened and then learn how to prevent a involving report interesting and similar accident, can be helpful to those who fly.

The private pilot involved had planned the same VFR 4:30 As an engine manufacturer we are sensitive to any state- hour cross-country which he had made several times previous- ment or report concerning an accident which cites "engine ly without refueling enroute. During his training, the pilot had failure" as the cause, when the facts reveal it to be engine stag been told erroneously not to lean his direct drive, normally page caused by fuel starvation, and not the "failure" of the aspirated Lycoming engine below 5,000 feet. Until the day of engine as such. However, the principal purpose in reviewing the accident, all flights to his same destination had been made this report and bringing it to other attention, is to prevent this at 5,000 feet or higher, and as a result he had leaned the mix- kind of accident from continuing. ture and always made the trip without refueling. This report entitled "Fuel Starvation", analyzes fuel star- On the day of the accident, about half of the return trip was vation accidents involving 29 selected makes and models of made at 7500 feet with the mixture leaned. However, the rest fixed-wing General Aviation airctft. Of the selected group. 12 of the flight was made at 2300 to 3000 feet with the mixture aircraft were found to be more susceptible to fuel starvation than rich. He ran out of fuel and crashed a mile short of the airport, the others. Accidents involving these 12 aircraft were review- killing two passengers and seriously injuring another passenger ed in detail to define the primary causes of fuel starvation and other associated causal factors. Chronic difficulties and influen- noticeable change in engine temperatures. However. enginler- tial factors, found in the accident file review and technical deal in ing people facts and not limited observations, so Lvcom- research, were discussed ~with representatives of the Federal ing Engineering ran a test in their test cells with our O-32b (150 Aviation Administration and three manufacturers of general HP) four cylinder engine certified for 80 octane fuel. Thev tested aviation aircraft. From these discussions, remedial measures the engine with 80 octane, then ran the engine again with 10Q to reduce the number of fuel starvation accidents were octane. and charted the results as shown in the illustration. Note formulated, that O represents 80/87 octane fuel, and X represents 100/130 low lead fuel. The fuel flows and charted Recognizing that fuel starvation has remained a significant temperatures were at 55ro, 65%, and 75% problem in general aviation safety, the NTSB examined 192 ac- powers. cident for a two For the reports year period. purposes of this There were no cylinder head temperature differences be- study, fuel starvation is defined as the interruption, reduction, tween the two fuels. or complete termination of fuel flow to the engine, although FUEL STORAGE ample fuel for normal operation remains aboard the aircraft.

Another we have been While manufacturers expressed the general opinion that fUel question asked concerned storage of aviation We contacted a senior system design improvements and operational procedure im- gasoline. engineer of the Shel I Company who us some answers. Shell's in- provements could diminish fuel starvation problems, they stress- gave experience dicated that 100 octane aviation fuel in sealed drums is ed the importance of pilot awareness with regard t~iproper fuel kept good for five The same 100 octane stored system maintenance and operation. The industry, through the (5) years. undergronnd with occasional use, and good is for use General Aviation Manufacturers Association, completed two housekeeping, good to two the time shown fine projects which could lead to the elimination of several fac- up (2) years. Beyond here, a gum substance develops that sticks to the carbuertor or fuel tors which contribute to fuel starvation. One was a study of the injector and disturbs fuel/air distribution--which feasibility of fuel system design standardizati~n in general avia- proper means rough and some loss of Old fuel also causes hard tion airplanes; the second is a standardization of the format and running power. content of the Pilot's Operating Handbook. starting. NO MIXING OF FUELS

Our experience as an engine manufacturer has proven time after time that mixing aviation octane fuels in the airplane tank creates trouble. The one best for fuels is the 0-320 (150 HP) place blending at CIL HEAD TEMPS refinery. The fuel people confirm our experience that different vs octane fuels when mixed do not necessarily give some in- FUEL FLOW termediate numbered, fuel, i. e. 100 octane mixed with 80 oc-

tome does not provide a 91 octane fuel. The pilot cannot be sure of cut HD TEUPS knowing what octane he has when mixing fuels.

L320RPN Q SSX Induction Icing 8 nmnsu We used to talk about carburetor icing in past years, but with all the modern fuel metering devices used today, a more Fun FLOW LB /nR up-to-date terminology describes this flight condition as induction system icing. The latter term includes all of fuel meter- LEGENO types Q-0 as well W/I~ EXXON G*SOLINE-OSJse PB/GaL ing (fuel injection as carburetion), and also the pans I-x 100/1~0 EXXON GISWCE.Z Os,, PB/GIL of the induction system where ice can accumulate such as the air filter, or bends in the system, as well as the critical areas of the fuel metering device like the throttle plate in the float More About Fuels type carburetor.

If operators understand what happens when the fuel meter- In a previous "Flyer", we answered a question concerning device (carburetor or fuel fuel into the air ing fnels which a number of operators had asked. They injector) inject being sucked into the induction the as it wondered if the new low lead Grade 100LL was used in our system by engine operates, they can take suitable to avoid engines certified for 80 octane aviation fuel, would the engine precautions preferably or eliminate induction system ice. But also need to under- run hotter? We pointed out that this was a good question because they stand how the engine reacts when heat is to in- many small airplanes requiring 80 octane fuel do not have applied prevent duction icing. cylinder head temperature gages, and oil temperature change tends to be slow and also difficult to read unless there is a marked There are two types of induction system ice: rise in temperature. 1. Impact ice--forms on the air filter and bends in system. When we flew a few airplanes requiring 80 octane fuel. 2. Refrigeration ice forms in float carburetor as result but used type Grade 100LL (blue) we could not observe any of fuel vaporization and low pressure. goes through the engine as water, causing some of the roughness and more power loss. Therefore, unless the pilot knows what i" is actually happening, the stress and confusion of the situation will tend to frighten him out of using heat, and thereby could result in losing his engine to icing. But most of all he must realize that despite temporary roughness and attendent moderate power loss, the pilot is not damaging his engine at a cruise power of 7545 or less with any amount of heat.

RELATED FACTORS WHEN USING CARBURETOR HEAT

When using heat, there are related factors or influences to remember. The engine loses about 151 of its power when full heat is applied. Carburetor heat also creates a richer mixture which may cause the engine to run rough, particularly at full I c~e_ heat. If there is any throttle available, the power may be increased 2 inches of MP over that previously shown with a governed engine, and an increase of 100 RPM with a fixed pitch prop. The mixture should be adjusted lean (at cruise power or whenever heat is Furthermore, CARBURETOR ICE less) applied. any application or removal of heat would call for an appropriate adjustment of the mixture during cruise. At lower power conditions such as ICING INDICATIONS required during flight in the traffic pattern, it may be imprac- tical lean the mixture. Do not use heat for takeoff or climb Typical icing indications to the pilot, where he failed to to on as it is not and it bring anticipate the need for heat, vary from a gradual loss of power, Lycoming engines necessary, may on detonation and An to the to vibration and roughness. it simply depends on how the ice possible engine damage. exception latter be in the severe of the Arctic which forms in the induction system. With the float-type carburetor, might temperatures calls for a or a severe weather since ice forms on the throttle plate, the pilot might note some special knowledge, special condition. stickiness when he attempts to move the throttle. Where there is a fixed pitch prop and the float-type carburetor, the pilot will If you are wondering how long to continue the use of heat, note a gradual loss of RPM and airspeed as ice forms. The same it would depend on the icing conditions. If icing happened to model engine, but with a constant speed prop, will indicate car- be severe, then heat should be used as flight continues in known burctor ice by means of a loss of manifold pressure and the ac- or suspected icing conditions. We have found in our flight tests companying loss of airspeed. on various models of Lycoming engines, and with special detonation pickups, that at cruise power with full heat or alter- THE FLOAT-TYPE CARBURETOR AND ICING nate air, we have never experienced detonation or damage to Under certain moist land "moist" is a word at- key here) the engine. If that is difficult to believe, a turbocharger heats when the relative is more than mospheric conditions, humidity the induction air hotter at high altitude than the typical carburetor with air from 200 to 900 50%, temperatures ranging anywhere heat or alternate air, without causing any detonation or damage it is for ice to form in the carburetor. The F, possible rapid to the engine. The principal concern of the pilot under icing in the carburetor is caused the coaling float-type by absorp- conditions is not the possibility of detonation from the heat at tion of heat from the air of the fuel, and during vaporization cruise power, but rather to keep the engine running no matter also due in to the air a low part high velocity causing pressure how much heat is required. in known or suspected icing condi- area through the carburetor ventunl. As a result of the latter tions, follow the instructions in the airplane Pilot's Operating the in the chamber of the two influences, temperature mixing Handbook. If the airplane does have an induction air or car- carburetor as much as 600 F below the may drop temperature buretor air temperature gage, the thinking pilot who anticipates of the air. If this air contains a amount of incoming large the possibility of induction ice can prevent it by maintaining the can cause in the form moisture, cooling process precipitation heat during cruise and letdown. Any aircraft without an induc- of in the of the or throttle ice, generally vicinity "buaerfly" tion air gage must use either the full heat or full cold position. and build to such an extent that a in plate, may up drop power as an unknown amount of partial heat can actually cause induc- output could result. If not corrected, ice accumulation may cause tion ice in the float-type carburetor, particularly where there complete engine stoppage, is moisture in cIystal form in the incoming air that would or- Now the thinking pilot will anticipate possible icing and dinarily pass through the induction system without any problem. utilize heat before the ice forms. However, should he fail to Partial heat melts these crystals and they form carburetor ice anticipate icing with the float type carburetor and ice begins in the venturii when they come in contact with the cold metal 200 to form. he must definitely use the full heat position initially of the throttle plate. At a temperature of F or below, any be in order to be sure of eliminating the ice. Using full heat will moisture in the air is frozen and heat should not used. Par- with induction cause a loss of power and possible engine roughness. Heated tial heat may be possible an temperature gage. air directed into the induction system will melt the ice which which means less power loss. STANDARDIZATION OF USE OF HEAT type of system. It is to differentiate between the necessary care_fully methods All Lycoming pressure carburetors have automatic mixture of heat the applying to various flat opposed piston engines in controls. On the ground, any application of heat will affect the induction icing conditions. Most light airplanes with float-type AMC unit so as to make it temporarily unpredictable in its ef- feet on the carburetor. If carburetors do not have a carburetor air temperature gage, and for some reason the pilot used heat on the e. the heat he therefore must use the heat position only in the full on, or full ground (i. checking system), must walt at least two minutes before takeoff in order to avoid an erratic off positions. and with the mixture leaned to compensate for fuel flow because of the effect of the heat the AMC unit. the richer fuel/air ratio mixture with carburetor heat, on Don't forget to check operation of manual alternate air control,\ Because instructors flight and other experienced pilots fly before entering icing flight conditions. If alternate air is used, various models of manufacturers' and it would airplanes engines, remember that heat means some loss of power and a richer mi.u- be helpful to standardize the instruction of the use of heat in ture. Do something to get the power back increase power the on aircraft the landing configuration using float-type car- 2 inches manifold pressure over former setting,and lean mi.u- buretor. Textron has Lycoming no objection to the consistent ture with a manual mixture control. standardized use of carburetor heat in the landing configuration. CONCLUSION THE GO-AROUND Now that the operator understands how ice forms in the Whenever carburetor heat is used in the landing configura- fuel metering device, and how the engine reacts when heat is he can with tion, and a go-around takes place (either unexpected or touch- applied, cope an icing problem without panic because he knows what is in his and-go), there are some important phases of operation for the happening powerplant.

pilot to remember. We don't insist on throttle first, nor heat off first. However, if throttle is first, it must be a smooth application. A straight-arm of the throttle generally results in the carburetor failing to respond, and no power. Cold Weather Tips

If the pilot forgets to remove carburetor heat on a go- let's make it around, loss of power may become critical at low altitude and First, clear that we are speaking of normal cold weather low airspeed, In addition, on the higher performance operation experienced at temperatures to -250 F. For powerplant, there is the danger of detonation and/or engine tips on operating below -250 F., we'll let the people who operate in those us the word. damage using full heat and takeoff power on the go-around. temperatures give

A good place to start would be to realize that we are all OTHER TYPES OF INDUCTION ICING. stuck with three cold weather starting penalities. They are: Thus far our discussion has limited itself to the float type 1. The lower the temperature, the more cranking energy carburetor which can incur ice in VFR flight conditions if there required. is the right combination of moisture, temperature and fuel mix- 2. The lower the temperature, the more reluctant the fuel/air ture. In the case of fuel injection and carburetors, it pressure mixture is to ignite. is the IFR type flight condition which generally causes induc- 3. The lower the temperature, the lower the battery tion system icing. The fuel injected engine does not have the output. threat of icing at the venturii; but other parts of the induction Now that we are aware of these penalties, let's not impose system can gather ice such as bends in the system, the impact other unnecessary penalties upon the engine through neglect or tubes, or on the air filter. lack ofknowledge. Therefore, before cold weather sets in, have the spark plugs and magneto points inspected for serviceability The pilot of a turbocharged powerplant should not be too and proper gapping. Check for proper operation of carburetor concerned with induction system icing except in extreme con- heat controls, priming, exhaust, induction and ignition ditions because of the high temperature of the induction air when system. A defect in any one, or combination of several of the aforemen- the compressor is running. However, slush/snow can be a tioned items, can be the difference between no start or good strut. blockage threat to the air filter if there is not easy availability This next cold weather tip is worthy of a separate little to alternate air, impact ice at high altitude with some turbo- sentence all of its own have the heating system checked for charged engines may cause a loss of4 to 6 inches ofMP when leaks. Remember, you can't smell carbon monoxide. going to the alternate air source, Let's examine some tips, starting'with preflight inspection The pressure carburetor is similar to the fuel injector in right through actual flight to landing. that it is not very vulnerable to icing, other than that outlined Guard condensation in the fuel in the previous paragraph. When a float-type carburetor is against system. Simplest fuel tanks full. placed next to a pressure carburetor for a visual inspection and precaution--keep note that the float carburetor fuel is comparison, jet below the Drain the fuel sump religiously before the flight. Don't at- venturi and thronle which fuel is butterfly, means being squirted tempt to save fuel here. Moisture may collect at a low point into the worst possible place for icing the carburetor ven- in the system and a skimpy sump drain may only move the turi. On the other hand, the pressure carburetorjets are squirt- moisture to another point in the system. fuel farther downstream ing beyond the venturi refrigeration At ground temperatures of 100 F and below, the engine chamber. which accounts for the less likelihood of icing in this and complete oil system should be preheated. Once an board the aircraft, check the fuel selector valve Again, mostly for the novice, don't run one set of fuel tanks for freedom of movement. It may be frozen fast and you'd bet- nearly dry before switching tanks. Switch with plenty of fuel ter find it out while still on the ground. remaining in the tanks first used. This is ''money in the bank''. should find the selector valve frozen. Assuming the engine has kicked off on the first attempt, you check for indication of oil pressure. Again, learn the Avoid power-off let downs. When possible, plan your characteristics relative to response of oil pressure indications descents far enough away from your destination that a power of your aircraft-engine combination. On most single engine air- let down can be made. If a fairly rapid descent must be made. craft an almost immediate response is noted. On twin engine we suggest the aircraft be slowed and the gear and flap be aircraft the response may be much slower. On some twins the lowered so that some power may be retained. oil pressure may go up and during warm up may drop again Should a reduced power let down be necessary through for a short period of time then again rise to normal. All cases possible icing conditions, don't hesitate to peak the exhaust mentioned may be normal, but the important thing is to know temperature gauge if one is installed. This will assure the greatest what to expect from your aircraft-engine combination. possible engine heat for the power setting selected. After start, do not idle engine below 1000 RPM. It's not good practice to idle engines below 1000 RPM at any time. This is particularly true during-cold weather to prevent lead fouling of spark plugs. (Exception Piper Pressurized Navajo). CoId Weather Operations

No take-offs should be made with carburetor heat on. The only exception being, should outside temperature be so low that A note that came in the mail from a Fiver reader included an increase in RPM is noted with the application of carburetor a suggestion which went something like tbis, "How about an heat, region). article dealing more extensively with the cold start problem..." A review of issues indicates that this is Now here's a tip for the novice pilots. When setting up for past Flyer suggestion a one. It has been a time since cold weather con- cruise configuration, be precise, read your instruments and good long any siderations have been addressed in the Fiver. and as the mail- -~emembcr what you read. Example: If you decide on 22 inches list continues to there are readers to share of manifold pressure, set it right on 22. If the RPM is to be ing grow, many'new our on this 2350, make it 2350. Select an altitude;Trim the aircraft to hold thoughts subject. that selected altitude. Note airspeed. Now if anything Most of the time, we think of starting any engine as a very changes, barring turbulent air, it has to be a change in power. simple process. Just engage the starter and listen for the engine Perhaps it is carburetor or induction air icing. Suppose you pick- to start purring. Unfortunately, when the weather turns cold ed up a bit of carburetor ice and the engine suffers a slight power it is not always that simple. When dealing with a reciprocating loss. There will be a slight drop in manifold pressure, a loss aircraft engine, it may be essential to get a start on the first try in airspeed. and the aircraft will want to lose altitude and if you in order to avoid icing over the spark plugs and making an im- hold altitude you'll find back pressure on the wheel is required. mediate start impossible. In order to achieve a start on the first Therefore, even though you didn't discover the power loss try, there are a number of factors to be considered. Those fac- through instrument scanning, you'll get a warning through the tars will be discussed in the following paragraphs. wheel or stick. "heavy" Let's start with the general health of the engine. When at- During cruise, check your oil temperature. Should it be tempting a start under adverse conditions, it is imperative that normal 1650 lower than (below Fl we recommend steps be taken the engine be well maintained and in excellent operating con- the to increase temperature to normal. Install the oil cooler kit dition. Spark plugs and magneto points should be properly gap- supplied by the manufacturer. ped and ready to function effectively. In addition to the ignition the of other such Remember, engines must breathe and in so doing, they take system, proper functioning systems as the and carburetor heat have in moisture. Normally the oil temperatures are high enough to induction, priming, exhaust, can effect the and of the evaporate this moisture. If oil temperatures are too low, the an on starting operation engine. will moisture collect in the crankcase and rocker box covers Although it might be good procedure to use an external causing rust. We have drained many a wet sump engine that power source for starting during very cold weather, most of contained as much as a quart of water. Keep the operating us expect our battery to do the job. We should remember that temperatures up, the battery is handicapped by cold weather. Particularly when If flight is planned for bad weather, the preflight inspec- a single viscosity oil is being used, the colder the temperature. tion should include observation of the relief opening in the the more cranking energy required. Combine this with reduc- engine breather tube so that any freezing of moisture at the end ed battery output at lower temperatures and it can be a serious of the breather will not result in a loss of engine oil. (See ''The handicap. Whistle Slot" in this book.) While on the subject of batteries, remember that freezinl During flight in very low temperatures, exercise constant temperatures provide a perfect opportunity to destroy an alr- speed props about every 30 minutes to help prevent congealing craft battery. The battery with a full charge survives nicely. of oil in the prop dome, but one which is discharged will freeze. Once this happens, the can be remedied by the battery, so It Should one engine of a twin, for any reason indicate the problem only replacing is worthwhile to take measures. Shouldthe b3t- prop must be feathered, don't tarry too long with reduced power very preventive be run down an to start, do not leave It; in very cold weather. At reduced power, the oil may congeal tery during attempt it immediately. And finally, be certain making t'eathering an impossibility, get charged absolutely that the master switch is OFF while the aircraft always is park- flies. When the correct number of primer strokes for each ed between flights. If left on, the will and battery discharge temperature range has been established, the engine will usual- freeze. These rather miribr mistakes can be start quite expensive. ly very quickly. We may find that an engine starts easily when Oil is another factor to be considered in the cold weather one stroke of the primer is used in the sixty degree range, starting process. All oils are affected by temperature and tend two strokes in the fifty degree range, three strokes in the forty to thicken as the temperature drops. The engine may be reluc- degree range, etc. This is an example of the trial and error we tant to turn over when the oil is stiff; a summer weight oil is might use to establish the number of primer strokes to use under not suitable in cold weather. It is also the condition which brings any particular temperature condition. out the of primary advantage multi-viscosity oils. Because these While discussing the priming of an engine, there have been oils are thinner (lower viscosity), they allow the engine to be situations where primer lines become clogged. This makes turned over more Because flow easily. they more easily and engine starting difficult and negates any trial and error ex- also quickly, they are available to lubricate the internal parts perimentation which may have been done. When maintenance of the more when it does is engine quickly start. Since the proper done on an aircraft before the start of winter, it may be wise oil viscosity is so imponant in all aspects of engine starting and to have those primer lines checked to insure that fuel will flow operation, the recommendations of oil grade vs. temperature through them. -range shown in Textron Service Instruction No. 1014 Lycoming The amount of fuel needed to achieve the correct fuellair should be followed, mixture for starting a fuel injected engine is controlled by tim- Preheat is another factor which must be considered prior ing rather than number of primer strokes. With the electric fuel to starting the engine. There are specific guidelines in Textron pump on, moving the mixture control to the rich position allows fuel Lycomingservice instructions which establish when preheat to flow to the cylinders. For cold weather starting, it may should be used, but how much, or the method of preheat is be necessary to keep the mixture control in rich somewhat longer generally left to the good judgement of the pilot or maintenance than in warm weather. person doing the Use of the heated stick is not The preheating. dip fuel part of the fuel/air mixture may be the pan we iecommcnded Textron most other by Lycoming, although have the most control over during the engine start, but keep methods are considered to be For most satisfactory. Lycoming in mind that the amount of throttle opening does have an effect models, should be preheat applied anytime temperatures are on the air which is pumped through the engine. Just as we com- below 10 degrees F. The to this rule is all 76 series for exception pensate cold/dense air by adding more fuel for stan, it may models; these should be engines preheated when temperatures also be appropriate to reduce the air part of the mixture when are below 20 F, It is recommended that these the degrees guidelines temperature is very cold. For example, if the throttle is nor- be followed even when oil is used. In ad- multi-viscosity being mally set open one half inch for warm weather startine, it may dition to hard failure to the entire starting, preheat engine and be helpful to reduce this to one quarter inch in cold weather. oil as recommended result in minor supply system may amounts Again, it will require some experimentation to determine what of abnormal wear to internal and to is needed engine parts, eventually to achieve the correct fuel/air mixture for any par- reduced and shortened TBO time. engine performance ticular aircraft at any temperature range. the most factor in Probably important starting an engine When an engine does not start easily, it can be frustrating. is a fuel/air mixture which is Of achieving satisfactory for com- course this can occur at any time of the year and it is very bustion, Since the engine usually starts very easily, many pilots tempting to just keep grinding away with the starter in an at- are unaware of or the ignore change of starting procedure needed tempt to get it going. Should this happen to you, RELAX. Take to successfully stan under varying temperature conditions. In care of that starter or it may fail. The general rule for starters warm weather the air is less dense and therefore must be mix- is that they should not be operated for more than 10 to 12 ed with a lesser amount of fuel than in cold weather. In addi- seconds; then a five minute cooling off period is required. tion to in warm weather the fuel this, will vaporize easily and Without this time limit for oper~ition and an adequate cooling make staning easier. Simply stated, as temperatures go down off period, the starter will overheat and is likely to be damaged it becomes more and more important that we have a plan for or to fail completely. which will achieve the correct fueyair mixture. priming The previous paragraphs have addressed several issues which When priming a carbureted engine, the pilot's plan must relate primarily to cold weather starting.There are some consider the temperature, the number of cylinders which have other cold weather items which should be considered in the priming lines installed, and the number of strokes of the primer operation of the engine. which are needed to the produce correct fuellair mixture. The Water is one of the most likely contaminants of aviation lines are ordered or installed the primer by airframe manufac- gasoline. The engine will not run on water, and although we turer and not all aircraft are configured the same. Some air- may get away with small amounts of moisture in the fuel dur- craft have been with actually produced only one cylinder being ing warm weather, flight into freezing temperatures makes any and these are hard of primed engines extremely to start in cold amount moisture in the fuel system very critical. Even a tiny weather. The number of cylinders which are primed must be bubble of moisture may freeze in the fuel line and totally cut considered since the total fuel delivered by the primer will be off the flow of fuel. Two steps should be taken to avoid this divided and sent to these cylinders. As the air becomes colder problem. First, avoid water contamination if possible. Keep fuel and the amount of denser, prime used must be increased, but tanks full to prevent condensation and be sure fuel caps do not the number of strokes to be used should be planned as a result allow leakage if the aircraft is parked outside in rain or snow. of trial and some error experimentation for each aircraft a pilot Second, look for contamination before every nie;ht by draining fuel tanks and sumps religiously. Although carburetor ice is not necessarily a winter time tions are taken. Although many of the Pilot's Operating Hand- phenomena, a check of carburetor heat should be made during books cover the basic procedures for simulating emergencv the engine run-up. Generally speaking, we can say that car- engine-out operation, there are gaps in the information on how buretor heat should never be used for takeoff, but there is one to protect the engine during simulated procedures. Following exception. This exception occurs when operating in temperatures are some questions which should fill in these gaps in informa- the of so cold that application of carburetor heat produces a rise in tion for protecting engine during this type operation: RPM. Most will never find themselves in circumstances pilots i. Avoid practice feathering or simulated feathered engine which use of carburetor heat for takeoff and climb; those require during flight in very cold temperatures. who fly carbureted engines will almost certainly have occasion 2. To abruptly simulate engine out (feather or for zero thrust, to use carburetor heat during cruise or let down. Use of the full first move mixture to idle cutoff to protect engine. hot or full cold position is recommended. An intermediate set- 3. Low altitude retard the throttle, (see following ting should only be selected if the aircraft is equipped with a slowly article on NTSB warning). carburetor air temperature (CAT) gage. A. DURING PRACTICE FEATHER Engine operating temperature is another item which is not usually given enough consideration in cold weather. We usual- 1. Limit shutdown time to a minimum. cowl on feathered ly are very cautious about high oil temperature which we know a. Close flap engine. is detrimental to good engine health, while a low oil temperature 2. Aircraft frequently used for training or sales demonstra- is easier to accept. The desired oil temperature range for Lycom- tions should have unfeathering accumulators for easier ing engines is from 160 degrees to 245 degrees F. If the air- in-flight starting. craft has a winterization kit, it should be installed when operating 3. During unfeathering, avoid strong surge in RPM. After in outside air temperatures (OAT) which are below the 40 to starting, set RPM at cruise speed for warmup at low the 45 degree range. If no winterization kit is supplied and manifold pressure (about 15"). is not with a thermostatic it engine equipped by-pass valve, may 4. Observe oil pressure at restart. Increase M. P. as engine be to a means of off a necessary improvise blocking portion begins to warm up to aid process and do not use cruise of the air flow to the oil cooler. the oil Keeping temperature power until CHT reaches 1500 F, or 650 C. about the minimum recommended temperature is a factor in 5. During flight on one engine, monitor good engine engine longevity. Low operating temperatures do not vaporize temperatures. the moisture which collects in the oil as a result of combustion. B. ZERO THRUST SIMULATED ENGINE When minimum recommended oil temperatures are not main- OUT PROCEDURE tained, oil should be changed more frequently than the normally recommended 50 hour change cycle. This is necessary in i. After closing mixture or throttle, have pilot indicate dead order to eliminate the moisture which collects and contaminates engine by moving that throttle to approximately 12 inches the oil. M. P. zero thrust position. And finally, power-off let downs should be avoided. This 2. Return mixture to rich position if used. is especially applicable to cold weather operations when rapid 3. Set RPM on simulated dead engine at cruise speed. head will be more Plan ahead, cylinder cooling pronounced. 4. Close cowl flaps on zero thrust engine. reduce gradually and maintain some power throughout power 5. Monitor good engine temperatures. the descent. Also keep the fuel/air mixture leaned out during 6. When simulated engine inoperative practice is completed, the descent. If an exhaust gas temperature gage is installed with gradually return retarded throttle toward normal required a normally aspirated engine, keep it peaked to insure the greatest power settings, and as CHT approaches green are, normal possible engine heat for the power setting selected; for a tur- power may be used. bocharged installation, lean to peak during descent unless otherwise specified in the Pilot's Operating Handbook or under con- EXPLANATION OF PROCEDURES ditions where the limiting Turbine Inlet Temperature would be QUESTION Why use the mixture control first when exceeded. practice feathering or simulating an engine-out condition? to snow, frost and cold weather while flying re- Exposure ANSWER If the power is suddenly cut off the engine. the consideration of factors, both airframe and quires many such as simulated engine failure or for practice feathering dur- related. This discussion deals with issues engine strictly relating ing flight, the mixture control should be cut first, leaving the to the While there be other issues, those items engine. may throttle in normal open position until the engine has slowed down which are asked about most have been discussed, frequently because of lack of fuel. With the throttle open, it permits the Safer and life could result from careful con- flying longer engine cylinders to fill up with air with resulting normal compression sideration of the material addressed. forces, which are sufficient to cushion the deceleration of the engine. QUESTION Why should the operator avoid rapid clo~- Protecting The Engine During Simulated ing or opening of the throttle? Emergency Procedure Operation ANSWER Rapid movement of the throttle will result in detuning of the counterweights on the crankshaft. This is par- ticularlv true of RPM and MP settings when the throttle In multi-engine aircraft, training procedures and sales higher is moved rapidly. This sudden reversal of forces results in un demonstrations can damage the engines unless certain precau- unnatural movement of the counterweights which detunes or the mixture to abruptly terminate power. By putting the mlx- weakens the metal considerably, setting a failure ture up potential control in idle cutoff position with the throale in a normal at any time thereafter. open or operating position, the pilot merely cut off the fuel. How QUESTION about reviewing power sequence for but allowed the air to continue to fill the cylinders with resulting the supercharged and turbocharged engines? normal compression forces, which are sufticient to cushion the ANSWER deceleration of the and the of the During the excitement of emergency pro- engine prevent detuning cedure crankshaft and flight operation, remember that to increase power: counterweights engine failure. First increase props (enrich mixture if leaned) However, any practice on simulated engine-out condition at low Second increase throttles altitudes should be best accomplished by a slow retarda- tion of the throttle in accordance To decrease power: with the NTSB recommendation. This careful will First decrease throttles technique protect the engine, and at the same time provide for instant power if it is needed. Second decrease props

Importance Of The National Transportation Safety Board Cylinder Head Temperature Warning On Simulated Engine-Out the smaller four Maneuvers Although cylinder engines of the low com- low pression, horsepower variety do not generally use a cylinder head temperature gage, the higher powered, more complex In mid-1976, the NTSB issued an urgent warning to all powerplants require a cylinder head temperature gage in order pilots simulating an engine-out condition on multi-engine to prevent unwitting abuse by the pilot. If head temperatures airplanes, to eliminate actual engine shutdown and substitute are higher than normal during flight, it should not be ignored instead reduction of power at low altitudes such as in the traf- because there is some reason for it. It may be caused by hot fic pattern. The recommendation resulted from the NTSB in- ambient temperatures, a lean fuel metering device at higher than vestigation of the fatal crash of a light twin in which a flight cruise power, bad baffles or leaking cowling, malfunctioning instructor and an applicant for a multi-engine rating were kill- of the ignition system, or a mechanical problem may be developed. The Board's investigation revealed that some flight insuuc- ing in the engine. tors do use the fuel selector or the mixture control to shut down As a temporary measure in order to keep the an engine to test a multi-engine applicant. The NTSB observed remaining the should that of flight safe, pilot attempt to reduce the head use such procedures at traffic pattern altitudes may not temperatures by: permit instructors enough time to overcome possible errors on the pan of the applicant, i. Enriching the mixture 2. Adjusting cowl The recommendation by the NTSB means that all simulated flaps engine-out operation at the lower altitudes will have to be ac- 3. Reducingpower the throttle complishcd by retarding and unless this is ex- 4. Any combination of the above ccuted slowly and carefully engine failure can result. We suggest that in order to help the mechanic diagnose the instructors down the used the Many flight through years problem, the pilot or some member of the crew should make of an with technique abruptly cutting engine a multiengine can- a written record of the engine instrument readings during the didate to test his emotional reaction and judgement with this above flight condition and present it to the maintenance people, extreme technique. Big radial piston engines with short, stub- by crankshafts could tolerate the abrupt technique. However, flat apposed piston engines with their long crankshafts and at- More On tached counterweights could not as readily take the abuse of Cylinder Head Temperature suddenly snapping a throttle shut, particularly at takeoff, or The cylinder head temperature (CHT) the climb power. Use of the laser technique would tend to detune gage helps pilot protect his engine against the threat of excessive heat. Most crankshaft counterweights and result in a nasty engine failure, General Aviation aircraft take the CHT off the honest single Since it was common technique by instructors to ter- flight cylinder of the four, six or eight cylinder powerplants deter- minate in simulated power abruptly engine-out procedure, we mined by extensive flight tests. Optional installations offer had to the As a we in protect engine. result, published our readings from all cylinders. In Lycoming engines, all cylinders Engine Operator's Manual, in Service Bulletin No. 245, and are drilled to accommodate a CHT bayonet type thermocouple. in the Flyer, the recommendation that if the was power abrupt- Some operators in the field have been using a spark plug ly terminated, it must be accomplished with the mixture con- gasket type installation in order to get cylinder head temperature trol. The student was to identify the dead engine by retarding Textron readings. Lycoming Engineering does not currently ap- that throttle to about 12 inches MP to simulate zero thrust, or prove this method of determining CHT. Not only is the method similar to having the prop feathered. At that point the instruc- less accurate than the recommended thermocouple type, but the tar could return the mixture to an engine operating condition. temperature readings differ noticeably from the approved In our publications we then explained the reason for using installations. Minimum in-flight CHT should be 1500 F (650 C) and general aviation engine instruments are not precision laborator~ maximum in most direct drive normally aspirated Lycoming types, so crosscheck, and/or give yourself an extra margm for engines is 5000 F (2600 C); but with some of our higher powered safety. more complex engines having a limit of 4750 F (2450 C). Although these are minimum and maximum limits, the pilot should his or her engine at more reasonable tempe~-atures operate Engine Starting Suggestions in order to achieve the expected overhaul life of the powerplant. In our sixty years of building engines, the engines have benefited Extra precautions should be taken when starting high per- during continuous operation by keeping CHT below 4350 F formance engines in cold weather, after changing oil, or after (2240 C) in order to achieve best life and wear of the powerplant. the engine has not flown within a week. On the initial start. In general, it would be normal during all year operations, in closely observe engine oil pressure. If oil pressure does not rise climb and cruise to see head temperatures in the range of 3500 to minimum idling range within 30 seconds after start, shut the F to 4350 F. engine down and investigate. If an engine has bayonet probes in all cylinders, it is not i. Damage to crankshaft bearings is possible if oil pressure unusual to see variations in CHT readings on fuel injected is not within minimums as described above, and potential engines of 1000 F betweerlcylinders, and as much as 1500 F engine failure can result. on engines with float-type carburetors. With the-latter, an im- 2. fast also result in scuffed skirts portant cause of the variation is the kind of distribution of fuel Cold, starts badly piston and air to the individual cylinders. Other influences on CHT and rings and scored cylinder walls with ultimately broken and are such items as cylinder baffles, cowling, cowling flaps, loca- piston rings malfunctioning engines. tion of of manual control of engine accessories, and, course, 3. Complete engine preheating is recommended at ambient fuel mixture, temperatures of plus 100 F and below, because below this Operators frequently ask about the difference between the temperature oil is like tar. Preheating for the 0-320-11 CHT and EGT (exhaust gas temperature) systems, and their and other "76 series" engines is recommended at 200 F meaning to the pilot during operation of the engine or engines. and below. The EGT is installed in a from the CHT, probe differentlocation 4. After start, do not exceed recommended RPM in the idle or about four inches from the cylinder head down the exhaust range initially until oil pressure is definitely within the EGT has some it stack. Although troubleshooting ability, minimums. is primarily a fuel management instrument. On the other hand, the CHT is an engine instrument designed to protect the powerplant against its enemy, excessive heat. More Suggestions On Engine Starts

An important part of the engine starting procedure is the Interpreting Your Engine Instruments priming technique involved. Of course, the pilot's operating handbook will specify the steps in starting a specific model The present day piston engine instruments used in the engine. However, some of the pilot handbooks may not explain used in the typical general aviation airplane are not precision laboratory why certain procedures are starting process. instruments. We exclude the turbine and aircraft jet powered Priming can be best accomplished with an engine priming from this discussion and will consider only piston engines, system, as opposed to use of the throttle. The primer pumps that the more twin recognizing expensive pressurized engine extra fuel directly into the cylinder intake port or induction models also be may exceptions. system. Some float-type and pressure carburetors also provide Nevertheless, the purpose of this brief presentation is a prac- a supplemental source of priming. Lycoming engines of more tical approach to interpreting the readings of your engine in- than 118 HP have a throttle pump which can be used for prim- struments in accomplishing a safe and efficient flight. If, for ing under moderate ambient temperature conditions while turn- example, you were to observe an irregular reading of one engine ing the engine with the starter. instrument, it calls for a cross-check on all other instruments, Pilots should, however, be advised that excessive throttle and not on one instrument as a basis for a decision af- relying priming can cause flooding of the carburetor and airbox, and fccting flight, result in a fire in the induction system or on the outside where Since the engine is dependent on fuel, we consider the the fuel drains overboard. If the operator floods the engine by gasoline gage as a related engine instmment. If pilots are go- pumping the throttle and has a fire, it is possible to handle such ing to attempt to stretch their flight range close to limits, they a frre in the early stages by continuing to turn the engine with should be aware of the errors in the gages vs, the actual useable the starter, thereby sucking the fire back into the engine. Fur- fuel. Some modern single engine aircraft have had the gas gage thermore, if there is any fire on the outside of the engine, If show several gallons remaining, when in reality the tank was the engine starts there is a good chance it will blow out the es- empty. Others have indicated a specific number of gallons when ternal fire. but the tank held several less than filled, actually gallons Flooding of the engine without a fire, the operator should indicated, open the throttle full and close the mixture; (see Opemtor'~ Therefore, in planning for each flight, remember that Handbook on mixture) and turn the engine over several times with the starter to clear it: then with a normal start it begin again would be safer to know that on the ground rather than in the routine, air when the fuel boost pump is turned "off'. Most Lycoming fuel are When in injected engines simply primed doubt, do the safest thing and use the fuel boost the fuel boost by turning pump on, opening the mixture briefly pump with Lycoming engines. Don't be "stingy" with the boost to full rich, and the throttle. cracking Any pump- pump. In most cases they last the overhaul life of the engine. of the throttle is ineffective until the ing engine begins to fire, and are then exchanged or overhauled themselves. AS A REMINDER The airframe Pilot's Operating Handbook is the authority if boost pump information is spelled out in it. Use Of Fuel Boost Pumps With Textron Lycoming Engines How To Avoid Broken

As an engine manufacturer, we are frequently asked about Piston Rings And Cracked Cylinders the proper use of the fuel boost pump with our powerplants. we can't be an on the fuel Although pretend-to expert boost A number of multi-engine pilots have contacted us over their itself, we have some pump positive recommendations concern- concern for the effect on their powerplants of in-flight instruc- ing its use with our engines. Where a boost pump is provided tions by air traffic controllers. These pilots frequently fly in the airframe manufacturer, and the airframe Pilot's by Operating and out of high density airports where they are consistently asked Handbook has a limited treatment of the use of the fuel boost to make fast descents by ATC. Our check of the service records this discussion can the fuel pump, perhaps provide necessary at the factory reveals that there has been a surge in the number boost information for the in order to his pump pilot operate or of complaints of excessively worn piston ring grooves accom- her engine as safely as possible. panied by broken rings, cracked cylinder heads, and warped exhaust valves in both of It is necessary to supply the engine with a steady, uninter- engines these multiengine aircraft, par- ruptcd flow of fuel for all operating conditions. Entrapped air, ticularly those which are pressurized. temperature changes, pressure drops, agitation in the fuel lines Unless the pilot takes certain precautions, fast descents car- and other factors affect the release of air and vapor from the rying high cruise RPM and low manifold pressure cause; broken fuel Under system. some circumstances where an engine piston rings from ring flutter, and also cause cracked cylinders mounted fuel pump is provided, it may not be able to pump at the spark plug and valve ports, and warped exhaust valves a continuous fuel supply free of excessive vapor. due to sudden cooling. In An effective continuous fuel supply is provided by use of order to prevent engine problems of this type, we recom- the fuel boost pump. As a general recommendation, the fuel mend the pilot maintain at least 15" MP or higher and set the boost pump should be useawith Lycoming engines in all con- RPM at the lowest cruise position which should prevent ring fluner. ditions where there is any possibility of excessive vapor for- Letdown speed should not exceed high cruise speed or mation, or when a temporary cessation of fuel flow would in- approximately 1000 ft. per minute rate of descent. During close- in troduce undesirable hazards. The conditions under which Tex- letdown, the aircraft can be "dirtied" by dropping the gear and tron Lycoming recommends operation of the fuel boost pump some flaps, or both. This will prevent high airspeed and are as follows: sudden cooling, and yet provide a good rate of descent. i, Everytakeoff. However, any technique that prevents sudden cooling during descent will be helpful. 2. Climb after takeoff unless Pilot's Operating Handbook Those aircraft used to tow and says it is not necessary. gliders drop parachutists should use similar precautions to prevent sudden cooling. 3. When switching fuel selectors from one separate fuel tank to another, the fuel boost pump should be "On" in the new tank until the operator is assured there will be no interruption of the fuel flow. Avoid Sudden Cooling of Your Engine 4. Every landing approach. Pilots must avoid fast letdowns with little or no 5. Any time the fuel pressure is fluctuating and the engine is power along with rich affected by the fluctuation, mixtures which cause sudden cooling and a number of engine problems. The Lycoming Flyer has published a 6. Hot weather, hot engine ground operation where fuel vapor number of articles over the years, recommending good operating problems cause erratic engine operation. techniques to prevent sudden cooling of the engines. 7. Some General Aviation aircraft require the use of the fuel Investigation of bent pushrods in our engines reveals that boost pump during high altitude flight. This will be spell- sudden cooling during operation can cause this problem. ed out in the Pilot's Operating Handbook. Engineering was able to produce like conditions that result in 8. If the mounted fuel fails. engine pump the exhaust valves sticking, which in turn causes bent pushrods. If the fuel boost is used pump during ground operation, Spark plug fouling is another of the problems brought on don't fail to check the condition ofthethe engine mounred fuel pump by sudden cooling during operation which we have written about before takeoff the boost off and then in by turning Dump briefly, past issues.. In order to avoid plug fouling, we have recom- back for ''on" takeoff. If the engine mounted pump has failed, mended maintaining the mixture at the leaned cruise condition during descent with a gradual richening of the mixture, carry- The second line of defense against dirt and abrasives is the ing some power, and at a sensible airspeed in order to maintain full now oil filter which is standard with most Lycoming engines the most efficient engine temperatures possible. now being produced. Older engines were manufactured with a pressure screen, but may be convened to a full flow filter for In another related article from the Flyer, we noted that Air more effective cleaning of the oil. Textron Lycoming Service Traffic Control had advised pilots to expedite their descent in Publication SSP-885-1 provides information and instructions some instances, which resulted in sudden cooling and engine needed for this conversion. problems. Aircraft used to tow gliders or drop parachutists have also been vulnerable to the effects of sudden cooling after their Another contributor to a variety of engine problems, in- is of inactivity. drops and the descent to the airport. Investigation of a number eluding valve sticking, frequent, long periodse of these engines at the factory revealed broken piston rings, An engine should be flown regularly to stay in tiptop condi- cracked cylinders at the spark plug and valve ports, and warped tion. The oil in the sump collects residue from combustion such exhaust valves due to sudden cooling. as moisture, acid, and lead sludge. Flying the aircraft tends to heat the oil enough to vaporize the moisture and help eliminate The operating techniques recommended in the previous ar- some of these contaminants, but an engine which is not flown tide, "How To Avoid Broken Piston Rings and Cracked will collect moisture, acids and gums which may contribute to Cylinders", are completely applicable to the items discussed corrosion and to valve train problems. In addition to frequent here. Whatever the circumstances, pilots must plan their flight flight, these contaminants are also eliminated from the engine operations so that the potential damage caused by sudden engine by changing the oil. Textron Lycoming Service Bulletin No. cooling can be avoided. 480 dated January 18, 1988 recommends:

a. 50-hour interval oil change and filter replacement fur all engines using a full-flow fitration system. Operational and Maintenance b. 25-hour interval oil change and screen cleaning for ail engines employing a pressure screen system. Procedures To Avoid Sticking Valves c. A total of four months maximum between oil changes for either of the systems discussed under a. and b. As many Flyer readers know, an application for warranty from aircraft owners continue to indicate that trouble- on any Lycoming reciprocating engine or engine part Reports automatically places that item within the Service Information free operation through TBO is most often obtained with engines oil intervals. Absurd it Report (SIR) system. This computerized system, along with the subjected to frequent change as may record of telephone calls and correspondence from aviation seem, an engine which does not fly regularly should have the maintenance facilities around the world provide the capability oil changed at more frequent flight time intervals than one which does fly regularly. to monitor trends and point out problem areas as they develop. of contaminants is as These indicators show that there has been a trend, over the past Preventing a buildup just important those that do form. of two years, to an increase in the incidence of exhaust valve stick- as eliminating Avoiding lone: periods is a vital since moisture forms readily ing. Therefore it seems very appropriate to provide our readers ground operation step while the is but will not when the oil with some insight into this problem along with methods to help engine running, vaporize avoid it, is not heated to normal operating temperatures. Ground running also involves a slightly rich mixture which contributes to First, consider that the properly timed sequence of valve the formation of lead sludge in the oh. During flight, the deposit and is essential to efficient and reliable engine opening closing of lead sludge in the oil can be minimized by proper leaning. operation. Also consider that the size tolel-ance between the con- Although some excess fuel is required for engine cooling tinuously moving valve stem and its stationary valve guide is during high power operation, proper leaning at cruise power extremely critical. Even if the valve to guide clearance chosen settings will promote complete burning of the fuel and, for use in an engine were perfect, the amount of clearance can therefore, a minimum of lead sludge deposited in the oil. This be affected and changed during the course of engine operation. is important since lead sludge is not filtered out, but is re- In other words, a sticking or broken valve may not be the fault moved by changing the oil. The airfI-ame manufacturers recom- of the It is to valve sticking, and there engine. possible promote mendations and limitations for leaning should be observed, but are actions which can be taken to reduce or eliminate the many it may be beneficial to be aware that when permitted by the of this These actions will affect engine possibility phenomena. Pilot's Operating Handbook, leaning to peak EGT at cruise fuel management, and internal engine cleanliness. cooling, power settings will produce complete burning of the fuel/cilr Engine cleanliness is a primary consideration which is af- mixture for best economy and reduction of combustion related contaminants. fected by many maintenance and operational procedures. Prop- er filter maintenance is one such item. The induction air filter Having touched on fuel management and maintenance items is the first line of defense in keeping dirt and abrasives from required to keep an engine clean internally, the final factor af- entering the engine. To prevent dirt from entering the engine, fecting potential valve sticking is engine operating temperature. the filter must form a good seal with the filter holder, and the Some operating procedures already discussed also have an ef- induction system should be free of air leaks. The air filter should feet on engine temperature. Prolonged engine ground run-up be cleaned or changed on a regular basis. In extremely dusty at high power settings, for example, can cause conditions, a Biter change could be necessary as frequently as overheating or hot spots since cooling air flow is not every few hours of operation. adequate when the aircraft is stationary. Since proper engine operating fall within a also beneficial to temperatures continue the engine cooling process after lan- minimum and maximum it is to consider all range, important ding by insuring that several minutes of engine operation at 800 Baffles direct air aspects. designedto cooling over the cylinders to 1200 RPM are allowed before shut down. At large airports must be maintained in good condition. If these baffles deteriorate this is usually accomplished by the time taxi to the parking area or are installed so that air is not contained is cooling adequately completed. At airports where clearing the runway puts the and directed, hot which a lead or aircraft in spots promote carbon buildup the parking area, a short period of additional opera- occur. hot weather in those baffles may During particular, or tion in the 800 to 1200 RPM range prior to engine shut down ducts which direct air cooling through the oil cooler must also will allow temperatures to stabilize. be maintained in good condition. A logical question after this long series of things to do and The as well as maintenance pilot, personnel, will play an things not to do might be this, "Is there any way to tell if a role in that important insuring engine operating temperatures valve is sticking before serious damage occurs?" There are do not promote valve sticking. As mentioned earlier, avoiding sometimes warning signs which should be investigated. ground running far in excess of the time necessary for engine Although there may be other causes, an intermittent hesitation warm up should be avoided. Also to be avoided is continuous or miss in the engine may be an indication that carbon or other at low aircraft operation very speeds which do not generate the similar contaminants have built up inside the valve guide caus- most efficient flow of air cooling over the engine. This lack ing the valve stem to drag instead of moving freely. These con- of effective cooling air may cause some areas of the engine to taminants should be removed by reaming the guide to its original be hot and therefore have size excessively an effect on any con- which should fall between .4995 and .5005 inch. The pro- taminants which may be in the oil. Essentially the oil becomes cedure to be used when reaming to remove valve guide deposit ''cookcd" and the formation of deposits is promoted. The ex- buildup is found in Textron Lycoming Service Instruction 1425. haust valve guide area is the most likely to be affected by these Known as "the old rope trick" to many A&P mechanics, this and stuck deposits a or sticking valve may result. valve guide reaming procedure restores valve stem to guide run- clearance The other end of the spectrum controllable by the pilot is ning and can be accomplished without removing the from the aircraft. excessively rapid cool down of an engine which has been run- engine To ning at normal operating temperatures. Lycoming engines are summarize, procedures to reduce valve sticking will also reduce the made with various metals which expand and contract at different probability of additional engine damage which may cause loss of rates when exposed to heat or cold. Engineering tests have power and the need for costly repairs. These procedures demonstrated that valves will stick when a large amount of very may be reduced to relatively simple terms: The cold air is directed over an engine which has been quickly throt- maintenance and operational procedures necessary to avoid tied back after operating at normal running temperatures. This sticking valves are those which keep the engine clean internal- is a good example for pilots. It is poor technique to "chop" ly and which cause it to run within proper operating temperature the power from cruise or higher power settings to idle and then ranges. The items discussed above should serve as a guide for start a rapid let down which develops excessive cooling air flow A&P mechanics and for pilots. over the engine. It is always best to reduce power in increments so that engine temperature changes will occur gradually. It is

~cl"-

n'hen indications ofvalve slickine are nepleclcd. a bent pwhrod and damaped shroud tube masÂ· result. In the picture obaÂ·e. note the sa~ere bend in the normnllsÂ· straight shroud tube. Sticking Valves Do Not Neglect vice Instruction 1425 provides recommendations to reduce the The Warning Signs possibility of valve sticking. In particular, Part iII of the instruction gives a procedure for reaming valve guides which can An article in Flyer No. 40 provided operational and be accomplished without removing the engine from the aircraft maintenance to avoid valves. The ar- techniques help sticking or the cylinders from the engine. tide prompted several individuals to relay items from their personal knowledge and experience. This information provides a worthwhile addition to the data printed previously. It could be very helpful and is passed along for that reason. Tips From The Danger One of the regional service managers here at the Lycom- indicated that his the including factory experience over years These are some of the more common questions asked at ed with valves. He commented that working on engines sticking our service hanger: the engine will almost always provide a warning by running QUESTION Do your new, remanufactured or overhaul- very rough at start up. As the engine warms up it may then ed engines require a "slow" flying or break-in period? smooth out after a few seconds and run normally, but the initial roughness is a warning that preventive maintenance action ANSWER--Definitely not. Fly them as you would a high is required, time engine. In fact, so-called "slow" flying may have harmful effects. The rings may not seat properly resulting in higher Just a few days after these comments were made, a con- than normal oil consumption. versation with an aircraft owner confirmed that the regional manager's comments were right on target. This is the story QUESTION At what rate of oil consumption does con- which thcaircraft owner related. tinued operation of the engine become a hazard?

An aircraft had been purchased recently and the owner flew ANSWER--Generally speaking, when the oil consumption it to altitude in the vicinity of his home airport to satisfy himself reaches one quart per hour, corrective action should be taken. af the aircraft capability to fly over mountainous terrain during However, maximum permissible for each particular engine is a planned vacation trip. Content that the aircraft and engine were listed in the engine operator's manual. capable of meeting his requirementsrthe vacation trip was QUESTION What is the chief danger of operating an undertaken. All went smoothly on the first 300 mile leg of the engine with high oil consumption? trip which ended with a planned overnight stop. ANSWER Oil soaked carbon forms at a fast rate. At When the engine was started the next day, it was very, very the same time, the presence of oil in the combustion chamber rough, but smoothed out and ran normally after a short time, has the effect of lowering the octane rating of the fuel. Operating With the engine running smoothly, the vacation trip continued temperatures go up. We have now set up conditions inviting to its destination. The aircraft then tied down and not was defonation and/or pre-ignition. operated until it was time for the return trip a period of about If I can't aviation I one week. QUESTION get fuel, may use automotive fuel if octane rating is equal or higher? As the engine was started for the return trip, it again gave ANSWER No. There are 4 or 5 reasons and all indications that a valve was momentarily sticking it ran good be summed in three words very rough for several seconds, but then smoothed out. With important. They can up potential failure. the engine running smoothly again, the return trip was started, engine hours of After one to two flight at altitude, over mountainous QUESTION What is the most common cause of terrain. the engine ran very rough again for a short period of premature engine wear? time, and then smoothed out. The pilot decided to land at the ANSWER Dirt entering the engine through the car- nearest airport, buretor or injector due to worn out air filter, torn induction hoses Examination of the engine revealed a considerable amount or broken air boxes. of oil leakage. The cause a valve which had stuck solidly QUESTION Does the spacer between the propeller and and caused the pushrod to bend. This bending ruptured the the engine currently becoming popular serve any purpose other pushrod shroud tube and allowed oil to escape. This is a classic than streamlining the nacelle? example of the damage which sticking valves can cause. ANSWER Yes. In many cases, moving the propeller The lesson to be learned is quite simple. Do not neglect forward, which increases the clearance between propeller and the warning signs. Perhaps the experience related here will allow cowl, increases propeller efficiency and reduces nacelle others to recognize a rough running engine at start as a possi- up vibration. ble indication of sticking valves. The next step is to take immediate action to prevent damage. QUESTION In some cases, we note a minor discreIaan- cy between the engine operator's manual and the airplane Pilot's Although there may be an occasional exception, it is almost Operating Handbook. Which one should be followed? always ;tn exhaust valve which sticks. To prevent further valve ~tickinp: and to reduce the possiblitity of damage, all exhaust ANSWER The airframe Pilot's Operating Handbook. For various after the is installed in the valve guides should be cleaned of any carbon, varnish, or other reasons. engine airframe. contamination buildup. This is accomplished by reaming the operational techniques may be altered or certain restrictions mav be the A would be guides to their original size as specified in Textron Lycoming placed on engine. simple example a placard Publication SSP 1776. Table of Limits. Textron Lycoming Ser- restricting continuous operation in a certain RPM range. QUESTION I fly an aircraft equipped with a fixed pitch The Pilot And Turbocharging propeller. During cruise I'm told to keep increasing the RPM as my cruising altitude is increased. Since I in fly pretty high, What should the General Aviation pilot know about tur- order to hold 65% I find the power, RPM is mostly at 2550 bocharging the flat opposed piston engines, and how could he to 2600. Won't this RPM reduce the life? high engine accumulate this information? He could read a number of the ANSWER No. The higher RPM won't harm the engine helpful articles published in aviation magazines during recent and some information. In addition this the or reduce service life. Remember, you are increasing the RPM years get to source, to hold the pilot could get demonstration in the various only same power you had at a lower altitude at say, flights equipment 2350 RPM. using turbocharging. Then to really complete his background the pilot could talk with the engineers responsible for tur- QUESTION Is there really difference between any good bocharging the flat opposed piston engines and he would in all automotive oil and aviation oil? probability have a pretty good basic understanding of ANSWER Yes indeed there is! Don't ever use auto- turbocharging. motive oil in your aircraft engine. Believe it or not, we still Perhaps we can save the interested reader or pilot a por- encounter engines that have burned holes in due to the pistons tion of the time and expense required to acquire this knowledge use of automotive oils which~ave an ash deposit causing preigni- by sharing our experience in the above areas. Although operation. It seems hard to convince awfully people ~ho have had tion of the varied turbocbarged powerplants is relatively sim- great success with the oil used in their car that it not be may pie, nevertheless the pilot can stay out of trouble and also realize used in their aircraft engine. more efficient use of this type equipment through a sound basic of the How, and of NOTE~- Since we have had several questions on fuels and knowledge What, Why turbochargnng. it oils, might be well to mention that we canltthink of a quicker Why Turbocharge? way to void your engine warranty than by using anything other than the recommended FAA approved aviation fuels and oils. Before explaining the various turbocharging systems in the QUESTION What are some common causes of excessive field and their operation, let us examine some of the reasons oil consumption other than the burning o_f oil due to high engine for turbocharging the flat opposed piston engines up through time? 450 HP, and the accompanying advantages from doing so. has that ANSWER Building up of crankcase pressure due to Experience taught us flying high and fast is most desirable "blow-by" caused by ring wear may result in oil being blown on cross country flights, but only in the past few years has the out of the breather. The same thing can result from broken piston industry produced a small, lightweight, and inexpen- sive to make this rings. Oil may be pumped overboard due to a faulty vacuum turbocharger possible, and at the same time pump or faulty automotive type fuel pump. utilizing standard production engines. Turbocharging has also given impetus toward continued ad- QUESTION My dealer advised me to use straight vancement and in aviation mineral oil in my new engine until it's "broken in". How do growth general by bringing on economical I know when it's "broken in"? cabin pressurization in general aviation aircraft. It has made it possible to climb above most of the ANSWER When oil consumption has stabilized. Exam- undesirable flying weather instead of banging through the poor pie: After continued checking of oil consumption you have deter- visibilities, bumpy air, icing, and slower speeds of the altitudes mined the engine is consistently using one quart in a known below feet. The number of hours. 10,000 rare loss of an engine in a twin will not necessarily result in the airplane being forced to descend What is normal oil QUESTION consumption for my into the weather, but will mean merely slower flight while still IO-320-B1A? maintaining the desired, safe altitude.

ANSWER The answer cannot be given in any specific With such great flexibility in choice of altitude, it will be number of hours Normal per quart. oil consumption rate can possible to take better advantage of favorable winds, or avoiding be anywhere from a quart in 5 hours to a quart in 20 hours. turbulance. Our larger engines may be considered normal with a consump- Much safer flight is now possible over high mountains for tion of a in 4 hours to a in quart quart 12 hours. general aviation aircraft. I have with lead QUESTION problems fouling of spark The turbocharged engine allows the pilot to maintain suf- What can as a do about plugs. I, pilot, it? ficient cruise power at high altitudes where there is less drag which means faster true and increased with fuel ANSWER Several things. See that you have the correct airspeeds range At the same time the has spark plugs that are recommended by the engine manufacturer's economy. powerplant flexibility and can be flown at a low altitude without fuel like charts, not oddballs recommended by some well-meaning friend. gulping a turbine. Avoid prolonged idling on the ground. Avoid power off thirsty descents. Lean out at cruise; even on short cross-country flights. The turbocharged powerplant is a blessing at high altitude Rotate from plugs bottom to top every 50 hours or 25 if airports. The normally aspirated engine may be mar~inal from necessary, these fields, but turbocharging takes it out of this category. When attached to the standard powerplant, the Nrbocharger does not take an~ horsepower from the engine to operate. it is relatively simple mechanically, and some models can pressurize pressures may go as high as 45 Hg. However, the powerplant the cabin, too, must be built to withstand the added stress. As an example of this, the Lycoming TIG-541 model engine, which is a Ground The pilot who may have been considering the expensive Boosted powerplant permitting 38 to 43 of MP for takeoff, turbine powered aircraft with its more limited utility might has inconel exhaust valves with ni-resist guides reconsider in favor of the more practical, economical tur- incorporated bocharged piston powered plane. which protect against the hotter exhaust temperatures, a larger and stronger crankshaft, lower compression ratio to protect the Thus turbocharging has made another very important con- combustion chamber, and oil squirts in the crankcase which tribution to the successful progress of general aviation by ex- direct a stream of oil at the pistons to help cool these critical panding its utility, and the modern general aviation aircraft has areas. achieved success largely because of its utility. As our turbocharged aircraft is flown higher, the com- run faster to thinner air. What Is Turbocharging? presser wheel must compensate for the One problem in compressing air is that it gets hotter. Therefore, the we the faster the must turn which At the risk of insulting the intelligence and experience level higher fly compressor produces a hotter charge to the cylinders, ususally reflected in of some readers, we should nevertheless review for anyone in- head The does not terested in the basic principle involved in turbocharging and higher cylinder temperatures. engine give out the same horsepower for the same manifold pressure set- answer the question What is turt~charging? ting where the air is not compressed. So don't be confused by Some 50 years ago, a smart engineer thought of using the the requirement to wry a moder;itely higher manifold pressure exhaust gases of the reciprocating engine for some practical pur- at altitude on some models, for this compensates for the power pose. The normally aspirated (unsupercharged) engines of that lost from heat by compressing the air. The pilot can also under- day were inefficient at altitude and therefore altitude flight was stand how important is the use of the correct fuel in a Ground not practical because the aircraft engine couldn't pump very Boosted powerplant. Detonation and probably engine failure enough of the thinner air to maintain sufficient power. would result from the use of a fuel with a lower than minimum Our intelligent engineer merely directed the flow of the required aviation octane rating. powerplant's exhaust gases over a turbine wheel attached to a compressor wheel by a common shaft and had these two wheels Automatic vs, Manual Controls contained within separate housings. As the exhaust gases from the engine pass through the turbine housing it causes the tur- Control of the turbine speed in the various rurbochagers bine wheel to rotate. The compressor wheel (fan or blower) be- used in General Aviation is by means of the waste gate, which ing mounted on tile same shaft rotates with the turbine and draws utilizes the same principles as a flood gate damning up water, in outside air, compresses it (packs it or makes thin air dense), When the turbocharger wastegate is closed, the full force of and delivers it to the cylinders. Thus the turbocharger can com- the exhaust gas is directed over the turbine wheel. Turbine speed pensate lup to a point) for the thin air at altitude simply by com- in the varying manufacturers' models is controlled by either pressing the intake air and making it dense, such as it is close manually or automatically adjusting the opening or closing of to sea level, and thereby giving the engine the oxygen it needs the wastegate. for and efficient combustion. So can see that the proper you Early versions of a typical manually controlled wastegate aviation on the market can typical general turbocharger today unit have separate controls for each engine, which the pilot sea level dense air land maintain sea level supply horsepower) operates in the cockpit. Although we will discuss operation in at least to 16,000 feet and on the of higher, depending type a later paragraph, it should be emphasized that the careless or This leads us to the variations in equipment. turbocharging uneducated pilot can easily overboost his engine with the manual which the aviation to understand before he general pilot ought system which can result in engine failure. attempts to operate any of them. Pilot workload is reduced with a turbocharger which utilizes an automatically controlled waste gate unit. The automatic con- Ground Boosting vs. Altitude Turbocharging troller adjusts for temperature or pressure or both, depending on the various applications, and permits the turbocharger to be Altitude turbocharging (sometimes called normalizing) is controlled by normal throttle movements. The automatic con- accomplished by use of a turbocharger that will maintain the trol feature is normally set at the factory and should not be sea level horsepower of an engine at higher altitudes. Thus a tampered with in the field. 250 HP engine for example would still put out 250 HP at full power to altitudes of 16,000 to 20,000 feet, depending on the Conversion Kit vs. Factory Mating of type of turbocharging equipment. This method of turbocharging does not take more from an engine than for what it was Turbocharger and Engine originally designed if operated properly. Conversion kits in the field utilizing turbochargers have Ground boosting is another application of turbocharging generally been quite successful. In order to be legal, the com- where more than the standard 29 inches of manifold pressure bination must have a Supplemental Type Certification issued are used in flight. This method of Nrbocharging increases the by the FAA. However, engine manufacturers have a lon~ stand- horsepower output of the engine without increasing the size or ing policy that anything attached to the engine other thr;n it was weight, and also improves the altitude performance. in the certified for at the factory eliminates the engine warranty if various aircraft using Ground Boosting, takeoff manifold malfunctioning takes place as a result of whatever was subse- the quently hung on engine. Likewise, it would probably be less tie, and at this point the pilot would actuate the turbo controls to attach a to an old practical turbqcharger or high time engine. g~adually so that climb power (at full rich mixture) can be main- kits Only for altitude Nrbocharging engines (both automatic and tained until cruise altitude is reached. At cruise refer to the have been used as conversions in the because manual) field, manufacturer's chart to set up desired cruise power. Lycoming it would not be safe or to a conversion practical attempt to permits leaning by reference to an exhaust gas temperature gage ground boosting except that done by the factory, or TIT. manufacturers have been Engine providing a mated tur- Remember that cylinder head temperatures may average bocharged engine package for both rotary and fixed wing air- at least 300 F higher than normally observed in the lower craft for If the many years. engine manufacturer certifies such altitudes when flying above 10,000 feet with turbo on. During a power package, the full warranty will go along with it. The let down be careful to avoid overboosting. The pilot must be boosted will have been beefed for ground engine up this addi- especially alert here so that reductions in power by turbo con- tional power requirement. trol are made first.

The interested also want to know that the pilot may tur- The pilot cannot be careless with this system. We have in- can be used with either a or fuel bochargcr carburetor injection, vestigated cases where the operator failed to check on the turbocharger before takeoff from a sea level airport and learned Operation the hard way during takeoff that they were fully actuated. Before he could control the power, the manifold pressure had gone to Both the mechanic and the pilot must know how to operate 60 inches, which resulted in failure of both engines. the specific turbocharged system on his aircraft; so this article Therefore, although the system is simple, carelessness or is not intended as a substitute for the Engine or Airplane a lack of knowledge concerning it can create serious trouble. Manuals, because the treatment here is more general. But we can augment those basic references with explanations from the pilot's point of view. The Automatically Controlled Systems Probably the most practical consideration of operation There are important differences in the AiResearch would be to treat the automatic and manual systems separate- automatically controlled system from that of the manually con- ly. However, before we dojust that, there are a few basic han- trolled Rajay system. dling or operational requirements that apply to both systems. Those engine owners with the Automatic Ground Boosted i. The throttle or throttles must be operated smoothly or the feature should bfnow that the turbocharger is on at all times engines will surge, which is hard on the turbocharger and whenever the engine is operating. the engine. Although this particular system automatically protects 2. Power sequence is very important with the turbocharged against overboost at all normal RPM and MP settings, it is possi- engine. ble to overboost a turbocharged engine nevertheless. Any sud- To increase power (enrich mixture) den straight-arming of the throtles, particularly on cold engines, Increase then RPM, MP can cause an overboost condition which would exceed the red To decrease power line. But overboost can also take place even though the red line Decrease NP, then RPM MP has not been exceeded where the pilot may have a low RPM and very high MP. An example of this has been observed where 3. High altitude flights mean higher turbine speeds and the pilot has let down at low RPM, then on the final approach hotter cylinder head temperatures. Observe these executed a go-around without first advancing RPM. Thus he temperatures and stay within the limits prescribed for best could be pulling maximum manifold red line) at engine life, pressure (to low RPM which would be a definite overboost condition, with 4. Cruise control at altitude is in accordance with the specific resulting heavy detonation and undersirable compressor surge. instructions in the airplane Pilot's Operating Handbook. The engine manufacturers have service bulletins and ser- 5. Turbocharged powerplants require 100 octane aviation vice instructions for reference if this should happen. A severe grade fuel as a minimum. overboost could require a major overhaul of the engine and replacement of the crankshaft. The Manually Controlled Turbocharger Of course the nice feature of the automatic system for the busy pilot during climb is that once the throttles are set, there The pilot operating this system would take off with the tur- is a minimum of adjustment required. Cruise handling is similar bocharger inoperative if the field elevation was below 4 to 5,000 to the other described earlier. let down there feet density altitude. Takeoff from fields with elevations above systems During is no worry about high MP because the retards his 5,000 feet requires presetting the turbocharging before landing pilot merely throttles and the automatic system does the work for him. or takeoff wherever possible. This should be learned by means of a demonstration from the checkout pilot. Where the tur- Since the turbocharger is operating during takeoff, all bochargcr is operating at takeoff, mixture should be full rich takeoffs at any altitude require full rich mixture because the tur- rcgardleu of field elevation. bocharger provides full rated horsepower, and full rich mixture is for that of During the climb, somewhere between four and five thou- required amount power. rand feet density altitude, the engine will have run out of throt- Manually Controlled Mechanical Interconnect connections for security, lubricant leakage or air leakage. There are the usual 50 and 100 hour inspections which are brief in Turbocharger System what they recommend. Mechanics should not tinker with the system unless they have been specifically schooled. A very in- Tcxtron Lycoming developed a simple mechanical control portant requirement is the necessity to avoid dropping any loose turbocharger system, primarily for use in single engine installa- items in the induction system. They will be sucked up and go tions. It consists of a mechanical interconnect between the ex- through the turbine wheel damaging it and also possibly damae- haust waste gate valve and carburetor or fuel injector butter- ing the engine as well. This could become very costly. fly, which is operated by the pilot's throttle control. The rela- Any overboosting should be entered in the log book by the tionship of the waste gate position to butterfly position is such pilot. The mechanic must then refer to the manufacturer's ser- that at ground level, the rated manifold pressure and power oc- vice publication for the necessary action to take. When the cur at less than full throttle. This is done so that the throttle engine is exchanged or overhauled, the turbocharger should also can be advanced by the pilot during climb to maintain rated be exchanged or overhauled. manifold pressure if desired or permitted in the particular installation. To guard against dangerous overboost from inadver- Summary tent excessive throttle opening, a pop-off type relief valve is installed between the turbocharger and carbureto~ (or fuel in- One of the most exciting and certainly most promising of jcctor), which will open to protect the engine, as manifold the new innovations in general aviation is the turbocharger for pressure exceeds the approved limit. the flat opposed piston engines. Combining cabin pressuriza- The should read the Pilot's Hand- pilot carefnlly Operating tion and engine turbocharging from the same compressor in- book this and also a check out a on equipment, get good by eluded as part of the engine package, provides simplicity, which in the aircraft. Pilot cau- competent pilot qualified technique leads to low cost and light weight. The helicopter people also tions sudden movements of the throttle, and recommends against tell us that the turbocharged piston engine revolutionized the inStead slow deliberate movements. At takeoff, before releas- helicopter industry, particularly for use in mountainous areas. brakes, advance the throttle to 30 inches manifold ing smoothly Altitude test flights and field experience have indicated excellent and then pause to allow the tullbocharger to build up pressure, fuel economy and range with the accompanying higher true the brakes and the throttle to take- RPM; release carefully open airspeeds. off manifold pressure. During climb at a fixed throttle condi- We recognize that the limit for the opposed engine will be tion, manifold pressure will decrease at the rate of approximately approximately 450 HP, and anything larger will be covered by one inch for each thousand feet. The throttle may be advanced the turbo-prop or pure jets. The turbocharger added to the piston to restore the desired manifold pressure. engine provides a great economy package and adds to the already manual is the At cruise, leaning accomplished by adjusting recognized utility of these general aviation aircraft. mixture in small amounts while monitoring the EGT gage, In closing, we observe that the turbocharger has been quite allowing sufficient time between adjustments for the Exhaust compatible with our piston engines. We tried to answer the ques- Gas Temperature to stabilize. Leaning to Best Power Mixture tion: Why turbocharge? What is Turbocharging? and, How do is accomplished by carefully finding peak EGT and then you operate it? There is no substitute for a good checkout by enriching until EGT decreases 1250 F. Best Power Mixture may an experienced pilot; and for a sound basic knowledge be sure be utilized at high cruise power where more than 75% power to read the airplane Pilot's Operating Handbook. Give the is used, or with climb power, but never at take off power. Best and turbo the maintenance they require and the economy mixture is peak EGT. If the engine roughens at peak powerpiant and will EGT, enrich the mixture slightly. Peak EGT will be different careful operation they deserve, they give you performance with a long and satisfactory life. far varied power settings, therefore when changing power, the pilot must go back to rich and find a new peak for the different setting.

The should be alert to the reaction of the manifold pilot Turbocharging pressure in this type engine when leaning at cruise power. At a fixed RPM and throttle setting, the manifold pressure will in- A Brief Refresher crease as the mixture is leaned to Best Power, and decrease when leaned to Best The recommended further Economy. procedure Turbocharging has been a part of everyday operations for is that the of the if the manifold at completion leaning procedure, some pilots and some A P mechanics for many years. The than inch from the MP pressure is more one beginning value, science of adding a turbocharger to an aircraft engine and mak- it is recommended that the mixture be returned to full rich and ing that system provide us with a big bonus in operating capabili- the MP so that the adjusted accordingly leaning procedure pro- ty was well established when a series of articles on the subject duces the desired manifold pressure. appeared in the Lycoming Flyer back in 1967. At that time. turbocharging was found primarily in the more sophisticated Maintenance twin engine aircraft, and as a result, exposure to turbochareing was limited to a relatively small number of pilots and mechanies. Maintenance for all the turbo systems covered here is There are several factors which have caused an increase relatively simple. The daily pre-flight merely calls for a visual in the number of persons who must now know more and more inspection prior to the first flight, of the turbo mountings and about the of the various peculiarities turbocharger systems. First, are directed over the turbine, both wheels will turn faster and the sophisticated twins have become with the very popular many density of the air supplied to the engine by the compressor businesses, which in recent have found it beneficial to will increase years allowing the engine to produce more power. These use aircraft for business travel. In airline company addition, two wheels mounted on a shaft are enclosed within housings has deregulation promoted the growth of many commuter which separate and contain the two functionsjust discussed; this airlines and charter operations where an efficient, piston- is the turbocharger. aircraft has to be the powered, turbocharged proved proper Although the turbocharger is sometimes used to obtain an machine for the More the and advan- job. recently, popularity increase of rated horsepower from a particular engine at sea of have caused it to be used in tages turbocharging a growing level (the engine is described as 'ground boosted'), its primary number of aircraft. With single engine this rapid growth in function in many aircmft applications is to provide the capability number of turbocharged aircraft, many pilots and mechanics of maintaining sea level power to a predetermined, critical are being exposed to turbocharging for the first time. As a result, altitude. At this altitude the turbocharger will be operating at its maximum capability and engine power will deteriorate as altitude is increased above the critical altitude. RJJY Since the speed at which a turbocharger must operate is dependent upon the power desired from the engine and also upon the density of the air at the altitude at which the aircraft is fly- it is to the with the of Nra~vr ~HurL ing, necessary provide pilot capability adjusting turbocharger speed. This is accomplished by controlling the amount of exhaust gas which is directed to the turbine side of the turbocharger. In those cases where air of increased density is not needed from the turbocharger Oow altitude or low power required), a wastegate in the exhaust system is allowed to remain open and the exhaust gas is vented around the tur- *v~ccr bine wheel and through the wastegate to the atmosphere, ver' much like the normally aspirated engine. As the demand foG dense air increases, the wastegate can be closed to a position which will force the proper amount of exhaust gas into the turbine and therefore the to meet cMnruac speed up compressor the current r~K /HLCT demand. f Adjusting turbocharger speed to meet changing power cÂ·nr~rÂ·raA f;mrl requirements is a matter of providing necessary controls over OA ~XHAyJT the flow of exhaust gas.

Control of the factory installed turbochargers is accomplished by two basic methods. These are manual control or some of the things which have been written about turbocharg- automatic control. Manual control is also divided into two ing in the past should now be repeated for the benefit of all types. concerned. The simplest form of manual control is the fixed bleed system which does not incorporate a wastegate, but which allows This refresher information will be a non-technical explana- some exhaust gas to continuously escape through an orifice of tion of what turbocharging does for the reciprocating engine, predetermined size. Size of the orifice establishes the critical As you know, the aircraft engine derives its power from the altitude of the engine. The remainder of the exhaust is used burning ofa mixture of fuel and air. Assuming that this fueyair gas to turn the turbocharger mechanism anytime the engine is run- mixture retains a constant ratio, the amount of power the engine ning. In this system, engine power is adjusted by the position develops will be directly proportional to the total mass of air of the throttle plate in the carburetor or fuel injector and the the to altitude in an aircraft pumped through engine. Climbing of amount exhaust gas available to turn the turbocharger is a equipped with a normally aspirated engine provides a very result of the power developed at that particular throttle setting. realistic example; as the air becomes less and less dense with A second manual system is a throttle/wastegate intercon- altitude, the engine is capable of producing less and less power nect in which the positioning of the cockpit throttle control ac- as indicated by the decreasing rate of climb and eventually the tuates both the throttle plate and the turbocharger total inability to climb higher. wastegate. The design of this mechanism causes a programmed movement In terms, the an air simple turbocharger provides pump of the throttle plate and wastegate; the throttle plate starts to which allows us to the with dense air not supply engine only move toward the full open position before movement of the at sea level, but also when in the thin air at altitude. operating wastegate affects any change in the exhaust bleed which will The pump used in a turbocharger may be described more ac- cause turbocharger speed to increase. At the fully advanced as a air which is mounted curately centrifugal compressor on positon of the throttle control, the throttle plate is at full open a shaft. To power the compressor, the hot exhaust gases which and the wastegate is closed to its maximum design limit. are as wasted in discharged energy a normally aspirated engine A pressure relief valve is normally included in the factory are now harnessed them by directing through a turbine wheel developed system of each manually controlled turbocharger in- which might be described as a windmill. The very sophisticated stallation. The purpose of this valve is protection of the engml turbine wheel is mounted on the same shaft the air as compressor in case.of an unintentional overactivation of the throttle lover so that the during operation compressor and turbine will turn boost) by the pilot. With a manually controlled turbochager at the same exhaust speed. Therefore, as more gases (energy) system, the pilot is the controller, and must limit throttle movement to keep manifold pressure within the limit specified for how they can create an unsafe flight condition. As an example. the engine. For takeoff, this requires very smooth application in most instances the moderate engine power loss that occurs of the throttle until manifold pressure indicates about two in- from attempting a takeoff at sea level where an absent-runded ches below the maximum for which the engine is rated. As the pilot has left the carburetor heat in full hot position from the a bur an ae- turbocharger speed builds up, the manifold pressure will increase previous landing, may cause scare, not necessarily cident. But the situation to a 5000 feet slightly to the maximum limit. As engine power deteriorates move plus (densltv during climb, the piler slowly advances the throttle to maintain altitude) small airport, again forget there is full carburetor heat, add a rich carburetor and the sum total of these com- the desired manifold pressure until the full throttle position is condition, add a takeoff accident. reached at the critical altitude. bined power thieves up to or g~around Similarly, a review of accidents over the years tends to prove The automatic systems used to control turbocharger opera- in the majority of cases that it has rarely been one factor respon- tion utilize devices which sense differences of air pressure at sible for a crash, but rather one small item, added to another various points in the induction system, and utilize any changes to adjust the oil pressure which controls the position of the wastegate. Not all of these systems are exactly the same and, thtrefore, it is very imponant that the piiot understand exactly I what manifold pressures he should expect when full throttle is applied for takeoff. Engines such as the Lycoming TIG-541 and TIGO-541 have controller which are set to red systems provide ~LI line manifold pressures when the throttle is full open for takeoff. 8 in the TIG-540 Other engines, most of those Lycoming series, a utilize a density controller which will maintain a set power output at full throttle regardless of variations in altitude and in temperatures above or below standard; as a result, manifold pressures at full throttle may indicate several inches above or below that specified for standard day conditions. One final item which should be stressed during this brief review of turbocharging. Those pilots trying a turbocharged installation for the first time should be aware of thronle sensitivity small factor, added to a third; all of these small items finally and the need for very smooth throttle movements. In case of add up to a total beyond the ability of the pilot to cope with the manual systems, the turbocharger requires time to follow in the combined situation. This is how accidents tend to hap- throttle movement since it may operate at speeds in excess of pen. So let's identify as many of these power thieves as space 80,000 RPM. The automatic control systems experience this permits in order to make flight as safe as we can. same phenomena and, in addition, all elements of the control system must stabilize following any movement of the throttle. PREVENT POWER LOSS ON TAKEOFF WITH An anicle on turbocharging which was printed in the 1960's DIRECT DRIVE ENGINES IN COLD WEATHER gave this advice, "Move the throttle controls SLOWLY and In cool or cold weather, pilots should take extra care prior WAIT." to attempting to takeoff with a cold engine and cold oil, and when the mixture since This advice is also good leaning thereby prevent a temporary power loss during a critical pan the mixture setting has a great effect on engine operating of the takeoff. Cold or heavy oil can and quite often does affect temperatures. The operating temperatures of a Nrbocharged normal operation of the hydraulic lifters. Remember that avla- engine will be somewhat higher than those of a similar normal- tion lubricants are heavier when cold than the commonly used ly aspirated engine because the intake air is heated as it is com- automotive engine oils and require a little more time in warm- the altitudes where pressed; this is particularly true at higher up to obtain normal now in order to function properly the compressor must work very hard to supply dense air to the throughout the air cooled aircraft engine. engine. Cylinder head temperatures will average 300 F higher To prevent possible power loss, a proper warm-up should at altitude, and smooth, steady operation of the mixture con- be conducted. The engine is ususally warm enough for pre-flight rrol will insure that turbine inlet temperature (TIT) limitations ground check in above freezing temperaturts after 2 to 3 minutes are not exceeded. running at 1000 to 1200 RPM. Below freezing temperatures. This brief review of various of the aspects turbocharged the warm-up period should be longer. With turbocharged is from a of view, engine primarily pilot's point powerplants, cold oil and cold engines require a longer warmup period to assure proper controller operation and prevent manifold pressure overboost. Thieves Of Aircraft Engine Power After the above recommended warm-up period in cool or cold weather, including magneto and runup check, if the oil and how to cope with them. pressure is consistently over maximum red line, have a knowledgeable mechanic adjust oil pressure so that it does not It appears that some General Aviation pilots are not really exceed red lint at rakeoff or climb powers, and yet it is within aware of the number of detrimental influences on their aircraft the recommended green are area at cruise. Cold weather tends engines which can be identified as thieves of engine power, and to require a longer warmup period. Another cause of the power loss under these temperature It is to possible compensate for the horsepower loss due to heat and conditions the of flight has_been use a heavier weight viscosi- means of the by latter technique if throttle or RPM are available. ty of oil than recommended for the ambient temperature flight condition. A heavier oil than recommended in weight cool or EFFE(3TS ON POWER AT A HIGH cold weather will tend to the normal prevent operation of the AL?TI~UDE AIRPORT ON A HOT DAY hydraulic lifters and thereby cause a loss of power. Safe flight at a high altitude airport (5,000 ft. density altitude Thus. to prevent loss on takeoff with direct drive and power above) on a warm weather day must consider the engines, select the oil for for proper weight your engine cold aerodynamic loss of efficiency on the airplane and propeller weather operation. Make a careful to takeoff with under these and run-up prior conditions, the power loss effect on the engine. cold oil and a cold and observe instruments. engine engine Ex- A good "rule of thumb" for the pilot to remember is for tend in cold weather until oil each your warmup period pressure is thousand feet above sea level, the takeoff run increases within recommended limits, or consult a mechanic concerning approximately 25 percent. In the case of normally aspirated a compromise adjustment. If in doubt about a power output, engines (not tmbocharged or supercharged), at an altitude of brief smooth full throttle check is recommended. 10,000 feet, about one-half of available engine horsepower is lost. CARBURETOR HEAT OR ALTERNATE ATR HEAT AS POWER THIEVES We can create a practical fight problem for the pilot who is faced with In a high elevation field takeoff. At Denver, Col- the opening paragraph, carburetor heat was used as an orado where the field elevation indicated of a cause of on the airplane example power loss, but many pilots aren't sure altimeter is 5000 ft., the pilot should consult the density altitude they understand the reason for it. During flight test, and in the chart for takeoff. He must know that the test we have published performance cell, been able to measure fairly a loss accurately criteria of of an aircraft is generally based on standard as much as r596 of engine power when full alternate air or a~nospheric conditions (temperatlue 590 F, pressure 29.92 inches of mer- carburetor heat have been applied. As a specific explanation, cury at sea level). In checking the chart and there is a small power loss when we use heat because the density applying pilot the ambient temperatun of a summer day of 800 F, the careful has switched from the direct, colder ram air to an indirect car- pilot will note that the density altitude is 7500 ft., and burcror heat muff, or a similar indirect source of warm air with actually the takeoff distance at this an alternate air density altitude will be 2.3 times the warm source from inside the cowling. This ac- sea level takeoff roll shown in his Pilot's Handbook. counts for an average 3A power drop because of the loss of Operating ram air. The If the same flew major portion of the engine power loss is caused pilot to Laramie, Wyoming for the next the carbuntor heat or alternate and by air heat. Aircraft engines are landing subsequent takeoff he might meet these typical checked for their conditions: horsepower output in a test cell or in flight flight with a pncision torquemeter at a corrected standard temperature The field elevation is 7,276 ft., and with an ambient of 590 F. Engineering has provided a simple rule of thumb for temperatun of 600 F, his actual density altitude will be 9.300 the effect of heat on power, i. e. for every 100 F of heat above ft., with a takeoff roll 2.9 times the sea level takeoff. Furthtr- the standard 590 F, there is a 1 4% loss. Since the power average more, the pilot must remember-the higher the ambient hear source on an engine provides at least 1000 F of heat above temperatue indicates, the higher the density altitude becomes. standard. this heat condition causes an loss of avenge power At this elevation, the pilot of normally aspirated aircraft engines 109E. Our measurable total loss power at Â·sea level, standard should consider takeoffs in tbe cool temperatures of early morn- conditions is alnady up to 13%. ing or evening hours, rather than during the hot hours of the dar. When warm air is used by the pilot, the mixture becomes Summing up the specific flight conditionjust discussed, the richer and the engine may roughen with a~iother slight power pilot must remember--when the temperature becomes higher loss as a result. In addition, the higher the altitude with its less than standard (590 Fl, the density of the air is reduced and dense air, the gnater the enriching effect because the fuel meter- aerodynamically affects overall airplane performance. The ing device will become richer at altitude and the engine less horsepower output of the Is decreased because efficient. engine its fucl- Thus, there will be another small, difficult to measure, air mixture intake is reduced. The propeller develops less thrust power loss to be added to the 1396 loss already accumulated. because the blades are less efficient. The wings develop less Most carburetors react or ineffi- because float-type very sluggishly lift, the less dense atmosphere exerts less force on the on a throttle ciently straight-arm technique during a touch-and- wings as airfoils. As a result, the takeoff distance is incnased go landing or an aborted landing with full carburetor heat. In and the climb performance reduced. the some cases, float-type carbuntor has refused to accept the In order to cope with elevation takeoffs throttle when the high airport with abrupt straight-arm technique was used, normally aspirated engines, whenever the density altitude is We should also remind the pilot that when he uses car- ft. or the 5,000 higher, pilot must compensate on the ground buretor heat or alternate air heat at cruise power that he should before takeoff. With a diner drive engine and a fixed pitch pro- his mixtnn lean, otherwise he will have adjust a rich mixture. peller, run the engine up to takeoff RPM and lean the mixture If the heat causes an undesirable loss at and the until power cruise, a maximum RPM is noted; leave mixture at that position pilot has throttle available, hemay bring the manifold and the takeoff. If the pressure accomplish eneine has a governor, run at least to the he had befon up power reading application of it up to takeoff RPM and then lean ~ntii the engine smooths heat: and if additional power is needed and he out and available, may gives the indication of maximum power. At 5,000 ft. add a maximum of two inches of MP, or 100 RPM (f~ted pitch density-altitude or higher, the available horsepower has been prop) above the previous power. and then the mixture. reduced that adjust so leaning as described will not damage a healthy Engine. If an EGT system is available, lean to 1000 F on the engines the leakage can be detected by observing fuel dye rich side of peak EGT on a direct drive normally aspirated evidence at the leakage area. Any time this condition is Lycoming engine, discovered, it must be remedied before the aircraft is flown

All turbocharged or supercharged engines must use full rich again. for takeoff at any elevation airport. This includes either manual- In those engines using a carburetor, we have observed ly operated turbos or the automatic type. power loss effects from wont air boxes where the carburetor heat flapper valve in the air box remains partly open. When IGNITION SYSTEM POWER ROBBERS the outside air temperature is above 590 F, this malfunction can There are several possibilities whereby the ignition system create a sneaky power loss, particularly at higher than cruise can be the cause of power loss in the engine. We have, for ex- power. ample, measured a power loss of approximately 3 4% with a single BLOW-BY AND COMPRESSION LOSS dead magneto or running on one mag. Ln fixed wing aircraft, Another loss condition is that of or oil if the pilot lost a magneto in flight it might not be a serious power blow-by the and into the combustion situation to complete the flight safely provided other power rob- blowing by piston rings getting chamber in more than desirable amounts. It with broken bets didn't begin to add to the problem. But in the case of the occurs scored and bell-mouthed rotor wing aircraft it could be serious during takeoff, hover or or worn piston rings, cylinder walls, exhaust valve Oil in the combustion chamber tends to landing because there are the regular unusual inro~ds on power guides. foul and reduce their It also lowers the such as operation of the tail rotor, the cooling fan, the spark plugs efficiency. octane of the fuel and tends loss of generator or alternator, the transmission, and also power loss rating to cause a power, takeoff or climb. If the is not close its from any excessive rotor blade trim tab position beyond the particularly at engine to manufactu~rers recommendation. Therefore, magneto normal overhaul life, then a top overhaul would be in order if than showed this condition. maintenance really is a critical item on ro~jr wing aircraft. more one cylinder Power loss from valve be noticeable in Other power loss influences in the ignition system include leakage may not to the If an exhaust valve becomes burned and wlorn or fouled spark plugs which tend to provide a weak spark, flight pilot. deteriorated at the of the it an miss Likewise, deteriorated magneto points will have some power edge head, may cause engine in But intake valves difficult to detect loss influence. We have also learned thsdifficult way that old, flight. leaking are during The latter either seated and cause a com- worn or cracked (insulation) ignition harnesses can cause a loss flight. get irregularly also loss if of power, particularly at altitude. If this is suspected, it can be pression loss, or they can cause a they get Nliped from A differential check will checked by means of a harness tester. pre-ignition. good compression pick up most of these discrepancies except for some occasions We know that magneto timing, either early or late, has a of broken rings. However, any oil in the combustion chamber detrimental influence on power. Sound maintenance can from broken rings would, in addition, call for a visual inspec- eliminate these problems. But coming back to spark plugs, the tion with a boroscope or a gooseneck light. correct plug is most important for efficient engine operation, and Textron Lycoming Service Instruction 1042 is the official SUMMARY: reference source. Maintenance must also be careful that long We can't list all the many power robbing factors here, but reach plugs are used only in those cylinders designated by an we have tried to list the important ones, along with recommen- area of yellow paint in the fin area between the spark plug and dations on how to cope with them. Again we want to remind rocker box. Cylinders designed for short reach plugs may be all concerned of the dangerous difference between an engine either grey, blue or unpainted in this area. If the wrong length problem where both spark plugs fail to fire in a cylinder, which plug is used in the cylinder, it will cause a loss of power and is immediately obvious as compared with the small power loss perhaps pre-ignition or detonation. problem which is not as obvious. The power thieves take power Champion Spark Plug Company published a bulletin f~ve away in small quantities per cylinder until several of them hap- years ago warning that one dirty cigarette or contaminated plug pen to occur at the same time, reaching serious proportions and barrel can rob an aircraft engine of two horsepower every a definite unsafe flight condition. Be aware--don't become a takeoff. When dirt and moisture are allowed to accumulate on victim of power thieves! the harness terminal (cigarene) or spark plug barrel insulator, connector well flashover can occur resulting in plug misfire. The high voltage current will take the to rather easy path ground Wet Air Effect On Engine Power than spark between the firing-end electrode gap. Cigarettes, harness terminals, seals, and spark plug barrels should be kept The FAA has published a pamphlet entitled "Wet Air", clean and dry. When cigarettes are clean, do not touch them which enlightens the pilot concerning this potential danger to as the moisture on fingers is enough to contaminate them again. engine power. Scientists state that we can dismiss any ap- Replacing these parts and pieces at reasonable periods is inex- preciable effect of dampness in the air on the efficiency of the pensive insurance against the power thieves. When the latter wing in lifting and the propeller in thrusting. But (they statel. are at work, sharp performance and economy are lost. the effect of water vapor or high humidity on engine power out- INDUCTION SYSTEM LEAKS put can be significant, and should be taken into consideration when takeoffs in or high humidity weather. If the intake pipes are loose at either end, leakage will take planning muggy place which tends to lean the mixture and cause a power loss. The pamphlet explains the power loss by pointing out the It could be critical in the takeoff or climb power ranges. In most fact that with water vapor present there is less air entenng the engine. Secondly, this creates an excessive enrichment because Throttle Jockeying Bad Technique the fuel amount is the same, but the amount of air is less. Fur- thermore, the water slows the which af- vapor burning slightly Does Throttle Jockeying, i. e., rapid movement of throttle fccts but offers no value the power, cooling to engine, from low to high power settings, have an affect on spark plug It FAA recommends a rough rule of thumb is to keep high operations? certainly does and here's how. moisture content in and the mind, suggests pilot consult his air- The deposits formed on spark plugs during extended idle craft owner's handbook for takeoff distances, and add another or low power settings are electrically conductive to some ex- 10 for the effects of percent possible engine power loss due to tent. However, sudden elevations of temperatures cause them water vapor on a muggy day. The pilot can easily identify a to change chemically through stages to increasingly higher elec- water condition the high vapor by muggy, hot, sticky feeling trically conductive compounds. Misfiring then can occur if the in this kind of weather. The the higher ambient temperature, gaps become bridged or the material covers a sufficient area the greater the water vapor content in the air; i. e. at 960 of the insulator nose. F, the water vapor content will be eight times as great as at 420 Low temperature carbon deposits formed on spark plugs F. The writeup also states that the effect of water vapor on super- during idle or low power can normally be removed by perform- charged piston and fuel injection engines is subsanh'allv the same ing a proper engine "burn-out". This is accomplished by slowly as the effect on other piston engines. "Fuel injection systems opening the throttle until full power is achieved. Should misfire meter fuel on the basis of a given volume of gas entering the occur during power application, decrease power slightly until combustion chamber, whether the gas is air or water vapor, just all plugs fire consistently for approximately 15 to 30 seconds, as the carburetor does. It cannot discriminate between com- and again slowly open the throttle until full power capability bustibles and non-combustibles." has been achieved. Pilots be alert to the effect of wet air arrthe performance DISCOURAGE THROTTLE JOCKEYING AND GET of your engine. BETTER PLUG AND ENGINE PERFORMANCE! (Courtesy of Champion Spark Plug)

Frequency Of Flight And Its Effect On The Engine A Daily Engine Prefiight Checklist

I. FUEL look We have firm evidence that engines not flown frequently for signs of fuel dye which means leaks, may not achieve the normal expected overhaul life. Engines check amount of fuel, drain for water. flown only occasionally deteriorate much more rapidly than 2. OIL check for leaks, check oil level. those which Pilots have asked What fly consistently. really 3. EXHAUST SYSTEM check for white stains which are to an when it's flown two times happens engine only one or exhaust leaks at the cylinder head or cracks in stacks, check month? An aircraft flown this per engine infrequently tends to condition of heat muffs for cracks or leaks. accumulate rust and corrosion This rust and internally. corro- 4. COWLING AND BAFFLES check for cracks in cowl- sion is often found when an engine is torn down. Some operators ing and baffles, check for proper position of baffles, secure are running the engines on the in an to ground attempt prevent cowling fasteners. rust between infrequent flights. This may harm rather than help 5. AIR FILTER good tight fit, good condition. the engine if the oil temperature is not brought up to approx- 6. ANYTHING LOOSE OR UNATTACHED wires imately 1650 F, because water and acids from combustion will or lines, fuel bird's nests, etc. accumulate in the engine oil. The one best way to get oil pump, rags, temperature to 1650 F is fly the aircraft, for during flight the The average pilot is not sure what he is looking for when oil hot gets enough to vaporize the water and most acids and he lifts the cowling to do a daily preflight. He can easily eliminate them from the oil. If the engine is merely ground run, memorize the six items just listed, which will serve as a helpful the water accumulated in the oil will gradually turn to acid, guide. which is also undesirable. Prolonged ground running in an attempt to bring oil temperature up is not recommended because of inadequate cooling which may result in hot spots in the cylinders, or baked and deteriorated ignition harness, and brit- tie oil seals causing oil leaks. If the engine can't be flown, then SPECIAL NOTE merely pull it through by hand or briefly turn the engine with in each issue of the Flyer we have listed all the the starter to coat the critical parts with oil. If the engine is flown Lycoming Service Bulletins, Service Instruc- so infrequently that it does not accumulate the operating hours tions, and Service Letters which have been printed which recommend an oil change (25 hours for a perssure screen since the previous Flyer. Concerned operators should system and 50 hours for a full-flow filter system), then the oil retain this listing for their reference and utilize it should be changed at four month intervals to eliminate water and acids, consistently. Spark Plug Fouling 9. Swap top and bottom spark plugs every 25 to 50 hours. Top plugs scavenge better than bottom. in ~our aircraft be a Spark plug fouling engine may prob- 10. After flight or ground operations and before shut down. Iem. It is desirable to reduce the as much as problem go to 1800 RPM for 15 to 20 seconds, reduce to 1200 RPM, Service Letter in- possible. Textron Lycoming L192 provides then shut engine off immediately with mixture control." formation which may be very helpful in reducing spark plug fouling. To aid our readers, the entire text of Service Letter L192 is printed here: Test Your Knowledge On Engines

"In many cases spark plug fouling resulting from the Check your knowledge of aircraft engines with the ques- tetraethyl lead (TEL) in aviation fuels can be reduced or tions below. eliminated by proper operation techniques. A. Multiple Choice. Circle the one best answer. The of lead arises when low problem fouling engine i. In comparison to fuel injection systems, float-type car- with a rich mixture the operating temperatures coupled prevent buretor systems are generally considered to be complete vaporization of the TEL. Under these conditions, lead (a) equally susceptible to icing as a fuel injection unit. deposits can form in the combustion chamber and may adhere (b) less susceptible to icing than a fuel unit. to the spark plug electrodes, causing misfiring. By establishing injection to when visible moisture is and maintaining proper engine operating temperatures, the TEL (c) susceptible icing only can be kept properly vaporized and pass out the exhaust system. present. (d) more to that a fuel unit. For operators experiencing lead fouling, the following susceptible icing injection 2. The basic of the fuel/air mixture control operating recommendations are made: purpose adjusting at altitude is to i. By use of the spark plug recommendation charts, be cer- (a) increase the fuel/air ratio for flying at altitude. tain the proper plugs are installed. Do not simply replace (b) decrease the fuel flow in order to compensate for the same part number of those removed. A previous decreased air denisty. mechanic may have installed the wrong plugs. Reference Service Instruction No. 1042. (c) increase the amount of fuel in the mixture to compensate for the decrease in pressure and density of 2. Do not accept an over rich carburetor or fuel injector at the air. idle or off idle engine speeds. Have a mechanic adjust decrease the amount of fUel in the mixture in mixture. (6) order to compensate for increased air density. 3. After a flooded start, slowly run the engine to high power 3. if the engine of an airplane is permitted to idle for a long to burn off harmful lead deposits, then return the engine period of time while on the ground, to normal power. (a) a hydraulic lock may develop in one or more 4. When parked for reason, avoid closed throttle idle. any cylinders. Set engine at 1200 RPM. The fuel contains a lead scaveng- (b) the lean mixture may cause the engine to miss or quit. ing agent but it only functions with a spark plug nose core the result be an oil tcmperamre at 8000 F or higher. To have a minimum of (c) may excessively high pressure. 8000 F nose core temperature you must have a minimum (d) the spark plugs may become fouled. of 1200 RPM. the will run cooler and engine Also, engine 4. Assume that on your runup at an airport where the eleva- smoother and the will have out- alternator/generator more tion is 6,000 feet MSL, you note a slight engine roughness 1200 RPM. is the minimum put at (Taxlmg exempt. Use that is not significantly affected by the magneto check but required RPM.) grows worse during the carburetor heat check. Under these 5. Use normal recommended leaning technique at cruise condi- circumstances, which of the following would be your most tions regardless of altitude and re-lean the mixture with logical initial action? application of alternate air or carburetor heat. If aircraft (a) check to see that the mixture control is in the full rich is used as a trainer, schedule cross country operation position. whenever possible. (b) reduce manifold pressure to control detonation. 6. Avoid fast, low power let down from altitude whenever (c) check the results obtained with a leaner setting of the possible. Plan ahead. Descend with power. (Avoid over mixture control. rich conditions.) (d) taxi back to the flight line for a maintenance check. 5. With to the of aviation which 7. Avoid closed throttle landing approaches whenever pos- regard use gasoline, statement is true? sible. Use a slight amount of power. Remember carburetors and fuel injectors are set slightly rich at closed throttle. (a) use of a lower-than-specified grade of fuel may result in a reduced output but is usually less harmful 8. Keep engine operating temperature in the normal operating power than higher rated fuel. range. Too many people think the lower the temperatures of the of fuel the better. Keep cylinder head temperatures in normal (b) use next higher-than-specified grade is if the of fuel is not operating range by use of normal power and proper iean- permissible specificed grade available. ing and use oil cooler baffles to keep oil temperature up in winter. (c) use of the next lower-than-specified grade of fuel is greater with full power or maximum power available permissible if_the specified grade of fuel is not for climb. available. (c) Using less than 10096 power for takeoff and cruising (d) use of a higher-than-specified grade of fuel usually at 755% power or below. lower-than-normal head results in cylinder (d) Running the engine at 1200 RPM for at least twenty temperatures. minutes before the first take off of the day. 6. If the of fuel used in an aircraft is lower than grade engine 12. The full flow oil filter is very useful in keeping an engine for the it will cause specified engine, most likely clean, but it will not filter out- (a) an increase in power which could overstress internal (a) Water engine components. (b) Acids 66) detonation. (9) Leadsludge (9) lower head cylinder temperan~res. (d) Alloftheabove (d) a non-uniform mixture of fuel and air in the cylinders. 13. For aircraft with an EGT gage, a good "rule of 7. Which statement is true aircraft that are regarding engines thumb" for most general aviation engines at cruise is to with a fuel instead of a equipped injection system lean to- carburetor? (a) 500 on lean side of peak EGT. (a) vapor locks during ground operations on hot days are (b) PeakEGT. less apt to occur with fuel injection. (c) 500 on rich side of peak EGT. (b) a disadvantage of fuel injection is the difficulty experienced in cold weather starting. (d) 1000 on rich side of peak EGT. (c) slow throttle response is one of the disadvantages of 14. With high relative humidity carburetor icing may be ex- fuel injection, pected within which of the following rangcs-- (d) fuel injection provides better fuel management and fuel (a). 320to590F distribution to the engine. (b) 00to150F 8. The presence of carburetor ice, in an airplane equipped with 69) 200to90oF be verified car- a fixed-pitch propeller, can by applying (d) 00to590F buretor heat and noting 15. An aircraft engine which develops less and less power from (a) a decrease in RPM and then a gradual increase in the point of takeoff to the service ceding is said to be- RPM. (a) Supercharged (b) a decrease in RPM and then a constant RPM indication. Normally aspirated (9) Turbocharged (c) an immediate increase in RPM with no further change in RPM. (d) Supercritical

(d) an increase in RPM and then a gradual decrease in 16. If full carburetor heat is used during cruise for the preven- RPM. tion of carburetor ice, some of the 1596 of power loss incurred be 9, If the engine oil temperature and cylinder head temperature may regained by- gauges have exceeded their normal operating range, (a) Enriching the mixture. you may have been (b) Squaring the power setting. with oil (a) operating higher-than-normal pressure. (c) Applying one pump of the primer every 15 minutes. (b) using fuel that has a higher-than-specified fuel rating. (d) Leaning the mixture. with much and with the mixture (C) operating too power 17. The final authority regarding operation of the general avia- set too lean. tion aircraft engine is with the mixture set too rich. (d) operating (a) Engine operator's manual provided by the engine 10. What change occurs in the fueyair mixture when carburetor manufacturer. heat is applied? (b) Pilot's operating handbook provided by the airframe (a) the fuel/air mixture becomes leaner, manufacturer. 66) the fuel/air mixture becomes richer. (c) Aviation circulars distributed by the FAA. (C) no change occurs in the fuel/air mixture. (d) Your local fixed base operator. decrease in RPM results from the lean mixture. (d) a 18. Use of partial heat to prevent carburetor icing is recom- 11. For maximum engine life and trouble-free operation, engine mended only if the aircraft has- of break-in during the first 25 to 50 hours engine opera- (a) A carburetor air temperature gage CAT. tion should be by: accomplished (b) A cylinder head temperature gage CHT. (a) takeoff to five minutes per flight and Limiting power (c) An exhaust gas temperature gage EGT. using 65% power maximum for cruise. (d) An outside air temperature gage OAT. (b) Runnmg the engine continuously at 75% power or B. Supply the best answer to the following essay questions: 8. Damage to an engine from leaning takes place at higher than recommended cruise detonation where an 1. Explain why aerobatics or inverted flight should not be power as aircraft does have attempted unless the engine has been modified for this type not the necessary engine instruments to flying. indicate the powerplant is being abused. 9. 2. List two purposes of engine oil. Requires proper leaning for safest, efficient performance at takeoff. 3. What are the two FAA approved oils for general aviation? 10. Two of induction ice: 4. When operating at the manufacturers' recommended cruise types ice power, at what altitudes may leaning be accomplished? (a) impact typically on the air filter. 5, Of what significance is the 5,000 ft. density altitude (b) Refrigeration ice forms in the float-type carburetor. reference point for normally aspirated engines?

6. What causes engine roughness when leaning an engine using a float-type carburetor at recommended cruise power? Lest We 7. The Exhaust Gas Temperature (EGT) system is more Forget precise as a fuel management instrument with which of the The Engine Will Not Run Without Air following? carburetor. (a) Float-type The gasoline engine operates on a fuel/air mixture which (b) Fuel injection. is ignited by the spark plugs. Engines do not run when any of these elements are missing. Pilots ~ow positively that they must 8. How can damage to an engine take place as a result of leaning? refuel the aircraft on a regular basis if they want to fly without incident, but the possibility of losing the air part of the fuel/air 9. What important consideration by the pilot for his engine mixture is not always considered and understood as well as it must take with a at _ place normally aspirated engine airports should be. Perhaps the personal experience of several individuals where the density altitude is 5,000 feet or higher? can be used to help FIyer readers avoid an accident caused by 10, List two of induction ice. lack of air for their types _ engine.

Remember that any material which reduces or cuts off the ANSWERS TO QUESTIONS flow of air in the induction system has the potential to cause A, MULTIPLE CHOICE RESPONSE a loss ofpower. A material failure of the air filter is one problem which is all too often. The filter is i. d 10i b reported very necessary to dirt out of the it must be 2. b 11. b keep engine; inspected frequently and should be on some schedule. A filter which 3. d 12.- d changed regular is several old and has filtered the air hundreds of 4. 13. years during hours of be tired. One that turn 5. b 14. operation may pilot reported on of the before takeoff, he could not the static RPM 6. b 15. b up engine get which his and fixed should have 7. d 16. d engine pitch propeller produced. He wisely elected to return to the line and have the engine in- 8. a 17. b spected. The air filter had pulled loose from its frame 9. c 18. supporting and was lodged in the intake system where it was cutting off` the air B. ESSAY RESPONSE supply. If this incident had occurred in flight, the engine would 1 Loss of engine oil out the breather can cause engine damage possibly not have been producing enough power to maintain or failure. altitude. Depending on the particular airframe, there are some 2. Lubricate (a) moving parts. options which might be utilized to regain some of the lost power. (b) Aid internal cooling of the engine. An alternate air system or carburetor heat system is designed 3. (a) Straight mineral, into the induction system primarily to combat induction icing, but use of these systems may possibly help when intake air is (b) Ashless Dispersant. blocked by other foreign materials. In some cases, just leaning 4, At altitude. any the mixture may help to regain a little of the lost power. 5. It is a climb reference for point normally aspirated power- Several years ago there was a reported loss of engine power Climb from sea level ft. plants. through 5,000 (some in heavy rain. In that case, a paper air filter was being used. Cessna's use 3,000 should be full rich. Continued may ft.) When saturated with water, the paper filter element became climb ft. should use some lean- beyond (3,000 ft.) 5,000 swollen so that airflow was impeded. In this case, the use of to ing improve engine efficiency. carburetor heat to bypass the filter and releaning to achieve a 5. The roughness is not detonation at recommended cruise better fuel/air mixture were successful tactics which kept the power, The leanest cylinder in the less than perfect distribu- aircraft flying until a safe, on airport landing could be made. tion pattern is cutting out. Operation in the roughness area We should keep in mind that it is not the ingestion of water is not acceptable, through the engine which causes a serious loss of power; It is the reduced 7. Ib) fuel injection. airflow. Some pilots of aircraft which utilize a fuel injected engine Next, it is imperative that the pilot recognize carburetor believe that this them immune to induction ic- ice when it engine_makes forms during flight. The loss of power which oc- ing. This is not so. As an the of a fuel will example, pilot injected curs cause a reduction of RPM when flying with a fixed single at 11,000 feet in drizzle. The reported flying light pitch propeller and a loss of manifold pressure when a con- was above and water temperature slightly freezing readily ran trollable pitch propeller is used. In either case, a loss of altitude off the windscreen. this would be Although seem to a no prob- or airspeed will occur. It is a good idea to consider carburetor Icm situation, the started to lose After considera- engine power. ice as the cause of any small unexplained power loss during tion of the available options, the manual alternate air system cruise flight. was activated. The engine the lost immediately regained power Once a power loss is noticed by the pilot, immediate ac- and was continued to the home base flight destination. After tion shouldÂ·be taken to eliminate ice which has already formed the aircraft was taken into the for landing, hanger examination. in the carburetor and to prevent further ice formation. This is It was found that the air filter was covered with a of ice layer accomplished by applying full carburetor heat which will cause which had cut off the airflow. This is not an isolated or unusual a further loss of power and, possibly, engine roughness. The case. When water is near movement of the freezing, water additional power loss is caused by the heated air which is be- molecules sometimes cause instantaneous may freezing. This ing directed into the induction system. Heated air makes the over of the air filter is a I~nown which glazing phenomena pilots mixture richer and also melts the ice which goes through the should be and be to with. expect ready cope Again, bypassing engine as water. The throttle may be advanced and the mixture the use of alternate air to be a successful blockage by proved may be leaned to help get some of the lost power back, but im- tatic for this pilot, mediately after the application of carburetor heat the pilot must The most subtle and insidious of the airflow blockage be patient and keep the airplane flying until the ice has com- melted and normal returns. How this will po~sibilmes is probably carburetor ice. Unfortunately, there are pletely power long take on the of the the many pilots who are not fully aware of what carburetor ice can depends severity icing, but pilot should do or what to do about it when it does occur. An indication expect a delay of 30 seconds to several minutes. Under the cir- this of time will seem than of this are statements made by pilots involved in power loss cumstances, period always longer accidents who have said that they tried carburetor heat, found it really is. it did not work, and then returned the control to the cold posi- Although carburetor heat is not recommended for takeoff tion. Carburetor heat does not provide instant relief when ap- and climb, It may be used continuously to prevent the formation of carburetor ice plied after ice has formed in the carburetor. Once heat is ap- during flight at cruis power. It is also applied, it should be left on until power returns. propriate to use full carburetor heat, if needed, to prevent icing when operating at low power for instrument approaches or Every pilot who flies an aircraft powered by a carbureted for flight in the traffic pattern. An intermediate position of the engine should be thoroughly educated about carburetor ice. They carburetor heat control should only be used in aircraft which should know that undermoist conditions (a relative humidity have a carburetor air temperature (CAT) gage; with no CAT of 50% to 6096 is moist enough), carburetor ice can form with gage, only full cold or full hot should be selected. any air temperature from 200 to 900F. It is most likely in the A review of the material discussed in this article should 300 to M)O range. Temperatures in the carburetor can drop 600 help to with reduction of when it is to 700F as a result of fuel vaporization and the carburetor ven- pilots cope engine power caused by loss of intake air for combustion. A turi effect. It also happens that carburetor ice forms more readily thorough of the air intake and the to when the engine is operated at the lower power settings. It will understanding system knowledge deal with induction are essential to safe form while taxiing and this makes it very important to check complently icing flight in general aviation aircraft. Pilots are to enhance engine power before takeoff and to remove the ice if necessary, encouraged the safety of their what to and what Care should be taken to avoid dust or dirty conditions when flying by knowning expect to take when the air flow to the is cut off for utilizing carburetor heat on the ground. steps engine any reason. PAINTENANCE INSPECTIONS

FAR 91.169 establishes minimum requirements pertaining Mechanic's Creed to annual and 100-hour inspections. Not only does the FAA require these inspections, but they stipulate that the owner/operator UPON MY HONOR I swear that I shall hold in must maintain the airworthiness of the aircraft and engine dur- sacred trust the rights and privileges conferred upon ing the time between the required inspections by having any me as a certified mechanic. Knowing full well that the airworthiness defects corrected. Although maintenance re- safety and lives of others are dependent upon my skill quirements will vary for different types of aircraft, the FAA and judgment, I shall never knowingly subject others states that experience shows most aircraft will need some type to risks which I would not be willing to assume for ofpreventive maintenance every 25 hours flying time, and minor myself, or for those dear to me, maintenance at least every 100 hours.

IN DISCHARGING this trust, I pledge myself ANNUAL INSPECTION never to undertake work or approve work which I feel This inspection must be performed within the preceding 12 to be beyond the limits of my l(nowledge; nor shall calendar months, by either a certified A P mechanic holding I allow any non-certified superior to persuade me to an inspection authorization, an appropriately rated certified approve aircraft or equipment as airworthy against my repair station, or the manufacturer of the aircraft. better judgment; nor shall I permit my judgment to be influenced by money or other personal gain; nor 100-HOUR INSPECI?ON shall I pass as airworthy aircraft or equipment about which I am in either as result of direct in- doubt, a An aircraft used to carry passengers for hire, or for flight spection or uncertainty regarding the ability of others instruction for hire, must be inspected within each 100 hours who have worked on it to their work accomplish of time in service by either a certified A P mechanic, an ap- satisfactorily. propriately rated certificated repair station, or the manufacturer. The annual inspection is acceptable as a 100Â·hour inspection,but I REALIZE the grave responsibility which is mine the reverse is not true. as a certified airman, to exercise my judgement on the airworthiness of aircraft and equipment. I, therefore, DAILY AND PREFLIGHT INSPECTION pledge unyielding adherence to these precepts for the The owner/operator may conduct a daily inspection, if so advancement of aviation and for the dignity of my vocation, desired, but the pilot must perform a satisfactory preaieht inspection before flight (FAR 91.5).

AIRWORTHINESS DIRECTNES

Airworthiness Directives, commonly referred to as "AD The Basics Of Maintenance In Notes'', provide aircraft owners with information of unsafe conditions. The AD's specify the aircraft or found to General Aviation component be unsafe by the FAA, and the conditions, limitations, or inspections, if any, under which the aircraft may continue to be Even the of "pros" our industry admit they need to be operated. reminded from time to time of the basics of General Aviation

maintenance. Therefore to review, the term maintenance means The Federal Aviation Regulation require a presentation the overhaul, and of inspection, repair, upkeep, preservation showing the current status of applicable airworthiness directives, an aircraft and engine, including the replacement of parts, ac- including the method of compliance, and the signature and cer- cording to the FAA. The owner/operator is responsible for the tificate number of the mechanic or repair agency who complied maintenance of his aircraft and The in proper engine. pilot com- with the AD. mand of an airplane is responsible for: It is the aircraft i. Maintaining his airplane in an airworthy condition. owner/operator's mandatory responsibility to assure compliance with ail pertinent AD notes. This in- 2. a Certificate and a valid Airworthi- Having Registration eludes those AD's of a recurrent or repetive nature; for exam- ness Certificate in his aircraft appropriately displayed pie, an AD may require a certain inspection every 100 hours. all during operations. This means that the particular inspection shall be made and recorded every 100 hours of flight time. 3. Having available in the aircraft an FAA approved flight manual, or operational limitations. MANUFACTURER'S SERVICE BULLETINS 4. Assuring that maintenance is properly recorded in the The FAA states that whenever an aircraft aircraft records. or engine manufacturer determines, through service experience, that his 5. abreast of the Keeping current regulations concerning product may be improved by some modification, or that the ser- and maintenance of his operation airplane and engine. vice life of his product may be extended by some particular maintenance or repair, he may issue a service bulletin. The lat- Ask About Reference Publications ter will tell what the troubl~is and how to remedy it. The ser- Before Your Engine Is Taken Apart vice bulletin is technically not mandatory unless compliance is made an FAA Airworthiness mandatory by Directive; however, People who fly should be concerned about the reliability where the service bulletin has a time limit requirement for com- of the aircraft they fly and the engine which powers that air- it becomes mandatory. pliance virtually craft. One key to reliability is regular maintenance by a A P mechanic. does not In addition to service bulletins, Textron Lycoming also knowledgeable "Knowledgeabie" publishes service instructions and service letters. A service in- necessarily mean the mechanic must have every detail of every struction is product information with which Lycoming definitely job locked in his (or her) memory. It does mean that the in- relevant information available and recommends compliance. The service letter at Lycoming is prod- dividual should have readily be able to refer to it needed. uct information which can be optional to the pilot/owner. as What has been stated above is not just good common sense, PREVENTIVE MAINTENANCE it is the law. Aviation mechanics are licensed (certified in aviation terms) under Part 65 of the Code of Federal Air Regula- Preventive maintenance means simple or minor preserva- tions (FAR). FAR 65.81 (b) states: "A certificated mechanic tion operations and the replacement of small standard parts not may not exercise the privileges of his certificate and rating unless involving complex assembly operations. The holder of a pilot he understands the current instructions of the manufacturer, and certificate issued under PAR 61 may perform preventive the maintenance manuals, for the specific operation concern- maintenance on any aircraft owned or operated by him that is ed." Is it possible for anyone to understand current instructions not used in air carrier service or air taxi. All other maintenance, or maintenance manuals if they are not available for reference'! repairs, rebuilding or alternations must be performed by per- The which a concerned owner should be think- sons authorized to do so by the FAA. point pilot ing about is this--does my A P mechanic or maintenance shop as noted under "Preventive Maintenance", all Except have appropriate maintenance publications available for rcp~airs and alterations are classed as either Major or Minor. reference? While many maintenance activities do maintain a Major repairs or alterations must be approved and returned to good reference library, others certainly do not. This can be easi- service by an appropriately rated certified repair facility, an ly determined from the questions which are asked of Lycom- A P mechanic holding an inspection Authorization, or a ing service representatives who continuously respond to phone representative of the FAA. Minor repairs and alterations may calls for help. While the service personnel are available to probe returned to service by an appropriately rated certified vide help when troubleshooting does not readily reveal the A P mechanic or repair facility, source of, or solution to, a problem, their time is being wasted when they are asked to dig out information for a mechanic who PROGRESSIVE MAINTENANCE has not made the effort to acquire required reference materials. This is a continuous maintenance progam whereby the re- Without these reference materials, the quality of maintenance quired FAA and manufacturer inspections are accomplished dur- is open to question. ing the most convenient time, while keeping the aircraft in a How can publications which apply to Lycoming state of continuous airworthiness. reciprocating engines be obtained--and which ones are need- Several General Aviation airframe manufacturers have ed? Starting with the last question, an Operator's Manual should have information the needs of the owner established sound Progressive Maintenance programs with FAA enough to satisfy engine For the maintenance what is needed approval. Owners and operators are reminded that certain FAA or pilot. person, depends the of maintenance to be and the requirements must be met before a Progressive Maintenance on depth performed particular models to be maintained. Once these items have been program can be used. These requirements are contained in the engine Federal Aviation regulations, Part 43, "Maintenance, Preven- determined, the latest revision of Textron Lycoming Service tive Maintenance, Rebuilding and Alteration", and Part 91, Letter No. L114 is a guide to all service publications which are "General Operating and Flight Rules". available for sale. It lists Lycoming Parts Catalogs and Overhaul Manuals which provide much of the information needed for ma- The Maintenance has had more Progressive program ap- jor work on Lycoming reciprocating aircraft engines. Sptcializ- where for hire are involved air peal planes (i. e., commuter, ed procedures and amplifying information are provided from rather than the owner. taxi, flight instruction), private time to time in the form of bulletins, letters, and instructions. These publications serve as supplements to the Overhaul TEST AFTER AIRCRAFT FLIGHT Manual. Without these publications to provide the latest data REPAIR OR ALTERATION published by the manufacturer, the A P mechanic may not be reminded of a required inspection, or may be unaware of The FAA reminds us that whenever a repair or alteration a new and helpful maintenance technique. has been made to your aircraft or engine, the person author- manufacturer which could ized to return the aircraft to service should decide if a flight Service Bulletins are publications bulletin is test is necessary. If the decision is affirmative, the aircraft must possibly affect safety of flight. Therefore, a considered the manufacturer to be In some be flight tested after repair or alteration before it may be used by mandatory. cases, bulletin will become the of an FAA Airworthiness to carry passengers in accordance with FAR 91.167. The test a subject The AD broad distribution to aircraft pilot must log the findings of the test flight in the aircraft or Directive (AD). gets and is law. Therefore. a which engine record, or maintenance record, owners mandatory by subject is covered by both a bulletin and an AD is much more likely overhauled engines, some small particles of metallic shavings to receive attention, might be found, but these are not dangerous. The oil filter does not remove water, acids, or lead sludge of combustion from Other more routine items of maintenance also requires a the oil. reference. When changing spark plugs, for example, a copy of Lycoming Service Instruction No. 1042 provides a listing of The oil filter is even more important to the high compres- recommended and approved spark plugs for each engine model. sion or higher power engine. Some of the aircraft manufacturers Use of this reference will insure that the correct plugs are used. have had good success in the small, lower compression, four cylinder engines without using a full flow filter. Generailv There is a message here which aircraft owners should con- speaking, these engines are also able to achieve their expected sider. Qaulity of maintenance cannot always be detennined overhaul life; as long as oil is consistently changed, and beforehand, but the chances for good quality will cenainly be operation and maintenance is accomplished in accordance with the better when adequate reference materials are available. The idea airframe and engine manufacturers recommendations. of simply asking what reference materials are available in your Pilots and mechanics should know what and mechanics reference library would seem to be a good one. It weight, type, brand of oil is used in the serviced. At each will encourage the mechanic or maintenance activity to acquire being engine being oil this information should be recorded in the and use appropriate reference materials and it may help aircraft change, specific owners to determine the quality of maintenance they will engine logbook. Except as a temporary measure in an emergcn- receive. cy, different oils should not be mixed. Consistent indiscriminate mixing of oil has created a high oil consumption problem, or clogged oil control rings and oil screens.

Oil consumption is a very important engine health trend The Oil And Your Efngine to monitor. The operator and maintenance people should know the- general history of oil consumption during the life of the It is of of There are two basic types of FAA approved aviation oils engine. typical an engine during seating new piston used in general aviation aircraft piston engines. rings that oil consumption may be erratic or high; but after the i. Straight mineral rings are seated, generally within the first 25 to 50 hours, oil consumption should level off below the maximum limits 2. Ashless dispersant (AD) established by the manufacturer. Later, during the life of the Most of these use mineral oil for "break- engines straight engine if there is a noticeable increase of oil consumption within in" with a or overhauled purposes new, remanufactured, engine; a 25 hour period, this could be a possible danger signal and then the AD after "break-in" has been operators switch~to ac- calls for an investigation. The oil screens and filter should be complished, (exceptions are our TO-360-C-F, TIO-360-C, carefully observed for signs ofmetal. Maintenance personnel TIO-541, and which AD TIGO-541qowerplants require only should take a compression check of the cylinders, using dif- Those mineral oil the oil). engines using straight beyond nor- ferential pressure equipment, and also look inside the cylinders mal break-in and later switched to must watch their period, AD, with a boroscope or gooseneck light to detect any unusual oil screens after each flight until clots of sludge no longer appear. conditions. Since modern FAA approved Ashless Dispersant oils already include additives which make them superior to straight mineral oil, the use of additional oil additives has not been con- More About Oil And Your sidered to good engine health and none were necessary ap- Aircraft Engine proved. The exception to this general policy is spelled out in Textron Lycoming Service Bulletins 446 and 471 and in Ser- We received such a favorable response to an article on oil vice Instruction 1409. These publications approve the use of in Flyer No. 14 titled ''The Oil and Your Engine'', that an ex- I~ycoming pan number LW-16702, an anti-scuffing, anti-wear pansion of the subject might also be of interest. In the previous oil additive, for all Lycoming reciprocating engines, and re- article, we listed the two basic types of oil used in general avia- quire its use in certain engine models. These models are the tion aircraft piston engines as mineral and ashless 0-320-11, 0-360-E, LO-360-E, TO-360-E, LTO-360-E, straight (AD). We also stressed the of clean oil TIO-541, and TIGO-541. dispersant importance in achieving good engine life; and oil consumption as an in- Clean engine oil is essential to long engine life, and the dication of engine health was another important item discussed. full;now oil filter is an added improvement over older methods Continuing our consideration of the oil and the aircraft of filtration. Generally, service experience has shown that the engine, the primary purpose of a lubricant is to reduce friction use of external oil filters can increase the time between oil between moving parts. Another additional responsibility of the changes provided filter elements are replaced at each oil change. oil is to help cool the engine. As it circulates through the engine, However, operation in dusty areas, cold climates, and where the oil absorbs heat from the parts. Pistons and cylinder walls infrequent flights with long idle periods are encountered, will are especially dependent on the oil for cooling. In addition to require proportionately more frequent oil changes despite use reducing friction, the oil acts as a cushion between metal of the oil filter. The oil and oil filter element should be routinely pans. The oil also aids in forming a seal between the piston and the replaced after each fifty hours of engine operation, and it should cylinder wall to prevent leakage of gases from the combustion be cut open in order to examine the material trapped in the filter chamber. Oils likewise help reduce wear by picking up foreign for evidence of internal engine damage. In new or recently panicles and carrying them to a filter where they are removed. when the outside is 100 F or lower, Using a direct drive, wet sump Lycoming powerplant as ed, temperature preheat of the is recommended before to an example, we can describe the basic lubrication system of these Lycoming engine attempting the result. Tex- less complex aircraft enginesrA more detailed description may start the engine, or damage to powerplant may does not the use of oil dilution for cold be found in the Overhaul Manual. In a wet sump engine the tron Lycoming approve of its It is that oil is contained in the engine sump as opposed to a dry sump weather operation engines. extremely important oil in the recommended be used. powerplant where the oil is in an external oil tank located only grade by Lycoming perhaps in the wheel well or the rear of the aircraft engine To simplify the selection ofoils, they are classified under oil tank which nacelle. In a dry sump engine, the oil is drawn from the an SAE (Society of Automotive Engineers) system, and pumped throughout the engine by the pressure section of divides all oils into groups as follows: the oil pump, and then returned to the oil tank by the scavenge Commercial Commercial Army Navy section of the oil pump. The other basic parts of the oil system Aviation No. SAE No. Spec. No. are very similar to those used in the direct drive, wet sump 65 30 1065 Lycaming powerplants. 80 40 1080 In the wet the oil draws oil from the sump engine, pump 100 so 1100 and sends it to the rear of the sump through the suction screen valve in some models is located oil and oil pressure screen. A bypass If you are looking for a can of 30 weight aviation the oil screen. between the pressure side of the oil sump and it has the number 65 on it, then it is 30 and also 1065 under the It permits unfiltered oil to bypass the screen and enter engine the Army Navy Spec. If it has a more complete designation when the oil filter is clogged, or during a cold start. The spring with theletter "W" added, then 30W indicates the viscosity before the loading on the bypass valve allows the valve to open (grade) of oil, it does not indicate quality or other essential cold con- oil pressure collapses the screen, or in the case of characteristics. At this time (1973) any FAA approved avia- around the screen. gealed oil, it provides a low-resistance path tion oil on the market does a good job and without using is better than no lubrication It is felt that dirty oil in an engine any additives by the owners in the field. Most oil offer as or standard, a ther- at all. systems optional Before we conclude our discussion, we want to remind our moshtIc valve in this same location which also con- items. by pass readers of a couple of miscellaneous but important related relief feature to the cooler in case it is tains a pressure bypass On multi-engine aircraft each engine is supplied with oil from As the name this unit regulates the temperature reminder clogged. implies, its own complete and independent system. Another of the oil either running it through the oil cooler if it ex- by _ every engine has a breather which can be considered a part the oil cooler if the ceeds a pre-set temperature, or bypassing of the oil system. If that engine does not have special provi- the thermostatic oil temperature is lower than by-pass setting. sions for aerobatic flight and is flown inverted, the oil will be Continuing its travel, the oil next encounters a pressure lost out the breather and a serious engine failure can result. We relief valve. The latter regulates the engine oil pressure by allow- definitely recommend that engines not built for aerobatic flight its ing excessive oil to return to the sump. The oil continues should not be flown inverted. travel drilled throughout the system and of oil through passageways In summing up this brief supplement consideration returns to the oil sump where it begins the detailed finally by gravity and your engine, it was not intended as instruction as all over think journey again. as the knowledge required to be a mechanic. But we you units in the wet are know about his Thus the principal typical sump engine will agree that the Typical Pilot should more the amount his a sump of sufficient size to contain necessary aircraft engine than Mr. Typical Driver knows about basics of oil, an engine oil pump, oil cooler and by pass valve, pressure automobile engine the penalty for not knowing the oil screen and by pass valve, pressure regulating valve, pressure is greater in aviation. and temperature instruments in the cockpit, an oil sump drain, the a filler neck to put oil in the engine, a dipstick to measure amount of oil, and a suction oil screen. The full flow oil filter but recom- is optional on the small four cylinder powerplants, Safety Tip-Sealant Use mended for higher powered engines. We need screens and filters in the oil system to keep the Textron Lycoming Service Instruction No. 1125 specifies the used oil clean as it circulates through the engine. If the oil is con- POB No. 4 Perfect Seal and silk thread as generally taminated, it carries that contamination as it circulates. We also items for sealing finished parting surfaces which do not employ LOC-TITE 515 need an ail cooler for most engines so that the oil temperature gaskets. Two other products RTV-102 or ap- oil is able to be used as alternate materials may be kept within prescribed limits and the per- plied as a very thin film, may have form its function efficiently. Of course, there is more to an oil for sealing crankcase parting surfaces. Other sealants not and NONE are system than this brief description. But for the operator who need been tested and approved for this purpose ap- of not be a mechanic, this basic information can be helpful, proved for other uses in the assembly Lycoming engines. use of these and other sealing compounds can create The oil companies tell us the basics about their product. Improper red colored sealant was used Viscosity of oil is resistance to flow. An oil which flows slowly serious problems. As an example, a in As has low a mechanic to hold the pressure screen gasket place. has a high viscosity. If oil flows freely, it a viscosity. by broke loose and eventually blocked Unfanunately, viscosity of oil is affected by high or low the material solidified, pieces the small oil causing oil starvation and engine temperatures. At below freezing temperatures some high viscosi- engine's passages failure. The bottom line: Use only approved materials fo;np- ty oils become virtually solid. which makes circulation and lubrication impossible. But no matter what viscosity oil is us- proved purposes. Maintaining Oil Levels of Multi-Viscosity Oils Wet Sump Engines Multi-viscosity oils are one of the newest items in the field of aviation products. Many aircraft owners and mechanics have In order to avoid confusion over wet sump engines, we are been asking about the use of these new oils which cover a broad of them for clarification that line listing examples so operators, band of viscosity levels. Both the 15W-50 and 20W-50 oils are crews and maintenance check oil. The personnel can properly approved by the latest revision to Lycoming Service Insuuc- following aircraft and engine models carry a capacity of six tion 1014. These aviation grade, ashless dispersant (AD) oils of oil: quarts are approved for all temperature operation. They should prove to be very beneficial in those aircraft which are operated in a Alrcrm Model Model Engine wide range of temperatures and in those situations where a scheduled oil does not seem coincide with a drastic Cessna Slryhawk 172N d32~H2AD change to change in seasonal temperatures. Ce~rna 152 0-235-L2C

Piper Tomahawk 0-235-L2C Becch Sldppcr 0-235-I~C Tips For Changing Your Piper Scminole (Twin) 0-360~E1A6D Spin-On Oil Filter Grumman American Q235-C2C Trainer Many of the aircraft engines produced today are equipped with full flow, spin-on oil filters. For long engine life, it is In addition to the above aircraft, there are others in lesser necessary to change both the oil and the filter at regular inter- numbers using these and other engine models with a~six quart vals. The information we receive indicates that problems are oil capacity. In order to be sure what an engine requires, con- sometimes encountered because not suit the Pilot's Operating Handbook. proper proceduns an followed when changing the spin-on filter. Therefore, it is ap- One problem reported to us concerning the six quart capaci- propriate to provide a few tips from a cumnt service instruction. ty engines has been that of over-filling the engine with oil. By The hardware which adapts many Lycoming engines for referring to the Pilot's Operating handbook the pilot will not use ofthe spin-on oil biter includes an oil filter adapter (Lycom- confuse his engine with those wet sump powerplants which have ing Part Number 15047) and a converter kit (Lycoming Part a capacity of eight quarts of oil. Number LW-13904). Not all engines use the oil filter adapter The Pilot's Operating Handbook for the Cessna models 152, because the accessory housing on some models is machined to have the information and 172N Skyhawk following concern- take a converter kit and a spin-on biter. The kit includes a con- ing the engine oil: vener plate which has a gasket permanently glued to the plate; this gasket seals the plate on the side which faces the engine. "Capacity of Engine Sump--6 quarts. Do not operate on If the spin-on filter seats too tightly against the side less than 4 quarts. To minimize loss of oil through breather, opposite of the plate when it is installed, the convener plate gasket fill to 5 quart level for normal flights of less than 3 hours. For may be slightly damaged when the oil filter is remov- extended flight, N1 to 6 quarts. These quantities refer to oil dip subsequently ed. This damage could result in oil leakage. stick level readings. During oil and oil filter changes, one additional quart is required when the filter is changed." To prevent damage to the converter plate gasket, the oil biter gasket should be lubricated with a thin coating of Dow- The Pilot's Operating Handbook for the Piper PA-44-180 Coming Compound @C-4) before the filter is installed. The Seminole states as follows concerning oil requirements: filter should then be installed andhand tightened until the seating "The oil capacity of the Lycoming engines is 6 quarts per surface makes contact with the lubricated gasket. The ftlter engine with a minimum safe quantity of 2 quarts per engine, should then be Nmed with a torque wrench until a torque of It is necessary that oil be maintained at full (6 quarts) for max- 18-20 foot pounds is reached. The 20 foot pound maximum tor- imum endurance flights." que should not be exceeded.

The phrase "a minimum safe quantity of 2 quarts per The oil filter element should normally be replaced each 50 engine" should be explained. If the operator checked oil after hours of engine operation. Before discarding the element of the a flight and found less than 2 quarts in the engine, it is quite full-flow filter assembly, an examination of the Ntcr element probable that engine damage has resulted. should by accomplished. The full now, spin-on filter may be opened by use of Champion tool CT-470. The element is then Pilots and mechanics should not confuse the models just removed from the filter and tilter material is cut from the end discussed with other Lycoming four cylinder wet sump engines, caps. Carefully unfold the element and examine the material which hold a maximum of 8 quarts of oil. There is no change trapped in the filter. In new or newly overhauled engines some in our recommendations when checking oil for the latter. Dur- small particles of metallic shavings might be found, but these ing normal routine flying, oil levels are best maintained at the are generally of no consequence and should not be confused 5 to 7 quart level. with particles produced by impacting, abrasion or pressure. Don't forget when in doubt consult the Pilot's Operating Evidence of excessive metal contamination found in the filter Handbook. element justifies further examination to determine the cause. After the filter element has been replaced and properly a test cell is not available. The Lycoming overhaul manuals for torqued, the lock wire must be replaced and the engine run to fixed wing powerplants allow it with certain qualifications. But check for oil leaks, the "Overhaul Manual (for) Lycoming Helicopter Engines" limits its recommendation to the following statement: Textron Lycoming Service Publication SSP-885-1 provides information about the installation of engine mounted oil filters. "After the completion of assembly of the engine after overhaul, it is recommended that the engine be mounted upon a test stand for its initial or run-in operation." For fixed wing aircraft, this advice applies. Lycoming Color Codes Understanding Engine recommends that a test cell be used for run-in of engines after overhaul. In the event that a test cell is not available, it is per- Hundreds of leave the Lycoming engines factory monthly missible to mount the engine in the airframe for the run-in pro- each These and are marked with a variety of colors on cylinder. viding the requirements of Textron Lycoming Service Instruc- colors have a definite and valuable informa- meaning provide tion 1427 are carefully observed. tion about the engine. Questions concerning these colors and their meanings have been asked by many owners and maintenance personnel. In the past, color coding of cylinders was confined to colored bands around the base of each cylinder. Today, new Engine Test After Overhaul methods of painting (enameling) engines, and a need for quick, With the engine installed in a Fixed Wing Aricraft easy engine identification were instrumental in changing color code location. (A reprint of Service Instruction 1427)

The factory color code, a large painted stripe, is now located Ideally, a newly overhauled aircraft engine should be tested on the cylinder head between the push rods from the spark plug in a test cell where operating conditions can be closely bi5ss to bottom of the cylinder head. Additional color coding monitored. Where a test cell is not available, the engine should has been added to identify cylinders requiring long reach spark still be tested on a test stand with a club propeller and a cooling plugs versus short reach spark plugs. Location of spark plug shroud. However, it is not always convenient to test an engine identification color code is between the spark plug boss and in even this manner. rocker box. If a test cell or a test stand is not available, an engine should COLOR CODE FOR CYLINDER IDENTIFICATION be properly tested after it has been installed in the aircraft.

Location Between rods on head, or band push cylinder The following procedure provides a guideline for testing around base of barrel. cylinder a newly overhauled engine that is mounted in the aircraft. In~ Engine grey or unpainted Standard steel cylinder barrels. formation on the "ground run after top overhaul or cylinder with and the test after overhaul Orange stripe Chrome plated cylinder barrels, change new rings" "flight top or cylinder change with new rings" procedures are published Blue stripe Nitride hardened cylinder barrels. in Lycoming operators' manuals and Service Instruction No. *Grcen stripe Steel cylinder 0.010 oversize. 1124B. "Yellow Steel 0.020 oversize. stripe cylinder PREPARATION FOR TEST "Color code applicable only to engines overhauled in the field, i. Pre-oil the engine in accordance with Service Instruction No. 1241. Lycoming does not sell oversize cylinders. 2. It is particularly important that the cylinder head temperature COLOR CODE FOR SPARK PLUG IDENTIFICATION gage, oil temperature gage, manifold pressure gage, and Location Fin area between spark plug and rocker box. tachometer be calibrated prior to testmg.

Engine grey or unpainted Short reach spark plugs. 3. Engine accessories, such as the fuel pump, fuel metering Yellow Long reach spark plugs, unit, and magnetos, should be overhauled or replaced with new units before testing engine. This applies to over- Caution Use only approved spark plugs for all models hauled engines only. of Lycoming engines. See Service Instruction No. 1042 for ap proved spark plugs. CAUTION

Check that all vent and breather lines are properly installed and secured as described in the airframe maintenance manual.

Test Procedure For The 4. Install airframe and intercylinder baffles and cowlin_r. Overhauled Engine 5. For optimum cooling during ground testing, a test club should be used. Where this is not possible, however, the regular flight propeller can be substituted but cylinder head The factory is always being asked by people in the field temperature must be monitored closely. ifa newly overhauled engine can be run-in in the airplane when GROUND TEST CAUTION

i. Face the aircraft in_to the wind. Avoid low-manifold pressure during high engine (under 15" and in 2. Start the engine and observe the oil pressure gage. If ade- speeds Hg). rapid changes engine with that have quate pressure is not indicated within 30 seconds, shut the speeds engines dynamic counterweight assemblies. These conditions engine down and determine the cause. Operate the engine can detune, or damage, the rollers, and in the at 1000 RPM until the oil temperature has stabilized or dampers, bushings counterweights. reached 1400F. After the warm up, oil pressure should not 6. Descend at low cruise power, while closely monitoring the be than less the minimum pressure specified in the ap- engine instruments. Avoid long descents at low manifold manual. plicable operator's pressure. Do not re~duce altitude too rapidly or engine 3. Check magneto drop-off as described in the latest revision temperatlre may drop too quickly. of Service Instruction No. 1132. 7. Afterlandingandshutdown, checkforleaksatfueland oil 4. Continue operation at 100011200 rpm for 15 minutes. fittings and at engine and accessory parting surfaces. Com- Insure that cylinder head temperature, oil temperature and pute fuel and oil consumption and compare to the limits oil pressure are within the limits specified in the operator's given in operator's manual. If consumption exceeds figures manual. Shut the engine down and allow it to cool if shown in maoual, determine the cause before releasing air- necessary to complete this portion of the test. If any cI-aft for service. malfunction is noted, determine the cause and make the 8. Remove oil suction screen and oil pressure screen or oil necessary correction before continuing with this test, filter to check again for contamination. 5. Start the engine again and monitor oil pressure. Increase NOTE enginl speed to 1500 rpm for a 5minute period. Cycle pro- To seat the in peller pitch and perform feathering ch~-dk as applicable per piston rings a newly overhauled engine, airframe manufacturer's recommendation, cruise the aircraft at 6596 to 7546 power for the first 50-hours, or until oil stabilizes. 6. Run engine to full-static airframe-recommended power for consumption a period of no more than 10 seconds. 7. After operating the engine at full-power, allow it to cool down moderately. Check idle mixture adjustment prior to shutdown. The Compression Check As 8. Inspect the engine for oil leaks. A Maintenance Aid 9. Remove the oil suction screen and the oil pressure screen or oil filter to determine any contamination. If no con- Those of us who visit maintenance tamination is evidemi-the aircraft is ready for flight testing. many organizations in General Aviation can't help noticing that the compression check NOTE is used quite universally as a maintenance aid. It was also used for the and airline maintenance Compile a log of all pertinent data accumulated many years by military people on their during both the ground testing and flight testing. reciprocating engines. Despite universal use, little, if anything, was available in writing as a reference concerning FLIGHT TEST its application to General Aviation powerplants. Therefore, this WARNING provides an ideal situation for misuse or abuse of this maintenance check method. ENGINE TEST CLUBS MUST BE REPLACED WITH APPROVED FLIGHT PROPELLERS Since almost everybody is using the compression check in BEFORE FLYING AIRCRAFT. one form or another as a method of determining the condition of the combustion chamber in our flat opposed engines, it might i, Start the engine and perform a normal preflight n~n-up be helpful if we, as an engine manufacturer, share our ex- in accordance with the engine operator's manual. perience on this equipment with all concerned. 2, Take off at airframe-recommended take-off power, while WHY A COMPRESSION CHECK? monitoring RPM, fi~el flow, oil pressure, oil temperature, and cylinder head temperatures. A compression test can be made any time faulty compression is suspected, and should be made if the pilot notices a loss 3. As soon as possible, reduce to climb power specified in of power in flight, finds high oil consumption, or observes soft operator's manual. Assume a shallow climb angle to a spots when hand pulling the prop. It is also considered pan of suitable cruise altitude. Adjust mixture per pilot's operating the handbook, 100-hour engine inspection and the annual inspection. But most experienced maintenance personnel feel that the compres- 4. After establishing cruise altitude, reduce power to approx- sion check is best used to chart a trend over a period of flight imately 752 and continue flight for 2 hours. For the hours. A gradual deterioration of charted compression taken second hour, alternate power settings between 65% and during routine maintenance checks would be a sound basis for 751 power per operator's manual, further investigation and possible cylinder removal. This 5. Increase maximum engine power to airframe-recommended maintenance attempt to reduce the possibility of engine failure and maintain for 30 minutes, provided engine and aircraft is generally called preventive maintenance. are performing within operating manual specifications. HQW IS IT ACCOMPLISHED? rotate engine with the starter and recheck compression. accidental As all maintenance people know, there are two basic 9. Caution. Take all necessary precautions against of the equipments in use, (1) the direct compression (Old automotive firing engines. and the differential, an input of 80 Ibs. of air. type), (2) using DIRECT COMPRESSION CHECK Of these two, the differential is considered best in that it is a This automotive type general compression check reveals more precise method of locating specific areas of trouble, it is actual pressure because the engine is turned over during the simple to use, and it is better than the direct method for locating check, but it only momentary pressure, and flaws are combustion chamber problems in an early stage of their provides furthermore there are related factors development, not easily detected; many to consider using this equipment. Therefore, it might be helpful It has been our experience that either method of compres- to review the basic procedure involved in the direct compression investigation can be handled in such a way as to give almost sion check as a first consideration. any reading. This does not infer that there are necessarily i. Check the engine as soon as possible after shutdown (hot dishonest mechanics, but it is an attempt to advise operators check is best). that cylinders should not be pulled indiscriminately, based on engine accidental of a single set of readings. Mechanics make honest errors, equip- 2. Take all standard precautions against firing ment becomes inaccurate, and since there is little or no stan- the engines, and place a guard in front of the propeller. for reference it is dardized information purposes, relatively easy 3. Remove the most accessible spark plug from each cylinder. to incur unnecessary maintenance charges. 4. Attach an external power source if available. Therefore. suppose we list some key points to observe con- 5. Rotate the engine crankshaft a minimum of 16 revolutions ccming direct and differential compression checks, review some with the starter to expel any excess oil or loose carbon in cross checks which should be made when low compression the cylinder. readings are observed, and state a brief logical conclusion. 6. Install the compression tester correctly in the spark plug TEST DIFFERENTIAL COMPRESSION bushing of each cylinder in turn. the instructions which We will attempt to repeat operating 7. Turn the engine with the starter through the compression the This should be read and followed accompany equipment. stroke a minimum of three times and record the compres- recommendations will carefully for best results. The following sion reading. supplement the instructions accompanying the equipment: 8. If any cylinder shows a noticeably low reading, recheck i. A standard 80 Ibs. of air is recommended. More input after turning engine over again several revolutions. pressure makes it difficult to hold the prop. At this point we should comment on the "related factors" 2. A loss in excess of 25 of the 80 Ibs., or a reading percent mentioned earlier which must be considered when using this of 60/80 is the recommended maximum allowable loss. equipment. Readings will be low or not valid if either the engine 3, The engine should have been run up to normal operating or the weather is cold, the starter weak, or the battery is low check. temperatures immediately preceding the compression when not using an external power source. Ina multi-engine air- In other words, we recommend a hot engine check, craft, if an external power source isn't used, by the time a check the is weaker. 4. The differential compression equipment must be kept clean is made on the second engine, battery usually We find that the slower rate will result in lower readings. and should be checked regularly for accuracy. Check equip- turning small do not have a means of ment with the shutoff valve closed and regulated pressure Many airplanes ready connecting external source. at 80 psi. (the cylinder pressure gage must indicate 80 psi an power plus or minus 2 psi) and hold this reading for at least 5 The principal difficulty with this method of compression seconds. Home made equipment should be carefully check lies in its vague standard, making it difficult to decide calibrated, whether to remove a cylinder when this is the only equipment condition of the combustion chamber. Our 5. Combustion chambers with five piston rings tend to seal used to check the dictates that when a problem does show up with a better than 3 or 4 piston rings, with the result that the dif- experience direct check it is too far to utilize ferential does not consistently show excessive wear or compression gone preventive maintenance. On the other hand, heavy reliance on this instru- breakage where 5 piston rings are involved. ment has resulted on occasion in maintenance cost increase due 6, If erratic readings are observed on the equipment, inspect to unnecessary removal of cylinders. compressor system for water or dirt. All of this brings us down to the controversial question: 7. If low readings result. do not remove the cylinders without What are healthy direct compressionreadings, and what are a re-check after running up the engine at least three minutes, possible unhealthy readings? Our experience reveals that it is and refer to the cross checks listed later herein. consistency of the readings of all cylinders in an engine which If valves show continual after recheck, remove 8, leakage is the important factor. By that we mean all cylinders shouldn't rocker box cover and a fiber drift on the rocker arm the place vary more than approximately 15 Ibs. from each other. On over the valve stem and the drift several immediately tap other hand, if one or two cylinders are noticeably lower than When times with a one or two-pound hammer. tapping the majority of remaining cylinders (more than 15 Ibs. lower). valves rotate the so that the will not be thusly, prop piston then we should be suspicious and carry out any of the cross This is in some to an top dead center. necessary engines checks we will outline. prevent the valve from striking the head of the piston. Then If the above is not necessarily a desirably clear cut descrip Spark Plugs I tion, it is because of the vague nature of the equipment. Its best Key To Smooth characteristics or useis as a crosscheck reference. Therefore, Engine Operation all of these "related factors" mentioned earlier tend to point Hot and Cold Plugs out that this direct compression equipment is not a particularly reliable means of the combustion accurately checking chamber (Courtesy: Chtunpion Spark Plug) condition. CROSS CHECKING IS IMPORTANT Today, the term ''hot and cold" is commonplace in general Rather than rely on one source of information concerning aviation especially when related to engine spark plugs. the condition of the combustion chamber, it is wise to make With the introduction of high compression, and high cross checks, particularly when the compression readings are horsepower engines, a need for improved spark plugs was emi- questionable. Therefore, we would like to recommend the nent. Spark plugs used in low compression, low horsepower following before removing a cylinder, engines were not compatible with the new, more sophisticated i, Consider using the direct check first and then compression powerplants. The non-compatibility factor of existing plugs with follow with the differential. The direct tends to blow out new engines resulted in development of spark plugs capable of loose deposits, it lubricates the piston rings, and serves as operating efficiently at high compression ratios and high power a general cross check on the differential and equipment settings. readings. Many aircraft operators have come in direct or indirect con- 2. Remember that spark plugs tell a story. Carefully check tact with the term "hot and cold" during the course of conver- the spark plugs removed from any cylinder with a low reading, sation with other pilots or mechanics. Its meaning and relationship to engine operation was sometimes rather vague. What do 3. Use at least a goose-neck light or preferably a borbscope we mean by "hot and cold'' What is the relation- and carefully check the top of the piston and cylinder walls. spark plugs? ship between an engine and spark plugs? How important is it 4. consider the health history of the engine. Has it had to smooth engine operation? There are but a few we previous difficulty of this nature? questions will try to answer in this article. 5. Has the pilot observed any loss of power in the engine dur- Both and manufacturer ing flight or during runup? spark plug engine working together determine the proper type spark plug suitable for each engine 6. How has the engine been maintained and operated during model. These plugs can be either fine wire or massive electrode its life? If the maintenance and care have been proper and Before consistent there is less likelihood of trouble. type. being released for production, each new type plup is checked in the laboratory and under actual flight conditions. 7. The supervisor of maintenance should evaluate the known They are tested through a wide of conditions factors such as those discussed here and make a recom- range operating and at different and after mendation to the pilot. power settings, only both engine and manufacturer are satisfied CONCLUSION spark plug completely with test data are plugs released for production. To eliminate any possibility Whatever your opinion of the compression check as a of error in spark plug selection both manufacturers provide spark maintenance aid, it is probable that no pilot or mechanic would plug charts as a guide for proper plug selection. Final authori- care to omit it during a 100-hour or annual inspection. On the ty concerning proper plugs for a specific engine is the engine other hand, since most everyone seems to use it on the flat op- manufacturer. When selecting spark plugs, be sure to also cun- posed engines, we ought to share our experiences with its sider the spark plugs' heat range. application to our powerplants. This has indicated that the dif- of the ferential is the best of the two equipments currently is use, and Operating temperature spark plug insulator core nose is one factor which formation of troublesome particularly so when the readings are charted as a trend over governs combustion To a number of routine inspections. It is a good tool for preven- deposits. help overcome this problem, selection of spark tive maintenance and aiding in avoiding in-flight failures. Cross plugs with the proper heat range should be made. Spark plugs checking is good procedure rather than relying on one source are susceptible to carbon deposits when the operating of information concerning the condition of the combustion temperature of the core nose insulator is at or below 8000 F, chamber, but an increase ofjust 1000 F is sufficient to eliminate formation of these deposits. Also, lead deposits form because the bromide scavenger contained in tetrethyl lead is non-active at Oil and Filter Change Recommendations low temperatures. At 9000 F temperature, the bromide scavenger is fUlly activated, disposing of lead deposits with combustion It has often been said that doses of fresh oil regular clean, gases during exhaust cycle. In this case, an increase ofjust 100U the provide least expensive maintenance an owner can give an F was sufficient to make the difference between a smooth and Textron Service Bulletin No. 480 makes these engine, Lycoming rough running engine. To eliminate or keep this problem at a recommendations: specific minimum, avoid prolonged idling at low RPM, avoid power- A. hour interval oil and filter Fifty change replacement for off let downs and after flooded starts run engine at medium RPM all engines using a full-flow oil filtration system. before taxiing. B. Twenty-five hour interval oil change and screen clean- Deposits formed between 10000 F and 13000 F are low In ing for all engines employing a pressure screen system. volume and electrical conductivity and are least to cause C. A total of four months maximum between changes for apt spark plug fouling. This is the reason for a that both systems listed under "A" and ''B". selecting plug will operate within the aforemention temperature range at all Cross-firing in the magneto distributor can also produce power settings. spark plug insulator failure and piston distress. Now let's get back to the term "hot and cold" as related The bottom of the insulator well around the contact cap loca- to engine spark plugs. Normally, a hot plug is used in a cold tion should be inspected for the presence of black contamina- engine low horsepower, and a cold plug in a hot engine tion on the walls and also at the contact cap. Black soot-like high horsepower, in actuality, these terms refer to the plugs deposits usually indicate that the insulation of the ignition lead ability to transfer heat from its firing end to the engine cylinder has been exposed to temperatures above normal. head. To avoid spark plug overheating where combustion chamber or cylinder head temperatures are relatively high, a Damage From Excessive Temperatures cold plug is recommended such as in a high compression of the barrel, sometimes caused by engine. A cold-running plug has the ability to transfer heat more Overheating spark plug baffles or missing cooling air blast tubes, may readily. A hot-running plug has a much slower rate of heat damaged cylinder deteriorate the leads. overheating of the transfer and is used to avoid fouling when combustion chamber seriously ignition Any barrel by a defective baffle or exhaust gas leakage and cylinder head temperatures are relatively iow. spark plug at the exhaust pipe mounting flange can generate temperatures From our discussion, it is clear to see that there is more in the insulator tip sufficient to cause preignition and piston set and installing them in your tospark plugs thanjust buyinga distress. engine. Be sure you know what type of spark plugsTo use with your engine. Also, good spark plug service and maintenance Interpreting Color of Insulator Tip Deposits is as important as proper plug selection. Take care in selecting The firing end of the spark plug should be inspected for and maintaining your plugs, it can result in many additional color of the deposits, cracked insulator tips and gap size. The hours of smadth engine operation. Additional spark plug in- electrodes should be inspected for signs of foreign object damage formation is always available from the engii~ or spark plug and the massive type also for copper run-out. manufacturers and other service organizations. The normal color of the deposits usually is brownish grey Spark plug tables are available by writing to Product Sup or gray tinted slightly with red. These colors are most prevalent, port Department, Textron Lycoming, Williamsport, PA 17701; but there be a different color combination which would Champion Spark Plug Company, Aviation Department, Toledo, may be normal for the type of operation the spark plugs have been Ohio 43661; or SGL Auburn Spark Plug Company, 89 York to. Street, Auburn, New York 13021. exposed Dull and smooth black deposits on the insulator tip usually indicate that the spark plug is lead carbon fouled. This type of spark plug fouling is caused by incomplete combustion; it usual- Spark Plugs If ly results from improper ground operation when the engine is and is when the is cold and Key To Smooth Engine Operation cold, more prevalent atmosphere very humid. It can also happen in a cylinder with weak compression, an engine with a defective primer solenoid or in a (Editor's Note: The following article is published with the cylinder that is using excessive amounts of oil. In many in- permission of AC Spark Plug Division.) stances, if both spark plugs are affected, the deposits will not Aircraft spark plugs removed from engines, especially if bum off under normal engine bum-out procedure, making has been should be in- engine malfunctioning reported, closely replacement of spark plugs necessary. spccted for abnormal indication or conditions because these Black, with some glaze or irregular formation and of suf- analyses could help in determining the source of the reported ficient amounts to short out the spark plugs, usually indicates malfunction. Spark plugs tell a story. prolonged ground operation with a very rich carburetor setting, followed a sudden increase in power output. This causes a Terminal End and Lead Connectors by rapid increase of the insulator tip temperature and prevents the "'k 20" terminal the insulator In "all-weathcr'' or type, deposit formation from being vaporized. This type of spark plug sleeve has an or end, which should be inspected exposed edge fouling is more prevalent in float equipped aircraft. for evidence of carbon tracks. These will appear as heavy lead Orange-yellow and glaze appearing deposits on the insulator pencil lines across the entire width of the end of the insulator usually indicate that the spark plugs have been exposed to sleeve and indicate that the ignition lead connector, which was tip higher than normal temperatures as it happens when detona- attached to the spark plug, may be defective. This permits elec- tion is experienced. trical discharge to the metal part of the spark plug shield. chalk-white surface on the The misfiring of the spark plug, induced by the defective An ash-grey colored surface or insulator and the metal indicates that the spark connector, will be noticed during take-off and climb engine tip, exposed parts, was exposed to very high combustion chamber operations, or at high altitudes, and may not be encountered plug caused by severe detonation or preigni- during ground operation or with new spark plugs. temperatures, usually tion. The free end of the side electrodes on fine wire spark plugs Short leads preventing a positive contact between the con- will be of a bluish-gray color and free of any accumulation of tact spring and the contact gap in the spark plug may cause the deposits. In massive type spark plugs. evidence of copper run- engine to misfire during take-off and climb operation and, in out could be visible. extreme cases during low power, especially with lean mixtures. The cylinders from which spark plugs with the above conditions were found should be inspected with the aid of a boroscope. It may be desirable to replace the cylinder, especially s e6~ if backfiring was reported by the flight crew. The reason for this precautionary action is that if the engine was operated under some detonation conditions, but not to the extent that it caused a complete piston failure, the piston rings could be broken and a piston failure requiring a complete engine change may show up at a later date.

A black-colored deposit on the spark plug gasket and the gasket flange indicates that the spark plug was insufficiently tor- qucd, allowing combustion chamber gases to leak past the spark plug threads. In aircraft engines using helicoil inserts, it may also cause a helicoil burnout. 'IÂ·

in which with cracked insulator Cylinders spark plugs tips ~4 have been found should be thoroughly inspected for damage due to abnormal combustion chamber conditions, even though the ceramic could have been caused in- separation by improper LI stallation procedures, improper method used to check or reset the gapior from being dropped. The electrode gap size should be for and the electrodes for of distor- inspected uniformity sign By comparing the two spark plugs in this picture, you can tion and nicks, see the results of overtorquing at the distorted end of the left Besides cracked insulator and lead carbon fouling, spark spark plug. Since this distortion may make the spark plug care should be taken the plugs may also be made inoperative by ice or oil bridging of unuseable, great to tighten connector in accordance with the manufacturer's instructions. the electrodes; and if both spark plugs are affected in the same cylinder, it usually requires replacement. Spark plugs with fine wire electrodes are less suspectible to this form of maIfnnction due to the smaller surfaces available to collect the moisture or oil. Why Rotate Spark Plugs Electrode Gaps The Positive and The Negative

The size of the electrode gap has a very definite effect on The of from to bottom has spark plug service life and also on the performance of the engine. policy rotating spark plugs top been mechanics and for It is Insufficient gap size will not only cause misfiring during idle, practiced by pilots many years. common in the that the bottom are but will also misfrre during cruise power with lean fuel/air mix- knowledge industry plugs the and the the clean ture. This intermittent misfiring during cruise lowers the always dirty ones top plugs are ones. By the from to bottom, temperature of the insulator tip to such an extent that lead periodically switching plugs top you get a action from the the deposits forming on the insulators may not vaporize suff~cient- self-cleaning engine whereby dirty plug in the is cleaned, while the clean in ly to keep the tips clean. placed top plug replaced the bottom gradually becomes dirty. Based on this cleaning action. a rotational time period must be established.

Due to the ever-increasing cost of aircraft maintenance and Is Your Spark Plug Connector Overtorqued? a desire to get the maximum service life from your spark plugs, the following information is offered on the effects of constant This is a brief summary of the Champion Spark Plug in- polarity and how to rotate plugs to get maximum service life. struction for connecting the spark plug to the connector: The polarity of an electrical spark, either positive or Terminal sleeves should be handled only with clean, dry negative, and its effects on spark plug electrode erosion has long hands. Before installation, wipe off the connector with a clean, been known, but has had little effect on spark plug life in the lint-free cloth moistened in methylethylketone, acetone, wood relatively low performance engines of the past. However, in alchohol, naptha or clean unleaded gasoline. Make certain that the later, high performance, normally aspirated and turho- the inside of the spark plug shielding barrel is clean and dry. charged engines where cylinder temperature and pressure are Then, without touching the connector or spring with the fingers, much higher, the adverse effects of constant polarity are becom- insert the assembly in a straight line with the spark plug. Screw ing more prevalent. As you can see in the picture compann% the connector nut into place finger tight then tighten an spark plug wear, when a spark plug is installed in a cylinder additional turn with the proper wrench. Damaged threads that is fired negative and is allowed to remain there for a lone or cracked shielding barrels mav result ifthe connector nuts period of time, more erosion occurs on the center electrode than are riRh~ened excessive!v. Avoid excessive side load while on the ground electrode, and when a spark plup, is fired poatlve. tightening more erosion occurs on the ground electrode than on the center electrode. From this we can see that a periodic exchange of spark generally considered to be ''shelf' life. All hose manufactured plugs fired positive with those fired negative will result in even for aircraft use is marked indicating the quarter year in which wear and longer spark plugservice life, it was manufactured. The listing "4488" means the hose was manufactured in the fourth quarter of 1988. Maintenance personnel should not use hoses with a high "shelf' life age.

PLVO FIRED NEGATIVE SPARI( PLVG FIREDPOSITIYE IPARK To eliminate relatively short "shelf' life limits. Textron Lycoming is phasing in Teflon hoses with silicone coated fire sleeves. These are the only hoses which are available as nplace- ment in the field, and they will be found on most engines which are shipped from the factory. Service Instruction No. 1247 lists the fuel and oil hoses used by Textron Lycoming. It also explains how the number- ing system defines hose size. This instruction should be used AWERSE *WERSE as a reference hoses are to be DENTER ELECTRODE GROUnO ELECTRODE anytime replaced. WEAR WEAR

To a polarity change, as well as switching the plugs get Air Filter Maintenance from top to bottom, the following rotational sequence is suggested. First, when removing the spark plugs from the engine, (Somethiug the pilot should Pfso ImoH) keep them in magneto sets. After the plugs have been serviced and are ready to be reinstalled in the engine, make the follow- Dust or some form of dirt is frequently the principal factor ing plug exchange. For six cylinder engines, switch the plugs in premature piston ring and cylinder wear. If a worn or poor- from the odd number cylinders with the plugs from the even fit air filter allows as much as a tablespoon of abrasive dirt numbered cylinders. For example, switch 1 with 2, 3 with 4, ly material into the cylinders, it will cause wear to the extent that 5 with 6, or 1 with 6, 2 with 5, and 3 with 4. On four cylinder an overhaul will be required. Evidence of dust or other dirt engines, you mud switch 1 with 4 and 2 with 3. During the material in the induction system beyond the air filter is indicative following operating period, each plug will be fired at reverse of inadequate filter care, or a damaged filter. polarity to the former operating period. This will result in even spark plug wear and longer service life. This rotational pro- To prevent undesirable combustion chamber wear, follow cedure works equally well on all four and six cylinder Lycom- the instructions outlined in the Aircraft and Engine Manuals on ing engines except four cylinder engines equipped with the filter maintenance procedures. They will stress such recommen- single-unit dual magneto. This is a constant polarity magneto dations as inspecting the entire air induction system to and the only benefit to be gained by rotating the plugs is the preclude the introduction of unfiltered air between the filter and reduction of lead deposit built-up on the spark plugs when a fuel injector or carburetor. The manual also recommends in- rotational time period is established and followed. Another ex- specting the carburetor heat door, or the alternate air door, to ception occurs on a few four cylinder engines where one ensure that they are operating correctly and sealing properly. magneto will fire all of the top spark plugs and the other magneto Any accumulation of dirt and dust in or near the entrance of will fire all of the bottom spark plugs. If the plugs are rotated the alternate air door or carburetor heat door, will be drawn as previously recommended, a polarity change will result but into the engine if the above doors are opened. Subsequently, since the plugs do not get moved from top to bottom, no self- aircraft parked or stored in dusty areas should have the unfiltered cleaning action by the engine will occur. This may result in the section of the induction system ahead of the air door examined necessity to clean the bottom plugs at regular intervals as these and cleaned, if dirty, before use. are always the dirtiest. For those engines with magnetos which fire all top or bottom spark plugs the choice of rotating plugs to change polarity or to obtain bottom to top cleaning action must be made by the aircraft owner or the A P mechanic. Checking And Adjusting Dry Tappet Clearance On Lycoming Engines

Engine Hoses Any time work is done on the valve train of an engine, such as grinding valves or seats, replacing valves or valve rockers. As airplanes and engines attain age, there appears to be a or any other component of the valve operating mechanism. the need to re-emphasize the inspection or replacement of engine dry tappet clearance should be checked and adjusted to insure hoses or Lines carrying fuel, oil, or hydraulic fluid. The hose that the correct tappet clearance is maintained. Any time tap- manufacturers definitely recommend the replacement of all such pet clearance is allowed to vary too far from prescribed limits, hoses at every engine change even though they look good. the engine will not operate properly. For example, if clearances are too small, burned valves or compression loss may result: Age limit of rubber-steel or fiber banded hose has general- and if clearances are too great, the engine will become noisy. ly been established at four years. This limit of four years is In both cases, the engine ~hanical haust valves on all engines except the TIG-541 and TIGO-W 1 failure may be the result. series powerplants; the latter should be .040 to .105. If clearance falls within these limits, no is It then The following is a b;ief description of procedures to check adjustment necessary. not, within and adjust the dry tappet clearance. After observing all safety adjust to limits in the following manner: If clearance is too remove the rod and install one. If precautions, rotate the engine until the piston is on top dead great push a longer clearance is too small install recheck center (TDC) of the cylinder to be checked. (1) Remove the a shorter push rod and to be sure clearance is within limits. rocker box cover, and also remove rocker shaft covers on angle head cylinders, valve rockers, thrust washer tangle head on- To determine a short push rod from a long one, check the ly), push rods, and shroud tubes. (2) Then remove hydraulic part number on the end of the push rod. The lowest number unit from the tappet body. On TIG-541 and TIGO-541 engines is the shortest rod, and the highest number is the longest rod. remove the unit with fixture ST-233. On all other engines use On older type push rods, machined grooves will be found on special tool Part No. 64941, that can be purchased from Lycom- one side of the push rod, three grooves represent the short rod, ing, or fabricate a puller from a piece of wire. NO MAGNET and no grooves represent the long rods. Consult Lycoming Ser- PLEASE. (3) Disassemble the hydraulic unit and flush out all vice instruction No. 1060, and applicable parts catalog. oil from the unit. Also, remove all oil from the tappet body. (4) Re-assemble hydraulic unit and install in the tappet body. Importance Of The Correct Cylinder Base Nut Tightening Procedure L

,1 The need to constantly stress the comet cylinder base nut tightening procedure seems apparent. Operators in the field are occasionally having engine problems and malfunctioning after reinstalling cylinders, and not tightening the cylinder base nuts ~flt correctly. The latter tends to cause crankshaft bearing shifting, ~iLu crankcase frening, or broken cylinder studs, and possible engine I failure. Â·Â·Cz I-: II -~iÂ·" Again we remind all operators in the field that we called

j-Â·Â·i this problem to your attention in Flyer No. 15, published in 1972, and repeated the information again in 1973 in the Key Reprints. In order to properly reinstall cylinders, consult Tex- .~,Â·Â·C tron Service Instruction No. 1029. Q Lycoming Maintenance people should ensure that torque wrenches I have been correctly calibrated before accomplishing cylinder Â·i base nut tightening. After reinstalling cylinders, a ground run of the should be as outlined in the r~ JIP: engine accomplished Lycom- followed a shutdown and i: ,,-Â·Â·la ing "Engine Operator's Manual", by inspection. Then the engine should be test flown normally, and ij.;Â·Â·-Â· following the flight, a good inspection of the engine should be u- made before the aircraft to routine use. r;Â·r~ returning

CAUTION: Be sure and keep hydraulic units as one Fuel Injector Nozzies Have assembly because mixing hydraulic unit result in parts may Been Improved changing the leak down rate of the unit and may cause a rough engine. operating Reports from operators of fuel injected engines and from CAUTION: After cleaning the hydraulic unit and tappet Lycoming service representatives provide some insights into the body, and unit is installed in the engine, do not turn the prop subject of clogged fuel injector nozzles. By providing our because this will pump oil into the hydraulic unit and result in readers with information from these sources, it may help some an inaccurate dry tappet clearance check. (5) Next, replace the of them to recognize and treat a similar problem in their own shroud tubes using new seals. (6) Install push rods, valve aircraft. rockers, and thrust washer on angle head cylinders only. (7) A recent letter from the owner of a twin engine aircraft with To check clearance, unit dry tappet depress hydraulic by press- Lycoming 10-540 engines indicated that after 900 hours of ing on the push rod end of the rocker, and measuring the operation the engines had performed flawlessly except for minor clearance between the valve stem and heel of the rockers by problems involving the fuel injection system. This particular using a feeler gage, aircraft was equipped with an exhaust gas temperature (EGT) On engines using rotators on the valves, the clearance is probe at each cylinder so the cylinder causing a problem could measured between the rotator and the heel of the rocker. In both be pinpointed by using the EGT analyzer. Here is a description cases, the clearance should be .028 to .080 on intake and ex- of how this problem was observed by this owner. From time to time there would be erratic combustion on two-piece fuel injector nozzle assembly. one cylinder which would either raise the exhaust gas temperature as shown on the analyzer lan indication of a lean mixture on that one cylinder) or in some rare cases the individual cylinder would become inoperative. Thorough cleaning of the Unauthorized Additions To Your nozzle and line had little effect, but simply replacing the noz- Engine Can Cause Trouble zle and line caused the cylinder to operate normally and brought exhaust back into EGT was temperatures line; again respon- Some accidents and forced landings have been reported to sive to mixture control, us which have been caused by adding certain equipment to the The basic problem boils down to almost microscopic pieces engines out in the field. In most instances, the equipment add- of dirt that get into the fuel nozzle. These bits and pieces are ed to the engine has not been approved by the airframe manufac- extremely hard to dislodge and they may severely restrict fuel turer or the engine manufacturer. Here are two of many ex- flow to the individual cylinder. Cleaning the line and nozzle amples reported to us: does not the dirt and correct the always remove problem, One owner added a magnetic pickup to the engine oil drain the surface it would that it should. although on appear plug which restricted oil flow to the oil suction screen, causing When fuel flow is only partially blocked by dirt in the in- oil starvation to the engine, and resulted in failure. nozzle, the exhaust will riseÂ·and not re- jector gas temperature Another owner installed an oil quick-drain plug on the to mixture control until idle cut off is reached. The reason spend engine sump of a plane with a retractable landing gear. When for this is that the blockage now becomes the restric- primary the gear was retracted, it ~ocked the protruding plug off, allow- tion and is of mixture control independent position. ing the oil to escape and resulted in engine failure.

In those aircraft which do not have an EGT on each probe Operators in the field desiring to add any part to the engine cylinder. erratic combustion or engine surging which may be should first consult with the engine and airframe manufacturer. indication of or fuel nozzles an clogged dirty injector may Any addition or change of engine parts also calls for a careful be checked the fuel flow Those fuel possibly by noting gage. ground run and inspection of the area of the engine after shut- flow gages which actually measure pressure will have an in- down. Then the engine should be flown and the engine in- of flow dicator calibrated to show gallons or pounds per hour. struments carefUlly observed during the test flight. After the With this of a nozzle will cause a type instrument, clogged latter, the engine should again be inspected for oil or fuel leaks, increase an fuel flow pressure and. therefore, unusually high etc., before flying with passengers. The Engine Operator's indication, Direct flow meters do not react in this manner. To Manual has a ground run checklist and a flight test record for pinpoint the individual nozzle or noules which are clogged, such occasions. it will be necessary for a mechanic to flow check all lines into The Textron Lycoming standard warranty statement sum- containers of equal size. Fuel flow in each line should be equal, marizes our discussion in the following all inclusive statement: so a line with clogged nozzT~ may be identified by a smaller Textron the to amount of fuel which flows into its container during the flow Lycoming reserves right deny any warran- check period, ty claim if it reasonably determines that the engine or part has been subjected to accident or used, adjusted, altered, handled, As indicated earlier. fuel injector nozzles have traditional- maintained or stored other than as directed in your operator's been difficult to clean. Under no circumstances should the ly manual. fuel injector nozzie be probed with a sharp instrument. The prop er method of cleaning described in Textron Lycoming Service Instruction 1275B includes washing the nozzle thoroughly with acetone and blowing it out with compressed air. Also, as indicated earlier, there have been times when cleaning did not A Simple Check Of return the fuel flow to normal and the only recourse was replace- Internal Engine Timing ment of the nozzle and line. The difficult job of cleaning fuel injector nozzles has been The A&P mechanic is often called upon to troubleshoot an made easier with the recent introduction of the "two-piece air engine problem relating to low power. There are many causes for this kind of This anicle will discuss bleed injector nozzle." These nozzles are now being installed complaint. one possibili- which should be considered if this after in production engines and are available as replacements for the ty problem occurs an has been overhauled disassembled for other nozzles which were used previously. They are physically and engine or reasons. fuctionally interchangeable with the corresponding old style First, let us consider the symptoms. In case of an engine nozzle. fined with a fixed pitch propeller, the static RPM may be several hundred RPM below what is for this The minor fuel flow problems cited by the aircraft owner specifred engine/airframe combination. For an with constant which in the first few paragraphs of this article were experienced with engine speed propeller has the and blade set it is old style fuel injector nozzles. The new two-piece injector nozzle governor propeller angle properly, that both static RPM and/or be low. has an advantage; it can be taken apart for easy cleaning. This possible performance mav feature should make trouble shooting and repair of dirt related The cause of these symptoms in an engine which has recently fuel flow restrictions much easier. See Textron Lycoming Ser- been disassembled may be the result of improper timing bet- the crankshaft and the camshaft. vice Instruction 1414 or Bendix Service Bulletin No. RS-77, ween Misalignment by one or teeth have occurred Revision i, for more details on installation and cleaning of the two gear may during engine assembly. If these symptoms exist and if improper timing is suspected, having unlike part numbers. it is not necessary to dis_assemble the engine to check the inter- This can be a little confusing and we have had reports from nal engine timing between crankshaft and camshaft. The pro- mechanics who assembled an engine using two different size cedure for this check will be detailed below for accomplishing rollers (two different part numbers) in the same counterweight. those A&P mechanics who have not been to this method exposed Fortunately, in the cases we are aware of, the error was cor- before. rected before assembly of the engine continued. insure that and electrical switches are in the First, magneto To help in clearing up this possible source of confusion, OFF position. Next, remove the cowling so that rocker box it should be remembered that each counterweight is installed and are accessible. Then rotate the covers spa~k plugs engine with two identical rollers. The rollers will have the same pan the in number one is at dead so piston cylinder positioned top number and be the same size. The next counterweight on the center on the stroke. The number one of compression cylinder same crankshaft may use rollers of a different size and pan Lycoming engines is the right front cylinder except for the 541 number, but these two rollers will also be identical. models which have number one cylinder at the left front posi- For more details on the assembly of crankshaft tion. For all Lycoming direct drive engine models, the top dead counterveights, see the latest revision of Service Instruction center of number be vertified observ- position one piston can by 1012. ing that the mark indicating the #1 TDC position on the rear side of the starter ring gear is exactly aligned with the split line of the crankcase at the top of the engine. As the last step of preparation, remove the rocker box cover from number two Maintenance Suggestions From The cylinder. Lycoming Service Hanger, I Engine timing is checked by first observing the number two cylinder valve rocker arms. Both valves should be closed or Spark plugs are an important engine accessory. Perhaps it's nearly closed. The next step is to move the propeller slightly because they do such an important job so well, yet are often -in one direction. Rocker arm motion should be seen as one valve taken for granted. This little fellow has character. For the alert, starts to open. STOP. Now rotate the engine back to the original knowledgeable mechanic, Mr. Plug is ever willing to reveal its position with the #1 TDC mark again aligned with the split in secrets pertaining to the health of the engine's fuel system, oil the crankcase halves. Both valves should again be closed or near- consumption, combustion chamber and even the engine treat- ly closed. Now move the propeller slightly in the direction opment given by the pilot. At the Textron Lycoming Service posite from the first movement. Rocker arm motion should again Hanger, we have come to lean heavily on Mr. Plug's ability be seen as the other valve starts to open. If the two valves started to "tell a story". Actually, he's our ace troubleshooter. to open as described with only a small amount of engine move- mcnt in each direction, the engine timing is correct. To make it possible for Mr. Plug to do even a better jab, we are listing some "do's and don'ts". These tidbits are directed For some individuals it may be simpler to rock the pro- at both the mechanic and pilot. peller slightly with a back and forth motion while observing that first one valve and then the other will start to open. If move- The massive electrode type are the least expensive to buy ment in either direction exceeds twenty degrees of engine rota- and do a fine job. The fine wire platinum plug is more expen- tion before motion of the rocker arm occurs, the crankshaft to sive but gives longer life, is less prone to frosting over during camshaft timing is not correct, cold starts and appears to be less susceptible to lead fouling. The more fine wire iridium has all the If the observed rocker arm movement indicates that inter- expensive plug qualities of the platinum plug, plus the fact that the iridium material resists nal engine timing is correct, then this is not the cause of the lead salts errosion to a much greater degree than platinum. This low power being investigated. On the other hand, if both rocker results in longer plug life. So make your choice. arms do not move from engine rotation within the parameters discussed earlier, the internal engine timing is not correct. This DON'T reuse spark plug gaskets. indicates and it a probable error during engine assembly can DO use the recommended torque when installing plugs. only be corrected by opening the engine and realigning the DON'T be a throttle jockey. For years we have been crankshaft and camshaft gears. Instructions for accomplishing preaching that engines don't like sudden throttle movement. this task will be found in the appropriate overhaul ri~anual. Well, the spark plugs don't like it either.

DO after a successful flooded start, slowly apply high power to burn off harmful plug deposits. Installation of DON'T close throttle idle any engine. Fuel contains a Counterweight Rollers lead scavenging agent that is effective only when the plup, nose core temperature is 9000 F or more. To attain this temperature. need a minimum of 1200 RPM, (TIGO-541 is an Textran Lycoming Service Instruction 1012D provides in- you exccp- tion). Besides, the engine's fuel system is slightly rich at formation on the location and assembly procedure for closed throttle idle. This ends up with Mr. Plug having a sooty counterweights on each Lycoming crankshaft equipped with face. cnunterweiphts. The illustrations in this service instruction show that some crankshafts may have two or more counterweights DON'T fly with worn or dirty air filters or holes in In- of the same part number attached to the crankshaft with rollers duction hoses and air boxes, for this :ts the fastest wav of wenr- due to of his worst The lack of printed matter on this suqiect may be ing out engines. Mr. Plug doesn't like it either. One the in and amounts ot enemies is silicon (a fancy name for dirt), difficulty adequately describing types metal. It's like asking for a precise measurement and _rettln_r mechanics to clean lead DON'T you attempt deposits bit". the answer, "why it's twenty five thousandths plus a little from plugs with an abrasive type cleaner tan excellent way to Therefore, what follows are meant to be general guidehnes. but keep the plug manufacturer on overtime filling replacement each case must be considered as an Individual one, Textron orders), Use the vibrator type cleaner sold by the plug manufac- does nor consider this discussion a technical bulletin. abrasive. Lycoming turers. Then. sparingly use the air powered but merely a source of generally helpful mformatlon. DO properly lean your engine in flight as recommend- GENERAL INFORMATION ed by the Pilot's Operating Handbook. and Lycoming Service small amounts of flakes or small Instruction No. 1094. In addition to being helpful to the engine 1. DON'T PANIC on shiny matenal. cleaner, more eff!- amounts of short hair-like bits of ma_gnetic in many ways, it also helps the plugs run are ciently and longer. Experience has shown that far too many engmes pulled unnecessarily. DO-you mechanics be a little more careful in gap setting low time A few bits of of massive electrode plugs. The top and the bottom of the ground 2. DON'T PANIC if it's a engine. in the oil screen or Alters on electrode should be parallel with the center electrode. metal is not too uncommon remanufactured of new or engines. DON'T reuse obviously worn plugs, regardless how erod- 3. DON'T PANIC. Again if it's a low time engine, it ma) they bomb check, Mon than 50Z of the ground electrode suffered a the center be a for one that had previously ed awav; the center electrode shaped like a footballs replacement have been If the answer is srmcrural failure. The metal may just dislodped core oi the ground electrode badly dimpled? oil tank. from some hiding place in the oil cooler, oil lines or yes, replace. all r4. Item 3 brings up the importance of properly cleaning DO use anti-seize compound when reinstalling plu~. items transferred from a failed engine to a replacement Caution: on the first three threads. Here is not only sparingly of engine. On dry sump engines. don't overlook cleaning a case of twice as much being twice as good. the oil tank. Oil coolers and oil lines should be cleaned by DON'T accept dirty and stained cigarettes: the~ may a proven method or replaced. cause misfirt. oil 5. In some rare cases where the pleated cylindrical type that has been One DON'T use any spark plug dropped. screen is used, the screen itself mav be making metal. Mice The manufacturer says "lf you drop it once, drop it Closely inspect the end of the internal relief valve ball. If second time in the trash barrel." the ball is deformed, this is probably the culprit. Replace the DON'T reuse any plug with cracked porcelain, screen assembly. have been or how it bomb is unknown. rcpardless of how it may working 6. In cases where metal shows up and its origin factory for checked. It will cause serious preignition. the metal may be forwarded to the Lycoming The can be expedited by callinr the DON'T shrug off oily spark plugs. New, topped, or ma- inspection. processing marenal. because factory Product Suppon Department when maiiine jorcd engines with some oil in the plugs is normal rin_gs haven't seated. High time engine oily plugs means rings are EXAMPLES: wearing out. One oily plug with others dry, means a problem in the cviinder with the oily plug. (The bottom-plugs are always Several pieces of shiny flake-like, non-maenetic. or several first to tell the story), short hair-like pieces of magnetic material: place aircraft back in service and again check oil screen or filter in 75 DON'T clean plugs with a powered wire wheel. This hours. is known as "a slow death on a fast wheel". 2. As in Item 1. but larger amount, such as 45-60 small pieces, DON'T you mechanics determine replacement spar~e clean screen, drain oil and refill. Run engine on ground referring to model number on old plug in the engine. plugs by If clean, aircraft for the model. for 20-30 minutes. Inspect screen. fly The man ahead of you may have installed wrong 1 to 2 hours and again inspect screen. if clean, inspect Use the manufactunr's chart on all plug replacements: also con- screen after 10 hours of flipht time. suit Lycoming Service Instruction No. 1042, "Factory Ap whether proved Spark Plugs". NOTE: In cases one and two, we are determining the small amount of metal was a ''one shot and done deal'' (not entirely uncommon). 3. Chunks of metal ranging in size of broken lead pencil point Remove suction screen as large pieces From The or geater. (sump) Maintenance Suggestions In of metal may have fallen into the sump. any event, Lycoming Service Hanger, II ground aircraft and conduct investipation. A mixture of magnetic and non-magnetic in this case oft-times means of failure. bottom The telephone is always a good indication of the type valve or rine and piston Removing spark information needed in the field. Therefore, for this issue, we'll plugs ususally reveals the offending cylinder. be taken when attempt a logical approach to the proper action to 4. Non-magnetic plating averaging approximately 5:," In in the oil screen or oil filter found 'ii metal shows up cartridge. diameter. may have copperish tint. Quantity teaspoonful or more; ground aircraft and investigate. If origin can't be determined, mail metal to Lycoming factory for analysis, attention Product Support. IMPORTANT 5, Same as Item 4, but may be slightly larger in size and minus copperish tint. On dinct drive engines, propeller action may Before installing this replacemenl cngme. all a~rcraft be impaired. Ground aircraft. If origin can't be deter- oil system components. oil coolers. hnes and supp)~ mined, mail material to Lycoming attention Product tanks, where used. must be thoroughtly cleaned for contarmna- Support. 6on. Textron Lycormng will nor be held responsible for contamination u, this newly installed engine. 6, Non-magnetic metal brass or copperish colored. Resembles coarse sand in consistency. Quantity of f& teaspoonful or PRODUCT SUPPORT DEPARTMENT more; ground aircraft, if origin can't be determined, mail TEXTRON LYCOMING WIUIAMSPORT PLANT metal to Lycoming attention Product Support. ~Viliiamsport. PA 17701 7. Anytime metal in the amount of'h teaspoonful or more, it is usually grounds for engine removal. An exception should be where problem is confined to one cylinder assembly (rings, valves, piston, cylinder). In this case, if the entire engine does not appear to be contaminated, the offending cylinder assembly kit may be replaced. After corrective action is completed, conduct the routine ground SAFETY NOTES running and screen' inspection as previousiy described in Item 2. In an attempt to reduce the cost of flying, some operators have nsorted to methods of operation which 8. If any singleorseveralpieces of metal largerthanpreviously are considered to be unsafe. Textron Lycoming makes mentioned an found, magnetic or non-magnetic, ground the following recommendations ngarding these aircraft. If origin can't be determined, a call may be made practices: to the Lycoming Product Support Department. A good description of the metal may result in placing its origin. i. Do not advance timing set timing in accordance When phoning Lycoming or when returning metal n- with the En~ne Operator's Manual for the specific moved from engines, supply the complete engine model engine model. designation, serial number, history of engine, oil 2. Do not use a hotter spark plug for low power temperatures, oil pressures, and any odd behavior of the cruise unless it is approved for the specific engine on ground or flight opeI-dtion, engine as listed in Lycoming Service instruction No. 1042. NOTE: Metal samples for analysis can only by accepted if the from which the is taken is engine sample a new, 3. Do not abbreviate the warmup of a turbocharged remanufacturcd, or overhauled engine from the Lycoming engine follow the instructions of the manual overhauled other facilities have factory. Engines by may penaining to oil temperatures, otherwise an over- which be identified pans cannot by analysis at Lycoming. boost or erratic power condition will result.

POSTSCRIPT 4. Do not use automotive oils in aircraft engines they will cause engine damage or possible failure. As an important postscript to "Maintenance Suggestions From The Service Hanger" column, factory personnel have 5. Do nor use automotive fuel in aviation engmes. of become concerned over unnecessary engine removals because Quality automotive fuel varies widely and metal was found in the new or remanufactured replacement additives may result in deterioration of fuel system engine after a prior malfunctioning removal. These unfortunate I components. The engine manufacturers contend that use of auto fuel in engine removals were largely caused by maintenance person- an aircraft induces nel failing to thoroughly flush and clean all aircraft oil system unnecessary risk. components. As a result, the factory Product Support Depart- ment now sends the following tag with every service engine leaving our factory: Engine Suggestions For Operators

OIL FILTERS

Clean engine oil is essential to long engine life. Generally. service experience has shown that the use of the external full flow filters can increase the time between oil changes provided that the filter elements are replaced at each oil change. Under normal operating circumstances the oil should be changed every 50 hours, and the oil filter element should be replaced after each 50 hours of engine operation, and the filter element cut open Recommendation Regarding Use the in the filter for evidence in order to examine materi_al trapped Of Incorrect Fuel of internal engine condition. However, operation in dusty areas or cold climates may require more frequent oil changes despite There has been an increase in the number of incidents In the use of an oil fliter. An engine which sits for long periods the past two years of the accidental use of the wrong fuel between flights should have an oil change at four month inter- particularly turbine fuel. Turbocharged piston engines with the vals regardless of the limited flight time accumulated. The filter term "Turbocharged'' painted on the engine nacelle have been cannot filter water and acids which may accumulate in the oil. interpreted by refueling crews to require turbine fuel. We must remind the pilot-in-command again, as we have over the years, OIL CONSUMPTION he or she must be responsible for the proper fuel in the aircraft Oil consumption is a very important trend to monitor in tanks at refueling. an engine. The operator and maintenance people should know Turbine fuel, or a mixture of turbine and aviation gasoline, the general history of oil consumption during the life of the .has proven to be a particularly ruinous fuel for piston engines. engine. It is typical of an engine during seating of new piston As a result, if the engine has been operated with this unspecified that oil consumption may be erratic or high; but after the rings fuel, qualified maintenance personnel must make a detailed in- are seated, within the first 25 to 50 hours, oil rings generally spection of the engine with particular attention to the combus- should level off below the maximum limits consumption tion chambers. If detonation has been severe enough, further established the manufacturer. Later, during the life of the by damage will occur to crank pins and main beanngs, if there is a noticeable increase of oil consumption within engine, counterveights and valve train components. In view of possi- a 25-hour tone or more hr.), this could be a period quart per ble damage, disassembly and inspection of the engine parts is danger signal and calls for an investigation, the only safe recommendation that can be made after the engine The oil screens and filter should be carefiilly observed for has been operated with improper fuels. If it has been determin- signs of metal, and maintenande personnel should take a com- ed that the engine has been run on unspecified fuel, do not con- pression check of the cylinders, preferably using differential tinue to operate it unless it has been inspected and cenified to pressure equipment, and also look inside the cylinders with a be airworthy by competent maintenance personnel. or light to detect any unusual condition. boroscope gooseneck Textron Lycoming Service Bulletin No. 398 is the latest THE AIR FILTER reference concerning Lycoming engines which have been operated with unspecified fuel. The induction air filter is a very important element in the life of an aircraft engine. With the modern high performance powerplant, the operator must keep dirt and abrasives out of the engine if it is to attain the expected life and trouble-free hours. Although this is ~maintenance responsibility, the Recommendations For Aircraft Or pilot/owner should be aware that excessive wear and early failures of reciprocating engine parts is due, in many instances, Engine Struck By Lightning to contaminates introduced through or around the air filter. The aircraft manufacturer's instructions for maintenance of the air Textron Lycoming Service Bulletin No. 401 makes recom- filter must be closely followed. When operating in very dusty mendations to operators any time an aircraft has been struck or conditions, it may be necessary to service the filters sandy by lightning. It points out that damage to an aircraft, which has or few hours in accordance with the airframe daily every been struck by lightning, is often confined to a specific area manufacturer's recommendations. of the structure. In such instances where the engine and its accessories, controls, fuel or exhaust systems are involved, it is necessary to evaluate and repair the damage before the aircraft is flown again. Top Overhaul The Service Bulletin explains that although the path of the lightning may appear to have been around the external hous- of the engine components, it is nevertheless impossible to We are frequently asked the question should my engine ings assess the internal damage that might have occurred by heat dur- have a top overhaul at some point between major overhauls? the discharge. Therefore, in the event the engine Our reply to that question is top overhauls should only be ing lightning has been damaged by lightning, disassemble and inspect the done when needed on the diagnosis of a competent mechanic, Heat by the arcing effect of the clec- It is unfonunate that too many people are spending money component parts. generated trical discharge can cause irrepairable damage to the hardened needlessly on a top overhaul. surfaces of ball bearings, crankshaft bearing surfaces, camshaft With proper operation, good maintenance, and frequent lobes, gear teeth and other parts that are surface hard- night. today's engines should reach their expected TBO without ened. These pans should not be reused if discoloration, cracks a top overhaul along the way, or other indication of damage by lightning is evident. Your Direct Drive Keep Engine page or a hard ground strike has caused subsequent en_glne failures. Some faiclures resulted from an overstressed crankshaft Starter Clean To Avoid Trouble gear dowel which ultimately sheared. When this part breaks, all power is lost. Too many starters used on our direct drive engines are be- In other cases, or strikes have resulted In ing returned to us at the factory reported as malfunctioning, but stoppage ground over-stressed rod bolts which failed thereafter. investigation here revealed the problem to be dirt. The loca- connecting soon When a rod bolt fails, it allows the rod loose tion of the starting motor on many aircraft engines subjects the connecting to get and flail inside of the Bendix Drive of the starter to contamination from dust, dirt and engine causing a nasty failure with a serious fire moisture because the drive housing is open and the engine con- potential. circulates air around the stantly starting motor. After a prop strike or sudden stoppage, the pilot and a competent A P mechanic must decide what to do after a careful Typical indications of a dirty Bendix Drive are: inspection of the engine; and the incident must be entered in i, Sluggish operation operator has to make several attempts the engine logbook. If a decision is made to disassemble the before the starting motor will crank the engine. engine, it will require a skilled mechanic who knows what to 2. Noisy operation a grinding noise when the starter is look for in the affected engine. When in doubt, do the safest energized, thing, consult Textron Lycoming Service Letter No. 163. 3, Failure to engage. Whenever any of the above complaints are received, the starting motor should be removed immediately and the Bendix Some Drive cleaned and lubricated. Oil should never be used because Tips On The Lycoming 0-235 Engine oil in thatrocation collects dust and dirt, becoming gummy and causing the Bendix Drive to stick. Little things are sometimes forgotten. For that reason, a reminder is sometimes necessary. In the case of the Textron In most cases it will be necessary to partially disassemble Lycoming 0-235 engine, it is a little different from most other the starting motor in order to service the Bendix Drive. The Lycoming models. Other models are equipped with hydraulic latter should he removed from the motor shaft to insure thorough tappets which do not require frequent adjustment. Occ~sional- cleaning and lubricating. Clean the arw in front of the Bendix ly there is a report of an 0-235 which is or not Drive pinion before removing the drive from the shaft. running rough producing normal power. Investigation often reveals that the Do not use carburetor cleaner or solution that any cleaning solid tappets of the 0-235 need adjustment. The L~coming could the rubber block inside the Bendix Drive. Use damage Operator's Manual states that valve rocker clearance should be only clean petroleum base cleaners such as kerosene or varsol. checked, and reset if necessary, at each 100-hour inspection. Thoroughly clean the Bendix Drive to remove all dirt and We find that since this engine model is a little different, this contamination from the sc~rewshaft threads and control nut. If inspection item is often overlooked. This reminder may help of the the drive is exceptionally dirty, the drive pinion cup can be operators 0-235 engine to keep it running smoothly. removed to insure a thorough cleaning job. Do not attempt to A second problem sometimes reported with the 0-235 remove the control nut, engine also is the result of it being just a little different from After the Bendix Drive has been thoroughly cleaned and other Lycoming models. Some 0-235 engines which use a full blown dry with compressed air, lubricate the screwshaft threads flow oil filter have had very low oil pressure at idle after being and rachet with a silicone spray. Lubricate the motor shaft with overhauled. The oil pressure would then increase as power was the same silicone lubricant before installing the drive assembly increased and decrease as power was reduced. This inconslsten- on the shall. cy from the normal oil pressure indications was traced to improper installation of the oil filter adapter. Textron Lvcomlnce For more details on the above, refer to Prestolite Service Service Publication SSP-885-1 provides instructions for this Publications ASM-7 (revised 3-15-75). Also refer to Textron installation. Lycoming Service Instruction No. 1278. These instructions specify that for the 0-235 engine only, a plare--lycoming Part Number LW-12999--is to be installed between the accessory housing and the oil filter adapter. The plate is sandwiched between two gaskets--lycoming Part Number LW-12795. The plate is designed with a hole that Propeller Ground Strike or Sudden meters the amount of oil flow and prevents an excessive flow of oil Stoppage Can Be Dangerous to the idler pear. When this plate is not installed as required, it results in the oil pressure discrepancy discussed eclrller Anyone who has occasion to install the oil filter kit after As an engine manufacturer, we are often asked to guide overhaul--or at any other time--should follow the pilots and mechanics concerning what to do about an engine carefully and should consider that the 0-235 installation is after sudden stoppage, or a ground strike by the propeller. Tex- ~llpht- ly different from other models. tron Lycoming Service Letter No. 163 states our position con- Lycomin_e eerninf this problem, This important publication points out there The preceding paragraphs seem to plctun the 0-'35 ~nrlnr mav be hidden internal engine damage from such an incident. as an eccentric problem creator which it certainly is nut. ~V'hen Fu;thermore. the unseen damage to an en_elne by sudden stop- the engine is malntalned and operated In accordance with The S indicates "slrvict: which manufacturer instructions. it is so reliable that in 1986 many ed with the letter S. a part" have a median weight. Use of a rod m~dels became eligible for an increase in TBO. Textran Lycom- will alwavs connect~ng will insure that the match between ing Service Letter No, L213 grves the details which owners of stamprd;Hith an S weight rods is within the tolerance allowed the an 0-235 engine may want to examine more closely. Starting always by Lycomlnce for that number. in June of 1986, all new, remanufactured, and factory overhaul- specification particulnr part which have ratios of 8.5: 1 or ed 0-235 engines compression If a piston is to be replaced, it is strongly recommended 8.1:1 are built with a new increased strength piston, Part that the powerplant mechanic refer to Lycominl Service Instruc- with ser- Number LW-18729. This part change. together past tion No. 1243. This service instruction shows that certain piston Textron to increase the vice history, will allow Lycoming part numbers are designed to fall within a specified standard 2000 hours to 2400 hours, recommended TBO from weight range. Any genuine Lycoming piston with that pmt although the HÂ·elchts For those individuals who own an 0-235 with 8.5:1 or 8.1:1 number will be a satisfactory replacement, of each should be before installation. compression ratio, a TBO Errension Kit is available. The kit piston compared all other for the includes four new pistons and parts necessary Other pistons are marked as A or B wrights and are used the TBO extension change. It should be noted that may only in matched sets when an engine is built. When these pistons which contain 100% GENUINE be applied to those engines must be replaced as a partial set, "service part" pistons are Lyeomine pans, provided by Textron Lycoming. These will be marked with AS restricted to a narrow whtch Those 0-235 models with a compression ratio of 6.75:1 or BS and are very weight range contain falls between the A and B Use of these pistons as are immediately eligible for a 2400-hour TBO if they weights. that the entire both old and new. 1004 GENUINE Lycoming pans. For those owners who have replacements will insure set, Testron maintained their engine reliability and durability by using only fall within overall weight limit tolerances set by ~ycominp parts, this notification of increased TBO is good Lycoming. news, Connecting rods and pistons are one more example of the need for appropriate reference materials when working on Lycoming engines. Overhaul Manuals, Parts Catalogs, or service instructions are the source for those details we cannot r~- Notes on Replacing rain in memory. Connecting Rods or Pistons

that certain An anicle an Engine Balance explained engine Maintenance Tip before are parts are organized in matched sets, by weight, they Oc- installed in an engine being built at the Lycoming factory. Fuel injector nozzles are occasionally blocked by casionally, it may be necessary to replace one of these parts microscopic pieces of brass, rubber or other foreign matenals. during the operational life of the engine. When this happens, Particularly with the older style, one piece nozzle, cleanm_e the field should know that which mechanics in the Lycoming parts which nozzle and line may not remove these tiny bits and pieces when an is built should be are matched by weight engine only after can serverely restrict fuel flow. Standard procedure any replaced with pans which fall within design specifications for cleanine or maintenance of fuel injector nozzles should Includr: service (replacement) pans, a flow check to determine that all noules flow a smooth, stead~Â· the of Staning with connecting rods, system marking stream with no fluctuation. The amount oftlow from each nozzl; that each will be marked with one of these let- ~pfcifies part should also prove to be the same when the fuel is viewed after or E. rods with the same ters: A, B, S, D, Connecting identify- a flow check. A fluctuation of fuel flow or variation in the flow installed when the is new: if one or and lint: ing letter are engine only to each cylinder may require a nozzle change or noule in the field, must be those mark- two rods are to be replaced they change to achieve satisfactory engine operation. LYCOMING MODEL CODE FOR RECIPROCATING ENGINES

Each Lycoming reciprocating engine has a model designation. The designation is made up of a prefix which is a series of letters, a three-digit number, and a suffix which combines letters and numbers. The letters and numbers in this model code have

meaning. Most people who fly or work on general aviation aircraft are curious about the meaning of the code, but only a small number thoroughly understand it. Perhaps the explanation and examples provided here will promote a better understanding of what the engine model designations do mean.

EXAMPLES: TO 360 CIA6D IO 540 AA1AS IO 360 A3B6D

PREFIX DISPLACEMENT SUFFIX

L Left Hand Rotation Crankshaft Cubic Inches* A or AA Power Section Rating T -Turbocharged (exhaustgasdriven) *Note (541)- A 3 Nose Section I Fuel Injected displacement B Accessory Section G Geared (reduction gear) ending in "1" 6 Counterveight Application

S Supercharged (mechanical) indicates a D Dual Magneto

V Vertical Helicopter specific engine (Subsequent changes to models

H Horizontal Helicopter model which are reflected in the suffix.) A --Aerobatic incorporates AE Aerobatic Engine integral

drive. O Opposed Cylinders accessory

With the information above and a few The three-digit number always provides fourth place in the suff~x will usually be a explanatory details, the Lycoming engine an indication of engine size in terms of ap- number to indicate a specific counterweight code is not difficult to understand. Starting proximate cubic inches of displacement. application. Depending; upon the need for a number, a D mav be used with the prefix section, an O will be found Engines currently in production at Lycom- counterweight aS either the 4rh or 5th chancier. The D in the engine designation of all flat op- ing Williamr;part have di~placemcntvalues indicates that the engine uses a dual posed cylinder engines. In addition to the of235, 320, 360, 435, 480, 540, and 720 magneto contained in a single housing. O, a combination of the other letters may cubic inches. To determine the minor differences in an be used to further describe the engine. The The suffix of the reciprocating engine engine model which are reflected in the O alone indicates a carbureted but code is a little more and the dif- engine, complex model code suffix, it is necessary to con- an IO will show that the engine is fuel in- ferences signified by each letter or number suit the engine specification. Mast aircraft jected. A further example is the TIGO are not readily apparent. The first owners or pilots will have no need for this prefix. Broken down, this says that the .characters of the suffix will always apply type ofdetail. Those who are curious about engine is TT) Nrbocharged, O fuel injected, to the parts of the engine indicated in the an engine can get a good idea of its size and lGj geared (which means the prop will run examples; in some cases, such as the character by simply applying the model at a lower speed than the crankshaft) and, IO-540-AA1A5. two characters are used to code information which has been presented finally. the (0) for opposed cylinders, designate one section of the engine. The in this brief outline. Lycoming FLYER

issue No. 49 December. 198')

Ibllshed by: Williamsport Plant Willlamsport. PA 17701

THE UNFORTUNATE CHOICE EDITOR'S COLUMN

While there W. There ore many who look for an aircraft engine on the open market. By ~en Johnson it sometimes is nothing wrong wi;h this approach to acquiring a needed powerplant, Dear Friends: which is an unfortunate choice. a little information on results in a purchase Perhaps This is m~ "Goodbve" issue after the possible pitfalls may help to reduce the number of bad choices. exactly ten'vears as~ editor of the Individuals on home built aircraft are to this working particularly susceptible L,Tomlng FI,er. As I move into retirr- there have been many calls from who an type of error. At Lvcoming. people grabbed ,,,t .t the end of 1989. it is evident which seemed to he an deal to find that this IÂ·neinr exceptionally good only that there ha\Â·e been many things that of their dreams" woultl not fit into the aircraft are "pnpine they building. helped to make the Fl~er and I~r)Â· Cooniider the circumstances which lead to these The looking problems. person Reprints what the!, Lire. is an aircraft from his own or from a kit lilr all engine usually building plans supplied First, the many vears as a Naval a~ ia- t,v it kit manufacturrr. tor did much to prepare me for my role In the latter case. a model is often recommended. Finding particular engine as editor. Second. my predecessor, blr. lhill mutlel engine available, and for sale on the open market, may be virtuallly J,, Diblin. had alreadv established the an core of the same model for any imy,oskible. Lycoming requires exchange engine Fl~rr and Reprints as publications ovcÂ·rhauled or remanufactured ordered. Since the home builder is starting engine with an eucellellt reputation. He also is the only Crtrnl scratch. there is no core to exchange. This means a new engine left volumes of written illformation from reilclilv available for this is option: many, option prohibitively expensive. which 1 acquired much of my know- be As the airframe hegtns to lake shape, obtaining a suitable engine may reason ledge of the flat. opposed cylinder with li,r concern and anxiety. When a 0-320. 0-360, or other engine kc,me Lvcomine Lvcominp engine. Third. the compnn~ is round: there is a to now and ask Ill'l'n,l''iil~e horsel'ower rattng temptation buy _ first A~ro and now Testron has later. This could be a serious mistake. paid the bills while giving me freedom *I'I1(Â· article "Low Time hlav Not Mean and Value'' which Engine Quality to write what seemed to be most apyru- in Fher No. 48 that old with low time are frequently ul'l"'u".'l explained engines priate for L!cÂ·omin~ engine owners. c~llÂ·cÂ·tcÂ·rl L,v int;nlal rust and corrosion. which is not used Any engine frequently But. it has been vou. the readers, who slllll~ltl I,cÂ· The condition or the is one of the items to he preserved. engine just have really helpetf the cause. when in the resale market. acquiring a power plant There have been numerous questions model. there are those ()tJlrr n,istakes often involve the engine Unfortunately ..d comme,,ts From readers which who I,~Â·licÂ·vr Illat all Lvcomine 0-320 engine models are alike and that all Lvcoming pointed the direction fur articles which certificated aircraft ()-3(,() cÂ·nFillr Inotlels are also ven~ similar. The Lvcoming later provrcl I~rllrlicial for all. The hlll)Wk 58 0~320 motlels ~ntl 51 0-360 models. While these (ItlFillll li~l engines may ,,j,, thrust of Ille Fiver hits been installa- I,rÂ· hil~lililT II1 tllilllV resl)ects. it is the differences which are likely to cause simple pro~ide information HhicÂ·i~ ~ioll atltl H.JliCII SIIould I,e well understood before an is I""'t,lcÂ·~lls engine purchased. will help readers to get the best possible The What are tllesr differences which may cause installation problems'! engine service from their Lvcoming enpille. n,oullch hllOUI~1 l,e considered. Older engine models were built with conical mounts ,,d t,.,,k, Il!in~ safer. which make illstallation somewhat easier. hut which do not vibration dampen engine It has I,eetl a Illeadure to speak wtth the and 1980s u~ well. With very Few exceptions, engines certified during 19705 FI,Â·er readers. L,oth by telephollr have dvnaFocal mounts. and 1,1 persoll. The illvitations I have Although tile of mount is not to be a serious the type engine likely problem, received to visit many of vour ur~anizil- of the the location of the cad,uretor. or an mounted oil filter mav sllill'C stlml'Â· engine tions are greatl~ Jpprrrioled. rcÂ·.sule in ilirfranle interference which makes installation of a model particular engine Finally. tile Illallv letters rec.etvecj tlinirÂ·ul~ or Some aircraft. For do not llave iml,ossil,le. example. enough space r,,,, readers all over the world from I~(Â·1WrlÂ·ll tile alltl the fire wall for an mounted oil filter. In the case of engitle engine Australia to %il~ll,a[,wr alld lust abollt which can be done since utr cÂ·np;illr with it hingle unit dual magneto. there is nothing r\Â·ervwherr rl~r ha\e provjtlecl mucÂ·ll All with two tile is a required part of the engine design. Lycoming engines praise for tile cÂ·oml,llnlr,l- irl(liviclunl l,e to without an oil filter. Shoultl a,l oil can conligurell operate tarv letters Irrolll ~ou. the Fl,er readers. IlltcÂ·r u,ld the needecl to remove it l,r the only in adapting this tyl,e of sl,acÂ·e problem have pn,,itl~Â·tl .snliaCacÂ·tioll ilntl Ill(.t~ll- to tile filter anti ran he removed and an oil c.~llzirlr an airframe. adapter pressure live for the editor. I thank vot! I;,r scÂ·rcÂ·cÂ·n Ilou,sin~ cÂ·an l,e installetl il,steatl. Shoultl this step be necessary. the recÂ·om- ,IlcÂ·~ltlrÂ·tl oil cllrlllFc. i~ltrnÂ·nl is rtÂ·tlurrd to ~5 hours. A second option would i,l~olve rtÂ·movine the filter fronl its stalldartl locÂ·ation atld mounting it remotely. I~npintÂ· to lirpwall is Ilot t~lr o~llv area \\here s~,acÂ·e nlav be limited. Tile sump is ollcrr in,sizr anti ~ll!l,r to rneet tJle re(luirements for a particular airframe.

I:or tllat T(`ilh()ll tile Il~,nlrl,uiltlrr rnav fitltl tl,at ~onle engine motlels will not fit tJlr

una*Gu~ El, oN 1'4(;E 6~ TEXTRON LYCOMING LIGHTWEIGHT STARTER CYLINDER BARREL SURFACES AVAILABLE FROM LYCO~IING

when the TBO's for Aircraft and balance is a criti- There are pilots a_nd technicians who remember general weight In the 1950's and cal factor in aircraft The aviation piston engines were much shorter than thev are today. design. weight for and in the curly 1960's, normal overhaul at 800 hours of operation was the recommendation of the engine accessories condition nose of the aircraft must be balanced by most Lycoming engines. An engine examined and found to be in good made hours the amount in the b~ck of mibht he extended for 200 hours on two occasions. This 12M) some equivalent the aircraft. Because of this, aircraft maximum TBO for even for the simplest direct drive engine, for builders both individual and Today, 1800 or 2000 hour TBO's are recommended many Lycoming cÂ·ompa- increases in recom- nies often find it desirable to reduce engines, There are a variety of reasons for these significant mended TBO. This discussion will be directed at the methods used to reduce the weight of the engine and accesao- the ries. This is not an task since most cylinder barrel wear and the reasons why Lycoming prefers nitriding process. easy attached to the are consid- The first Lycoming opposed cylinder engines with a design similar to today's items engine with ered to be necessary. models were certificated in the early 1940's. These early engines were designed built with steel To assist aircraft builders with low compression, were relatively low in horsepower, and were plain weight cylinder barrels, reduction, Lvcoming has developed and certified the stnr- ratios were Lycoming light weight As higher horsepower engines were developed, compression ter which weighs less than 11% increuked. The higher compression ratios caused increased cylinder wear, To com- will in recommended POU"dS. Use of these new starters bat this increased wear, and to provide a desired improvement reduce weight approximately 5'/r to 6'/,. TUU, harder cylinder wall surfaces were needed. surface p"U"dS depending upon the model The plating of cylinder walls with chromium to obtain a harder wearing devel- being replaced. was an invention of the 1930's. As larger and more powerful engines were standard in the manufacture of oprd, the use of chrome plating became Lycoming oil rvlinders. Cast iron rings were used in a variety of combinations to keep consumption within specifications. The increased cylinder lire did contribute to longer TaO's than could be obtained with plain steel barrels. In spite of the good results in terms of cylinder wear, the use of chrome plating Any barrel surface must created many manufacturing and quality problems. cylinder l,r capable of trapping and retaining enough oil to provide good lubrication between piston rings end cylinder wall. Chrome is not oil wettable, and therefore, each which could c)rrome plated cylinder barrel had to receive a secondary treatment hold the needed create a channel chrome surface which was porous enough to lubricating oil. For Lycoming this was not a cost effective program. also when chrome Obtaining a quality product consistently is very unlikely cleanliness is plating cylinder walls. The plating process is very sensitive. Absolute where the chrome does not ,lecessnry. Even a tiny speck of dirt mav cause a spot STARTERS ofthe cylinder barrel not reveal this naw adhere to the cylinder wall. Inspection may Th,., Lvrumlne Jtnrlrr u c,n Ih~ clnd until slier tile engine has been run. le/I Ihe Pr~slol,lr slnrler rs; on Ihr of ehronle After the engine has been run, it may be too late. Should a tiny piece riFrhl. the this very hard r,rcl away from the cylinder wall and be dispensed through engine, The I" mo"t cases, the Lycoming light ~nutc?riul will contaminate the engine causing bearing surfaces to wear quick". weight starter is a direct replacement rC'huIt could be a very short TBO. fO' fhe standard Prestolite starter the need for a pres- Lycoming had years of experience with chrome, and as a result, used on most direct of the nitride hardened steel allov entry LvcominF Il~ltr?r was very evident. The development process Some with altrr- is and the engines. engines was a great step forward. Manufacturin~ simpler, compdrive ""~O'S mou"ted on the left side nlav nut homogenous surface results in consistent high quality in the final product. Nitrided accommodate the lightweight starter. cvlintlrr~ also produce excellent oil consumption results when the engine is properly The pad used to attach the starter to the Lrokol in, engine is the same, and the electrical What ih nitriding'! It is the addition of nitrogen to the surface of an alloy steel connections are also duplicated. The introduction of into the wiring I"udu'ine B hard, wear resistent surface. nitrogen I" Some cases the alternator allorhinp luvers of allov steel is brought about bp subjecting the prdcticallv nnisherf hU~(Â·C link require modification bv himplv The heat map I'L"I" 10 ill) atmosphere of ammonia gas. process requires special treating adding a spacer, but this is a verv minur hlnlacÂ·rh wllicÂ·h are air tight and capable of holding the parts at high temperature. into the furnacr adjustment. At a hc!at level of 975 degrees rahrenheit, the ammonia gas nowing The pinion Fears on starters For ih l,roken down into its elements, hvdroSen alld nitrokell. This is the source of the in 1~14 nitrided LYcoming engines come pitch wl,icÂ·h tile surface of;he sleet. To produce a satisfactory llenetrates and ]0/12 To utilize the 1%/1~ 80 hours. pitch. ~urfut.e, tile ~,mc.ess must be continuously operatetl for up to I'ifch, the starter ring gear will havr I'rotlucÂ·tjon of nitritled cvlintler barrels began at Lycoming in 1960. The service 149 teeth. A ring pear with 1'''' teeth rcÂ·cÂ·ortl of tJlc.be nitritled cvlinders has been excellent. Only a few small, low power Will accept the 10/12 pitch pinion gear. The vast of cÂ·ngi~lrÂ·h are l,uilt with plain steel barrels todav. majority Lvcomin~ The light weight starters are currenl- have nitritlrd I,arrels when leave the Carton'. Some favorable character- c~ngineh they Iv available in both 12 and 2Â·1 volt motl- iMfi('k of I,arrels are: els wit)t 12/14 pitch pinion gear~. II I.s the more cliflicult to i. cÂ·vlillder wall wear the harder a surface e?tpecÂ·ted that 10/1:' pitch lipllt weight wear down. (COATINUEI, ON PAC;E 71 close visual check at each EXHAUST SYSTEM MAINTENANCE The third type of exhaust flange rence. A available from Lycoming has periodic inspection and prompt atten- PAY NOW OR PAY LATER gasket V-shaped spiral wound layers of stain- tion to correct any defect which mav be found will be to avoid It is unfortunate that the exhaust less steel and asbestos. These gaskets usually enough for all the need for more expensive repairs. systems attached to aircraft engines are are available Lycoming engines 3-hole Exhaust systems with slipjoints one of the most overlooked and ignored using the 2 or gasket design. are a resilient action another problem. The joints parts of the aircraft. Almost all aircraft This design provides present because the must with normally aspirated engines have that automatically adjusts for mechani- necessary pipes with the air- cal internal var- move. Vibration, along heating an exhaust system supplied by compression, pressure The and of the which causes frame manufacturer. Engines which are iations, and temperature changes. cooling system and contraction make it turbocharged by Lycoming will also spiral wound exhaust flange gasket has expansion unless essential that the be designed so have most of the exhaust system sup- superior sealing qualities and, system be that it has flexibility. Exhaust residue plied by Lycoming. an exhaust leak is evident, may is and heat cause slip- Lycoming technical representa- reused when the exhaust manifold may eventually seize. Because a or removed. New joints to slipjoint tivcs get many calls about exhaust sys- loosened gaskets be used when the which has seized can be expected to tem problems. It makes no difference should always engine cause breakage of the exhaust system who supplied the system. There are sev- is overhauled, which regular maintenance to keep eral areas where discrepancies may All exhaust flange gaskets pipes, with asbestos these free is a must. Mouse hlilk occur loose baffles in the muffler, were originally designed joints be now or a similar lubricant should applied exhaust leaks at the exhaust flange as one of the basic materials are standard. to the at regular intervals to Rasket, and slipjoints which do not slip. manufactured to a new slipjoint the number be the seizing of the pipes. Exhaust gas leakage at the exhaust Although part may prevent has been with Maintenance of an exhaust system flange gasket will cause erosion of the same, asbestos replaced with is a now or pay later aluminum cylinder head material, and an alternate material. siipjoints pay cracks in At each the situation. If the preventive maintenance a frozen slipjoint will cause periodic inspection, checked to is not it will mean bu~- the exhaust pipe system. Loose baffles exhaust system should be accomplished, the exhaust exhaust are not leak- new for system. in the muffler may result in a loss of insure that gases ing parts exhaust is not be minim- at the exhaust A leak can be Paying for a new system power. These problems can ing flange. which the worst A broken pipe could ized by regular exhaust system mainte- identified by the powdery residue part. be evident around the where allow hot exhaust gases to escape into nance at each periodic inspection, will place where there is The muffler should be checked the leak is occurring. This residue may the engine compartment brown in color. the for fire which would fur- carefully each time the exhaust system range from white to light potential and a A leak at the exhaust ther damage the aircraft present is inspected or anytime a loss of power flange gasket serious hazard for and is evident. Baffles which have come is often caused by improper torquing. pilot passengers. connnection Maintenance on this type of loose tend to lodge at various places Too little torque and the that it he taken inside the muffler. When the exhaust loosens. Too much torque and the exhaust system requires bow allow- if the slipjoint will not move. outlet is blocked, a power loss will gasket will slightly again apart Mouse to leak. If left uncor- Should a slipjoint be frozen, occur due to the excessive back pres- ing exhaust gases be the aluminum Milk or a penetrating oil should sure created in the exhaust system, rected, erosion of cylin- good will used to free it Then each joint must Attempting to look into the muffler may der head material occur quite up. material to be cleaned of all exhaust residue and reveal baffling which is loose, but usu- quickly. A loss of amounting insure that of an inch could examined to ally this is not something that can be only a few thousandths thoroughly that the unus- there are no cracks or damage determined visually. A sharp bump on be enough to make cylinder free movement. Before the muffler with the palm of the hand able. Therefore, correcting the problem would prevent the exhaust system, the while listening for any rattling sound quickly is essential. reassembling look- If the aluminum cylinder head slipjoint surfaces should be coated with may produce better results than lubricant such as ing. II. loose ba~fling is found, the muf- material has already s;oded as the high temperature is Fel-Pro C5A or equivalent. fler should be replaced with a new or result of an exhaust gas leak, repair Exhaust maintenance overhauled unit before the next flight, sometimes possible. This cannot be system probably should not be considered as com- Another important part of the done by hand. Studs must be removed unless it has included a review of exhaust system is the exhaust flange and the damaged surface refinished by ple;e No more airframe and manufacturer bul- gasket. Three different types are avail- use of a milling operation. engine letins which From time to able from Lycoming. The manufactur- than twenty thousandths of an inch may may apply. made ing standard is the copper/asbestos be removed. Should it be necessary to time product improvements are than twenty thousandths available. A prior review of service bul- gasket or the beaded gasket. Where the remove more the letins would allow these to be ineorpor- beaded exhaust flange type gaskets are of an inch to obtain a true surface, ated when the periodic muinte- ubed, they must be assembled (two each cylinder should be replaced. regular Where erosion of the nance is being done. per exhaust port flange) with their cylinder The of this entire discussi(,n beads interlocking. The flat side of the head has not occurred, replacing the point with a new one is to out the need for regular gasket must face toward the cylinder exhaust flange gasket point the leak. and exhaust sv~- head, and the raised or bead side, will usually eliminate Insuring inspections preventive maintennnce. Prevention is alwa\Â·h toward the exhaust stack. After initial that the correct torque is applied during tem less and less hazardous than installation, exhaust nange nuts should installation of the gasket is necessary to expensive be carefully retorqued after the first 25 avoid future problems. waiting for serious problems to occur. leak at the Ilours of engine operation. These stan- Fortunately, an exhaust dilrd gaskets should not be reused. exhaust flange is not a frequent occur- THE "SAME ENGINE" MYTH

Questions which frequently are asked of Lycoming sales personnel, engineers and technicallepresentatives indicate that there is a myth regarding I~ycuming piston engines. This myth aircraft seems to be prevalent among In the owners and aviation writers. minds of these individuals, each engine series is essentially cubic the same. For example, all 360 inch displacement engines are inher- differences in ently the some except for The fuel metering or turbocharging. these are the same is idea that engines ~iÂ· false. A few specific examples may help to put this myth to rest. Lycoming builds 0-320 engines which produce 150HP or 160HP. The TEXTRON LYCOhÂ·IING T1O-540-J2BD cierr3~ri thr 11; prrlcÂ·s 150 HP 0-320-E series engines operate Th, TW`en~mepirrurpd on Ihe next pc~e ic A'OT n q/the nlnlo cltÂ·lalL. I ~The of 7.0:1. The abulr. "The 5A~IE EIYGINE' M,Â·th" nrticle on Ihes~yaptÂ·s hns morr at a compression ratio en~ine pictur~cl 0-320-D series has high compression pictur~s are nol Ihe strme sccrle) pistons which raise the compression ratio to 8.5:1 and increase rated output that 10.0:1 compres- AF1A and the ~a\aJo ?;eries rnFlnrb to 1GOHP. Those who believe that the gested by putting main instead of difference in these sion ratio pistons in an 10-360 engine, are: small I,earinp large pihtons are the only ratlu it could be the same as the main l,earing. 8.0:1 comprrssion engines will be disappointed when they intercÂ·uuled and nol~- the HIO-360-D1A. These are some charac- rather than 7.3:1. plan to upgrade their 0-320-E to of the HIO-360-D1A helicopter intercooled. presaurized Slirl; mapntÂ·tus hiaher horsepower by simply changing teristics and an which can be compared with the versus BendisiTChl nlapnetos, pis~l,ns. Many models in the 0-320-E engine fuel in of the of data on the 10-360 listed in the previ- R~.45AD1 i~ljector place ,s~Â·ries were designed for the purpose To start, the HIO has K~AIOADI inirctor. Thrrr are aomr kcÂ·el)ing the cost down. Thousands of ous paragraph. rather than mounts. other differences. I,ut those comyerl- these low compression engines were conical dynafocal thick wall bear- sons listed shoul(l convince even built with plain steel cylinder barrels The main bearing is a crush tile most that these engines inÂ·~cnd of the nitrided barrels used in ing instead of the thin wall, high skeptical the 10-360. Other dif- are vastly different. the CJI-320-D series engines. They also bearing used in of various of ferences include: crankshaft designed By making comparisons had two narrow bearings instead one and accessories used in engine long front main bearing. The engines for small crankpins, high speed cam- parts mounted RSA7AAI fuel models which some individuals have certified at 150HP and were not shaft, rear w~Â·rr it is intake valves, and tor- considered to be much the same, intended to withstand the additional injector, large differences. sional vibration damper magneto possible to illustrate the .slres.s of higher horsepower. models artÂ· Although some L~coming Because of the similarity in designa- drives. related, this cannot he the Finallv. l,oth the engines and closely tion, it would be easy to believe that Navajo Lycoming used in assumed. A of the engineering ().361J-A1A and the IO-360-A1A are the new turl,ocÂ·har~ed dif- list for each model by a the first the Illoonev TLS are with parts engine the hnmu engine except that equul,l,eed the onl\ ferential a;ld density controllers which knowledgeable individual is h:i a curburetor and the second IÂ·~lginu and tile maximum allow- sure way of establishing similarities Here are some autonlaticÂ·all~ set a fuel injection system. when the throttle is differences. For those who ma, have fcu~urcs of each engine for comparison. al,le horsel,;,wtÂ·r the mvth that 811 aclvanccÂ·rl hlttv for takeoff. Some who been taken in by The 0-3(j0-A1A has a bottom mounted diu- time to L~eoming engines of a particular carburetor, parallel valves, have not taken the compare uprlruft much the Ila\r to tl,e rÂ·on- placemeent are same. 8.5:1 ratio, and produces these engitles jumped compression with better knnn- that tile which vou are now armed a IHI)HI'. The 1O-360-A1A features a cÂ·lusion TLS is a ledge of this subject. Irorizontill front mounted fuel injector, I,owers the Moollrv sinll,lv This cÂ·onclusioll angle valves. 8.7:1 compression ratio, c~erated Navajo rll~illr. cÂ·oulcl harcllv I,r nl~,re inaccÂ·urate. The ;Irrd is rated at 200HP. The IO-360-A1A cliCfrrenc.r. e\.e!~ to the ill~r, these design items Illost ol,viou~ Ilo~icÂ·r. (Â·n11 I,e srr~l look- ilre not included in the 0-360: cÂ·oml,lelr tile rocÂ·lrr I,o\ co\rrs. Tile I~jhlOll I1OZZ1lÂ·5, stronger crank- illi: at PERRIISSION TO KEI'HINT l'l()-540-AFlr\ i~ rated at 2701-11' a,lcl .shult. tollRur and groove connectill,P clowtl rs)lilu~t cÂ·vlill- rclrls witll hlTC1CII bolts. tuned intake Ilax srrirh liatl tilrrC intake valves. cftÂ·rs. l'lltÂ· Nil~ajl, ol lll1()rlll~lllOll hySt(~l)l. lll1d rotator tyl,u 2l, loll:: Illr (()llt"\t rl,~i,leh at 325HP. alld 'I:llcÂ·rcÂ· ilrcÂ· ilcr~ually few cÂ·~rÂ·lÂ·l'l I~lr Lha 300 cÂ·ubic illlÂ·ll disl,l;l~Â·e- cÂ·rcÂ·tlrt i?. 111('t1t. in tile '70Ht~ 'I'lrcnÂ·;lre i,ldividualx \\hu havct.uÂ·l!p- dilrrrrllccÂ·b rrhl,rcÂ·li\Â·rl!~ ENGINE ACCESSORY TBO

Do engine accessories have a specified TBO' This question has been asked by Flyer readers on several occasions. Except for early throw-away versions of Slick magnetos (4000 and 5100 series) which were produced during the 1970s, accessories are not assigned a specific number of hours which they are expected to operate. bIay we assume then, that the TBO for accessories is the same as the For engine on which they are used' many accessories this is not a bad assumption. An Air Research Industri- al Division Service Letter states that turbochargers, controllers, wastegate ."i :tÂ· valves, and pressure relief valves manufactured by AirResearch should be overhauled when their service time reaches the TBO of the engine. A com- municaticln from the Romec Division elf Lear Siegler also indicates that Romec TEXTRON LYCOMING TIO-540-AF1A fuel pump overhaul should coincide with overhaul of the engine on which It lubricate felt is used. According to manufacturer NEED TLC cloth if necessary, (c) MAGNETOS fuel such located at the breaker points and at the documents, system products time as and flow dividers from Ben- It would seem to be self-evident that distributor gear bearing, an (d) injectors in accordance with instruc- dix, and hIarvel-Schebler or Facet cilr- magnetos err: a critical element in the magnetos be overhauled at the reliable and efficient operation of the tions in the operatois manual. buretors are to overhaul. In the case of reciprocating aircraft engine. A review The magneto manufacturers also time of engine for the carburetors. Facet does state that of the Tcxtron Lvcoming Index for ser- make recommendations inspection be to the vice bulletins, instructions, and letters and maintenance of their products. The service m~v required prior TBO. reveals that both the magneto and latest revision of Slick Service Bulletin engine series are a cntlc~l engine manufacturer have printed 2-80 says that 5200 and 6200 Magnetos particularly should accessor?l. Bendis Engine Products bul- Ilumemus recommendations for the magnetos now being produced 100 hours letin SB586A recommends maFlleto maintenance and inspection of magne- be inspected externally every The overhaul at the time of overhaul. fUh. and internally every 500 hours. engine would include such This statement is qualified by stating A,s il,l esaml,le, Textron Lycomine 500 hour inspection that overhaul is recommended ~lÂ·rvicÂ·e 183A was written in items as contact points, carbon brush, magneto other at four-year intervals regardless of the LS)57 nlorr tllrtn 50 years ago and impulse coupling and components I,ulle- Based on the time accumulated on the engine. ih still all il(Â·tiVr l,lll,lication. This subject to wear. inspec- be Unison Industries. the manufacturer li,i hllllph that faulty engine perCor- tion, these components should that the cur- Tail- as necessary. rotor of Slick magnetos, requires tlli~ll('c'. ~)lln11 I)iStOllS illl(l engine replaced blagneto be timed must be every rent 4"0016%00 series magnetos un's were tracrrl to inll,rol,rrlv shaft bearings replaced ianit;l,n;lntl illaclerluate ig,litioll insl,er- 1000 hours. inspected externally every 100 hour.s and internall\ every 500 hours. Should tioll. Sl,lllr n,aintenunce personnel have These standard maintenance sched- series of the find discrepancies illhl'L'''f~'l ipllitiUI1 tinljllg without using ules are supplemented by a inspections to be bulletins from the man- which require it, the magnetos are ~I timil,F light to inrlicate I,reaker poillt service magneto Bulletins completely overhauled. In an~Â· case. 1.,I'L'"il~g. This is all error in ~ecÂ·hnirlue ufacturer. usually require hardware in total time in service mav not exceed the killc'e it lilllille liSllt is IleCeSSaTY 10 inspections or changes maintenance manufacturer's TBO for the engine on IlcÂ·llir\e rPcluirrtl arcÂ·uracÂ·v. addition to the routine which the is installed. Il~aintcnance items for special atten- items mentioned earlier. maeneto The manufacturers of other aecessv- tiol~ is the subject of Textron Lvcoming To summarize, magneto inspection ries such as S~Â·rvirÂ·e instruction 1080A which is and maintenance should be a part of propellers, governors, I~rll- tion harness, starters. anti al~rmnlura claterl January, 1978. This instruction every regularly scheduled inspection. To insure reliability, this main- mar have specified TBOs for their prucl- warns that inellicicnt engine operation, engine be ucts, but no written ducumrnlntion loss DC power, and detona- tenance must conscientiousl) these item,s Hab a~illlable ti~,rl dcvclul,ing into pre-ignition could accomplished. Perhaps the best advice regarding when this article was linlc.sh all I,e the result of lark of maglleto for the powerplant mechanic is to prepared. there is notillcatlon frolll the milllurarÂ·- Illclin~cnurlee. These maintenance research and follow the manufacturers' at turer. it will be ntÂ·ces,zan. to cÂ·onsldrr iuÂ·tioll.s are rccÂ·onlnlc~ldcd: (al check instructions every periodic inspec- olcÂ·rhaul "aa ncÂ·etled" I,i. nlile~lrto breaker points. Ih) tion. accrssorv as a~l (Â·II(Â·IÂ·I\ fr,r I)il in bPeaker cÂ·onl- requirement. I'ullll,~Â·rll anrl wills dr! with a clei!~l ENGINE OVERBOOST SERVICE BULLETINS, LE?TERS, INSTRUCTIONS PUBLISHED FROM JUNE 30, 1989 TO NOVEMBER 30, 1989 Many Lycoming turbocharged listed below are those which have been issued most engines are equipped with density con- The service publications of these be trollers. These engines are used in air- recently. We strongly recommend that a complete set publications which work on craft such as the Piper Aztec, Piper maintained by all maintenance organizations Lycoming reciprocating Navajo series, the Lake Renegade, the aircraft engines. A subscription may be obtained through any Textron Lycoming the Textron Product Aerospatiale Trinidad TC, and the Moo- distributor or directly from Lycoming FVilliamsport Support write for a of Textron Service Letter No. L114 ney TLS. Department. Call or copy Lycoming of available and instructions. The purpose of the density controller which provides a listing publications, prices, ordering is to aid the pilot. When the throttle is SERVICE BULLETINS fully advanced, the controller should Assemblies assume responsibility for obtaining 486 Inspection of SINGLE BELT Driven Ring Gear Support from rated horsepower from the engine. Note All new, remanufactured and overhauled engines shipped two very important items: (1) Should Textron Lycoming from January i, 1988 until June 12, 1989. is based on the assume responsibility with serial num- 487 Fuel pump vent restriction TIO-540-AE2A engines controller being adjusted as described bers up to and including L9064-61A. in the latest revision ofTextron Lycom- 488 Propeller governor line support All four cylinder engines with rear ing Service Instruction 1187 and, (2) mounted governor. Rated horsepower does not mean a spe- 490A Installation of intake and exhaust valve T10/LT10-550- cific manifold pressure. guides It is unfortunate that pilots who ny V2AD, -W2A engine. these aircraft do not always understand SERVICE INSTRUCTIONS what the density controller is designed -A1B, to do. This may also apply to some A 1187G Turbocharger density controller adjustment TIO-530-Ali\, -AAli\D, P technicians. Let's take an example. -A2A, -A2B, -A2C, -C1A, -F2BD, -J2B, -JZBD, -N2BD, Cold weather has just arrived with fury -ABIAD, -AF1A; LTIO-540-F2BD, -J2B, -JZBD, -N;?BD On takeoff and Mr. Pilot goes out to fly. 1445 Precision Airmotive Service Bylletin No. PRS-91 Testron he notes that the manifold pressure is Lycoming HIO-360-D1A engines. two or three inches below the red line 144~ Possible ruptured pressure regulator diaphragm in AN fuel pump. manifold pressure on the gage. Back on All Textron Lycoming engines equipped with AN type fuel pumps. the around he tells his favorite A P that he is not getting enough manifold SERVICE LETTERS pressure at takeoff. When the A P 114AC Reciprocating engine and accessory maintenance publications. rtnds nothing wrong with the engine, he Discontinuance of reconditioned camshaft adjusts the controller so that the needle 214A exchange program. on the manifold pressure gage goes to 227 Listing of parts catalogs and applicable revisions or special service red line when the throttle is fully publications. advanced. Both of these individuals are

in error, and each time the throttle is fully advanced, the engine is being overboosted. the engine is being forced THE UNFORTUNATE CHOICE Continued to produce more power than its type this were not to be concerned certificate allows, plane being built because of interference. As if enough also be considered. These fuel Generally speaking, overboost is bad about, the carburetor or fuel injector location must in devices are mounted under the engine an up-draft confipur~- for the engine. It may cause exhaust metering frequelltly Some models but there are also front and rear mounted configura~ions. enRinr ciystem leaks. Internal engine damage tion, with horizontal carburetors. All of these variations in model may have from preignition or the excessive loads are equipped also an effect on fit. put on internal engine parts may engine/airframe is the of an I will Another error in choice which occurs all too frequently purchase occur. But, you say, as a pilot builder has a low which for a wing aircraft when the H'infi take my ehnnees with a controller engine originally designed high but the under construction. The low wing needs a fuel pump, high wing causes the engine to produce more pow- design delivers fuel to the carburetor by gravity. in most cases a fuel pump cannot cr than it is rated for. It may come in usually built in be added to the because the drive mechanism was not during engine handy if an engine should fail and I am engine of a fuel manufacture and the was not machined to allow mounting faced with a Single engine situation on accessory housing the twin I fly. Keep in mind that aircraft pump. with individuals who have made engine I~u"Â·hnses fur performance is only assured when all As a result of contacts outlined in thl,s the their aircraft, we know that the variations in engine configuration parameters are the same as when resulted in The of bringing these issuea to the aircraft was test nown for certification, article have problems. purpose others attention of Flrer readers is to them avoid making the same mistakes The available rudder may not be adequ- help have made. Ifa model has been recommended by a kit manufactur- ate to handle additional power on one particular engine models may nut it is best to search out that model. Although similar, other engine engine. That extra power with too little er, not make illl needs. When a used in the market, do rudtler might be enough to cause the meet vour buying engine open choice it the first time. uircÂ·rart to roll inverted. Too much pow- unfortunate get right cr may l,rÂ· just as l,atl as too little. (CONTINUEI) ON L'AGI~ 7) TEXTRON LYCOMING CYLINDER BARREL SURFACES Continued RECIPROCATING ENGINE 2. Natural choked barrels providing improved piston ring life due to a resulting and a belter of TROUBLESHOOTING SCHOOL straight cylinder wall when engine is hot or operating, Job sealing. Texlron Williamsport which are more wear Lycoming 3. Nitriding permits use of chrome plated piston rings offers a four-day, Monday through resistent and quite compatible with hardened steel. for troubleshooting course surface with an increased Thursday, 4. Nitriding provides a hardened fatigue strength. is the aircraft mechanics. Emphasis on 5. Nitrided barrels also have the ability to resist softening when heated during correction of in diagnosis and problems engine operation. various or accesso- when used piston engine parts The main advantage of chrome over nitriding comes into play rics such as turhocharger systems, mag- barrels which are out of sen.ice Jlmita cylinders are to be overhauled. Worn cylinder the nelus and fuel injectors. k tour of them back to their can be coaled with enough chrome to bring ori~inal ~pecification. Plant is included. matched Williamsport The problem with this is that the up-to-specification cylinder barrel will be is offered at no charge, ready to The course with used cylinder head. The steel barrel with its chrome coat mav now be but each individual attending will be that the head will perform through another full TBO, but it is very unlikely cylinder for travel, meals and responsible lodg~ survive for that period of time. between local limits have worked ine. Transportation Typically, cylinder barrels which are worn bevond service motels and the school will be provided aluminum head which is the other through more than one TBO. The major cumyo- if at %-IUC) required. nent of the cylinder will also have heen in use for this period. Running the schedule for 1990 is Over a of Although RPM, that head is exposed to 72.000 firing impulses everÂ· hour. period not as this notice is written, thermal The cuntplete 2000 hours, this is over 140 million impulses or quick changes. aging about classes are normally scheduled and each time the process is also affected by the continuous heating cooling ellFine twice each month. For further informa- this is 100() i~ started and shut down. Assuming average flight lengths of two hours, lion on class dates and to The an specific thermal cycles during the life of a 2000 hour TBO ell~ine. longer enptne resPrve a in a future class, con- heads which space runs, the more susceptible the cylinder head is to rracÂ·kin~. Cylinder tact: which has found to are cracked are often repaired b; welding, a procÂ·ess Lvcoming and the chrome Don Stahl be of limited value. While the overhauled cylinder nlav look good, the unknown of the over- Instructor/Training Center barrel may provide an excellent wearing su;facÂ·e. quality This Textron Lycoming Williamsport hauled cylinder head is typically the weakest structural part of the cylinder. the has h52 OLiver Street could be the place where cylinder prol,lemu occur before engine again of the cylinder barrel is of little Williamspurt. PA 17701 reached TBO. In this case, the quality coating Phone: (717)327-7338/7308 co"se9uence. all from the factun (ne\Â·. Lvcoming has adopted a policy of shipping engines this, the reman;factured. and overhauled) with brand new cvlindew. By doing factorv en~ine has the best cylinder quality it is possible to provide. all distributors. Each kil c~untalnk ivcoming cylinder kits are available through ENGINE OVERBOOST and all the needed to assemble the rvlindrr oll a brand new cylinder assembly parts L~cÂ·onl- Continued the engine. Currently selling at reduced prices, these high quality genuine the same time eliminate all lhr cylinder kits are an exceptional value, and at What ing back to the density controller. and of 9uesf'o"s relative to the value of chrome plating reworkin~ ,should the and how should pilot expect To summarize, the improved hardness of cylinder barrel surfaces is all Illl~,or- the controller be set' The A P the tant Tactor in the increase in recommended engine TBO. For Lvcoming. the tools mrchunic must have specified These include elr~ciencv and cÂ·onaiL~- process has manv advantages. manufacturink revision of service instruc- in the luteht focused on methods of lent quality. Although this article has primarily ob~alninF lion 11117. and must follow the proce- the entire cylinder which cylinder barrel hardness for good wear characteristics. it is be at durcs outlined. The engine must cylinders to be used for must be considered when making a decision about the Induc- normill operatin~ temperature. of a cylinder for any reason. engine overhaul or for replacement single lion air temperature is then checked ;Ipainbt manifold pressure utilizing the

curves in the service instruction. The FO' Ihe pilot. expect lower than red DID YOU KNOW') cÂ·untroller should only be adjusted if line manifold readings for all the manifold pressure this ih necessary to h;ing The style fuel pump~ uhed takeoffs. Once it is set correctly. the diaphragm within the limits shown on the I""""U"r on many engines are penenll- densitv controller will insure that vou Lycominp Since Ihc~ ofT. IV k"O"" as AC Fuel pumpa. pet rated en~ine power for take conlrollcÂ·r is set (:I1Nwq;cn the properly, have I,een used on Lvcominp enFules. Once the function of the density con- the manifold the pilot shoultl not expect the' ha\Â·~ I,oth an i\C numt,er and troller is urlderstood. it truly is an aid to I,ilrt needle to settle on the mani- Todal. Ihe~r i""""" a Lvcomin~ I,art numl,er. the pilot. In addition to supplying rated fol(l limit marked on the pressure gaee. will "'e I"O'1U'f of Teutron LZcc,nl- it one EÂ·tep further. It pUmpS filrtor in the I'O"e'- goes Air is a major T~lrv 51111 carry an r\C and a ccml,rrature also overboost. ing. Since the prevent engine umountof power produced. Lvcominp I,art numl,er. The AC Ilum- tlcÂ·~lsity controller is sensing tempera- l,er is rrtainecl for reference I,ur),o.seh.

as well as it will demand sl,l,ulcl b~ ture, pressure, The Fiver I,rovider: prorlucÂ·1 in- hut the Lvcominp nunll,tÂ·r in hot weather mr,rr manifold 'Isetl whrll a i:, to I,r or~lerrd Irc,m I,ressure f~rmnlion. In/ormed pilotb anti ~unll, anti IChS ill cold weather. In either case. Lvcomin~. mecÂ·hanicÂ·~ rontril,utr to sn/e of will I,e at, cÂ·cluivelu~lt amount I,ower ~,rodurPd. 11?Â·inp. Doifrioht. Do it new,

Don't settle for salvage: reconditioned cylinders that may, or may not reach TBO. Reconditioned is, after all, used. Our experience has shown that when the engine is operated by-the- book and normal maintenance is performed, factory-new cylinders will typically last beyondTBO. Lycoming cylinder kits come with nitrided barrel", aluminum head, intake and exhaust valves, piston, rings, springs, valve seats, keys, gaskets, seals. Everything you need, all brand-new and warranteed for one full year, regardless of the number of hours flown. Parts and labor. If reconditioned cylinders were as good as new cylinders, they'd come with the same kind of warranty. And, they don't. The price for new lycoming kits? Your customers will be delightfully surprised at how competitive we are. i- ~B Call your local distributor today, and I see for yourself. There's no reason to settle for 't. salvage anymore.

Li ~C i~:l Lycoming Â·s;LIÂ· Â·e Texlron Lycom;ng SUD.; diary ot Torrron Ire 1C~r, 652 Obver Street Wlliiamsport PA 17701

PI 4) i. Your Lycomlng dlstnbutor

~3C10 TPZlrOh Lycom~og Certln low-com~ress an mcde(s ACCESSORY TBO Continued MOBIL AV 1 OIL LIGHTWEIGHT STARTER APPROVED FOR USE IN Continued An "as needed" accessory overhaul starters will be available early in 1990. may be the result of normal wear and LYCOMING AIRCRAFT ENGINES Individuals building an aircraft ma~ unusual conditions tear. Exposure to Textron Service Instruction Lycoming find it convenient to plan for use of the could also bring about the need for which No. 1014 states that the company when such light weight starter cnlculatinf: accessory overhaul. Conditions as oil produces a lubricating is responsible weight and balance. Although these or lightning strike, engine overspeed, for that the oil conforms to insuring ,,,,t,,t,, are capable of .rudden stoppage are examples of condi- MILL-22851. The results of extensive replacing the mounting and starting tionci which could have a detrimen- very done MOBIL were to testing by presented of the standard starter now in tal accessories. capability effect on engine for evaluation. The Lycoming engineers use on many certified aircraft which are Should on overhaul accessory require tests indicated that Mobil AV 1, a fully Lvcoming powered, this mav not be before the engine reaches its recom- synthetic oil, exceeded the requirements done without careful consideration of mended TBO, a careful logbook very of MIL-L22851. Based on the by testing the effect on aircraft weight and record should be kept. This will provide MOBIL and evaluation of the results by balance. Because of the weight differ- information which to base a decision on Mobil AV 1 Oil is Lycoming, approved ence, weight and balance must be at overhaul time. A new or over- engine for use in aircraft by Lycoming Lycoming recalculated and proper FAA approval hauled accessory which has had only engines, obtained. After recalculating weight limited service on an engine which is synthetic oil Although this fully ..d balance, the filing of Form 337 would not be due for overhaul probably received in Decem- Lycoming approval with the FAA ma~ be adequate fur repaired at the same time as the engine. ber, 1989, compliance with Lycoming approval, but this change in certitica- An which continues to accessory pro- is and may service publications required, tion data must not be overlooked. service for the life of vide satisfactory certain of the qualify aspects approval. F,, those who may need a before light the engine or for a long period For service instructions 1015 example, weight starter, the!: can be ordered the engine reaches TBO should be over- and 1392 set specific temperatures below Lvcoming distributor. The the time the through any hauled or replaced at same the should be which engine preheated, 12V model with l~lÂ·IÂ· mav be will this pitch engine is overhauled. Not only of the of oil used. Service regardless type identified by use of this part number LIÂ· more convenient and less expensive bulletin 480 recommends oil and filter 31A21198. The 2-tV model with tllr the it will assure over long term, usually at 50 hour intervals. replacement pinion gear pitch has this part a long period of relatively Engines which do not have filters should number 31B210~. Port numbtÂ·rr maintenance-free with the operation have the screen cleaned at 25 pressure for light weight starters with 10/12 pitch newly overhauled engine. hour intervals and oil at the changed pinion gears will be assigned when From this discussion it becomes time. In a maximum of same any case, these models are available. well defined clear that TBO is not a four months between oil changes should for most accessories. period engine not be exceeded. (vcerhlul will usually be accomplished N,,,tter what oil is used, Lycoming on an "as needed" basis and it is not with all service considers compliance LYCO~IING "FLYER" unusual for this need to occur prior to publications dealing with lubricating oils the requirement for an engine overhaul, to be important in achieving lone engine December 1989 Unlehs an accessory has only a very life. In particular, the oil change inter- the brief period of operation before vals specified in Lycomin~ Service Bulle- ISSUE NO. 49 is overhauled, the I,np;inu overhauling tin 480 are necessary to avoid a build up at the time of overhaul accessory engine of contaminants which result from com- Editor ii. W. Johnson ih a reasonable course of action. bustion. ~t

Wllliamsport Plant PAID TFJÂ·xtron LycomlngfSubsldlary of Textron Inc 652 Qllver Street P*rml~ ~o lb3 Wllllamsport. PA 17701 U.S.A. 7171323Â·S181

ADDRESS CORRECTION REQUESTED

49 Iiave You Moved'

If kO, I,lense brncl your

olti arlcl new atldrcÂ·ss. LYCOMING

issue No. 50 Published by Textron Lycoming April, 1991 Williamsport, PA 17701 Lycoming

I I Synfhefi~ Oil Approved Flying In Clean Air

Although fi~lly synthetic oils are not an entirely new development, Will your flying be affected by approving one for use in a Lycoming air cooled, piston, aircraft engine is the Federal Clean Air Act! Most new. When Lycoming aircraft engines were first produced, mineral oils of us who fly have had no were the only product available for the lubrication and cooling of warning that our hobby and engines. Until recently, only mineral oils had across the board approval possibly our livelihood may soon for use in Lycoming aircraft engines. be subject, to change. Take heed, A brief look at history will provide some insight into the oil use and it is not just the handwriting on approval process. During the many years before the arrival of jet en- the wall, it is now written in the gines, the U.S. military used piston engines. The oil to be used in these law of the land. The changes standards the in engines was required to meet set by military written which are forthcoming are those specifications MILSPECS. Because the standards for oil set by the aimed at eliminating all lead and military were completely appropriate for the engines produced by lead additives from motor fuels. Lycoming, those specifications were adopted, and have been the guide- The law also applies to the line used the throughout years. engines which use these fuels.

Mineral oils did change as oil companies attempted to make Before we become involved in in their Additives mixed with mineral improvements products. were where aviation fuels are headed, oils to create viscosities which could be used across a wide range of lets review where they have been Other additives to dirt in the oil temperatures. helped keep suspended and where they are now. In so that it could be a filter or drained out when the oil was trapped by years past, aviation gasoline was rather than become a of in the bottom of the changed deposit sludge split into five octane grades engine. These improved oils for use in aircraft engines are known as 80, 91, 100, 108, and 115. As U.S. Ashless IXispersant (AD) oils. Because these oils continued to meet the airlines and the U.S. military MILSPECS, they were given automatic approval for use in Lycoming uansitioned from piston engines engines. to the of Please rum to Page 2 Column 2 turbines, consumption aviation gasoline decreased to

I I u less than one half of 1% of the Rocker Arm Id~ntificafion gasoline market. As the market volume of aviation gasoline Recently there have been the rocker arm by its part num- became less and less, octane questions about rocker arm ber. The calls to our Technical levels were consolidated into two identification. In many cases, the Representatives make it apparent primary grades 80 octane (.5 rocker arm for the intake valve is that some A&P mechanics do not mt/gal lead) and 100 octane ~4 different from the rocker arm for know where to look for the part mt/gal lead). For many refiner- the exhaust valve. The two parts number. The caller will provide ies, the very low volume made may look very much alike, but the raised number on the side of even two aviation fuel grades they must be identified in order the fin when asked for the part difficult to justify. In the middle to tell which is used with the number. This very easy to find 1970s, a final consolidation exhaust and which is used with and read number is a forging occurred. The result was 100 Low the intake, number (see picture). One Lead aviation gasoline (2 mWgal First it is necessary to identify forging may be used to make lead). Please tunz lo Page 7, Column Please lurn to Page 3. Column I Textron Throughout the years, have Lycoming Lycoming engines been used in many areas of the world where the climate is much less temperate than that Reciprocafing Engine which we experience in Pennsylvania, the location of the Lycoming School Schedule Before factory. the advent of multi-viscosity oils, extremely cold climates caused oils to become so viscous they would not flow within This is four-day course pro- the and therefore engine, could not lubricate. To overcome this vided by Textron on a Lycoming a lubricant problem, synthetic called Anderol 471 was in no charge basis. Personnel developed the 1960s. This oil flowed easily in very cold climates, but because it attending will be for responsible had a detrimental effect on seals and gaskets in the oil it the cost of meals and A system, lodging. received limited approval from Lycoming as a tour of the Textron Lycoming 'Special Purpose" lubricant to be used where mineral oils could not be used Plant will be in- effectively. Williamsport This early synthetic oil was used on a limited basis and has eluded in the course. To sched- not been available to aircraft owners in recent years. ule for one of the four-day Over the past 15 or 20 several classes listed below, call Donald years, synthetic and semi-synthetic Oils have reached the The E. Stahl, Liaison Training Instruc- marketplace. semi-synthetic oils generally were produced to achieve viscosities which tor, at 717-327-7127 could be used over a fairly wide of July 8,9,10,11 22,23,24,25 range temperatures. Being mineral oil based, the semi-synthet- ics usually met MILSPEC standards and hugusr 5,6,7,8 19,20,21,22 were automatically approved fo' in September 9,10,11,12 23,24,25,26 USe Lycoming engines. On the other hand, the full synthetic lubricants did not meet the October 7,8,9,10 21,22,23,24 MILSPECS and were not approved. This was not to that the November 4,5,6,7 18,19,20,21 say synthetic oils were inferior. They did not meet the December 2,3,4,5 simply guideline standards used by Lycoming. To receive a full Lycoming approval, scale testing program was needed to determine the effect of new oil any on a Lycoming engine over its entire recommended Time Between Overhaul (TBO). Mobii Oil re- Safety cently extensive Tip completed testing of Mobil AVI, a fully synthetic aviation engine oil. Xt is extremely jmpastanr Mobil AV1 development back to 1978. This to check the goes product was Erst pressure tested under laboratory conditions. Flight resting began in 1980 and screen, suction screen, and about 100,000 hours of in-the-field have been the oil filter at each oil flying accomplished. The results of this testing and change. Utilize Lycoming experience provided the data needed by Lycoming Williamsport to AV1 for use in all Special To61 SSP 885-I to approve Lycoming piston engines. In addition to the data, Lycoming looked open the spin on filter can engineers at the history of an HIO-360-D1A so that the filter material engine operated by the Las Vegas Police Department. It was one of the first can be examined for metal engines in the field to be operated exclusively with Mobil AVI. Installed as required by the 50-hour in a Schweizer helicopter which the police used as a this Inspection check list tn the trainer, engine was often run in outside air temperatures over 100 Fahrenheit. Lycoming Engine Operator's degrees The engine was operated fo' 280 hours over the recommended Manual. Also look for metal 1500 hour TBO. The engine tear in the down was accomplished at the screens. Metal will Lycoming plane and revelled a very clean engine with little or no never be found in the filter sign of wear on the crankshaft or camshaft. Also, all were free or screens if the individual rings and all valve guides were free of changing the oil does not deposits. Based on the data look for it. Should metal be available, and the observed condition of the HIO-360 found, it will be necessary engine at tear down, Textron Lycoming will issue Service to examine the Letter No. L229 as the interior of approval for use of Mobil AVI in Lycoming the Because engine more closely, engines. water, acids, and lead sludge will accumulate inside Metal which has the the oil contami- engine, change recommendations of Service Bulletin No. nated the 480 to Mobil engine and which apply AVI as well as to the AD oils which will continue is not found the to be used in during many engines. These recommendations are: regular oil changes could A. 50-hour interval oil and change frlter replacement for all en- lead to catastrophic engine gines using a full-flow filtration system. failure.

Please rum to Page 7, Column I 2Â·April 1991 FLYE~

At the time of the consolida- automotive fuel tended to pro- will be searching for the data tion to a single fuel grade, mote valve seat wear. Solving every Lycoming engine owner approximately 65% of the general this problem required the use of and operator will need. Our aviation fleet was powered by better metals. Today's aircraft purpose is to help you get the low compression engines which engines already use improved best possible performance and were built to operate on 80 materials in these areas so it is longevity from the Lycoming octane fuel. As a result of using unlikely that removal of lead engine you own now or those the higher leaded 100 octane LL from the fuel will result in a wear you may own in the future. fuel, these engines were subject problem. to some lead fouling not experi- Many of the high performance enced previously. Engine manu- Lycoming engines operating facturers vied to counteract these today may not need 100 octane problems by coming out with fuel to obtain rated takeoff and Recalled For new engine models with higher climb performance due to the Temporary Dut~:y compression ratios; these engines richer mixtures used for cooling could digest the higher leaded during these operations. If EDITOR'S COLUMN 100LL more iasily. Some opera- unleaded fuel with a maximum For many, many years the Flyer tars turned to the use of auto 93 octane rating is adopted, has been a means by which fuel. Although some characteris- changes in cruise leaning proce- Lycoming has communicated ties of auto fuel were quite dures will be necessary because with thousands of customers different from aviation gasoline, of reduced detonation margins. around the world. An excellent the lead content and octane level With a change in cruise perfor- rapport, has been established by were similar to the original 80 mance and in leaning limits, Pilot providing information about octane aviation gasoline. What Operating Handbooks and engine maintenance, operation, has been discussed to this point Engine Operating Manuals would and safety. Because this is 2 way is history. Ndw it is time to look require changes. to help Lycoming engine owners to the future. There are two This discussion of new fuel get the best possible service from specific amendments to the and engine requirements should their Lycoming engines, and to Federal Clean Air Act which may indicate to every reader that promote flying safety, there is a affect general aviation flyers. there are many questions to be suong desire to continue pub- First, after 1332 no aircraft answered before the proposed lishing the Flyer on a regular engines requiring leaded aviation regulations which interpret this basis. gasoline may be produced or law become effective. Texvon To accomplish the resumption sold. Second, after 1995 the law Lycoming Williamsport has of publication after a short prohibits the sale of any motor initiated a program to develop period of delay since issue No. gasoline which contains lead or the data which will help to 49, I have been recalled to work lead additives. answer these questions. A on issue No. 50. Although this is It is quite likely that the recipe quantity of unleaded aviation strictly work to be accomplished for aviation gasoline will not gasoline has been obtained and on a part time basis, I am happy change except for the removal of detonation and endurance to again be able to write and edit the lead. This will have the effect testing is scheduled over the next materials which will be of help of changing 100 octane Low Lead several months. Based on the to so many Flyerreaders. fuel to a No Lead aviation gaso- results of these initial tests, the You will note that the format line of approximately 93 to 94 program will be directed toward and appearance of the Flyerhave octane. There are at least two those areas where it may be changed to provide a more areas of uncertainty to be ex- possible to find solutions to the modern look. The information plored before 100LL disappears potential problems presented by presented is intended to be the from the market place. What the use of unleaded fuel. same 'this is what you need to effect will no lead have on A change to unleaded fuel will know" data as in the past. Should today's engines and how will affect the way we operate our you have questions which could those engines tolerate the re- engines and the performance possibly be the subject for future duced octane level, which may be expected of them. articles, please communicate The removal of lead from Texuon Lycoming Wiliiamsport them to us. Ken W. Johnson

LYCOMING FLYER 3 I

Safotu Tipl Birth of an AD The Airworthiness Aircraft owners should Directive, or what is is usually referred to in aviation understand that Textron language as simply an AD, is an amendment to Federal Air Regulation Part Once Lycoming considers compli- 39. issued, AD's have the force of law and they remain in force until ance with Service Bulletins superseded or revoked. The AD is written against all types of aeronautical to to be MANDATORY. If your products mandate safety in the use of those helicopter or, fixed wing products. Unfortunately an AD often requires inspections and work which would not be if aircraft is powered by a necessary manufacturer recommendations we'e followed as should piston engine the they be. This article is a case study which indicates the of requirements of Service importance publications in proper maintenance. It also shows that at least one AD would Bulletin Na, 388A should not have been necessary if all aircraft not be overlooked. For owners and maintenance personnel had been utilizing the i"formation helicopters, the inspections provided in publications made available by Lycoming. As we look back about ten should occur at 300 hour years to the beginning of this case, let us that what is intervals, For fixed wing hope written here will be a lesson in safety for aircraft Ow"e'S. Over the the aircraft, inspections begin at years Lycomlng Flyer ha's stressed many times that use of manufacturer the mid-point of engine publications is absolutely essential to mainte- "a"ce which service life as recommended practices lead to safe flying. When an aircraft in LycominS Service! ~Cetter or engine part develops an unexpected problem during its period of field and the 201. There are two pur- use, manufacturer becomes aware of that there are several poses for this critical problem, publications which can be used to inspection procedure. The communicate this information to maintenance facilities. Which publication is used the first is to determine if wear depends upon urgency of the situation. A Lycoming Service Bulletin is in and has caused excessive printed red, always indicates a high degree of The information and exhaust valve guide ctearÂ· urgency. procedures provided in a bullerin must be observed for ance. Excessive valve guide safety reasons, and therefore are considered by the manufacturer to be clearance may eventually mandatory. Service Instructions and Service Letters cause the exhaust valve to give maintenance information with somewhat lower levels of The Service Letter is the break The second purpose urgency. least urgent of the three. Although there ofthe inspection is to are many good maintenance facilities, it is unfortunate that there a'e those which determine if there has been either do not have the necessary publications available or do not take the information a lead or carbon bundup in provided seriously. Although owners the exhaust valve guide are ultimately responsible for the airworthiness of their aircraft, some choose to save a few which has resulted in dollars, and risk their lives until an AD makes a recommended insufficient valve to guide procedure or part mandatory. When an AD a clearance. Too little clear- covering particular product has been issued, most owners take action ancr! between the valve to comply. To this review of stem and guide may result begin events, we go back to May of 1982 when Service in a sticking valve. These Lycoming Bulletin No. 240K was issued. This bulletin deals with the of kinds of failure are prevent- parts a Lycoming engine which are to be replaced at overhaul. Where a is able if aircraft owners will product improvement to be incorporated, it is often recommended that it be done require that SE 388A be at overhaul. In the case of four-cylinder engines With a rear mounted compiled with at the appro- governor, this publication clearly stared that the aluminum elbow which priate inspection intervals, connects the propeller governor oil line at the f'o"t of the crankcase should be and that an appropriate log replaced with a steel elbow at over- haUI. Engines have been found in book entry attest to compl- service today which were overhauled in the field and which still ance with the Service have the aluminum elbow. This is an indication that someone not Bulletin. was aware of the bulletin or simply chose not to comply. They reused the old aluminum elbow. The of subject this propeller governor oil line was addressed How should in Part II of you operate again Service Instruction No. 1435 which was issued in your aircraft? The Pilot's of 1986. As a April product improvement, the line was to come Handbook is the Operating equipped with a steel nut which would final join the steel elbow previously authority! discussed. The instruction also has a drawing which shows where the aÂ·April 1991 FLYER

line is attached to the engine and that it is to be supported with Cam and Tappef clamps. Failure to support the line as shown can lead to a chafed or broken line, oil loss, and possible engine failure. It has become Wear evident that many individuals working on these engines do not have The lobes of the camshaft and the information provided in this service instruction, or do not under- the tappets which they continu- stand the need to correctly clamp and support this type of line. These ally operate against have always examples of poor maintenance practice have been found in the course been subject to wear. Someone of accident investigations. recently stated that in recent Accident investigators were finding that some Lycoming engines years there has been an unac- with rear mounted governors had indeed failed from oil starvation; the ceptable rise in the occurrence of oil had been lost because of a break in the propeller governor oil iine. spalling tappets and worn cam Investigation also revealed that the breaks were occurring in engines lobes. Is this a factual statement! where the propeller governor oil line was not supported as recom- Perhaps it may help if we take a mended by Lycoming. In all cases, one or both of the Textron look at one or two of the causes Lycoming supplied governor oil line clamps and/or supports, which of wear on these parts. From this had been installed at the pliant, were missing. Maintenance records we may reach a conclusion about indicate very poot attention to detail in several of these cases. in one why this statement could possi- case the steel line failed and was replaced, but the supporting clamps bly be true today. were still not installed. In another case, a broken clamp was removed Corrosion is a known cause of from the line, but it was not replaced. The accidents which resulted tapper and earn lobe wear. The from these poor maintenance practices are ones which could have engines of aircraft that are not been prevented. flown regularly may be extremely In the interest of safety, it was necessary to get the attention of vulnerable to corrosion. 7JQhen those who were not maintenance following good practice. Utilizing the film of oil drains from the the publication which would show the most urgency, Lycoming issued interior parts of the engine after Service Bulletin No, 488 in September of 1989. Entitled'Propeller it has been run, those parts Governor Line Support", Service Bulletin No. 488 required an inspec- become prey to the chemical tion of the Propeller Governor Oil Line on all four-cylinder engines changes which are caused by with rear mounted governor within the next 25 hours of operation, moisture, acids, and oxygen. and at overhaul. Tappets from engines which The engine failures which have resulted from mainte- improper have not been operated for long nance of the oil line are unfortunate reminders of propeller governor periods have been closely the importance of compliance with manufacturers publications. Be- examined. Under a microscope, cause there were too who failed to follow these instructions many it is not unusual to find micro- voluntarily, it became necessary for the FAA to issue Airworthiness scopic pits on the face of the Directive 90-04-06 in February of 1930. The AD is the law and should tapper. This is the beginning of be complied with. It requires an inspection of the propeller governor trouble. Starting with these very oil line within 25 hours of Any found, or operation. damage improper tiny pits, tiny particles of rust installation of the even if no is would support clamps, damage found, also affect the cam lobes. Once require that the line be changed. It also that aluminum requirP~ fittings started, the process is not likely used in the installation of the line be removed from service and to stop until the wear reaches a replaced with the steel fittings which Lycoming has been recommend- point where these parts are ing for years, doing an unacceptable job. For the information of those concerned, FAR 91.163 places the Some people might question for the airworthiness of an primary responsibility maintaining aircraft, the assertion that engines can with Airworthiness the including compliance Directives, upon owner attract unusually large amounts or In FAR operator. addition, 91.173 also requires aircraft owners and of moisture. Brief operating to maintain records operators which include the current status of periods, low en~ine oil operating ADs. In of those applicable spite requirements, and more than a year temperatures, and condensation after AD 90-04-06 was accident have issued, investigators recently all contribute. It might be very found an aircraft in which there was no with this AD. It is compliance surprising to take an engine also that interesting to note this aircraft had its annual inspection in which has flown 15 to 25 hours the interim, over the course of four to six For those individuals with AD complying 90-04-06, the information months and drain the oil into a Please lurn ro Page 8, Column I Please turn to Page 6, Column r LYCOMING FLYER 5 I I clear container. The amount of Service Bullefins, Letfers, Insfructions water which settles to the bottom is likely to be more than one Published from Decem~ber 5 1989 would eKpect. Also remember tg Feb~uary 18, 1991 that combustion causes acids to

in the oil. When these are collect The service publications listed below are those which have been not removed by regular oil issued most recently. We strongly recommend that a complete set of changes, the acids as well as the these publications be maintained by all maintenance organizations moisture will promote the growth which work on Lycoming reciprocating aircraft engines. A subscription of microscopic pitting which may be obtained through any Textron Lycoming distributor or directly eventually leads to excessively from the Textron Lycoming Product Support Departmant. Call or write worn tappets and cam lobes. for a copy of Textron Lycoming Service Letter No. L114 which pro- Another factor in the unaccept- vides a listing of available publications, prices, and ordering instruc- able rise of tappet spalling in tions. general aviation engines may be the product which is put into Sent~ce Bulletkzs many of those engines at over- 369H Engine Inspection After Overspeed or Overboost All haul. To reduce the costs of Textron Lycoming piston engines. overhaul, there is an increasing 411B Adapter Kit for Magneto Isolation Drive Certain 0-3tj0- tendency to put reground cam- A3A, A4A, A4J, and IO-360-B4A engines. See Bulletin for shafts and tappets into these serial numbers and ship dates. engines. Although camshafts may Crankshaft Modification and Procedures be reground, there is a very strict 4758 Gear Assembly All Textron Direct Drive Piston Aircraft limit on the amount of grinding Lycoming Engines which can be tolerated. Grind except: O-320-H, 0-360-E, LO-360-E, TO-360-E, LTO-360-E, too much and the hardened and nO-541 series engines. surface of the cam lobe is gone. 488A and Propeller Governor Line Support All Textron Lycoming After this kind of grinding, the Supple- four-cylinder engines with rear mounted governor. cam may look great, but it will ment 1 Corrects part number in Piper Aircraft Corporation note be wearing on the soft metal on Page 2 of 2. which was once protected by a 489A Oil Sump Baffle Assembly Inspection All Textron hardened surface. Textron Lycoming six cylinder fuel injected engines which incorpo- does recommend Lycoming not rate Baffle Assembly P/N LW-13383. the use of reground tappets 491A Inspection of Exhaust Transition Bolts TIO-540-AE2A under circumstances, but any engines installed in Piper Malibu Mirage Aircraft. See many engines overhauled in the bulletin for serial numbers to which Part I and Part II apply. held today come back to the 492 Redesigned V-BAnd Couplings for Tailpipe Installation owner with reground tappets and All n0-540-AE2A engines with serial numbers up to L-9156- camshaft. In some cases at least, 61A and also L-9158-61A and L3159-61A. these items ate nothing more than good looking junk. 494 Installation of Restricted Fuel Pump Vent Fitrings TIO- Because of the high percentage 540-C1A, -EIA, -G1A, -HIA, -AA1AD, -ABIAD, -AFIA series with serial numbers to and L-9244-61/61A. of refurbished used parts which including go into many overhauls, and the 495 Reprint of Precision Airmotive Corporation Service Bulletin many airplanes which sit for long MSA-1 Subject: Replacement of composit floats with periods without being flown, metal floats. All Textron Lycoming piston aircraft engines there could be more tappet employing Marvel-Schebler carburetors. spalling today than in the past. 496 Reprint of Lear Romec Service Bulletin 101SB019 Subject: These are some of the reasons Rotary Fuel Valve Diaphragm Replacement why the statement that there has All Textron Lycoming engine series with applicable fuel been rise in an unacceptable pump models and serial numbers listed in this publication. spalled tappets and worn cam 497 Installation of new, restricted Fuel Pump Vent Fittings in AN lobes in recent might just years Drive Fuel Pumps See bulletin for engine models affected Please lum to Page 8, Column I and fittings to be used. 6Â·April 1991 LYCOWEK)~ FLYER

Seruke Instruct~ons several different part numbers. 10388 Propeller Flange Bushing Location All Textron Lycoming The part number is direct drive engines. vibropeened on every rocker 1125B Alternate Crankcase Parting Surface Sealants All Textron arm. it is always in the same Lycoming Opposed Cylinder Engines. location on top of the rocker 1334A Crankcase Tappet Bore Repair All Textron Lycoming arm, but with hours of operation reciprocating aircraft engines. it may be difficult to read. The Supple- Adjustment of the Linkage Rod between the Fuel Injector pab "Umber is pointed out in the ment 1 and the Variable Pressure Controller TIO 540-AE2A. accompanying picture. It may be to 3431 necessary to dean the area very with Scotch Brite. Should 1442 Improved Oil Filter Bypass Valve All Textron Lycoming Be"fly the number still be difficult to piston engines with dual magneto accessory housing. use a It is 1447A Light Weight Starter Installation Instructions All Textron See, magnifying glass. important to identify the part Lycoming direct drive piston engines except the 10-720 and number of both the intake and those engines with alternators or compressors mounted on exhaust rocker the left side. arms. These Should then be compared with 14Â·18 Installation of Tailpipes and Heater Muffler Covers n0- the numbers in the Parts Catalog 540-AE2A engine installed in Piper Malibu Mirage aircraft. for the appropriate engine 1443 installation of Rotomaster Turbocharger (46A21184) TO/ model. In most this will no-360-clA6D; TO-360-F1A6D. cases provide all the information which 1450 Alternate Connecting Rod Bolt and Torque Application is necessary. You will know Textron Lycoming engines using Connecting Rod Assembly which is intake and which is P/N LW-11750 or Conncecting Rod Assembly P/N LW-13865. exhaust from checking the actual 1451 Alternator, Starter and Compressor Installation All TIO- part numbers against the num- 540-AE2A engines. bers specified in the Parts Cata- 11152 of 0-360-C1G Reindexing Prop Flange Bushings engines log. installed in Christen Husky aircraft with serial numbers up But suppose the numbers on to and including L-32584-36A. the valve rockers do not agree with those shown in the Parts Seru~ce Letters Catalog. Don't panic. There is a L201C Recommended Time Between Overhaul Periods AII possibility that the rocker arms Textron Lycoming Piston Aircraft Engines. taken from the engine may have L228 of Exhaust Port All field recondi- Cracking Cylinder-Head been superseded by rocker arms tioned, heads. parallel-valve cylinder with a different part number. The superseding number is now I I I shown in the Parts Catalog. If this happens, it is time to call B. 25-hour interval oil change and screen cleaning for all engines your Textron Lycoming distribu- employing a pressure screen system. tor and ask if the part numbers C. A total of four months maximum between oil changes for both on the rocker arms have been systems listed under A and B. superseded. By providing the With the approval of synthetic Mobil AV1 for use in Lycoming engine model and serial number, piston engines, it joins the line of mineral based AD oils which are you should be able to get assis- known to provide good lubrication and cooling results in Lycoming tance with this matter, and also engines. Owners and operators of Lycoming engines may now choose find which number is the intake either a mineral based or fully synthetic oil for use in their Lycoming and which is the exhaust. engine. There is one further scenario which might be encountered. On rl:il engines with parallel valves which have been produced in recent years, the intake and exhaust rocker arms may be the

Pleare rum to Column For01n0 number Put number Page 8,

LYCOMING FLYER 7 in Supplement 1 to Service Instruction 1435 may be of interest. This same. They will have the same supplement authorizes the use of a flexible hose in place of the part number. Should your engine existing stainless steel tube assembly for the propeller governor oil be one of these, you will find line on engines with rear mounted governors. It further states that that a rocker arm previously used 'Textron Lycoming teflon hoses with steel braiding and firesleeving only on the exhaust side is also conforming to FAA TSO-C53A Type 'D' specifications must be used being used for the intake. In this for this installation." The supplement provides part numbers for case you can expect to find a various hose lengths which may be needed and it also provides drip hole on the bottom of both installation instructions, rocker arms. There is a message in all of this. Use of manufacturer publications This discussion should help is vital~co aircraft safety. Overhaul manuals, parts catalogs, and the those individuals who need help service letters, instructions, and bulletins provide the data needed to with identification of rocker accomplish maintenance on an aircraft or engine. These Lycoming arms. Keep in mind that rocker publications, their cost, and ordering instructions are found in the arms, like all other parts, should latest version of Service Letter No. L114. Some shops which maintain be identified by utilizing the aircraft do not have a publications library for reference. Others do not Parts Catalog and other service use the reference materials. In still other cases, an owner may be publications which apply to the advised of a manufacturer recommendation, and choose to ignore it engine model being worked on. because of the cost. In the interest of safety, the person or shop doing Distinguishing between the maintenance on an airplane should have and use the necessary refer- intake and exhaust rocker arm is ence materials; owners should insist on it, and they should also accept just one problem which can be recommendations which are made to enhance their flying safety, solved by using the proper Attention to this detail of aircraft ownership may serve a two-fold reference publications. purpose: (1) saving your aircraft from damage and yourself from embarrassment, and (2) possibly helping to eliminate the necessity for PERMISSION TO REPRINT the issuance of additional Airworthiness Directives. Permission to reprint from the Lycoming gnnted, so long ~s the eontca of infarrm~bn rrnclins intia md Ippropriate cÂ·cdit is given. than be true. Ask about the parts time of overhaul it is to pay for worn out which are Being into your replacing parts before has reached overhaul. It may be less expen- your engine its TBO. sive to pay for new parts at the expected April 1991 Issue No. 50 Editor: Ken W. Johnson

FIFbCiT~ Lycoming Williamsport Plant US POSTAGE Textron LycominglSubsidiary of Textron Inc. PAID 652 Oliver Street WILIVAMSPORT. PA PA 17701 USA Williamsport, PERMIT NO. 163 717/323-6181 ADDRESS CORRECTION REQUESTED

8 Â·April 1991 LYCOMING FLYER #50 LYCOMING

Ileue No. 51 Published by Textron Lycoming November, 1991 Williamsport. PA 17701 Lycoming

_JII I I I

~he Aviafion FueT OLlflook Oil Flow Screens,

Recent Congressional Legislation aimed ar stiffening environmental Filter, Cooler, and re~uiation has created a scramble for informatioil in the general Pressure Relief aviation public. As usual, various interpretations of the printed word and outright speculations have resulted in confusion. The flow of oil through a What Happened? Lycoming reciprocating aircraft Congress recently passed amendments to strengthen the 1970 engine is known to be a neces- Clean Air Act. One of the amendments specifies that after 1992, no sary function during the opera- more off road engines requiring leaded gasoline may be sold. The key tion of the engine. Pilots are issue here was exactly what type of vehicles would be covered by the often not at all concerned about "off road" definition. Certainly chain saws, lawn tractors and dirt bikes how this function occurs, as long fell into this category, but what about aircraft? Critics pointed out that as the oil pressure and oil in the original Clean Air Act, aircraft engines were treated separately temperature indicators show a and distinctly from the off road category, and therefore were nor proper reading. A Sr P mechan- intended to be covered under this requirement. The whole question ics, on the other hand, often was resolved on September 4, 1991 when the EPA ruled that recipro- need to know how the system eating aircraft engines are not included under the category entitled "off works and what parts control the road", This means that, at least for the immediate future, reciprocating flow of oil during various phases aircraft engines may still be operated utilizing a leaded aviation of operation. Because of the gasoline, large number of calls concerning Please tum I~ Page 2 Column 2 this subject which are received I I LY by Lycoming Service Engineers,

we can be sure that there are Mow Moclf is Elfough? Inany nÂ·ho do not have a good understanding of the oil system How much oil does my engine shape of that sump will diff~r It is not surprising that many need? When should the oil level with the various models. engine A g: p mechanics do not have a be checked? Questions like these Because of this, the d;pstick to firm grasp on the operation of continue to be asked of Textron be used must be calibrated for a the oil system. There is room for Lycoming Service Engineers. particular engine model. Further, a great deal of confusion since Depending upon the specific the dipstick is usually calibrated there are two basic systems and model being discussed, for the aircraft model in which engine several variations on each of the answers to the the is used. Most aircraft questions may engine these. not be exactly the same in all do nor sir exactly level, and the Except for the screens, filter, but there aircraft attitude while will cases, are some points at rest and oil cooler, the flow of oil which those who have affect the obtained may help reading on through the engine is completely like these. the To accurate questions dipstick. get an pre-determined by the designed The oil used in a wet it is that sump reading, important engine running clearances and engine is stored in the sump inflation of the landing gear by the passages which are drilled which is attached to the bottom struts be exactly as specified, and i, the crankcase and accessory of the engine. The size and that the dipstick provided with

Please Iunt to Page 3, Column Please Iu171 ro Page 4, Column I I

Do Engines Survive Without Lead? The automotive industry has already been down the road of write the Before you call or conversion to unleaded fuels. One of the problems which they en- about factory with any question countered was with valve seat recession (wear of the valve seat) when your engine, be prepared. If your using cnleaded fuel. This could also affect aircraft engines. Appar- about question is your engine, entry the lead acts as a lubricant between the valve and valve seat, number and the the engine serial cushioning the impact of the valve on the valve seat. Their solution complete model designarion are was to use a harder valve seat material. Today, this is nor an issue In necessary. This is the absolute automobile engines. Lycoming reciprocating aircraft engines already minimum of information needed ,,e high quality material for valve seats. A rest program conducted to access any records Lycoming by the FAA Experimental Test Center, using unleaded fuel in a have. other data may Any you Lycoming engine, showed no significant valve seat recession. The also be can provide may helpful country of Sweden has operated its general aviation low compression in answering your questions, engine fleet on unleaded aviation fuel for the past eight years with no overhaul or Hours on the engine, adverse consequences. To confirm these results, Lycoming procured a modification information, and sample of unleaded aviation gasoline. A series of comparative endur- maintenance history are ex- ance rests were conducted to document wear characteristics. No well amples of items it would be significant difference in valvelvalve seat wear was noted between in hand before to have initiating engines run with leaded and unleaded aviation gasolines. a call to Textron Lycoming. To summarize the unleaded issue: When your question deals with aircraft included in the "off road" spare or superseded parts, you Are engines category! included. should request help from EPA has ruled that aircraft engines are not aftermarket sales. Maintenance Will present valve seats in Lycoming engines be acceptable for use assistance is the responsibility of with unleaded aviation fuels anticipated for the future! the Service Engineers. Being Test data indicate yes. When we must progress to unleaded prepared before dialing will help fuels, existing valve and seat materials are satisfactory. to reach the party you proper Any Other Fuel Issues? more quickly and to attain the ~iost definitely. The fuel specification for aviation gasoline, AST~I information you need more was for high performance engines efficiently. D-910, developed many years ago which, for the most parr, do not exist today. Aviation fuel utilizes the cream of the petroleum barrel to meet its fairly simple formulation. With the competitive situation which exists today with fuel stocks, the cost of Avgas will continue to be substantially higher than Autogas. AD ~lotes of Interest Ironically, energy and environmental concerns are now forcing righter controls on Autogas. The formulation process, additives, and vapor AD 91-0b-07 and Textron pressure characteristics are being scrutinized and changed. The auro- Lycoming Service Bulletins No. motive fuel of the future will be a different product than the fuel 434 and No. 437 address the which is available today. installation of new, restricted fuel Another recent amendment to the Clean Air Act prohibits the sale pump vent fittings in turbo- of leaded motor gas after 1995. Although aviation fuel is not directly charged engines with AN drive affected by this legislation, it will be the only leaded fuel type remain- type fuel pumps. ing after enactment. It is easy to predict the refining and distribution AD 31-14-22, Textron problems which will result when a high volume of unleaded fuel must Lycoming Service Bulletin No. share the stage with a very low volume of leaded aviation fuel. Sepa- ~75A, and Service Letter No. ration of storage facilities, processing facilities, and transportation unfavor- L163C address crankshaft gear systems will be required. In the long term, this factor will be modification and assembly able for both the availability and cost of aviation gasoline. procedures. These procedures What Should the General Aviation Industry do are required during engine to Deal With Its Impending Future "FUEL CRISIS"? overhaul, after prop strike or There is a definite need to develop a new aviation fuel specifica- other sudden stoppage, or tion which will be more with future motor fuel blends. whenever crankshaft gear re- compatible moval is required.

2Â·November 1991 LYCOMING FLYER

Keep in mind that future motor fuels will be substantiall)I changed in the engine for a particular areas which concern the aviation industry today, such as additives and aircraft model be used with that aircraft. Even with vapor pressure. Regardless of claims, there have been and continue to everything be problems with the use of today's Autogas in aircraft. The wider above just as specified, it is still difficult tolerance in vapor pressure and use of additives and alcohols in the to get an accurate composition of autogas have resulted in sudden operational and long- reading with some engine mod- term material compatibility issues. Until these issues are resolved, els. With the O-540-J and L for the autogas users will continue to evaluate the effect of these differences models, example, slow, deliberate insertion of the and changes on their engines and aircraft. dip- As motor fuel stocks are better controlled, a new aviation fuel stick into the tube is helpful in specification must be developed which is more compatible with the obtaining an accurate reading. While an is new formulation practices, and yet still acceptable for our more engine running, stringent requirements. Aviation gasoline consumption represents less the oil is continuously being oil than one quarter of one percent of the total gasoline usage in the pumped through supply United States. To exist in the 21st century, it is imperative that Avgas passages to all locations which be more consistent with future motor fuel stocks. Economically or must be lubricated and cooled It logistically, Avgas cannot continue to be a specialty product. will take several minutes for the Textron Lycoming is participating with the General Aviation oil to drain back into the sump Manufacturers' Association (GAMA) on the ASTM J2 Fuel Committee to after engine shut down. There-

fore it is a idea to wait Please lurn to Paae 7, Column I good several minutes (10 minutes will do) after shut down I probably before attempting to check the Changing fhe 8il oil level. What oil level is satisfactory for It has been said that "changing A. 50-hour interval oil change flight! This is a question with the oil is the least expensive and filter replacement for all many answers. It depends on the method of maintaining an aircraft engines using a full-flow filtra- particular engine and the length engine." The reports received tion system. of night being planned. As from Lycoming engine owners B. 25-hour interval oil change indicated earlier, each engine over the years have affirmed the and screen cleaning for all model is equipped with a sump truth of this statement. Although engines employing a pressure designed for that engine as it Is the addition of a filter in the oil screen system. used in a specific aircraft model. system helps to reduce dirt C. A total of four months Many Lycoming four-cylinder which causes wear; water, acids, maximum between oil changes engines are equipped with an and lead sludge still accumulate for either of the systems listed eight quart sump and six-cylinder in the oil. This contamination of under A and B. engines are often equipped with the oil can lead to sticking valves The recommendations of SE a 12 quart sump. Owners of and deterioration of tnetll 480 assume the aircraft is being these engines frequently maintain surfaces inside the engine. To operated from a paved runway the oil level at one to two quarts avoid these problems, regular oil under normal operating condi- below the full mark. Unless these changes which remove the tions. For operation from a dirt engines are known to be using contaminated oil are necessary. strip where conditions are dusty, excessive quantities of oil, these The oil change recommendations or for aircraft used in Agricultural oil levels will probably be of Service Bulletin No. 480 apply Applications, more frequent oil adequate for most normal flights. with any oil which is chosen for changes may be necessary. A second group of Lycoming use; whether a mineral based AD An item often missed in the engines come equipped with oil as defined in Textron routine of oil change mainte- smaller sumps. A number of four Lycsming Service Instruction No. nance is the checking and cylinder models have a six-quart 19~11, or a synthetic oil as ap- cleaning of the suction screen sump. Several six-cylinder proved by Textron Lycoming which is located in the sump. models have oil sumps which Service Letter No. L229. The This should be done at each oil hold as little as eight quarts. recommendations stated in change, regardless of the change Textron Lycoming Service Bulle- interval which has been selected. Please turn to Page 6, Column tin No. 480 are:

LYCOMING FLYER 3 housing during engine manufac- system are reduced allowing the routed through the oil filter ture. This flow of oil three serves by-pass valve to close and adapter, the filter, and then again it but purposes. First, lubricates, forcing oil flow through the oil through the filter adapter, acces- cooling the engine by carrying cooler. Although the By-pass sory housing and finally into the away the heat generated by valve helps the engine to warm crankcase. combustion is a second purpose up more quickly by routing cold The oil filter is another part of which is often just as important. oil around the oil cooler, its the system where blockage could Many engines, particularly those primary function is for system cause serious problems. For this which are turbocharged, have oil safety; should the oil cooler reason an oil filter by-pass is in each which become squirts cylinder plugged for any reason, built into the oil filter adapter, or are to direct oil designed cooling system pressure will rise and the in the case of engines utilizing a on the back side of the piston. differential pressure across the dual magneto, Into the accesslirv And finally, the oil cleans the by-pass valve will again cause housing. These by-pass valves engine by picking up dirt and the valve to open. This by-passes are a built-in safety feature which depositing it in the screens or the oil cooler and prevents a activate as a result of excessive filter, or by keeping that dirt in possible rupture of the cooler pressure in the oil filter. The oil suspension until the oil is and loss of oil. filter by-pass is not adjustable. changed. Oil enters the crankcase of r-' The oil which has done its most Lycoming engines near the lubricating, cooling, and cleaning top of the right rear cylinder nows by gravity back to the oil where it passes through the sump. From the sump, the oil pressure relief valve. There are pump pulls oil through the three types of pressure relief

suction screen. This screen will valve. With either the short or iilrer of our large particles 'i longdomevalve, pressure is carbon, dirt, or metal. The pump 1 r--. adjusted by removing the dome then forces the oil through one and adding or deleting washers of the two basic systems. In each which are located under the of the basic there two systems is FC~i,: controlling spring. There is also a a valve which forces the oil OilTillerrldopler third style pressure relief valve through the oil cooler when the which may be adjusted with the

valve is seated, or allows the oil The Thermostatic Oil Cooler twist of a wrench or screw to by-pass the cooler when the By-Pass Valve was designed to driver. valve is open. Lycoming engines provide better control of the An individual looking for the were originally equipped with a engine oil temperature while also pressure screen housing may not By-Pass valve which was con- maintaining the safety ot the oil find exactly what he or she is trolled by a spring. Referred to as system by by-passing oil around looking for since there are two a spring and plunger type, it an oil cooler which is plugged possible variations. The housing functioned as a result of the for any reason. The thermostatic for the pressure screen may have amount of pressure in the oil oil cooler by-pass valve may be one hole facing the rear of the system. The spring controlled by- used on engines which use the engine. This housing is used on pass system was superseded by a pressure screen system and on engines incorporating a spring system controlled by a Thermo- engines which have a full flow and plunger to control oil flow, static Oil Cooler By-Pass which oil filter. For most engine models and the single hole will be used reacts to oil temperature an oil filter also requires an oil for the oil temperature probe. changes, filter adapter. While the oil is Another style pressure screen Operation of the spring con- cold, this system allows oil to housing has two holes facing the trolled By-Pass system is the flow through the oil filter without rear of the engine. The small result of thick oil which causes passing through the oil cooler. hole is used for the oil tempera- an increase in differential pres- As oil temperature rises to ture bulb connection, and a sure across the by-pass valve and approximately 1.80 degrees Thermostatic Oil Cooler By-Pass causes the by-pass valve to be Fahrenheit, the valve closes and Valve is installed in the large open, thus by-passing the oil forces oil to pass through the oil hole. cooler. As the oil warms up, oil cooler. The oil then returns to Even more attention to detail viscosity and pressure in the the accessory housing where it is may be required when an oil

4Â·November 1991 LYCOYINO ~LYER

filter is installed. The pressure A Review of Old Ir~ives Tales screen housing must be removed and the oil filter adapter installed Tale Number One "The most timefor an engine/allure to in its place. With the oil filter occur is at thefirstpoLL~er reduction after takeof~ Ever~ individual who adapter installed, either a spring pilots an aircraft has probably heard this statement at some time. Is it controlled by-pass valve installed a true statement! We will venture a guess and say that perhaps it may in the accessory housing just have been at some time in the distant past. above the adapter, or a thermo- Several years ago this question was asked of me and it led to static by-pass valve installed in questioning some FA-~ employees and a number of other pilots about the bottom of the adapter may be where the justification for this statement might be found. After several used to control oil flow to the oil weeks of poking into this subject, it was finally necessary to conclude cooler. Because of the better oil that we could find no justification that it was simply an "Old Wives temperature control, use of the Tale." thermostatic oil cooler by-pass A letter which recently came from a Flyer reader takes this one valve is preferred by Textron step further. First it appears that there are many who continue to repeat this tale. This caused our reader to delve into the subject a little deeper perhaps a little more scientifically than I did. Our reader studied a computer readout which had data on incidents of engine failure over a recent three year period. Based on the material in that report, this reader concluded that engine failures during takeoff are quite rare, and that failures during cruise are far more common. This does seem logical since the engines of fixed wing aircraft run a majority of their operating life in the cruise power range. Our reader also had a very believable theory about how this tale may have gotten starred. He wrote, "I! seems likely to me that this Pressure Screen Zlouslngs idea got started when twin engine flight instructors would simulate an engine our during takeoff right about the time that the student put Lycoming. For engines shipped his hand on the prop control to reduce power.... Gradually the idea from the factory with an oil filter, was propagated that this was the most likely rime for an engine failure and requiring an oil cooler in the when in reality it was a likely time for an instructor to simulate a aircraft installation, it is standard failure." procedure for Textron Lycoming From these two searches for justification with none being to supply a thermostatic by-pass found in either case, I believe it is fair to conclude that 'the idea of an valve. The hole in the accessory engine failure being most likely to occur at the first power reduction housing which is provided for a after takeoff" is in fact an old wives tale. For the sake of safety, lets spring controlled by-pass valve is stop repeating this false tale and start promoting the idea that we capped with a plug. A hole on should be ready to deal with power failure at any time. the top of the adapter is pro- A second Old Wives Tale which is still being promoted by some vided for the oil temperature individuals involves the constant speed propeller and goes like this: bulb. "The RPM in hundreds should not be exceeded by the manifoldpressure One case of confusion over the in inches ofmercury. Referred to as a "squared power setting" (i.e. possible variations of this instal- 2400 RPM x 24 inches of MP), it appears that this tale may be the lation was documented in the result of a carry-over from some models of the old radial engines November '1390 issue of Light which were vulnerable to bearing wear at high power settings. Plane Maintenance. The owner of Changes in engine design along with improved metals and lubricants a 1376 Cessna 172 could not permit changes in the operation of modern flat, opposed cylinder determine why oil temperature in power plants. his engine tended to be high Any piler who believes that squared power settings continue to be during hot weather. Upon exami- necessary should be urged to read and understand the information in nation, he found that the filter the Pilot's Operating Handbook (POH). While there are limits to the adapter had a plug installed power which should be raken from most engines, particularly those instead of a Thermostatic By-Pass which are turbocharged, the combinations of RPM and MP listed in the Valve. This led to an article power charts of the POH have been flight rested and approved by the entitled "The Case of the Missing Please rum to Page 7. Column I Please ~um to Page 7, Column 3 LYCOMING FLYER Â·5 While these smaller sumps Service Bullefins, Letters, InstructIOnS provide a very adequate oil supply, there is less margin for Published from March 1, 1991 error. The pilot must be more to August 31, iS9i dedicated to carefully checking The service publications listed below are those which have been oil levels and filling the sump as issued most recently. We strongly recommend that a complete set of needed. For engines with these these publications be maintained by all maintenance organizations smaller sumps, one quart below which work on Lycoming reciprocating engines. A subscription may be the full mark may be adequate obtained through any Textron L~coming distributor or directly from for a short night, however any the Textron Lycoming Product Support Department. Call or write far a night of extended duration copy of Textron Lycoming Service Letter No. L114 which provides a should bcgir? with the oil level at listing of available publications, and instructions. the: full mark. prices, ordering One problem which sometimes Sen/ice Bulletins occurs with engines having 240L liandatory replacement of parts at normal overhaul All smaller sumps is overfilling at the Textron Lycoming reciprocating aircraft engines. time of oil change. The Pilot's 3691 Engine inspection after overspeed or overboost All Operating Iiandbook should be Textron Lycoming piston engines. consulted to determine the oil 456D Replacement of oil pump impellers with change of compli- sump capacity. When the filter is ance time to "within 1CtO hours, next annual inspection or changed, an additional amount of overhaul, whichever comes first." Applies to 0-235, O- oil possibly as much as one 320, 10-320, LiO-320, 0-360, HO-360, 10-360, HIO-360, VO- quart will be required to bring 360, Ivo-36c, AIO-360, LIO-360, 0-540, and 10-540 with the reading up to the full level. limiting serial numbers and models as specified in this This should be checked after the bulletin. Note: AD 81-18-04 applies. engine has been run following 498 Reprint of Precision Airmotive Corporation Service Bulletin the oil and filter change. hlSA-~ 0-235, 0-230, 0-320 series engines. Finally, some Pilot's Operating 439A Installation of one-piece exhaust pipe kit (05#21503) Handbooks may give a minimum Ti0-540-S1AD. safe quantity in the discussion of 500 Reprint of Lear Romec Service Bulletin No. 3402 All oil levels. These numbers, in Textron Lycoming engine series with applicable fuel pump some cases as low as two quarts, models and serial numbers listed in this publication. must De taken in the proper 501A Recall of piston pin Fart No. L\1C'-14077 Iciodels and serial context. What this indicates is an numbers of all engines affected and shipped from Textron oil level which might possibly be Lycoming between June 18. 1391 and August 5, 1391 are found after flight when a great listed following the text of the bulletin. deal of oil has for some reason been used or lost. As one might Service expect, this minimum oil level 1187G Supplement No. 1 provides curve No. 13495-A which re- can be extremely attitude sensi- places curve No. 13435 on page 8 of 3. T0-5400AAli\ tive. I-Iowever, if the dipstick engines. does: not show an amount below 1343A Set screw for propeller governor idler shaft 0, IO, LIO, the minimum safe I~vel stated, it AIO, AEIO-320 series; O, LO, IO, LIO, AIO, AEIO, TO, TIO- is unlikely that engine damage 360 series; O, 1O, AEIO, TIG, LTIO-540 series; 10-720 wide has resulted from the unusually cylinder nange engines equipped with a front crankcase low oil level. Obviously, no flight mounted prop governor. should ever be initiated with 1448 Supplement No. 1 gives proper installation of crossover pipe only a minimum safe quantity of supporting hardware and hear shield TIO-540-AE2r\ oil in the sump. engines. This brief discussion of "How 1453 Replacement of oil filter converter plate gasket All Much is Enough" may help those Textron Lycoming dual magneto engines and T1O-541-E 8~ aircraft owners who have had nGO-541 series engines. questions on this subject. But

Pleare turn to Page 8, Column I

6Â·Novemberl991 FLYER

1454 Parallel valve rocker arm installation All Testron Bypass Valve". Engines delivered Lycoming engines incorporating parallel valves escept 0- to Ces,Ena for this model year 235 series, 0-290 series, 0-320-11 series, and O, LO, TO-360- were delivered with a pressure E series. Note: Service Bulletin No. 477 and AD 17-10-06 screen housing and a spring apply, controlled oil cooler by-pass valve. \Slhen the aircraft manufac-

Sentice Letters turer provided an oil filter as an L163C Recommendations regarding accidental engine stoppage, option, the adapter and filter propeller strike, loss of propeller blade or tip Applies to were installed at the aircraft all Textron Lycoming opposed series aircraft engines. manufacturer's plant, but the L229 The use of MOBIL AV 1 synthetic lubricating oil in Textron original spring controlled by-pass Lycoming reciprocating aircraft engines Applies to all valve was retained and installed Textron Lycoming opposed cylinder aircraft engines. in the accessory housing. As stated in Textron Lycoming Service Instruction 1008B, instal-

lation of a thermostatic oil cooler initiate the development of a new fuel specification for an unleaded by-pass valve will provide better aviation fuel. An initial fuel has been devel- specification guideline control of the engine oil tem- the GAMA fuels committee and will be to the (3ped by presented perature. This aircraft owner did American Society for Testing and Materials (ASTM). This proposed fuel achieve better control of his oil will have the octane to minimize the need to highest possible modify temperature by modif)Iing his oil models. For if the minimum octane level of future engine instance, system to include a thermostatic unleaded Avgas was 98 octane, very little would need to be done to by-pass valve instead of the accomodate this fuel in installations. This work has been existing just spring controlled one. initiated and will several until a final is require years specification There is one more possible and will further completed. Testing, certification, production delay variation to the flow of oil which introduction of the new fuel at the until the latter of this pumps part ,,y b, found with a Lycoming decade, engine. Some air frame manufac- The EPA has stated that do not have to positively they plans today turers have utilized small engine eliminate the lead in aviation fuel. The should be present fuel, 100LL, models nÂ·ithout an oil cooler. At available for aviation use for at least the next decade. How- general the request of these airframe it is time to act to the aviation industry for the ever, protect general manufacturers, these engines are decades to come. It is also for aviation to be important general socially not machined to accomodate an responsible and share solutions for environmental and energy prob- oil cooler. Individuals who lems. acquire these engines for use in In there is reason for aviation to be concerned summary, general their home built aircraft may about future of 100LL aviation Some of this threat availability gasoline. need an oil cooler to keep from environmental and some from very real stems legislation energy temperatures within operating issues. If the acts and today, it will head industry promptly effectively limits. This can be accomplished off a crisis in the future. Textron has initiated action to Lycoming by utilizing an adapter those tasks which must be done meet near term accomplish to require- Lvcoming part number 62418. ments and ensure long term availability of a compatible aviation Utilization of this adapter will As events unfold and this situation is Textron gasoline. clarified, allow the engine to be used and will available informed. Lycoming use every means to keep customers the oil to be cooled, but there

are limitations. An oil Filter cannot be installed, and only the one-hole airframe and powerplant engineers. For example, if the POI-I chart lists pressure screen housing Ca" be used. This limits the 2200 RPM and 26 inches of MP as an approved power setting, pilots system to use of a spring con- should not be apprehensive about using that setting if it meets their trolled oil cooler valve needs. by-pass which is installed in the adapter. Isn't it strange that some bits of information come to be believed There are several bits of by large segments of a population even when they are untrue! The two issues discussed above are good examples. \Y'ill it ever be pos- Please ~urn to Page 8, Column 2 .sible to get all of our fellow pilots to reject the two false ideas outlined here? Let's keep trying. LYCOMING FLYER 7 Safefy Tip' information which may be Safety Tip helpful to those who have now If field overhauled your acquired a better understanding Textron Lycoming Service Textron Lycoming engine is of the Lycoming engine oil Bulletin No. 483A requires equipped with parallel valve system. Lycoming Service Instruc- inspection of the oil suction heads which have cylinder tion 1008B gives instructions for screen at each oil change. been reconditioned, it is installation of a Thermostatic Oil In those fuel injected six to the subject inspection Cooler By-Pass Valve on engines cylinder engines which recommended in Service which have a pressure screen incorporate Oil Sump Baffle Letter No. L228. Field housing and no filter. Special Assembly P/N L'Vir-13383, have inspections revealed Service Publication (SSP) 885-1 reports from the field have that the cylinder-head gives instruction for the installa- disclosed that in some exhaust port area on some tion of engine mounted oil filter instances vertical deflectors parallel-valve cylinders kits. And finally, a kit (Number on the Baffle Assembly have reconditioned in the field 05K21437) for a remotely been loose. if a rivet is

may be prone to cracking, mounted oil filter has been found in the suction screen These fine cracks are developed. Instructions for the during the normal oil difficult to detect visually, installation of this kit are not change, the baffle assembly and therefore a dye pen- complete as this article is being must be removed and ctrant must be used. If written. replaced. In recently as- is Textron cracking evident, The Service Engineers at the sembled engines, an im- advises Lycoming replace- Lycoming factory receive many proved riveting procedure is ment of die cylinder-head/ calls about the oil system and its used to eliminate the loose barrel assembly. See Service many possible variario~s. The rivet possibility. Letter No. L228 for more material presented here is in- detail about how to conduct tended to help answer many of the inspection. those questions.

----LYCOMING PERMISSION TO REPRINT the Pilot's always remember, Permission to reprint material from FL~ER Operating Handbook is the the Lycoming "FFyer''s granted, so lo"g Is the context of information authorized source of information remains intact and appropriate credit November 1991 Issue No. 51 about your airplane. is given. Editor: Ken W. Johnson

LifiCi~:ILycoming BULK RATE Plant Wllliamaport US POSTAGE Textron LycominglSubsidiary of Textron Inc. PAID 652 Oliver Street WIILIAMSPORT. PA Williamsport, PA 17701 Us'A 717/323-6181 PERMIT h'O. 163 ADDRESS CORRECTION REQUESTED

1 1A 2 HO AHNINO AIRCRAFT TECHNICAL PUBLISHER 101 SOOTH HILL DRIVE BRISBANE CA 94005

8Â·November 1991 LYCOMING FLYER #51 LYCOMING

May, 1991JLIJ:CILT.I:1 Lycoming Reciprocating Engine Division

Reeog%rizing and Treafing Carb~efor Ice #igh Time Cylinders

A recent incident at the local airport is just one reason for reviewing The aluminum alloy cylinder this subject. The pilot of a light general aviation aircraft flying above the heads used or. air cooled aircraft clouds reported a partial loss of engine power to the controlling FAA engines are subject to high facility. After a brief period, a safe let down and landing were accom- stresses while operating. In plished. The radio transmissions from the aircraft were monitored in the addition, they are heated and facilities of the local FBO where they were heard by a Lycoming Field cooled with each engine start up Service Engineer who is both a licer~sed mechanic end a licensed pilot. and shut down. Over long When the pilot of the troubled aircraft came into the FBO facility, he periods of operation, these was offered assistance in determining the cause of the power loss by the stresses can lead to fatigue and Lycoming employee. The pilot bluntly indicated that he was not inter- eventually the cylinder head may ested in any discussion or assistance. He also asserted that there was no develop cracks. possibility that carburetor ice could have caused the problem because he Lycoming metallurgists argue was flying above the clouds and not in them. that welding of cracks in alumi- While many pilots are well versed on the insidious characteristics of num cylinder heads is not likely carburetor ice, there are some who could use a thorough review of the to meet with long term success. subject. One of the best sources of information is a study done by the Therefore, an overhauled cylin- National Transportation Safety Board. Much of the following data are der has little chance of being as taken from that report. Some of the material will be verbatim, but other serviceable as a new cylinder. Even if there were no cracks at Please rum to Page 2 Column 2 the time of overhaul, metal

is still a ,Factor to be I IL I a L fatigue considered. But how! There is no ~he CrankShaff Gear about the contents of Textron record of time in use required for Lycoming Service Bulletin No. a cylinder assembly. An over- At first glance this would 475A and AD 91-14-22. These hauled cylinder could have 4000, seem to be a pretty boring documents have been issued to 6000, 8000 hours or more when Who needs subject. really to help assure safety of flight it is put on an overhauled en- know about a crankshaft gear? through compliance with the gir.e. Even a cylinder from your The answer to that question procedures outlined therein. own engine with only one tnp to would be "Any aircraft owner Service Bulletin No. 475A is TBO may not make it to TBO a who depends upon his engine titled "Crankshaft Gear Modifica- second time. to provide the power for flight." tion and Assembly Procedures." As a result of the scenario Although the subject may seem The introductory paragraph outlined above, Lycoming has for boring, a failed crankshaft gear should lend emphasis to the many years recommended new will cause engine failure and need For compliance at each cylinders when engines are that is when the excitement may specified time. That paragraph overhauled. To practice what is undesir- reach levels which are states: "Damage to the crank- being preached, Lycoming uses able, shah gear and the counterbored new cylinders on all engines What is all this leading up to? recess in the rear of the crank- shipped from the Williamsport A reminder to Flyer readers shaft, as well as badly worn or Plant, including factory over- Please rum to Page 4, Column I Please rum to Page 2, Column I hauls. It is less expensive to items will be condensed to keep the length of this article within reasonable limits. install new cylinders during the the from which this data is there overhaul as compared to having During five-year period taken, accidents carburetor the engine torn down once or were 360 general aviation involving ice as a cause twice for cylinder replacement factor. There were 40 fatalities, and 160 persons were injured, 40 of before it reaches the recom- them seriously. The number of persons exposed to death or injury in

mended TBO as an overhauled these accidents was 636; Â·i7 aircraft were destroyed and 313 were engine. The added reliability substantially damaged. must also be considered. "Carburetor ice", as used in the report, meant ice at any location in

With all the above a matter of the induction system of aircraft equipped with reciprocating engines. The is is used in aircraft accident record, there are still aircraft term uaditional. It records, even owners who write to ask for an though many reciprocating engine installations have fuel injectors rather honest opinion regarding "the than carburetors. risks of serious cracks in high- The report noted that carburetor ice normally does not remain in time cylinders." One such letter evidence for very long after an accident occurs. Thus, there may have chat five which stated, "...we owners all know been additional accidents during year period were nor so that Lycoming would prefer to appraised because of the lack of evidence at the time of the investigation. sell us new cylinders at overhaul time." This is true, because Unlike mechanical failure, over which the pilot has little in- flight carburetor accidents can be the in experience tells us that new control, icing prevented by pilot all Increased awareness and action ~ylinders are in the owners best virtually cases. pilot proper, timely of accidents caused carburetor ice. To aid in interest for the long run. can reduce the number by Per all those doubters who improving awareness and to suggest the proper procedures to be taken, of details which should know. have read to this point, it is not the NTSB study covers many the pilots for to knowthe three of carburetor necessary to take the word of It is important pilots categories and the manner in which each is formed. aics-'' anyone at Lycoming on this ice, These categories subject. The following material impact ice, fuel ice, and throttle ice. the NTSB ice is formed the was written by Richard L. According to report, impact by impinge- Collins, long time editor of ment of moisture-laden air at temperatures between IS degrees F, and 32 elements of the induction which are at Flying Magazine and currently a degrees F. onto the system F. Under these contributor to AOPA Pilot temperatures below approximately 32 degrees conditions, Magazine.Â·The material written ice builds up on such components as the air scoop, hear valve, carbure- and carburetor elements. Pilots should be by Mr. Collins seems to confirm tor screen, throttle, metering the stand which Lycoming has particularly alert to such icing when they are operating in snow, sleet, ice taken the more hours of rain, or clouds. The ambient temperature at which impact can be is about 25 F. when the moisture is still in operation on a cylinder, the expected degrees supercooled more likely it is to crack. The a semi-liquid state. following material is reprin'ted Ftlel ice forms at and downstream from the point at which fuel is from PLYING, March, 1337. introduced, when and if any entrained moisture reaches a freezing Copyright 1387, CBS Magazines, temperature as a result of cooling of the mixture by fuel vaporiza- from "Qn Top" by Dick Collins. tion. This cooling process takes place in the aircraft induction system when the heat necessary for fuel vaporization is taken from the Cylindrical Objects surrounding air. Then, because the cool air can hold less water the form of which "It's amazing how long it can vapo'l excess is precipitated in the condensation, take to catch on to basic me- then freezes. When any structure, such as an adapter elbow, lies in chanical truths. This realization the path of the water, ice accretion develops on that structure. If no action is the ice can increase until the was sparked by a conversation anti-icing taken, buildup with Jack Riley, Jr., principal in obstruction throttles the engine. for fuel air of RAM Aircraft. The subject was Visible moisture in the air is not necessary icing, only the overhaul of the TSIO-520 high humidity is required. This fact, coupled with the fact that fuel icing ambient make it difficult for a engine in my airplane. Riley was can occur at high temperatures, may pilot surprised that the engine had to believe that ice is forming unless he is fully aware of the fuel Icing been overhauled twice (both process. It can occur in no more than scattered clouds, or even In bngh~ times at TBO) and had not had sunshine, as often happens in Florida.

Please lunt ~o Page 3, Column 3 2Â·MAY1992 LICiOMl~i FLYER

The usual range of ambient temperatures at which fuel icing may new cylinders. Then he launched be expected is 40 degrees F. to 80 degrees F., although the upper into a dissertation on how the limit may extend to as high as 100 degrees F. The minimum relative metal in cylinders wears out with humidity generally necessary for fuel icing is 50%, with the icing operating time. The engine log hazard increasing as the humidity level increases. Fuel ice is not a revealed how right he was. On problem in systems designed to inject the fuel at any location be- the first run of the engine from yond which the passage surfaces are maintained above freezing. new, there were no cylinder Thus injection of fuel directly into each cylinder obviously ~iill problems. On the second run, preclude the possibility of such icing. with the original cylinders Throttle ice is formed at, or near, a partly closed throttle (butterfly) chromed, there was one incident when water vapor in the induction air condenses and freezes due to the of cylinder cracking Cbetween a expansion cooling and lower pressure as t~e air pasbes the restriction spark plug and the fuel injection imposed by the throttle. This temperature drop normally does not line). On the third run of the exceed 5 degrees F. When the'ambient temperature is above 37 degrees engine, still using the original F, then the pilot need not be concerned with throttle icing as long as cylinders, there were four inci- only air passes the throttle, such as in a fuel injection installation with dents of cylinder cracking the fuel introduced downstream from the throttle. three between a plug and the When there is a fuel-air mixture at the throttle, however, any ice injector and the fourth a large formation would be attributable to water vapor freezing from the cumu- crack that finally led to a little lative effects of the fuel ice and throttle ice phenomena. Icing at the chunk coming out of the inside throttle then can occur at ambient temperatures much higher than 37 of the cylinder. If I had sprung degrees F. Throttle ice is not a problem in some fuel systems which are for new cylinders on the second designed so that the throttle is located in a warmed region. For example, overhaul I would have saved a Lycoming designed turbocharger systems place the fuel metering device lot of money, because changing downstream of the compressor which places it in a warm area. a cylinder isn't exactly inexpen- Any one or a combination of these ice-forming situations may cause sive. That knowledge coupled loss of power by restriction of induction flow and interference with an with the fact that there was appropriate fuel-air ratio. One reason it can be important to use carbure- another cylinder with 4000 hours, tor heat as an anti-icer rather than a deicer lies in the "vicious circle" and Lhe rest had an vndeter- aspect, especially in fast-forming conditions and when the ice buildup mined amount of time on them might not be diagnosed at an early stage. An uncorrected carburetor ice (because they were recondi- condition can mean less power, and thus reduced carburetor heat which tioned cylinders and no record is may result in the formation of more ice. It is certainly only prudent to kept of total time on individual guard against a buildup of carburetor ice before deicing capability is parts) added some urgency to lost, the matter of getting the engine The results of tests conducted on light aircraft utilizing a float to RAIM for another overhaul and type carburetor may provide a better concept of when ice formation new cylinders. There is simply a might be expected. Serious Icing occurred up to carburetor air rime when some parts wear out. tenlpcratures of 62 degrees F. and relative humidity of 80% or more TJnril Riley told me that cylinders at high-cruise power settings. At low-cruise power settings, ice wear out, I had never heard of formed at carburetor air temperatures as high as 63 degrees F. with this. Bur they do. and I'11 never relative humidity as low as 60"/o. These tests clearly indicate that again waste overhaul money on carburetor ice may form while the engine is operating at cruise cylinders that have more than power. The tests also indicated that the possibility of ice forming in two TI)O runs on them. And I'11 the carburetor is much greater under glide-power conditions. With never buy a reconditioned this lower power serring, ice formed at temperatures as high as 93 cylinder that has an undeter- degrees F, and with relative humidity as low as 30%. mined amount ot rime on it Carburetor air heaters in small aircraft are usually of the exhaust pipe cuff type. The exhaust-heated air is directed into the carburetor air duct as desired, so that with full carburetor hear the normal air duct is essentially closed off at the carburetor heat valve location. The I;lyer provides product Under certain conditions, partial carburetor heat may be wO'Se than infornlarion Inf!,rnted pilots none at all. For the fuel/air mixture be at 20 example, temperature might ,,d mechanics contributu re, degrees F, with no hear applied.'l`his normally would be less conducive safe flying

Please lunt to Page 4, Column 2 LYCOMING FLYER 3 Bulletin these two to be broken gear alignment dowels 22 and jervice 475A publications They are the result of improper have been completed. extremely important. should be considered assembly techniques or the In the interest of flight safety, equally and the mechanics, reuse of worn or damaged parts both Textron Lycoming important by pilots, and aircraft during reassembly. Since a FAA consider compliance with owners. Failure of the gear or the gear attaching parts would result in complete engine stoppage, the proper inspection and reassembly of these parts is very impor- of tant, The procedures to ice forming than a temperature brought to 30 degrees F. by use dcscribed...are mandatory." partial heat. Full heat could be expected to raise the temperature out of THIS BULLETIN AND THE AD the icing range entirely. With smaller engine installations where there is WHICH MAKES COMPLIANCE no instrumentation to determine the temperature of carburetor air or MANDATORY apply to all fuel/air mixture, the general rule should be to apply full heat whenever Lyeoming direct drive piston carburetor heat is to be used. The use of full carburetor heat will reduce aircraft engines except the O- the amount of power available and can raise cylinder head tempera- 320-H, 0-360-E, LO-360-E, TO- tures. Since carburetor heat is rarely required under high power condi- 369-E, LTO-360-E, and TIG-541 tions, it is generally recommended that the carburetor heat be set st the series engines. The time of cold position for all high power operations such takeoff, climb, or go compliance is normally during arounds. overhaul, BUT ANY PROP With larger, higher output engines, the installation usually includes STRIKE OR SUDDEN STOPPAGE temperature instrumentation which the pilot should use as a reference in ALSO REQUIRES COIMPLIANCE. controlling all engine temperatures, including that of che fuel/air mix- instrumentation serves to assist in the The loss of a prop or prop rip is ture. L:se of induction temperature included in the definition of anti-icing effort, and also aids In protecting the engine fiom possible sudden stoppage. Also, the overheat damage. bulletin and AD are to be Carburetor ice should be considered immediately as the possible a loss complied with any time crank- cause of a power loss. With a fixed pitch propeller power is When there is a manifold shaft gear removal or gear train indicated by a reduction of engine speed. repair is required, pressure gage installed, a reduction in manifold pressure would show For the majority of aircraft up along with the engine speed reduction. With a constant speed the manifold would be owners, the requirements of AD propeller installation, however, only pressure 31-14- 22 will only come into decreased. iced play when their engine is over- Engine roughness may also be an indication of an carburetor. the hauled or when they exchange it is not a good indicator because in some casts roughness might their run out en~ine for a newly not appear until the engine is close to complete stoppage. overhauled one. In either case The susceptibility to induction system icing varies greatly among the: the engine being installed in the various aircraft models. For example, an engine installation emploving a aircraft should have had its neat-type carburetor and having fuel introduced upstream from the crankshafr and crankshaft gear throttle valve would be the most susceptible to carburetor icing. At the inspected in accordance with the opposite end would be an installation with direct cylinder fuel iniection. step by step instructions which However, the induction system might still be subject to impact icing. of the to avoid carburetor make up Service Bulletin 475A. Consider use following procedures help NeFv parts may be required icing troubles: check carburetor heat and controls for based on the inspection, but as 1. Periodically systems and a nllnlmum a new lockplare and proper condition operation. in the "cold" bolt must be used in assembling 7. Start engine with carburetor heat control position avoid to the carburetor heat the Bear to the crankshait. IT the to damage system. heat function by sclect- lofibook entry rcquiriÂ·mrtnts of 3 :\s a preilighl item, check carburetor indtcatcd a In SLI Â·i75A are completed by the Ing heat "on" and noting a power drop by drop IT In have the carburetor heat overhauler, you as an n~ncr can there is no drop power, actually check to be sure that s)Â·stcm checked BEFOKI: I~LIGH'I'. ambient tile tasks required by nI) It the relative humidl~v Is above 500,i and the

4Â·MAY 1992 temperature is below 80 degrees F, use carburetor heat I~MME- Densify Confroller DIATELY BEFORE TAKEOFF to clear the system of ice which may have formed during taxi. Return the selector to COLD Adjustment before takeoff. In general, carburetor hear should not be used during taxi because air is unfilrered in the "alternate" or Many Lycoming engine models carburetor heat "on" position. are equipped with density 5, Conduct takeoff without carburetor hear unless EXTREhlE conrrollers. This is a listing oi those models which Service carburetor icing conditions are present and the use of carbure- to Instruction TIO- tor heat is approved in the Pilot's Operating Handbook. If heat 1187G applies: is used, insure that ample runway is available for the reduced 540-A1A, -A1B, -A2A, -A2B,-t\2C, Bower condition and that the increased engine temperatures -CIA, -F2BD, -J2B, -J2BD, -N2BD, willnot incur engine damage. -,4AIAD, -AB1AD, -Ar'lA; LnO- 6, Remain alert after takeoff for indications of carburetor icing, 540-F2BD, -J2B, -J2BD, -N2BD. To insure that these especially when the relative humidity is above 50%, or when engine will visible moisture is present. models develop the masl- mum for which 7. With supplemental instrumentation, such as a carburetor air power they are the controller temperature gage, partial carburetor heat should be used as certified, density be defined necessary to maintain safe temperatures and forestall icing. must adjusted as in the latest of Without such instrumentation, use full heat intermittently if version Textron Service considered necessary. Lycoming Instruction The latest issue of this 8, If carburetor ice is suspected of causing a power loss, i;VIMEDI- 1187. ATELY APPLY FULL HEAT AND KEEP IT ON. Go not disturb instruction is 1187G dated August and the throttle initially, since throttle movement may kill the 18, 1989, Supplement No. 1 Service Instruction engine if heavy icing is present. Watch for fUrther power loss to 1187G dated The to indicate effect of carburetor heat, then a rise in power as April 22, 1391. supple- the ice melts. Once heat has been applied, BE PATIENT. DC) ment updates the instruction to NOT EXPECT IMMEDIATE RESULTS AS IT WILL TAKE TIME include the TIO-540-AF1A en- FOR THE ICE TO BE CLEARED FROM THE INDUCTION gine. Density controller settings SYSTEM. for TVO-435 and TIVO-540 covered in the 9. In case carburetor ice persists after a period of several minutes engines are of full heat, gradually move throttle to full open position and Lycoming Engine Operator's Manual. climb aircraft at maximum rate to obtain the greatest amount of carburetor heat. Cautiously adjust the mixture to the leanest Although all engines are practicable setting. thoroughly tested after manufac- 10. Avoid flying in clouds as much as possible, but also remember ture, remanufacture, or overhaul that carburetor ice can occur in clear air. at the Tex-tron Lycominl: Recipro- 11. Consider that carburetor icing can occur with ambient tem- cation Engine Division, it is perarure as high as 100 degrees F andÂ·humic~ity as low as 50%. impossible to duplicate the 12. PRIOR to reduced throttle operation, such as for a descent, individual installation chaiacteris- apply full heat and leave on throughout the reduced throttle ties an engine will encounter in sequence unless the Piler's Operating Handbook indicates the aircraft; conslquently the otherwise. Periodically open throttle during extended reduced density controller, which sovernÂ· power operatio~Â·1 so that enough engine heat will be produced the turbocharging, must be to prevent icing. Be prepared to remove carburetor heat if a adjusted after the engine is go-around is initiated. installed and before the aircraft Is 13. Return control to "cold" position immediately after landing to flown. Densir)Â· controllers avoid the use of unfiltered air. shipped as spare parts must also Because the formation of carburetor ice in general aviation engines be checked and adjusted after seems to be just as prevalent today as it was 20 or 30 years ago, it is installation and before the imperative that each pilot have a good knowledge of the causes and the aircraft is flown Before anv cures. With knowledge, carburetor Ice is a phenomenon which need not adjustment is made to the denslr)Â· be a hazard to safe niKht.'l'hc: information which was presented in the controller, the accurac~)Â· of rhrÂ· I1"I'SU report on "<:arburelor Ice in ~;LÂ·neral Aviarlon* and which is manifold pressure gage shoulci reprinted here is an effon to help make general aviation flying safer, be established.

Please ~unt to Page C~iumn i LYCOMING FLYEA 5 L I Log Book Entries Service Bulletins, Letters, instructions Published from 1992 The Federal Air RegulaIi~ns are September i, quirr speci8e in designating fo March 31, 1992 those individuals and organizations who are authorized to The service publications listed below are those which have been approve aircraft, airframes, issued most recently. We strongly recommend that a complete set of aircraft engines, propellers, these publications be maintained by all maintenance organizations appliances or component parts which work on Lycoming reciprocating engines. A subscription may be for return to service after mainte- obtained through any Textron Lycoming distributor or directly from nance, preventive maintenance, the Texuon Lycoming Aftermarket Sales Department. Call or write for rebuildiag, or alteration. These a copy oETextron Lycoming Service Letter No. L114 which provides a include the holder of a mechanic listing of available publications, prices, and ordering instructions. certificate, inspection authority, repair station certificate, or the Service Bulletinr manufacturer. 4560 Supplement No. 1 states that replacement of an oil pump also The regulations require body incorporatiag a pinned idler shah requires that Service that those who are authorized to Instruction No. 1341 must also be complied with. after return an aircraft to service 501B Recall of piston pin part no. LW-14077 Subject piston pins maintenance do so by supplying received and used between June 18, 1331 and August 5, 1931 written details of the mainte- must be returned to Textron Lycoming Williamsport for nance which was performed, exchange. Affected engine' models and numbers are listed in This information is to be an entry the bulletin. in the maintenance record of the equipment. The record will I I contain this information: 1. A description (or reference Service 8ul~etins, Letters, data the oaTE to acceptable to instructions ~AD Notes of work P,dministator) performed. i;, a ~h O/C~ -4, rJL~ Ancr 2. The d'dte of completion of r~lr g the work performed. T~ C\L-- C;\ -3 3. The naine, certificate number, and kind of certificate held the the Q,, -\\o by person approving rzcl c sh3~e u c: -o work and returning the aircraft to auj~ ibce Sn, (.,f service. It is important' that we understand the intent of these require- 3 ments. First, that only those who have the necessary training and skills will work on aircraft and their components. Second, that these maintenance records Exbit~it I provide a history of what has been done to the equipment over the entries made in the aircraft certif~ing information including its entire life, and engine logbooks are some- kind of certificate and certificate To accomplish the spirit and times woefully inadequate. number. Except for the three intent of the regulations, each Refer to Exhibit 1 as the items black circles in the lower right aircraft is delivered with an in that log book entry are dis- corner of that black mark, the airframe log book and an engine cussed. Note that this IS a cop)' of log book entry was blacked out log book. If the subsequent a logged entry which actually just as shown here untrics In these documents applied to an airplan~- In ServiCL. item number one of the logged cun~ain the appropriate derails, a 'I`hc- \-crv first Item ~ilih we secÂ· cntnÂ· declares that two cvlindcr~ very mainttÂ·narice I~ Ihc~ large black mar~ c,n the WCTL' rcpir-1CCd From the data hi~tor!r will rcÂ·sult. Unfortunately, io~iÂ·r right which obliterates the furnished, we do nc,t know why

6Â·MAY~992 Ll(iVMIPl(i FLYIER

SEru~ce Instruct~ons cleaned, gapped and tested 1164A Oil Pump Application~ All direct drive Textron Lycoming would add to the history of this Also there is engines except engines that incorporate an integral crankcase engine. no mention of the from and accessory housing assembly. rotating plugs top to 124UC Valve Spring Replacement All Textron Lycoming aircraft bottom which is a fairly standard engines, maintenance practice. 1304G Engine Nameplate Replacement All Textron Lycoming Perhaps items four, five and aircraft engines. six are adequate to tell what was 1374B Slick Magnetos All four and six cylinder Textron Lycoming accomplished, but simply stating engines equipped with Slick magnetos. "tach 346" does not give the information needed for the 1443A Approved Slick magnetos on Textron Lycoming engines aircraft and The Engine model breakdown makes up the text of the instruc- engine history. tion. total airframe hours and engine

hours since new or since over- Service Letters haul are needed for a complete history. L114AD Reciprocating engine and accessory maintenance publications Exhibit 2 is a second Applies to all Textron Lycoming opposed cylinder aircraft example of a book engines, log entry which tells lit'le or nothing about the main- L223A Revision A provides additional information about the use of tenance of the aircraft. the MOBIL AV 1 synthetic lubricating oil in Texrron Lycoming Again, certification information has been reciprocating aircraft engines Applies to all'l'exuon obliterated. The abbreviated Lycoming opposed cylinder aircraft engines. entry is extremely difficult to read and leaves much to the

L I I II imagination. What was accomplished prior to the engine

run and ENGINE LOG SERIAL No. ground flight! stated, these TIME Simply examples onÂ·re *UYII~ do with h,~lMln Â·.IIYICI-IIYÂ·IÂ·I rlou~lull not comply the spirit and intent of Federal Air Regulations. re. F\a, A 3 \r' /L\Â·OS Ci/W They do not provide the data needed to establish a mainte- c~J JPC Po nance history of the aircraft and engine which they represent. Unfortunately. Lycoming p~rson-

nel who have occasion to exam-

ine log books on a regular basis are finding that entries such as

those shown in these exhibits are PÂ·9Â· Toc~l ~II RÂ·CÂ·lr DÂ·tÂ· MbÂ·t 8Â·Â·r tkÂ· E~ndorrÂ·mÂ·n ot CÂ·rytlc~tÂ·d MÂ·ghÂ·nlc. Â·nd hi, RÂ·clng all too common. While there are Broupn~ ForwÂ·rd eno CÂ·rtltk~1Â· Num~Â·r MUST bÂ· Shown. many excellent maintenance organizations which do a very good job of following up their Exb~liN 2 work with adequate records, which they were replaced or single viscosity, multi-viscosity, there are also those which do a cylinders they were. Any me- or perhaps a synthetic oil! What poor job of maintaining a run- chanic working on this engine in brand was it! Was the filter ning history of maintenance the future will not be able to tell changed too? And was the performed. which cylinders were replaced suction screen removed, cleaned, Aircraft owners are ultimately on June 12, 15)30, This makes and checked for metal. This entry responsible for the airworthiness Future trouble shooting difficult. leaves many unanswered ques- of their aircraft. Therefore It is Item would two appear to tions. important that owners examine mean that the oil was changed. Item three deals with spark the logbook entries ~Â·ilch make ?hcre is intiication of what no plugs.'l`he condition of the plugs up the maintenance history of kind of oil was used. Was it which required that they be PleaJe ~unt to Pa~e S, Column ,1 LYCOMING FLYER 7 I

A characteristic of the adjustment, require reference to may prove to be lust as Impor- controller which is nor ,nsl2r- the latest version of Service rant as the work on the alrcrait stood by some operaron Is its Instruction No. 1187, or the or its components. ability to adjust engine ~urput at appropriate Lycoming Engine full throttle to obtain the rated Operator's;Manual. power of the engine reasrdless For installations which have Engine Nameplate of air temperature. This is ion- had an intercooler added in the Replacement fusing because manifold plzssure field, it is required that the at full throttle will var~ with the owner/operator consult the Policy temperature of the air entering Pilot's Operating Handbook A nameplate, to replace the engine. Pilots should noc Supplement or hlainrenance one that has been lost, nÂ·ill jump to the conclusion rhar a Supplement for density controller be issued only upon wrlrten problem exists when the?Â· do nor set up instructions which are request, and when accamp~- see the manifold pressure at red specific to the applicable Supple- nied by a document Irom the line or do not see the s3me mental Type Certificate CSTC). FAA authorizing a replace- manifold pressure with 23Ch This general requirement also ment nameplate. Upon takeoff, applies to all turbo system receipt of the FAA letter, your It is required that densit\- modifications done by STC. written request, and a check controller operation be chkcked for $7.50, a new nameplate before an engine is flown tor the will be issued. Requests first time, and periodicaliy during their aircraft each time mainte- should be sent to Testron the life of the engine. This nance is accomplished. Do the Lycoming Lusromer Service, relatively simple procedur~ entries tell what has been accom- Aftermarker Sales Depart- consists of measuring air rem- plished so that it can be under- ment, ~52 Oliver Street, perature at the compressor stood when read at some future Williamsport, Pennsylvania discharge (induction sir rem- rime! Remember that a good 1770i. perature) under operating condi- record of maintenance performed tions, and comparing it with indicated manifold pressure. ~nou*o Then, if necessary, the jensity FLYER controller should be adiusted. PERMISSION TO REPRINT Permission to reprint material from Accurate determination of the Published by the Lycoming 'Flyer'is granted, so the iextron iycomlng need for an adjustment to as the contexl of information long Heciprocating Engine Division and the remains intact and appropriate credit density controller, Mny 1992 Issue No 52 is instructions for making that given. Editor: Ken W. Johnson

Reciprocating Engine Division, US POSTAGE Subsidiary of Textron Inc. PAID 652 Ollvel Street WILLIAMSPORT. PA PA 17701 USÂ·t WllllamspOrl PERMIT NO 163 717,323-6181 ADDRESS CORRECTION REOUESTED

1 1A E HO ANNIHO AIRCRAFT TECHNICAL PUBLISHER 101 SOUTH HILL DRIVE BRISBANE CA 94005

B MAY 1992 LYCOMING FLYER ff52 LYCOMIIVG

Lycoming Reciprocating Engine Division

Refieslter On Engine Break-in Fuel Information

Service Engineers at the Textron Lycoming Reciprocating Engine Flyer Number 51 discussed Division get a surprising number of telephone calls asking about recent amendments to the Clean engine break-in. Because aircraft owners who are having a replace- Air Act and the affect these ment engine put into their aircraft are very interested in achieving the amendments were likely to have maximum in service and performance from that engine, a review of on the availability of aviation break-in planning and procedures is in order, gasoline. First and foremost, Textron Lycoming Service Instruction No. 1427A is entitled 'En- these amendments prohibit the gine Test After Overhaul With Engine Installed in AircraR" In some sale of leaded motor gas after ways this title is misleading because the procedures for break-in are 1995. Aviation gasoline will then not limited to overhauled engines. Any Lycoming reciprocating engine be the only leaded fuel type installed in a fixed wing aircraft as a replacement should be subjected remaining. Considering the very to the break-in procedures recommended in this service instruction. low volume demand for aviation The engine may be new, remanufactured, or overhauled. Even an gasoline as compared to the engine which has had a cylinder replaced, or just had new rings large volume of unleaded auto installed after the cylinder barrels were rehoned, should be broken in gas, the logistics will tend to all over again. Service Instruction 1427 is being updated to also make leaded aviation gasoline include the break-in of engines installed in helicopters. costly, or perhaps not available at all. Plearo hem to Pago 5 Column 2 Because of the circumstances

outlined above, there is a need to develop 1 new aviation fuel Does Your Nose Seal Leak? specification. The Textron Lycoming Reciprocating Engine Perhaps the first step in dis- Before installation of a crank- Division is working with the cussing this subject is to first get shaft oil seal, it is important to General Aviation Manufacturers' the terminology correct. check the recess into which it fits Association on the ASTM J2 Fuel Lycoming Service Instruction for proper size. Excessive wear Committee to initiate the devel- 1324A calls it a Crankshaft Oil which enlarges the crankcase opment of a new fuel specifica- Seal. Although almost everyone bore for any reason may cause tion for an unleaded aviation knows exactly what you are the crankshaft oil seal to leak. An fuel. talking about when the term under size crankshaft could As one of the first steps in Nose Seal is used, correct termi- result in the same poor fit and ;1 developing this new specification nology can be important, leak. This is usually caused by a for unleaded aviation gasoline, Should this seal leak immedi- rusty or pitted surface which has Textron Lycoming has run ately after installation, it is been polished excessively. premium grade unleaded auto- possible that the seal was dam- Lycoming Service Instruction No. mobile gasoline in Lycoming aged during the installation 1111 specifies the maximum engines designed for a minimum process, but a poor fit between under size grind or polish which of 91/96 octane aviation gaso- the crankcase and seal or the is allowable for the removal of line. At the service station pump, crankshaft and seal could also be rust or pits. It also prescribes the these automotive fuels am listed responsible for the leak. Pleat~ hem to Pogo 4, Column I P~sÂ· turn to Pogo 2 Column I at 94 octane. Results of the tests What is the of the objective engine break-in? To obtain a compres- proved to be less than satisfac- sion gas and oil seal between the cylinder walls and the piston rings because tory detonation occurred while also keeping friction to a minimum. This objective is achieved when the leaned engine was for by first ground running the engine as prescribed in the latest version cruise of Service Instruction operation, 1427 and then continuing the break-in by run- Of course there is 1 reason for ning the engine at high cruise power settings during all flights until these results. Aviation gasolines break-in is complete. These high power settings cause expansion of are both assigned a lean and rich the piston rings so that excess oil will be scraped from the cylinder with the lower number walls. Under these rating conditions, the oil is not baked into a shiny glaze being the lean rating. These on the cylinder walls and the rings and cylinders will form the seal octane rating numbers are not which is desired. determined with the same test Engines which are shipped from the factory in Williamsport, methods as the octane rating Pennsylvania always arrive with an hour or more of running time in numbers found on the at pump the test cell. This applies to all engines, new, remanufactured, and local service station. The your overhauled. This in-plant test run assures new owners that the engine auto fuel is found taring by meets all specifications for RPM, manifold pressure, fuel flow, oil averaging the Research Number and pressure, the amount of power produced. Although this test run (which is based on light duty starts the engine break-in, a thorough break-in sometimes takes as and therefore operation tends to long as 50 hours. The initial engine testing in the aircraft will be be high) and the Motor discussed quite here. Following this initial engine running, the new owner Number (which is usually quite should continue to utilize the recommended power settings for engine close to an aviation lean rating). break-in until a satisfactory break-in is assured. This the 93 or average provides Before proceeding further, the subject of oil used for engine 94 octane taring which is placed break-in should be discussed. Lubricating oils recommended for use In on premium automobile fuel. Lycoming opposed cylinder engines are listed in Textron Lycoming Aviation octane performance Service Instruction No.l0l4K along with general information regarding tests on these same 94 premium lubrication. The general rule for engine break-in is: Llse Straight octane automobile fuels resulted Mineral Oil. There are a few engine models which are exceptions to in octane in the ratings high this rule. These are: TO-360-C, TO-360-F, TIO-360-C, TIO-541, and eighties when the aviation using T1GO-541. These engine models are to be serviced with ashless lean test method. This is the dispersant oil for the entire life of the engine, including the break-in reason an aviation engine rated period. for a minimum of 91/96 octane Certain additional information applies to the break-in of these fuel might not satisfac- operate engine models: 0-320-H, On0-360-E, TO/LTO-360-E. Although the torily with these fuels when general rule of using straight mineral oil during break-in does apply leaned for cruise. for these engines, Service Instruction No.l0l4K also states that If we do not consider the high Lycoming oil additive, Part Number LW16702, must be added to the or additives vapor pressures oil of these engines when the engine is installed in the airframe and which may make automobile every 50 hours thereafter, or at every oil change. fuels less than for satisfactory use The factory produced engine, as stated earlier, will always have an in many aircraft fuel systems, initial test run. Installation of the engine in the airframe should be in these premium automobile fuels accordance with standard shop practice. To avoid contamination of the do have octane levels which replacement engine, the oil cooler and lines should be cleaned and should prevent detonation in flushed before they are installed. All vent and breather lines must be engines designed for 80 octane properly installed and secured as described in the airframe mainte- aviation gasoline, nance manual. Airframe and intercylinder baffles must be installed The most important result of along with the engine cowling to insure that optimum cooling is these tests is the finding that achieved, and that engine temperatures are maintained within speci- premium automobile fuels, in fled operating limits during both ground and flight testing. spite of the octane level adver- Although all engines shipped from the Textron Lycoming factory tised at the are not pump, haYe been run in the test cell, an engine ground test in the aircraft as suitable for use In aviation described in Service Instruction No. 1427 will be beneficial for these engines which were designed engines as well as for those overhauled in the field with no test cell for a minimum of 91/96 available. On start up it is imperative that adequate oil pressure be Please turn to Column Page 7, S shown on the gage within 30 seconds or the engine should immedI- 2Â·JANUARY1993 ~LYER

ately be shut d,,,The engine should be run until it is completely 101360 TBO Mystery aircraft is warmed up so that several items can be checked before the released for flight. These items include a standard magneto check with The Lycoming IO-360-A was the engine producing power, and a quick OFF and ON check at first produced in the 1960s. hÂ·iany engine idle to insure that the magneto is not hot with the switch in the versions of this 200 horsepower OFF position. Operation of the alternator, vacuum pump, and carbure- engine have been built over the These include the tor heat or alternate air system should be checked during this period years. IO-360- of ground operation. Cycling of the propeller for models with a c, IO-360-D, and the IO-360-J. of these such as controllable prop, 2 feather check if the engine is installed in a multi- Some models, have been engine aircraft, and a brief run to full power determine the proper the LIe360-C1E6, functioning of the engine/propeller combination. During this engine manufactured for use in twin determine if aircraft and rotate to the run up, the oil pressure should be carefully checked to engine cool left rather than the which is any adjustment is necessary. After a period at idle for engine right down, idle mixture and idle speed are checked to see if adjustment standard. Although the 10-360 for has also been for use in may be needed. After shut down, the engine should be inspected adapted oil leaks. Finally, the oil suction screen, and oil pressure screen or oil helicopters, the paragraphs filter should be checked for contamination. If no contamination is which follow will deal only with evident, the aircraft is ready for flight testing. those engines used in fixed wing The flight test after installing a replacement engine should follow aircraft. the procedures outlined here. They are taken from Service Instruction Because of its long history, the No. 1427A. recommended TBO for some of 1. Start the engine and perform a normal preflight run-up in the older 10-360 engines which accordance with the engine operator's manual. are still operating seems to be a 2. Take off It airframe-recommended power, while monitoring mystery to their owners, and in RPM, fuel flow, oil pressure, oil temperature, and cylinder head many cases to the A&P mechan- temperatures. ics who are called upon to work 3. As soon as possible, reduce to climb power specified in the on these engines or provide operator's manual. Assume a shallow climb angle to a suitable cruise advice about their use. This is altitude. Adjust mixture per pilot's operating handbook. not surprising considering that Â·I. After establishing cruise altitude, reduce power to approxi- there have been a number of mately 750m and continue flight for two hours. For the second hour, product improvements over the alternate power settings berween 65% and 75% power per the years, and the recommended operator's manual. TBO has generally been in- 5. Increase engine power to maximum airframe-recommended and creased as these improvements maintain for 30 minutes, provided engine and aircraft Ire performing have been incorporated. within operating manual specifications. Let's start at the beginning. Early 10-360 engines utilized a CAUTION stepped dowel to hold the bearings in place. TBO for these Avoid low-manifold pressure (under 15" Hg.) during high engine 1200 hours and is speeds. Also avoid rapid changes in engine speed with engines that engines was Still 1200 hours for any engine have dynamic counterweight assemblies. These conditions can detune, which has nor been modified as or damage, the dampers, rollers, and bushings in the counterweights. required by Lycoming Service 6. Descend at low cruise power, while closely monitoring the Bulletin No. 326 or 326A. There engine instruments. Avoid long descents at row manifold pressure. Do a'e very few engines not reduce altitude too rapidly or the engine temperature may drop probably which fall into this category, but too quickly, fhere is the that a few 7. After landing and shutdown, check for leaks at fuel and oil possibility engines overhauled in the field nttings and at engine and accessory parting surfaces. Compute fuel may not have been updated and and oil consumption and compare to the limits given in the operator's Still in manual. If consumption exceeds figures shown in manual, determine a'e operation. Service Bulletin No. 326 the cause before releasing the aircraft for service. 'e9uired the stepped dowels to 8. Remove oil suction screen and pressure screen or filter to check be with straight dowels again for contamination. replaced i" all saddles the After the initial flight has been accomplished and the aircraft is bearing except Pleara tun? lo P~go 8, Column I Plear~ rum Io PagÂ· 4, Column 3 LYCOMING FLYER 3 procedures for the ers know this is replating a possibility, and front main in the 10-360. Be- crankshaft flange and seal area. since with the they design cause the bearings required h~ieasurement of both the crank- intention of preventing engine larger holes to accommodate the shaft and the crankcase to insure related problems of this kind, larger straight dowels, dowels that they meet Table of Limit some means of preventing and bearings were replaced in tolerances should be standard of the crankcase freeze-up complete sets following the maintenance procedure before breather is usually a part of the instructions printed in Service installation of a crankshaft oil aircraft The breather tube design. Bulletin No. 326. All new 10-360 seal, be may insulated, it may be engines starting with serial To avoid damage during designed so the end is located in number L7100-51A incorporated it is a hot installation, important go area, it may be equipped the straight bearing dowels. follow the instructions with provided an electric heater, or it may Except for five engines which in Service Instruction a L~coming incorporate hole, notch, or slot have serial numbers listed in No. 1324A. This instruction which is often gives called a "whistle Service Bulletin No. 326A, all information on the two of slot." Because of types its simplicity, remanufactured engines which seals which be used in the whistle slot is often used may and were shipped from the direct drive is located L~coming engines, in a warm area near Williamspore Plant after January the part numbers of both the the where it will engine not 26, 1970 were updated. All IO- standard and the freeze. oversized seals, Aircraft operators should 360 engines with the larger -and the method of both know which method of installing prevent- straight bearing dowels were types of seal. is used and then ing freeze-up then assigned a recommended When a leak at the crankshaft insure that the configuration is TBO of 1400 hours. oil maintained seal develops after many as specified by the A second product improvement hours of airframe normal operation, it is manufacturer. which affected TBO occurred in usually the result of other Should at prob- leakage the crank- 15)72. A redesigned camshaft was lems. The Field shaft oil seal experienced occur as a result of introduced. It featured a Service Engineers at oil clearance Lycoming slinger which is too smoother cam profile that greatly indicate that a leaking cranl;shaft tight, the problem can initially be improved the action of the valve oil seal is frequently caused by a identified by checking for exces- train which consequently in- restricted breather or an oil sive end clearance. This can be slinger clearance that is too tight. done with a dial indicator. The leak might also be caused by Remove the prop and then push a propeller defect which the to the places prop flange extreme appropriate clearance is the an abnormal side load on the ah position and zero the indica- result of excessive wear on the crankshaft oil seal, tor. Then the pull prop flange Crankcase Thrust Face which will To avoid the problem of oil full forward and read the travel allow oil to be pumped out past at the crankshaft on the indicator. leakage oil seal Compare this the crankcase oil seal. because of an breather figure with the limits listed in the engine Overhaul time Is usually when examination of Table of Limits for the restriction, the appropri- the crankcase thrust face might breather tube to determine ate model. its engine receive needed repair. Should condition is an excellent idea. If Should the end clearance the srankcase oil seal be leaking the tube is in good condition, exceed the limits the specified, excessively, it may simply mean also remember that the engine oil slinger clearance should then that overhaul time has arrived expels moisture through the be checked. remove the old First, early. Fortunately this is some- tube. Under freezing conditions nose seal and clean the work thing which does not happen there is some thas. the possibility area. Again, push the crankshaft very often. moisture may freeze at the end to the rear of the engine. Insert a Crankcases with worn or of the tube and ice will build .002 inch feeler about up gage 3/16 damaged thrust face areas can be until the tube is completely inch wide between the oil slinger repaired by reworking the thrust restricted. Should this on the crankshaft and happen, the crank- face area to permit installation of pressure build in the case. may up Again, pull the crankshaft new thrust bearing washers. crankcase until something gives forward. If the .OOi inch feeler These bearings are available as usually the Crankshaft Oil is gage pinched tight, the re- repair items. Thrust bearing Seal. quired .002 to .007 inch clear- washers may be reused If they Since the airframe manufactur- ance has been exceeded. Lack of do not show wear and if their 4Â·JANUARY1993 FLYER

creased the service life of the had both of the improvements quent requests about the recom- exhaust valves. The redesigned discussed here aarger straight mended TBO for the 10-360 camshafts were incorporated in bearing dowels and redesigned engine, it seemed appropriate all engines with these serial camshaft) would have 2 recom- that this detailed explanation numbers or higher: L524-67A and mended TBO of 1600 hours. At start at the very beginning and L3762-51A. For those who own that time, there were three attempt to clear up the reasons 10-360 or LIO-360 engines with possible recommended TBO for the many changes which have serial numbers lower than these, times for these engines: 1200, occurred over the years. With you could be the owner of a 1400, and 1600 hours. As time this information, owners of older 1400 hour TBO engine. If the passed, all engines engines should be able to review camshaft was changed during remanufactured or overhauled It the logbook data on their en- overhaul, and one of these the Lycoming factory incorpo- gines and determine if the redesigned camshafts is now in rated these new features which changes outlined above have the engine, the TBO recom- increased the recommended TBO been made. For those whose mended In the current version of time to 1600 hours. Overhauls engines have all the recom- Lycoming Service Letter No. 201 done in the field should also mended changes and those with would apply. The TBO have incorporated these changes, engines which have higher serial recommendation for aerobatic but to know for sure, the records numbers than those listed above, engines is qualified by Note 6 of for older engines overhauled in congratulations, you am the Service Letter L201C. The part the field must be examined on owner of an engine which has numbers for clmshafts with the an engine by engine basis. proven to be worthy ofa 2000 revised cam profile are: LW- The product improvements hour recommended TBO and 13222 (with separate cam gear), which were made to the 10-360, that's not 2 mystery. LW-11754, LW-12311, and LW- 200 horsepower engine in the 12312 (with integral cam gear). early years made it an excellent Lycoming Service Instruction engine which is still being No. 1009T was issued on October manufactured today. By tracking 13, 1972, It stated that IO-360, engine performance and reliabil- I~ainfenance 200 horsepower engines which ity records over the years, Nofice Lycoming was again able to recommend another increase in Textron Lycoming Service TBO time when Service Instruc- Bulletins 446 and 471 require the thickness is sufficient to maintain tion No. 1009AE was issued on use of oil additive LW-16702 in compliance with the crankshaft June 19, 1981. At that time all IO- certain Lycoming reciprocating and crankcase end clearance 360 engines which had been engines. Textron Lycoming specifications in the Lycoming upgraded to be eligible fora Service Instruction No. 1409 Table of Limits. 1600 hour TBO were recom- recommends its use in all Instructions for repairing the mended for a further increase to Lycoming reciprocating engines. 1800 hours. crankcase thrust face are found In the northern hemisphere we in Lycoming Service Instruction The publication by which now have cold weather affecting No. 1354B. This repair should Lycoming makes TBO recommen- many aspects of our flight bring the oil slinger clearance dations was changed to Service activity, so it may be an Pppro- back into tolerance and should Letter No. 201 in 1984. By priate time to consider the cure the leaking crankcase oil continuing to observe the condi- benefits of using LW-16702. The sell which would also have been tion of engines when torn down additive is carried to all parts of repllced during the reassembly at TBO, wear characteristics and the engine by the oil and forms a of the engine, reliability of the 10-360 engine protective film on all metal parts. The information provided in remained under evaluation. This This protective film is particularly this brief article may help aircraft resulted in an additional increase helpful in reducing wear on cam owners to prevent the possibility in the recommended TBO to lobes and tappets. Using LW- of a leaking crankshaft oil seal 2000 hours when Service Letter 16702 or an oil which already and to understand the serious No. 201C was issued on March 9, has the equivalent of LW-I6702 nature of the repair required if 1990. included may save your engine this seal is found to be leaking Because Lycoming Field from unnecessary wear during excessively. Service Engineers receive fre- cold weather starting. LYCOMING FLYER 5 AD Notes of Interest Service Bulletins, Letfers, Instructions

AD 90-04-06 has been revised. Published from April i, 1992 to Revision one placed May 1, 1992 as the date by which compliance November ~5, ~992 with the AD was to be completed. The AD and its revision The service publications listed below are those which have been apply to any Textron Lycoming issued most recently. VQe strongly recommend that a complete set of four cylinder piston engine these publications be maintained by all maintenance organizations manufactured prior to January 1, which work on Lycoming reciprocating engines. A subscription may 1930, and equipped with a rear be obtained through any Textron Lycoming distributor, or directly mounted propeller governor and from the Textron Lycoming Aftermarket Sales Department. Call or external oil line. Any governor write for the most recent issue of Textron Lycoming Service Letter No. oil line assembly having integral L114 which provides a listing of available publications, prices, and aluminum connecting nuts must ordering insuuctions. be replaced with a similar line utilizing steel fittings. Engine Service Bulletins case/governor aluminum fittings 225B Replacement of valve rocker thrust washers All Textron must also be replaced with Lycoming angle head valve engines. corresponding steel fittings. An 240M Mandatory replacement of parts at normal overhaul All optional method of compliance Texuon Lycoming reciprocating aircraft engines. with this AD is the installation of 342A Fuel line (stainless steel tube assembly) and support clamp steel fittings and a fire resistant inspection and installation All fuel injected Texuon flexible hose assembly. Although Lycoming engines as indicated in fuel line and clamping the time for compliance with this diagrams. AD has passed, it is recom- 388B Procedure to determine exhaust valve and guide condition mended that owners of these All Texvon Lycoming reciprocating aircraft engines. engines review maintenance 425B Continental Motors Service Bulletin No. 599D records to insure that appropriate Teledyne All Textron with S-20, S-1200, lines and fittings are now in- Lycoming engines equipped riveted stalled in their aircraft, and D-2000 and D-3000 series magnetos having impulse

examine the work to see if those couplings. of sintered iron oil lines are supported as specified 456B Replacement pump impellers Many affected in the AD. Textron Lycoming Textron Lycoming reciprocating engine models are Service Bulletin No. 488A and by this bulletin; serial numbers and other engine identifica- Service Instruction No. 1435 with tion data are included in the bulletin. Bulletin Supplement 1 to each are appli- 495A Reprint of Precision Airmotive Corporation Service cable to this AD. No. MSA-I, Revision No. 1 All Textron Lycoming piston AD 92-12-10 is applicable to aircraft engines employing Marrel-Schebler carburetors. L~coming TIO-540-S1AD engines 498A Reprint of Precision Airmotive Corporation Service Bulletin installed on Piper PA-32 series No. MSA-2, Revision No. 1 Textron Lycoming 0-235, aircraft. This AD required the 0-290, and 0-320 series engines. fist visual inspection of the fuel 501B Recall of piston pin part no. L~Jlr-14077 Attachment 1 injector fuel lines between the provides and issue date of November 15, 1991. fuel fuel manifold and the 502 Replacement of part number LW-13262 intake valves etched within injector nozzles ten flight with date code K-L. Bulletin applies to some engines of hours after its effective date. these models, TO, TIO-360-C1A6D; TO-360-F1A6D; (L) TIO- Lines which are not supported as 540-V2AD; TIO-541-E; TIGO-541-E. Specific serial numbers in the AD which specified or and time of new intake valve installation are spelled out in show signs of leakage or damage the bulletin. must be Follow replaced. up 503 Exhaust valve guide replacement on TIO-540-AP18 engines of these lines and inspection _ All TIO 540-AF1A engines up to and including number L- is replacement as necessary 9293-61A except those which have exhaust valve guides hour required at every 100 changed since April 1991. Fuel Inc. service bulletin Please htm to Page 7, Column I 504 Consolidated Systems mandatory 6Â·JANUARY1993 FLYER

I: I

CF66~-915 with No. CF1-92, Revision 1- Carburetor flolt ldt Reciprocating Engine All Texuon CF30-766 float, date stamped 1091 Lycoming Mainfenance School 0-235 series, 0-290 series, and 0-320 series engines equipped with Marvel-Schebler, F~cet Aerospace, Precision 'Ihe Texuon Lycoming Recipro- Division offers a Airmotive MA-3, U~-3A, MA-3PA, MA-3SPA, MA-4SPA series eating Engine hlaintenance and Service Training carburetors overhauled by Consolidated Fuel Sysrems Inc. or School in two forms. The first is in the 8eld by referenced carburetor floats listed ;Ibove a four-day course held at the between November 1, 1991 and July 14, 1992. He~d Williamsporr/Lycoming Count~ 507 Missing spotfaces on P/N 74218 Cylinder Assembly Airporr located in Montoursville, All Textron Lycoming VO-435 and TVO-435 series engines. Pennsylvania. The school schedule for Seruice Instruct~ons of 1993 is: All January through June 1009A] Recommended Time Between Overhaul Periods January Texuon aircraft engines. Lycoming piston 28 assemblies with 25, 26, 27, 1012P Supplement No. 1 states that counterweight 11 and LW-19227E ue February 8, 9, 10, pan numbers LW-19225E, LW-19226E, 22. 23, 24, 25 nor to be used on the crankshaft of an engine equipped of some March 8, 9, 10, 11 with reduction gears. Measurement and marking 24, 25 counterweights will be required. 22, 23, 15 lld3B Supplement No.2 replaces Supplement No.l. Changes April 12, 13, 34, dimensional and tooling information for grinding of counter- 26, 27, 28, 29 weight bushings. May 20 11139 installation of new integral camshaft and gear assembly 17, 18, 19, 0-540, 10-540, and TIG-540 standard cylinder flange en- June 7, 8, 9, 10 gines. 21, 22, 23, 24 for Pacific 11139 Supplement No. 1 lists a new telephone number A mobile Training School is Aviation Pry. Ltd. as (61) 2-708-9200. also offered to provide Textron kit Put No. 1455 Installation of new fuel injection manifold Lycoming customers with mainte- 05K21433 TIO-360-C1A6D engines equipped with two nance and service training at fuel manifold assemblies and TO-360-C1A6D engines con- their base of operation. enroll- verted to n0-360-C1A6D engines using SSP-584. More information on and 1457 Textron Lycoming remote mount oil filter kit All 0-235 ment, tuition, transportation, oil be obtained by series engines with the accessory housing machined for scheduling may Robert Ohnmeiss It (717) cooler installation. All 320, 360, 540, and 10-720 direct drive calling 327-7127 or by sending 1 fur to series engines equipped with two individual mlgnetos. his attention a (717) 327-7100. 1Â·158 Soft connecting rod bolts All Textron Lycoming recipro- caring engines. Service I;etten L230 A listing of and ordering instructions for Textron Lycoming Microfiche. publications which are available on octane aviation fuel. Thue- L231 An updated listing of variable absolute pressure controller fore, the Textron Lycoming calibration values for AiResearch turbo control test set Pan Reciprocating Engine Division Number 481070-1. strongly recommends that owners of these engines and An updated INDEX of Service Bulletins, instructions, Letters, refrain from attempting to use and be ordered from the SSP-292, was issued in June 1992 may any kind of automohIle fuel in is 52.00 Tcxuon Lycoming Aftermarket Sales Department. Price per theit engines. What you read on copy, the automotive fuel pump at your local service station does not equate to the same octane TO REPRINT PERMISSION value found on the aviation fuel Permission to reprint material from pump at your local FBO. The inspection, annual inspection, the Lycoming granted, so context of information difference might result in less and engine overhaul. Textron long as the remains intact and appropriate credit Lycoming Service Bulletin No. than satisfactory engine perfor- is given when it is least 342A applies. mance expected. LYCOMING FLYER 7 nlelsed for flight, it is the responsibility of the owner/piler to con- Mainfenan~e Tip tinue the break-in procedure. To seat the rings properly, the engine should be run at cruise settings between 65% and 750/6 power for 50 Murphy's Law prevails. Two hours of operation or until oil consumption stabilizes. If the engine is damps which hold the curbo- low operated at power settings during this break-in period, a condi- charger transition and tailpipe of tion commonly known as glazing of the cylinder walls may occur. the TIO-540-P2BD and nO-540- When this happens, the ring break-in stops, and excessive oil con- J2BD engines ~Piper Navajo 325 sumption often occurs. Extensive glazing can only be corrected by and Piper Chieftain) have been the and removing cylinders rehoning the cylinder walls. Because this used in reverse locations by is an expensive procedure it is a good reason for accomplishing a individuals in the held Although correct and break-in of the thorough engine. these clamps Ire similar in size which are asked about Many questions being engine break-in and appearance, they are not the should be answered by the material in this article. To summarize, same. The result of reversing these are the items which owners should keep in mind when a re- these two damps is transition is installed in their aircraft. placement engine (1) Follow the engine -exirnrsc- pipes which come manufacturer's recommendation regarding the oil to be used for break- loose. The confusion involves in. Run the (2) engine at high cruise power levels for best piston ring/ Lycoming part numbers LW- wall cylinder mating. (3) Continue-break-in operation fo~ 50 hours or 12093-6uld LW-12125-3. Part until oil consumption stabilizes, then switch to an Ashless Dispersmt number designed CAD) oil to keep the engine clean during its operating life. to be installed at the bottom of the wastegate which is the wastegate to nit pipe connec- No~ice tioa Part number LW-12125-3 should be installed to connect

CMC Aviation Limited would above should there be one the waste gate to the transition. like know if to any Lycoming available which is not being distributor or other maintenance used. Any organization having has 1 Turbo-Conuol organization such a test set which they would Test Set which is in excess to be willing to sell may contact h FLYER their needs. This unit with Part M. Dastur, Managing Director of No. 481070 would be suitable for CMC Aviation, at Wilson Airport, testing controllers fitted to P.O. Box 44580, Nairobi, Kenya. Published by Textron Lycoming TIG-540 series engines. Mr. Dastur be reached Lycomlng may by Reciprocating Engine Division CMC Aviation would like to telephone in Kenya at 501221 or January 1993 Issue No. 53 purchase 2 test set as described 501213. Editor: Ken W. Johnson

C~ ~C ir~ Lycoming BUU( RATE Reciprocating Engine Divisionl US POSTAGE of Textron Subsidiary Inc. PAID 652 Ollver Street PA W1LamspoR.PA ~7701 U.S.A. WIIlIAMSPORT, 717/323Â·6181 PERMTTNO.163 ADDRESS CORRECTION REQUESfED

1 IA Z AIRCRAFT TECH PUBLISHERS fiS HARRIET ANNINO 701 SOUTH HILL DR BRIS~ANE CA 94005

8Â·JANUARY 1993 LYCOMING RYER #53