DIGEST No 23, SEPT., 1960

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PRINTE D BY HEDGES 8: BELL PTY. LTD. \

AVIATlON SAFETY DIGEST

No. 23 SEPTEMBER, 1960

Prepared in the Division of Air Safely Investigation ,. Department of Civil Aviation Contents Page

Know Your Radio Compass

Ruptured Fuel Cell 3

Super-Constellation Overturns During Landing, Montego Bay, J amaica 4

The Digest to the Rescue 7

Freight Movement Causes Loss of Control, Great Barrier Island, N.Z. 8

Backward Mechanic Endangers F light 9

Dove in Fatal Fly-Past, Cardiff, Wales 10

Aircraft Servicing 10

Isolated Case! 11

Convair Crashes D uring Instrument Approach, Midway Airport, Chicago, U.S.A. 12 KNOW YOUR RADIO COMPASS Elevator Controls Disconnected, Abilene, Texas, U.S.A. 14 Although flie radio compass is one of our oldest radio navigation aids, i:eports D esign for Safety 17 are still received from time to time concerning abnormalities experienced in using t~ aid. As some of these reports indicate a misunderstanding of the limitations 17 Cessna Brakes of ·medium frequency direction finding systems, the purpose of this article is to DC3 Captain's J udgment Astray 18 restate the factors which affect the performance of the radio compass and suggest how to obtain optimum performance under varying conditions. Not T oo Old to Bite . . 21 General pending upon the strength of the signals received Pilot's Dilemma - Defect Diagnosis 22 because the receiver tends to select the stronger of At its best, the radio compass indicates the the two signals. Maintenance H azard - Inadvertent Gear R etraction 23 direction of arrival of the radio wave to which it Overseas Passenger Termina l, is tuned. H owever, because the radio wave is sub­ Error in Reading Altimeter Leads to Britannia Accident, Kingsford Smith Airport, ject to a number of outside influences which can Sydney Christchurch, Rants, U.K. 24 Night Effect result in a deviation of its path from the Non­ The Vital Link 25 Directional Beacon to the compass, the bearing in­ Radio waves taKe two paths to the radio com­ dication of the latter will not always be the bearing pass receiver. The first and normal path is along Carbon Monoxide 1s Lethal 26 of the N.D.B. from the aircraft. It is also possible the earth's surface. If only these waves were re­ ceived, the compass would point directly to the 28 for the wave of a n N.D.B. on the same or an ad­ How Considerate arc You? jacent frequency to be received in addition to that N.D.B. The second path is via one or more wave of the station tuned. When this happens the in­ refracting layers above the earth (the ionosphere) dicated bearing could be that of either N.D.B., de- returning to earth to mix with the direct waves . . Commonwealth of Australia

S EPT EM BER . 1960 Complete changes in the nature of the wave take similar to those discussed earlier may be noted but Adherence to the correct tuning procedures is of place on this J?ath and produce errors in direction. these day time effects are uncommon and therefore major importance with the introduction of newer Ruptured Fuel Cell It is the ratio of the intensity of the indirect to easily recognised. types of compasses wh ich require precise tuning to the direct waves in the total received signal which It is most important to appreciate that an un­ be effected by aural means instead of the previous­ 600 GALLON SPILL determines the liability to error of the radio com­ wanted N.D.B. may not be strong enough to cause ly used visual tuning meter method. It would be any bearing errors. The fact that its identification inappropriate to deal with the new tuning tech­ pass. As the strength of the indirect waves is The events which led up to th1s accident greater at night, errors are then more common and signal is audible does not necessarily indicate that niques in this article as the methods to be used may of greater magnitude, and so the term "night the bearing of the wanted N.D.B. is not correct, differ, not on ly from one type of receiver to another, started in the repair base. The aircraft had effect" is given to this phenomenon*. It is often although it must be considered suspect and should but also in relation to a particular type of receiver undergone a major fuel cell repair. In the be checked by other means. because of variations in ancilliary equipment in the found that this effect is most pronounced within final stage of this maintenance, a clear the hour either side of sunrise and sunset when the various installations. The 1020 cycles per second changes in the state of ionisation of the upper Mountain Effect .. RANGE filter which usually forms part of the acetate tape was p laced over the No. 3 main atmosphere are particularly violent. An effect similar to night effect is sometimes ob­ selector box and the mechanical or crystal filters tank and cavity vents during the purging tained in mountainous areas where the energy re­ whi ch may be fitted within the receiver for SHARP Near the N.D.B. the ground wave will pre­ tuning purposes are examples of this. operation. After completion of the job, this dominate but as the distance increases the ratio of ceived from an N.D.B. consists of two or more waves, one of them direct and others by reflection If a radio compass receiver is not tuned in accord­ tape was not removed, but the aircraft was indirect to direct waves will increase and bearing ance with the manufacturer's prescribed method its indications will become erratic. At night the maxi­ from the mountains. Bearing indications are found signed off as ready for flight. to change rapidly until the affected area is passed. efficiency wiJI be affected. Faulty tuning may re­ mum reliable range of an N.D.B. is approximately su lt in- The flight crew performed the preflight in­ 60 miles over land and 100 miles over the sea. (a) incorrect bearing indication (produced elec­ These ranges are virtually independent of the power Thunderstorms trically), spection at night, using flash lights, and did of the transmitter-increasing power increases the A thunderstorm generates a tremendous amount (b) increased adjoining channel interference, not see the clear tape covering the vents. A strength of the ground and sky wave by the same of radio frequency energy and when the aircraft is (c) in correct bearings when the atmospheric inter­ amount and the ratio of indirect to direct waves near to a storm centre, the radio compass may in­ ference level is high, ferry flight was completed w ithout incident. would therefore remain the same. The exception to dicate the direction of the storm and not that of (d) reversed sense indications, and Before the aircraft was returned to schedule, this rule is the low powered locator beacon which the N.D.B. to which it is tuned. Caution should (e) restricted service range. seldom has a range exceeding 30 miles, day or night. therefore be exercised when flying in the vicinity maintenance and preflight inspections again It is essential to know when night effect is pre­ of a thunderstorm to check by other means when­ Use the Most Appropriate N.D.B. fa iled to detect the presence of the tape, as it sent and to thoroughly understand its effect upon ever possible the accuracy of the bearing indica­ Frequently efforts are made to use an N.D.B. at b lended into the usual discolouration on the the performance of the equipment because these tions. distances far beyond its maximum range. Often lower w ing surface. errors are not only most common but impossible this is done even when there is another and more of correction. The Effect of Terrain appropriate N.D.B. available for use. An example Later fuel was transferred from the main The useful range of an N.D.B. is influenced by of thi s is the main ·high-powered N.D.B. at Sydney Co-channel and Adjacent Channel the type of terrain over which the radio wave which should be used for any considerable distance tanks to the outboard tanks to stabilize the Interference from other N .D.B.'s travels. It is greatest over the sea and least over in li e~ of the lower powered locators which should· tip gear on the ground. Approximate!~ sandy or mountainous country, and an N.D.B. with only be·used for approach procedures. It should be As mentioned earlier, if the signal from another thirty m inutes cifter this transfer started, t he N.D.B. operating on the same or an adjacent fre­ a daylight range of 600 miles over the sea may remembered tbat these locators were never intend­ quency is received with sufficient strength, the auto­ only have a range of little more than 100 miles ed for other than restricted coverage, usually for No. 3 main tank co llapsed inward from matic bearing determination circuits of the com­ over the least favourable types of soil. Therefore, instrument approach procedures and certainly not negative pressure. The tank ruptured, spilling when an N.D.B. is located on the coastline, its for en route purposes. pass receiver will be influenced and a bearing error approximately 600 gallons of fuel on the will result. Non-directional beacons are normally range in different directions can be expected to When overtlyin& an N.D.B. make use of back­ spaced geographically and by frequency allocation vary considerably. tracking procedures. The bearing indication from ramp. to minimise these effects. At night, however, when thi s N.D.B. will be far superior to that obtained the sky wave component of an N.D.B. extends to Height Effects by switching to a more distant N.D.B. ahead of This accident would not have occurred the aircraft. a far greater range than that of its ground wave, it The range of an N.D.B. over the sea is relatively may cause interference. This effect will be aggravat­ ind·ependent of aircraft height, but over unfavour­ Tndentification Tnterference (i) hc1d warning streamers been attached ed by attempting to use an N.D.B. beyond the able soil increases considerably with height for As indicated previously, the identification signal at the closed vents, range for which it was intended; when its signal each 10,000 feet increase. In extreme cases the strength may be low and therefore prone to inter­ of an unwanted· N.D.B. may be audible without range may be doubled by a change in height of the that N.D.B. ca using bearing errors - but where (i i) had signing off the tank repair been ference. This is further discussed later in the aircraft from 1,000 to 20,000 feet. article. there is any doubt it is wise to proceed with caution. preceded by an adequate inspection to Sometimes an ionospheric disturbance occurring Tuning the Compass Receiver Night Effect make certain the job was completed. duri~1g the day may make long distance propagation Remembering that the dependable night time It is of vital importance when using the radio Both (i) and (ii} indicate unsatisfactory possible by means of the wave passing to the re­ compass receiver to ensure that it is correctly tuned range of an N.D.B. is only dependable over distance fracting layers above the earth's surface. Effects to the frequency of the required station in accord­ equal to its ground wave transmission. Treat with supervision. ance with the techniques specified either in the ca ution night bearings obtained at distances greater * The possibility of these phenomena is not confined to manufacturer's instruction book or the company's than 60 nautical miles over land or 100 nautical the hours of night therefore the term "night effect" is miles over sea. (Extract from A viation Mechanics Bulletin) a misnomer. operations manual.

S EPT EMBER . 1960 3 2 AVIATION SAFETY DIG EST Super Constellation Overturns during Landing

On 21st January, 1960, a Lockheed Super-Constellation crashed MONTEGO BAY, JAMAICA whilst landing at Montego Bay Airport, Jamaica. Two crew members and 35 passengers were killed, but five crew members and four pas­ (Summary based on the report of the Public I nquiry) sengers were able to escape before the aircraft was consumed in an intense fire. point of rest behind the main port undercarriage assembly to sub­ the pressure in the oleo strut wreckage in a tip first attitude, the side in a rearwards direction, and was checked and found to be THE FLIGHT the aft cabin, were suspended in­ As subsequent examination of root end being supported by the ex­ the starboard leg to fold over in a 450 p.s.i. which is 182 p.s.i. b verted by their seat belts. They wreckage showed the nose under­ tended port undercarriage unit and The aircraft was engaged on a relative outwards direction, causing excess of normal. Five gallons quickly contrived to free them­ carriage strut of the aircraft to be No. 2 engine. This wing was also distortion of the undercarriage sup­ of oil were removed from the scheduled flight from New York to selves; the other two had released undamaged, it therefore can be Bogota, Colombia with intermediate on fire and during its passage along port beam and retracting strut. On dismantling the leg, their belts on initial impact. Efforts established· that the propeller slash the airport surface the No. 1 stops at Montego Bay and Kings­ mechanism. This latter movement a mark on the top of the ram to free the port emergency exit marks on the runway could only engine became detached and rolled ton, Jamaica. The aircraft with a was made possible by the members piston extending around 280° were unsuccessful at first. The sur­ have been made if the port wing along the runway, coming to rest crew of seven and 39 passengers becoming ductile due to heat. of the circumference, was found viving steward managed to open immediately prior to this, was de­ immediately behind the main to coincide with a similar mark departed from Idlewild at 1035 The port undercarriage unit was the starboard emergency exit and tached from the fuselage and in­ wreckage. It was also on fire. on the orifice plate of the hours local time. The flight proceed­ removed from the wreckage, dis­ escaped from the aircraft, but when clined in an abnormal leading edge cylinder, which indicated that ed normally to a point about 30 During the process of the air­ mantled, and subjected to detailed the others attempted to follow they downward position, which could the strut had been compressed minutes beyond Wilmington, North craft rolling over, the port outer examination. This revealed the fol­ were beaten back by flames. not have been achieved if it were to its maximum extent, and Carolina when malfunction was de­ Ultimately the port emergency exit still attached in its correct position fin and rudder with a portion of lowing - tected in No. 3 engine. The cap­ the port tail plane, became detach­ had bottomed. No other de­ window was opened and all four to the fuselage structure. In ad­ (a) There was no evidence of any fects were found. tain elected to divert to Miami and passengers together with the sur-· dition, as the slash marks were of ed from the tail unit, and proceed­ the aircraft landed at 1657 hours. ed along the runway coming to impact damage, and on the viving stewardess left by this exit. equal pattern and depth the wing tread and side walls there was The starboard undercarriage unit must have moved downwards at rest a few feet from the No. 1 The defect was rectified and the no evidence of rim cutting. was removed from the wreckage flight was airborne at 0012 hours the tip, deflecting its centre line engme. and on examination it was found INVESTIGATION There was some lateral scoring on 21st January, and the flight to through 7-t° to a position approxi­ As the aircraft proceeded along and cutting on the No. 1 tyre. that both wheels and tyres had mating the horizontal. Montego Bay was uneventful. The first indications that this the runway various portions be­ The side walls of the tyres had burnt away, and that the oleo Shortly before arrival overhead, a accident was caused by a heavy came detached from the structure cylinder had split due to excessive Marks on the runway extending been lightly burnt and both standard instrument approach landing were some tyre marks which which included pieces of the wing internal pressures presumably caus­ from this position indicated that the inner tubes had burst due clearance was obtained and a nor­ were imprinted on the threshold and f4selage frame, wing structure ed by the combustion of the oil it the major portion of the aircraft to heat and the weakening of mal instrument approach procedure markers of the runway. The relative from th'e ·i·egion of station 105 and contained due to intense heat. Dur­ rolled to the left, and that the the tyre due to burning. was carried out. On completion of positions of these marks made it No. 2 fuel tank, and also a panel ing this disintegration the piston centre line of the fuselage was also the procedure turn at 2,000 feet, the possible readily to identify them as from the underside of the wing be­ (b) Wheels and Brake Units. There and ram assembly had been forced deflected to the left, during the airport was sighted and the ap­ having been made by a Super Con­ tween No. 1 and No. 2 nacelles. was no evidence of any rim or beyond its lower limit due to the course of which the aircraft turned proach continued visually. The stellation and the tread pattern, These pieces of the structure con­ spoke cracking, and the tie partial collapse of the stop sleeve. over onto its back before slithering initial contact with the ground was which differed between the No. 1 firmed that the port wing was de­ bolts clamping the two halves The nature of the collapse of the finally to rest 1,900 feet from the reported to have been very hard, and No. 2 tyres of the port under­ tached. Subsequ~nt examination of the wheels together were in stop sleeve indicates that it failed and almost immediately after con­ carriage assembly, proved to be threshold of the runway and 200 showed that the wing had fractured due to extreme heat rather than feet to the left of the centre line, good condition, indicating that tact, the flight crew state that identical with those which would at Station 80. the wheel rims had not parted. fracture due to a shock impact. and on a heading 130° to the run­ they were conscious of a depres­ have been produced by the aircraft There were, however, score Further outward movement of the way. Photographic evidence was pro­ sion of the port wing and a at the time of the accident. The marks on the inner face of piston assembly was prevented by duced to show that at the time the flash. The aircraft fuselage came to starboard tyres were destroyed by From the evidence it would ap­ No. 1 wheel and the outer face the torque links. There were no in­ rest in an almost inverted position. the fire, but the port tyres were wreckage came to rest both the dications of strut bottoming on the pear that fire occurred in the air­ port and starboard undercarriage of No. 2 wheel, which had been The captain ordered the flight readily identifiable. craft when it was in a position piston head. units were in their correct positions caused by contact with the top engineer to open the door between where the propeller slash marks From this point on the thres­ for landing, in relation to the main bolts positioned around the the flight deck and the crew rest commenced and increased in inten­ circumference of the brake The nose landing gear had sur­ hold, the aircraft appears to have structure to which they are attach­ cabin, but this he was unable to sity as the aircraft proceeded to its assembly. This indicated that vived the fire, and was still attach­ do. A pilot's bad visibility window bounced into the air, and the next ed, and subsequent investigation the tops of the two wheels had ed to pieces of the supporting struc­ indications of its progress along final point of rest where it practic­ showed their retracting mechanisms was then opened and the flight ally burnt out before the fire could been displaced towards each ture. It was intact and correctly crew left the aircraft through this the runway were a series of slashes to be correctly locked in the down other due to the upward deflec­ locked down. The left wheel outer which were identified as having been be got under control. means of exit. position, despite the fact that the tion of the wheel axle extremi­ rim had been scored and damaged, produced by the propellers of No. 1 The port wing followed a slightly supporting structure had been al­ ties. due to contact with the runway, Two of the four surviving pas­ and No. 2 engines, at a distance of different course to the main portion most completely melted away due and the outside of the left tyre had sengers, all of whom were seated in 700 feet from the threshold. of the aircraft, and slid to its final to fire in each case, allowing the (c) Oleo Strut. Before dismantling, been scrubbed, and was deflated.

4 SEPTEMBER, 1960 AVIATION SAFETY DIGEST 5 The left wing of the aircraft had In evidence the Department of 115 knots, represented an broken away outboard of the Station Manager of the Lockheed Aircraft aircraft sinking speed· in excess 80 wing joint, and through No. 2 Corporation Projects Stress Group of 10 feet per second. fuel tank. The identifiable portions gave the following data appertain­ 'Prepared in ' of the left wing structure which re­ · ·ion O> Whilst it is impossible wholly to 1 mained, included part of the top ing to the structural design strength tne D l~vestiga tion wing skin with rib No. 125, the of the Super Constellation Aircraft exclude a degree of conjecture Air Salcty front spar inboard of Station 80, when reconstructing the aircraft's the rear spar to Station 80 and· the coNiENiS (1) That the aircraft structure was approach, the following presents a bottom skin. The structure out­ d Views designed to withstand a rate of fairly accurate picture of what in NeWS on ( Parts ...... board of Station 145 remained with .\\rcra t · fon fact occurred:- Bogns . 'd Cont<1rn1na I the wing and had been virtually sink during landing of 10 feet . f\UI .. }!ydrflap at a height of about 500 feet above the terrain, mechanism showed that all flap strut which was correctly the port rudder pedal suddenly moved forward to The port rudder cable was found to be broken at sections had been fully extended. charged was 187,000 pounds. CAUSE the bulkhead and ·?. the starboard pedal moved for­ the point where it passes around a fibre pulley The cause of the accident was ward about four inches. At the same time the air­ craft yawed violently to starboard. attached to the cabin floor. An inspection of the The control booster system (5) That the rate of sink necessary the adoption of a final approach starboard cable revealed that it was worn at the operating mechanism was in the to bottom an oleo strut as at path resulting in a heavy landing From the movement of the rudder pedals and same point to the extent that the diameter in this "ON" position in the case of the (4) above, at an aircraft land­ during which a major structural the behaviour of the aircraft the pilot assumed area was .006 inches less than the original diameter, elevators, rudder and· right aileron. ing weight of 110,000 pounds fai lure occurred in the port wing that the port rudder cable had failed. Recalling a and one strand of the cable was broken. Both the The left aileron unit was beyond report in an Aviation Safety Digest of an accident port and starboard cables had been in service for would be between 12 to 14 feet the normal "ON/OFF" position, in the immediate vicinity of the involving the same type of aircraft when a loss of 922 hours. Failure of Auster rudder cables at the apparently caused by the extension per second, that is 2 to 4 feet Station 80 joint caused by the trans­ directional control resulted from the same cause, floor pulleys is not uncommon; there have been 13 of the operating controls as the per second above the design mission of stresses through the and the advice in the report on how directional partial failures and 10 total failures reported in wing became detached. maximum. undercarriage in excess of those control could be regained in this situation, the this country since 1953. In an endeavour to pre­ which would be encountered if the pilot followed the advice given in the Digest at vent these failures, different types of cables have The propeller hubs were dis­ (6) That the tyre marks on the rate of sink of the aircraft at the that time. The throttle was closed to reduce pro­ been tried without success. Following this incident, mantled and it was determined peller torque and the starboard rudder pedal was and pending a positive fix, a letter was sent to all runway threshold, presuming a that a ll propellers were in the 14° time of impact had been controlled pulled backwards by hooking the toe under the Auster owners drawing their attention to the pos­ fine pitch position, at the time of landing weight of 110,000 with in the designed maximum of 10 pedal. Directional control was gained in this way sibility off such a failure and suggesting frequent impact. pounds with a forward speed feet per second. after a loss of approximately 100 feet of height. inspections.

6 AV I ATION SAFETY DIGEST SEPTEMBER. 1960 7 Calculation of the inertia forces an aircraft is not stressed to with­ As turbulence can be encount­ Freight Movement causes Loss of Control at the impact established that had stand forces which can be impos­ ered without warning on any the differential been on the seat at ed by a heavy piece of freight be­ flight, it is essential to ensure at GREAT BARRIER ISLAND, N.Z. the time, the comparatively sharp coming dislodged and being all times that freight of any kind edge of the crown-wheel would thrown about, such as can easily is securely restrained against any At 1335 hours on 13th January, 1960, a Piper have severed the seat belt and happen in conditions of turbulence movement from its position of PA. l SA approaching Great Barrier Island was seen to thrown the unit into the port upper if not adequately secured. stowage. area of the cabin. However, as the assume an acute angle of port bank, the nose dropped belt was still intact and the impact and the aircraft spiralled into the ground. The pilot, damage inflicted on the aircraft by who was the only occupant, received fatal injuries. the differential was concentrated on the seat structure, it was clear that the aircraft which could be recon­ the unit must have been in the (Summary based on the report of the Accidents I nvestigation ciled with the vertical wing-down BACKWARD MECHANIC ENDANGERS FLIGHT Branch, Air Department, Nf'w Zealand) space between the seats before im­ attitude. The pre-impact integrity pact. of the control runs, hinges and at­ tachments of control surfaces and Ever know anyone to do the paper work before the aircraft was flaps were confirmed. The tail It was concluded that the dif­ serviced or before the maintenance work was completed? Such a back­ THE FLIGHT the belt, one each side of the dif­ ferential escaped from underneath ferential. No other lashing or means plane trim indicator was at the full ward system may save a minute or two at despatch time, but it is not The purpose of the flight was to nose heavy setting, coinciding with the seat belt by toppling 90 degrees of securing the freight were used. to starboard before sliding for­ conducive to accurate records; it is contrary to all the rules, and it is transport urgently needed spare. the trim setting of the tail plane. The impact forces had been taken wards. Under the influence of a very dangerous practice, dangerous for everyone concerned. parts for a motor lorry from Man­ The aircraft took off and the on the left side of the aircraft, leav­ negative G or deceleration associat­ gere on the mainland to Great flight was normal until arrival over ed with turbulence, it then fell for~ ing the right hand wing and under­ Let's learn from an incident that happened in Europe. Barrier Island, N.Z. The pilot had Great Barrier Island. The normal carriage relatively undamaged. The ward, forcing the rear control flown to the island on several approach to the island was to cross differential was wedged in the space column socket bard over to the a coastal range of hills at a point between the front and rear seats, left and slightly forwards. About 30 minutes after a twin-engined aircraft departed on a five­ occasions previously. known as "the saddle" and it was jammed underneath the rear of the hour flight, an employee of the oil company which had serviced the well known that under southerly pilot's seat. The rear safety belt, In these circumstances the only The aircraft used was a Piper wind conditions, a small area of still done-up, was underneath the controls available to the pilot to aircraft reported that he had reason to doubt the accuracy of the record PA.18A equipped with a rear bench moderate to severe turbulence was differential casing. The chair seat counteract the acute angle of bank that both engines had been serviced with 6 gallons of oil. The record invariably encountered· in this area. seat and tandem controls on the upon which the differential had been and pitch down of the nose would in question was the duplicate page of the Technical Log. It showed left side. The rear control column resting had slipped forward and be top rudder and tail trim. It is Five witnesses watched the air­ that on arrival both tanks contained 17 gallons, that 6 gallons had was removed for this flight. was tilted into the area between the probable that the instinctive re­ craft approach across this range of front and rear' seats. The two pac­ covery action of the pilot was to been added to each tank, and that on departure each tank held 23 hills, at about 800 feet above the kets of brake linings were jammed apply 'full top rudder and wind the gallons. The freight consisted of an Aus­ ground. All agreed that, just after under the front port rudder pedal. trim fully back in an effort to get. tin 5-ton truck differential weigh­ crossing the saddle, the port wing the nose up. Realising that the On being questioned, the mechanic who certified the oil and fuel ing l 40 lb., together with brake lin­ of the aircraft dropped suddenly Examination of the rear control effect of nose-up trim was to into a vertical bank position. The record admitted that at no time had he checked the oil tank contents. ings, paper gaskets, nuts, bolts and column socket revealed that the tighten the spiral he probably then nose pitched down and the aircraft upper edge of the steel tube was wound it fully forward. This effect, He had completed the paper work on servicing that was never started. washers. To facilitate stowage of rotated to the left, with engine de1~ted and· bad been burred over plus top rudder and the gradually A further check with the oil company disclosed that 6 gallons of oil this equipment, the pilot obtained noise progressively increasing. As increasing speed, progressively con­ by a force delivered from the star­ had been added to both tanks of another aircraft for which no instruc­ an upholstered 3-ply chair seat, the dive progressed the radius of board rear. verted the steep spiral dive into a and placed it, upholstery down­ turn became larger and the angle wide left-hand slipping turn. tions had been issued, and no oil bad been added to the aircraft just wards, on the rear aircraft seat. of dive decreased, until, just before despatched. inlpact, the aircraft was describing The front seat supporting struc­ It was concluded that the cause The truck differential was then a wide left hand arc, still vertically ture had failed in shear as a result placed on the chair seat with the banked. of a forward movement of the seat. of the accident was the jamming of Fortunately no accident resulted. The aircraft was contacted by the controls by the breaking loose crown wheel vertical, teeth to star­ All witnesses were unanimous in their opinion that the aircraft was of inadequately stowed freight. radio and the captain advised to divert to the nearest company station. board, and the universal joint to flying normally until it assumed a On landing it was found that the left oil tank contained 7 gallons and the rear. The assembly was secur­ steep angle of left bank and that The foregoing accident report the right 3-} gallons. ed by passing the rear seat lap strap INVESTIGATION this angle of bank still existed when conveys a very important lesson around the front edge of the crown the aircraft struck the ground. It for all persons who carry freight Thus it was that in the age of flight a "backward" mechani c learned wheel where it emerges from the Investigation of the wreckage was a logical conclusion, therefore, in aircraft of a type not especially trail confirmed the witnesses' de­ casing. Two packets of brake lin­ that the cause of the sudden ap­ designed for the purpose with ap­ the inadvisability of putting the cart before the horse. scription of the crash. No fault plication of bank was also the ings were stowed vertically within propriate tie down points provid­ could be found in the structure of primary cause of the accident. ed. It must be remembered that (Extract from Aviation M echanics Bulletin)

8 AVIATION SAFETY DIG EST SEPTEMBER. 1960 9 • Dove Ill Fat al Fly Past ISOLATED CASE Some a.ccidents a.nd many hairy incidents are caused by stray tools, CARDIFF, WALES and parts being adri,ft in aircraft. From the number of cases reported it appears that maintenance personnel are not aware that such mis­ placed hardware can lead to disaster. On 6th May, 1959, a Dove DH.104 engaged in a "fly past" propeller windmilling and with Oew at an extremely low altitude with the starboard propeller maximum power from the other The U.S. Navy provided some tragic and near tragic examples, but feathered. After continuing some distance, the starboard propeller engine, wo uld permit only a very it should not be assumed that they happen only in the Navy. Usually commenced rotating and a few seconds later the aircraft dived small rate of climb. The fact that labelled "Isolated Case", they occur far too frequently throughout civil steeply to the ground. All on board were killed instantly. the starboard propeller was not feathered and that the cockpit pitch\ aviation. control lever was in the feathered A Marine Air Wing reported that an FJ-4 pilot THE FLIGHT INVESTIGATION position indicates that the pilot had THREE NAVY CASES initiated refeathering action at the A F9F-5 was just out of check and on a rocket­ suddenly found his flaps had lowered during a turn. The aircraft took off at 1320 Inspection at the scene of the last moment. bombing run. Full recovery was not made from a The flap handle was still UP and the accelerometer hours with three passengers on a accident confirmed that the aircraft run on its target and the aircraft struck the ground showed 8.4 g had been imposed. private flight to fly over the open­ had dived into the ground in a near The pilot was the holder of a in an upright flat attitude, and then exploded. A 5/16 inch washer had edged across the terminals vertical attitude. With the exception of the flap control relay, completing the "flap down" ing ceremony of the Welsh Ideal commercial licence and had com­ Cause of the accident was not conclusive, due to of the outer sections of the main­ circuit. The washer had not come loose from any­ Homes Exhibition being held in pleted a total of 256 fl ying hours the explosive forces which destroyed the aircraft plane the aircraft was almost entire­ thing. It was just part of the trash that all too often chiefly on single-engined aircraft. on impact. But the unexplained presence of a Sophia Gardens near the centre of ly burnt out. The flaps and under­ His experience in Dove aircraft is adrift in aircraft. Cardiff, Wales. The pilot flew over carriage were retracted, and the screw driver handle found in the wreckage, and was 28 hours of which approximate­ considerable other evidence led the Accident In­ the exhibition at least three times starboard fuel cock was in the "off" ly four hours only had been in IT CAN HAPPEN AGAIN position. There was no evidence vestigation Board to believe that jamming of the at a very low altitude, the length command. He had failed to obtain elevator controls by the screw driver was the most The inference from these "isolated cases" is that that the starboard engine was run­ a Group 1 type rating endorsement this kind of thing can only happen once. There is of each run extended for some three ning under power at the time of probable cause. or four miles and its altitude dur­ as he was not competent to fl y the no such thing as an "isolated case". If it happened impact. aircraft under conditions of asym­ In the next case the consequences were not as once, it can happen again, and again. Perhaps the severe. The discovery of control difficulty was made ing the first two of these was esti­ metric flight. exact same circumstances may never be combined during a less critical manoeuvre, and skill of a pro­ mated to have varied between 200 It is probable that during the again, but you can bet your bottom buck the end and 1,000 feet. The engines were unfeathering action of the star­ fessional type brought home the aircraft as well as results will be the same. CAUSE the evidence. operating normaUy and there was board propeller the pilot omitted to What can you do to help eliminate this type of turn on the fuel. Consequently, the Immediately after becoming airborne, the pilot no outward sign of any malfuncti on­ It is considered that the cause of accident? engine did not develop power and of affl FJ-2 noted a definite stress in the aileron con­ the accident was loss of control by The following should help: ing of the aircraft. the aircraft lost airspeed due to an inexperienced pilot during an trols. ·The stiffness became progressively worse. drag from the windmilling propeller. attempt to restart an engine follow­ During the a·pproach to landing the pilot attempted • Remember first that an aircraft is most vulner­ On the final run towards the ex­ Under the prevailing conditions the ing asymmetric flight at a very to raise the left wing and encountered an abrupt able after maintenance and service checks. hibition the aircraft was seen ap­ performance of the aircraft, with a low altitude. stop in the stick movement to the right. The stick • Second, that trouble usually comes from where proaching from the south-east at a would move about one inch past centre and then you don't look. range of about It miles and at an stop. • Inspect thoroughly for tools, parts and other altitude of about 100 feet. The The pilot levelled the wings with the rudder and hardware which may be adrift. starboard propeller was then what aileron control he bad, then added power and • Vacuum out all residue and other foreign stationary and was later identified AIRCRAFT SERVICING climbed to 15,000 feet. He tested characteristics materials after maintenance. as being feathered. It passed over and decided a landing would be possible at 150 • Be as meticulous as a surgeon, use a check list­ the exhibition with the propeller Recently, when the cowling panels around a jet power plant were knots airspeed, with the use of the rudder and by inventory your tools, parts and other equipment feathered at an extremely low making gentle turns. Touchdown was made 1,000 after each job. altitude and, after continuing for opened for a routine power plant inspection - a n empty oil ca n feet down the runway after a constant power-on • Make sure the inventory is accurate. If a short­ about half a mi le, rotation of the dropped to the ground. Paint from the exterior of the can was found descent. age is noted this is reason for a thorough in­ starboard propeller indicated that on the fuel heater - close to the fuel control unit. An investigation was made immediately. The vestigation of the aircraft involved. Otherwise the pilot was attempting to restart left-hand wing leading edge was dropped revealing you may be setting the scene for a major the engi ne. A few seconds later the One of the basic rules of aircraft maintenance is to complete a a JJ in ch piece of aluminium tubing jammed be­ accident. aircraft yawed from side to side and tween the outboard fold aileron bell crank assembly climbed slightly to clear some high thorough "Final Inspection" for tools, loo.se objects or foreign articles • Learn to associate tools with the jobs on which and the nut on the second Phillips head screw, out­ they're used - if any are missing you are more trees. It then went into a steep before closing inspection panels and cowling. No ci rcumstances should board of the wing fold which secures the forward­ likely to locate them. right-hand climbing attitude from cause deviation from this rule. most stringer of the outboard section. which it dived almost verti ca lly to The report call ed this one an isolated case. (Extract for A viation M echanics Bulletin) the ground. ( Extract from A viation Mechanics Bulletin)

SEPTEMBER . 1960 11 10 AV I A TI ON SAFETY DIG ES T only a short distance to the left of propeller governor was set to obtain reaching mmunum altitude at or Convair Crashes during course. The c:aptain stated that he 2,220 r.p.m. and the right propeller near the middle marker six-tenths did not see chis lighted area but was at 31 degrees pitch. The left of a mile from the approach end of suddenly saw a steel tower through governor was set to obtain 2,310 the runway. Upon reaching the Instrument Approach a break in the clouds, attempted to r.p.m. and the left propeller was at middle marker or shortly thereafter, pull up, applied power, and ordered 30 degrees pitch. if the pilot does not have at least MIDWAY AIRPORT, CHICAGO, U.S.A. the landing gear up. All ground radio navigational ceiling and visibility minimums, and The first officer stated that he facilities utilised during the final the lights identifiable with the run­ (Summary based on the Report of the Civil Aeronautics Board, U.S.A.) observed ground lights as the air­ approach were checked by the way are not in sight, a missed ap­ craft passed intermittently in and Federal A via tion Agency and found proach procedure must be started. out of cloud bases and suddenly to be functioning normally. The evidence clearly indicates that (All Times U.S.A. Central Standard) During the approach the pilot re­ saw a red light on top of a trans­ The correct altimeter setting was this procedure was not followed. A Convair 240 aircraft engaged on a cargo flight crashed in ported to the tower that the mission tower. Previously he had given the flight before the approach The captain's inability to execute a .railroad _yard during an instrument approach to the Chicago localiser indicator in the aircraft called out "minimum altitude" to Midway and tho crew set their the first approach properly stems Midway Airport on 15th March, 1959. Neither pilot was injured was not functioning correctly. The when his altimeter read 1,000 feet altimeters accordingly. Investigation from his failure to study the ap­ although the aircraft and cargo were destroyed. controller then advised that the (400 feet above airport level) and also showed that the ground alti­ proach plate and his lack of know­ .A.t the ti'?~ of the accident the company's prescribed cargo localiser frequency for Runway 31 then concentrated his attention to meters from which the setting was ledge of the procedure, even the mmunum cedmg of 300 feet existed; visibility was one mile in was 109.5 mes. The captain chang­ looking for the runway. He stated given were indicating accurately. frequencies involved. As he had r:Un whi.ch was one-fourth mile more than cargo minimum. The ed from 109.9 mes. to the proper that he believes he started the gear­ Both of the aircraft's altimeters studied the approach plate between flight missed one approach to Runway 31, was again vectored frequency and the trouble was cor­ up as ordered. Almost simul­ functioned properly and were cross­ the first and second approach, it is into proper position and then started anofher. Descent continued rected. He explained later that he taneously the aircraft struck the checked during the flight from La apparent that he must have been below 300 feet until the aircraft struck the top of a 96 foot was using the wrong frequency be­ tower, was substantially damaged, Guardia including the landing in aware of the proper procedure dur­ steel tower, crashed and burned. cause at that time he thought he and nosed down sharply. Up rain at Detroit. ing the second approach. A descent Investigation disclosed no functional difficulty with the ground was making a "back course" ap­ elevator was applied and descent Investigation disclosed that the to a dangerously low altitude must aids, the aircraft or any of its components. Descent below the proach utilising the Runway 13 was lessened somewhat as the air­ reporting of the Midway weather to have been made early in the second ~mum approach al~tude, before the runway was definitely in l.L.S. He said that the controller craft plunged into a railroad yard. the flight was both accurate and approach. Several facts point to this stglht, stands as the basic reason for the accident. used the words "back course". This It skidded across tracks, coming to current. Thunderstorm conditions belief. The tower struck was only approach was discontinued at 600 rest close to a moving freight train prevailed in the general area and 96 feet high. It was located more INVESTIGATION a good reason not to." According­ feet above field elevation and the about 2,600 feet from the tower. lightning flashes could be seen in than a mile from the approach end The flight originated at La, ly, the flight departed Detroit for missed approach procedure was Both pilots got out through the the northwest and northeast quad~~ of the runway and it was 3,000 feet Guardia Airport, New York, for" Chicago with Cincinnati as the started. captain's window just ahead of a rants. Nevertheless, there was no· to the left of course. At impact the frontal passage at the time and aircraft was in the approach con­ Midway Airport, Chicago. The cap­ alternate. There is no evidence that The first officer flew the aircraft fast growing fire which consumed tain and first officer were the only the despatcher urged the captain to during a portion of the return to the aircraft and its cargo. place of the accident which could figuration with respect to propeller occupants. The aircraft's gross continue. Kedzie while the captain studied The steel tower is 96 feet higher have caused wind changes of suf­ governors and propeller blade pitch ficient magnitude to have significant angles, and wing flaps with landing weight was within limits as was the The flight proceeded to Chicago the Runway 31 I.LS. approach than the airport, 6,350 feet from the location of its centre-of-gravity. in continuous rain and was cleared plate. approach end of Runway 31, and effect upon the approach path. gear down and locked. It is evident The aircraft departed from La to Surf intersection 12 miles east of approximately 3,000 feet to the left The captain had not been flying that during the approach both the Guardia at 2145 hours and was The landing gear was extended regularly into Chicago. His last !.L:S. and A.D.F. pointers clearly Midway. The airport weather was and the aircraft was trimmed for a of the extended centreline of the cleared only to Detroit because of reported at that time as ceiling 500 runway. previous landing there had been md1cated that the aircraft was off rate of descent of 300 feet per course to the left. In fact, the I.LS. adverse weather conditions at feet, vis~bility one mile. Runway about three weeks before this acci­ Chicago. The flight to Detroit was minute. Both pilots stated that on Examination of. the wreckage dis­ dent and the preceding one had pointer must have been fully de­ 13, the mstrument landing system this second attempt, according to closed that both~. I.LS. receivers uneventful and after landing. fuel runway, was then in use. Shortly been six months earlier. He and the flected quite some time before im­ was added and the captain talked their altimeters, they were never were at the proper frequency. Little' first officer had flown together only pact. The captain was a well quali­ th.ereaft~r. ~ecause of a change in less than 400 feet above ground could be learned from the remains by telephone with the company's wmd duechon, the active runway once, some 16 months earlier. The fied instrument pilot and would level and never more than two dots of the A.D.F. receivers because of captain testified that he was normally easily detect these dis­ d·espatcher at Chicago concerning was change~ to 31 and the flight deflection from the centreline on the fire damage, although the captain crepancies, this can only mean that the expected Midway weather at was so advised. The I.LS. equip­ familiar with the Chicago area but I.LS. indicator. The captain testi­ had been using both of them, ap­ he was not referring to his instru­ arrival time. The despatcher, after ment for Runway 31 differs from had not studied the Chicago ap­ consulting with the company fied that there w1s turbulence dur­ parently satisfactorily. Nothing proach plate recently nor prior to ments during the final portion of that for Runway 13 in that Run­ ing this second approach and that whatever could be learned from the the approach. meteorologist, advised the captain way 31 does not have a glide path the Detroit-Midway leg of the flight. that the weather was not expected he was checking power and attitude remains of the altimeters nor their or approach lights and the fre- instruments as well as looking over static systems. The wing flaps were ANALYSIS to go below minimum, although 9uency of its localiser is 109.5 mes. PROBABLE CAUSE t~~ glareshield while making a de­ found at a setting of approximately thunderstorm activity was likely at mstead of 109.9 mes. According to the approved ap­ The Board determines that the Midway. In reference to this c1s10n to go around or continue. 20 degrees, and the landing gear proach procedure for an I.LS./ Upon reaching the Surf intersec­ Directly under and ahead of the air­ was down and locked. probable cause of the accident was weather information the captain tion, the tower controller vectored A.D.F. approach to Runway 31, the the pilot's descent below his allow­ testified, "At that point, I could craft approaching Runway 31 was a Examination of the engines and Kedzie fan marker should be cross­ the flight to the Kedzie fan marker large railroad yard with well-lighted propellers showed that they were able minimum altitude and his in­ see no reason to say 'No', so I went. 3.3 miles from the active runway'. ed at an altitude of 900 feet above attention to flight instruments while I didn't want to, but I couldn't find areas, and a heavily travelled and operating in an approach condition airport level, a gradual descent be­ and the final approach was started. at the time of impact. The right attempting to locate the runway brightly illuminated highway lay gun, and the descent continued until vistr1ally. 12 AVIATION SAFETY DIGEST SEPTEM BER . 1960 13 Elevator Controls Disconnected

ABILENE, TEXAS, U.S.A. (Excerpts from the Official Report of the Civil A eronautics Board, U .S.A.)

On the afternoon of 2nd September, 1959, a C46F crashed on runway 16 at 500 - 1,000 feet without an audible the elevator control tail section separated by a bulkhead containing Air Force Base, Abilene, Texas. The crash occurred while the pilots were power reduction. It then skipped assembly (see Fig. 1). The bolt 3! inch lightening holes. The bolt attempting to land the aircraft with the elevator controls inoperative. The about 1-2 feet above the surface and which normally connects the clevis did not have a washer, castellated captain and co-pilot, the only persons aboard, were killed and the aircraft was again contacted the runway on the and link assembly was missing. nut, or colter key on it and no such demolished. \ main gear only. This contact caus­ The effect of this disconnect con­ item which would fit the bolt was Examination of the longitudinal control system of the aircraft disclosed that ed the tail to rotate downward and dition would be the loss of all recovered. the alt end of the aft link assembly was disconnected from the clevis in the I the aircraft "porpoised", leaving longitudinal control except that ob­ Examination of the bolt showed elevator control horn assembly. the runway nose-high. It reached tained through use of the elevator it had been in recent use. The 4-6 feet, then descended slightly trim tab system and that which shank surface was moderately From irrefutable physical evidence the Board concluded that the bolt which nose-down and again contacted the could be obtained by manipulation bright and there was no evidence of normally secures the link assembly-clevis attachment was not in place at impact. runway, this time with greater force of engine power. Under this condi­ rust, corrosion, or grease film on the It concluded that the bolt worked out following departure from Dyess resulting on the main gear. The force ampli­ tion the autopilot could not be used bolt. The peaks of the threads re­ in the loss of control which caused the accident. The Board further concluded fied the downward tail rotation for pitch control; however both the vealed minor wear and polishing. that the bolt worked out because it was improperly secured, a condition which causing a second, more severe manual control system and the A small amount of loose residue should have been detected during a No. 2 maintenance inspection completed just "porpoise". At this time power, autopilot system could be used nor­ was found in the cotter key hole. prior to the origination of the flight. The inspection was performed by a certi­ estimated by several observing mally to furnish lateral and direc­ This residue appeared to be the ficated repair station which performed under contract the maintenance work for pilots as full power, was applied. tional control. same as residue which was accumu­ the operator. The aircraft climbed in a steep During a search of the tail area, lated in the bottom of the fuselage nose-up attitude to 150-200 feet a bolt of the same size and speci­ in the area below the link assembly­ above the runway. There it stalled, fication, AN5-12, as the missing clevis attachment. Relatively, the pitched down violently and crashed bolt was found. It was found lodged shelf where the bolt was found was INVESTIGATION the GCA frequency and advised better control using power and on the runway in a nose-down on the right side of a shelf of a brac­ clean. him to switch to that facility. The trim." The flight then proceeded At 1611 the flight departed Dyess angle in excess of 45 degrees. ket in the tail compartment. The At the request of the Board, the controller advised local traffic of several miles north of the Base. The fuselage forward of the lead­ shelf where the bolt was found is recovered bolt, clevis, and link for Carswell. At 1631 the flight con­ the emergency and gave the flight The flight manoeuvered with GCA ing edge of the wing was demolish­ located aft of and above the link assembly were examined by the tacted the Abilene, Texas, Muni­ complete latitude of action. cipal Tower. The pilot stated be assistance for a long (about nine ed by impact. This section was torn assembly and clevis attachment and National Bureau of Standards. was about 30 miles east of Abilene, Radio communication was estab­ miles) final approach. Alignment off anc'i moved 425 feet ahead of the declaring an emergency, and re­ lished between the flight and the was very good and when the glide remaining aircraft structure when turning to Dyess. He reported that GCA and, about 1645, GCA had path was intercepted, the GCA con­ the cargo broke loose and shifted he bad lost elevator control and positive radar contact. troller gave, as the pilot had re­ 1 forward with great force. Relative­ was on autopilot. The Abilene con­ The pilot requested a straight-in quested, glide path information. The ly, the remaining fuselage and troller passed this information to approach to runway 16, which is position of the aircraft on the glide J empennage was .undamaged. The the Dyess Tower and requested the 13,500 feet in length. path was good. The closest observer left wing was slieared off at the flight to contact Dyess. Dyess noted that pitch control was better attachments to the fuselage and the GCA assisted with alignment, promptly alerted the Base emer­ but still jerky and over-controlled. right wing remained attached only gency facilities. elevation, and distance information A C-46 pilot suggested, through by control cables. Both engines he asked for. To observers the ap­ GCA. that the pilot roll in forward were torn from the mounts. A fire About 1638 the flight contacted proach seemed good although the trim as soon as touchdown occurred. occurred but was extinguished in Dyess Tower. The pilot reported closest observer. a qualified multi­ T he captain responded, "Roger, seconds by the efficient and well­ the flight was on emergency because engine pilot. noted that control of we've already got that figured out". equipped Dyess rescue and fire­ of the loss of elevator control and the aircraft in the pitch plane was fighting team. would attempt to land at Dyess. He jerky and slightly over-controlled. A Touchdown occurred at 1715. It Because the pilot had indicated then requested ground - control­ short distance from the runway was a "wheel landing" with the an elevator control failure, investi­ led approach (GCA) assistance. threshold and about 50 feet above aircraft speed greater than normal gation was immediately directed to (Weather was no factor in this re­ the ground the approach was dis­ and with considerable power. The the longitudinal control system of quest. GCA assistance would help continued. At that time the pilot wing flaps appeared to be extended the aircraft. Upon removal of the the pilot in his visual judgment of transmitted, "I'm going out north · between 10 and 20 degrees. The yoke assembly access panel, it was alignment, distance, and elevation a couple miles, I'm going to try to touchdown was considered excellent immediately noted that the aft or during the approach). The tower land this thing on elevator tab in­ by all observers. The aircraft rolled bearing end of the link assembly controller advised local traffic of stead of autopilot. I get a little on the main wheels for the next was not connected to the clevis in

14 AVIATION SAFETY DIGEST SEPTEMBER. 1960 15 From the examination it was not tests to failure were made on the forces could not have sheared the possible to identify the bolt with attachment assembly. The tests bolt but would have badly damaged DESIGN FOR SAFETY the specific link assembly and were performed by the National the components. It is on this ir­ clevis from N5140B. It was pos­ Bureau of Standards at the request refutable physical evidence that the sible, however, to determine from of the Civil Aeronautics Board. Board concluded the AN5-12 bolt FUSIBLE WHEEL PLUGS REDUCE THREAT marks on the bolt that it had been which normally secures the link OF BLOWOUTS AND WHEEL FAILURES installed in an assembly with the The stress analysis data showed assembly-clevis attachment was not in place when the aircraft crashed. same dimensions as the clevis forks that the strength of the AN5-12 by and bearing bore of the link bolt was greater than the strength assembly (see Fig. 2). of several other components which In addition to the above it was VERNON A. TAYLOR the Board's opinion that the re­ comprise the link assembly-clevis Flight Safety Foundation It is worthy of note that the attachment; this therefore showed covered bolt is not evidence that a AN5-12 bolt is not specified for other components in the assembly bolt of the required specification any other attachment or assembly would fail first. As stated, all com­ for the attachment, one of recent Fusible wheel plugs, designed to deflate the tyres through several tyre plies and failure due to re­ in the empennage section of the ponents of the attachment recover­ use, and one with markings match­ on the big birds before a heat induced explosion duced tyre strength may follow. Tyre side walls C-46. ed from N5140B were undamaged. ing the bearing bore and clevis can occur, are making airports safer for ground may also become over heated to the point of blow­ fords, was left in the tail during personnel. Installed in all tubeless tyre and wheel out simply because of excessive taxiing at full gross In an effort to satisfy the con­ previous maintenance. On the con­ assemblies on the heavy turbine transports they have weight. Fusible or thermal relief plugs however, trary, it was the Board's opinion tention that it was possible for the ANALYSIS AND significantly reduced the hazards of blow-outs and will undoubtedly prevent a great majority of blow­ that this is evidence that the bolt bolt that had connected the bear­ CONCLUSIONS wheel failures. out incidents that would otherwise be experienced. ing end of the link assembly to the was the one holding the attachment clevis to have been properly in Examination of the longitudinal together immediately prior to the The high landing speeds, reduced tyre size and place at impact, and that impact control system of N5140B revealed accident. Considering the inflight new gross weights of the modern transports have forces could have sheared the bolt the link assembly was disconnected jostling, the forward forces when increased brake energy requirements to a fantastic CESSNA BRAKES and that the pieces could have from the clevis and all of the com­ the aircraft struck the runway, and degree. Any expended brake energy spells heat, fallen free and could have been ponents which comprise the link the aft forces when the tail toppled and the problem of dissipating this heat is com­ When brakes were applied on the landing run to the runway, it is entirely pos­ lost. the longitudinal control assembly-clevis attachment were pounded on the jets by the lack of cooling air from in a Cessna 172 the starboard brake remained system was re-examined in its undamaged. Stress analysis data and sible for the bolt to have reached a propeller. With a lot of heat and a built-in heat locked in the " on" position. Subsequent investiga­ entirety. In addition, the stress tests by the National Bureau of the location where it was found. transfer from brake-to-wheel-to-tyre, the result was analysis data on the pertinent parts Standards conclusively proved that dangerously high tyre pressures. tion into the defect established that it was caused of the link assembly-clevis attach­ bad an AN5-12 bolt been in place In view of the aforestated analysis by the cross arm of the parking brake unit partially ment were carefully reviewed and in the attachment, high impacn and conclusions, it was the judg­ The threat of a blow-out or wheel failure coupled turning over, due to incorrect rigging of the link­ ment of the Board that the bolt with the possibility of a brake fire made a rough age of the parking brake mechanism. worked out of the attachment, caus~ situation. After extreme braking, as in the case of ing the loss of elevator control. It an abor~ec:l take-off or an exceptionally fast land­ The spring linkage mechanism had been m is­ follows that the bolt could have ing, mechanics were warned to stay clear of the aligned to the extent that it had pushed the cross worked out only because it was im­ aircraft for at least thirty minutes. And when there properly secured, a condition whicll was a fire the firefighters were cautioned to ap­ arm toward the firewall, causing the cross arm to had to exist and should have been proach the wheel only from the front or back, turn over, and the loop in the centre of the cross discovered when the No. 2 mainten­ never from the side where they could be struck by arm to ride over the top of the looped clip on the ance inspection was made less than the fragments of a·~ exploding wheel. end of the spring linkage. This misalignment had two flying hours before the accident. In the opinion of the Board it also the same effect as applying the parking mechanism Fusible or thermal relief wheel plugs have chang­ and resulted in tilting the cross arm, lifting the followed that, had the inspection of ed all this. Designed to melt at a pre-determined the attachment been performed by temperature they release the air pressure in the starboard lockplate to the parked position. the inspector, the insecurity of the tyre before an explosion can occur. Plugs vary For satisfactory operation of the brake parking bolt would have been detected. from a rivet or screw of fusible alloy to hollow bolts filled with a eutectic metal. One such metal is system it is essential that an angle of 90° be· composed of 91% zinc and will melt between maintained between the vertical and horizontal 390 - 400°F. This is just below the critical tempera­ arms of the spring linkage, in order to preserve­ PROBABLE CAUSE ture for nylon tyres and well below the critical an equal lif t on each of the lock plates. The Board determined that the temperature for wheel assemblies. Three or four plugs are spaced around the wheel so there will probable cause of this accident was Though this occurred on a Cessna 172, the always be one near the top where the wheel is the loss of elevator control because ofl hottest when at rest. same defect could occur on other Cessna models, an impro11erly secured bolt, a con­ as the parking mechanism is similar. It is impor­ dition which was undetected be­ Thermal relief plugs will not eliminate tyre ex­ tant that the manufacturer's instructions for rigging Fig. 2 cause of an inadequate inspection. plosions under all conditions. A skid may wear of the brake mechanism are strictly adhered to.

16 AVIATION SAFETY D IGEST SEPTEMBER. 1960 17 lower altitudes, but following a between San Antonio A.R.T.C. and the third pilot, with assistance, DC 3 Captain's Judgment Astray fu rther request from the flight an the flight at 2257 hours. The pilot quickly got out and clear of the air­ A.R.T.C. clearance to the minimum advised that he was at 3,600 feet, craft as fire broke out. KERRVILLE, TEXAS, U.S.A. route altitude was granted. unable to pick up the Kerrville beacon, and was "awfully low on The co-pilot was not on pilot (Summary based on the Report of the Civil Aeronautics Board, U.S.A.) The flight reported over Big gas". duty during the Pueblo-Kerrville Spring at 211 5 hours at 5,100 feet. flight. Shortly after take:off he went At that time and again at 2138 In an effort to maintain con­ to sleep in the cabin. He was the (A ll Times Central Standard) hours, the flight was asked if a tinuous contact, San Antonio Centre only pilot to survive and his testi­ higher altitude was required. It utilised a U.S.A.F. aircraft in flight mony is most enlightening. Por­ A DC.3 cra shed shortly before midnight near Kerrville, Texas, on 1st Feb­ advised being in severe icing and as a relay station. This aircraft re­ tions of it are here quoted: ruary, 1959. Three of the 28 occupants including the captain a nd reserve using climb power to maintain ported at ·z313 hours that the flight captain were killed, four were seriously injured and the remainder received altitude. In answer to a request, was over Kerrville attempting an "I did not awaken until I heard minor inj uries. the San Angelo and Junction approach, and that the pilot had the sound of the engines revving weather was transmitted to the reported intermittent stalling. At which was approximately forty-five flight. Both were above minima 2325 hours it was reported that the minutes before the accident. This For the flight from Boise to telephone from the U.S. Weather THE FLIGHT with light freezing drizzle. A.R.T.C. flight had missed the first approach was my first indication that we had Pueblo to Lackland Air Force Bureau Station for the Pueblo - The aircraft was engaged on a records indicate that the flight re­ to Kerrville and would make a any unusual problems. The captain civil air movement of 25 military Base the load consisted of twenty­ Lackland portion of the flight. This second attempt. Six minutes later explained that we had been picking unrecorded briefing, according to ported over San Angelo at 2158 personnel from Boise, Idaho, to five members of the Idaho National the aircraft was observed commenc­ up ice for about an hour previous testimony of the Weather Bureau, hours at an altitude of 5,000 feet Lackland Air Force Base, San Guard, 597 pounds of baggage, and ing an approach and the Kerrville to that. The revving of the engines the three-pilot crew. The flight plan was comprehensive in regard to the experiencing severe icing. The pilot Antonio, Texas. The final segment reported that he did not believe he 2245 hours weather observation at this time was for the purpose of of the flight was from Pueblo, filed with the F.A.A. combined probability of widespread icing con­ was relayed to it. At 2339 hours flicking ice off the propellers. When ditions. The pilot, who did not could make San Antonio owing to Colorado, where the Weather station-tower facility provided for the relay aircraft reported being we first went forward we were hold­ identify himself, displayed consider­ shortage of fuel. Bureau station furnished weather­ the use of Victor Airway 4 at 9,000 unable to maintain radio contact. ing an approximate airspeed of 120 briefing which indicated icing con­ feet, l.F.R., to Malad City, Idaho, able interest in the expected weather At 2215 hours, San Antonio At 2347 hours, a person living knots with cruise power 29 inches ditions that were likely to continue. with the intention of refiling at and questioned the observer exten­ A.R.T.C. requested the operator to near the Kerrville Airport called and 2,050 r.p.m. An I.F.R. flight plan specifying Malad City without landing and in­ sively. An l.F.R. flight plan was have its agent at Kerrville, Texas, the San Antonio Tower and report­ cruising at 9,000 feet was filed. dicated sufficient fuel for six hours then filed by telephone with the proceed to that airport and put "In a few short minutes the air­ ed that at approximately 2337 hours and 30 minutes. The estimated time F.A.A. combined station - tower runway lights and radio beacon in speed slipped from 120 knots to Departure from Pueblo was made an aircraft passed over his house en route to Pueblo was given as five facility. operation in the event the aircraft 115, to 110 and finally 100 at at 1800 hours and at 1916 hours hours and 30 minutes, with Salt and that he then heard an ex­ which time as nearly as I can re­ The aircraft was cleared for landed there. the flight requested an altitude Lake City as an alternate airport. plosion. call the pilot added power to 35 change from 9,000 feet to 7,000 feet, take-off and was off at 1800 hours. Investigation of the actual amount At 2219 hours, the flight advised The crash site was located at an inches and 2,250 r.p.m. which reporting light icing. Approval was Eight minutes later it reported to San Angelo of ice 1{- inches thick brought the airspeed up to around granted at 1945 hours and shortly of fuel on board revealed an error Pueblo as at 9,000 feet. elevation of 1,535 feet m.s.I. in of 624 pounds in fuel weight and on the .aircraft's landing lights and moderately hilly, wooded terrain 11 5 to 120 knots. The icer boots thereafter, the flight again reported at 2220 hours requested 4,000 feet were engaged and ice on the lead­ light icing. An involved series of as a consequence the aircraft being At 1916 hours, the flight reported 6.8 statute miles bearing 123 degrees approximately 517 pounds over its over Dalhart at 9,000 feet and the being unable to maintain 5,000 T from the Kerrville Airport and ing edge of the wings came off radio contacts ensued as the ice feet. At 2229 hours it advised being which further increased the air­ accretion became worse, then permissible take-off weight when pilot requested a change in altitude 4.4 statute miles bearing 11 8 degrees departing Boise. Again after re­ to 7,000 feet as he was encounter­ at 4,000 feet and descending. At T from the Kerrville radio beacon. speed. By the time we were a few critical, then incapacitating. A 223 1 hours the pilot reported hav­ minutes short of Kerrville airport !Jrivately used airport at Kerrville, fuelling at Pueblo, Colorado, the ing light icing. A change in altitud e It is in the approximate area where aircraft had a total of 622 gallons was not approved at this time. At ing regained 4,000.!feet and Junction a procedure turn from an outbound the pilot had tuned in the homer Texas, was staffed and lighted but radi o relayed the ·Kerrville Airport at Kerrville and found we were re­ after an attempt to land there had and not 380 gallons as shown on 1945 hours over Amarillo, a further heading to an inbound heading the weight and balance form. Thus, request for a change in altitude information. would normally be made fo r a pre­ ceiving it properly and at this point failed, the aircraft was crash-land ed made the decision to attempt to nearby. the apparent discrepancy of 242 was approved by A.R.T.C. At 2022 scribed DF approach to Kerrville gallons amounting to 1,552 pounds, hours the flight called Lubbock At 2243 hours the pilot advised Airport. land at Kerrville rather than con­ made the gross weight at take-off Radio and reported encountering Junction that he was at 3,600 feet tinue on to San Antonio since the and at this time Kerrville weather At impact the cockpit was de­ fuel supply was getting real critical INVESTIGATION from Pueblo 26,322 pounds rather light icing at 7,000 feet. Weather than the 24,870 pounds shown in and terminal forecasts for Wichita as ceiling 700 feet, visibility one molished by contact with trees. The by this time. At this point we The crew of the aircraft consist­ the weight and balance fo rm. The Falls, Texas, and Oklahoma City, mile was relayed to the aircraft. captain and reserve captain, and were flying at 4,000 feet presum­ ed of a captain, a reserve captain maximum allowable take-off weight Oklahoma, were requested. The in­ one passenger received multiple ably to have been cleared to that and a co-pilot. After a rest period At 2249 hours, Junction heard from Pueblo (elevation 4,725 ft.) formation transmitted to the flight severe injuries, which in all prob­ altitude; we were allowed some of approximately twelve hours they the pilot report that the aircraft was 24,950 pounds. The aircraft, indicated above minimum condi­ ability were instantly fatal. The few feet less than 4,000 feet in that commenced duty in the early morn­ was stalling and that he had "less third pilot, in the cabin, was serious­ section which would put us approxi­ therefore, was overweight upon de· tions at several locations. than 100" .* ing of 31st January and were on parture from the latter airport by ly injured and momentarily pinned mately 2,000 feet above the terrain. continuous duty for more than <:10 A change to the minimum en a computed 1,372 pounds. Communication was established in the wreckage until extricated by We went to the homer at that hours until the time of the accident route altitude (5,100 feet) was re­ one of the passengers. The twenty­ altitude and then took an outbound at approximately 2337 hours on 1st Either the captain or reserve cap· quested at 2031 hours. The flight four surviving passengers were in­ heading for a normal descent and February. tain obtained a weather briefing by was advised of icing conditions at *Airspeed in knots. jured in varying degrees. They and approach; completed the procedure

AVI AT I ON SA FETY DIGEST 18 SEPTEM BER. 1 960 19 turn, returned to the homer and statement and point to the aircraft piloting, 9,000 of it in DC.3's. This, from there to the airport descend­ being about halfway through a combined with the weather brief­ ing continuously. I don't believe turn from downwind to approach ings he obtained, should have alert­ anyone in the cockpit saw the air­ and descending. ed him to the fact that by decreas­ port though we must have been ing altitude as he did he would be close. Ice was covering the front There was about a 40-minute staying in clouds, with below windshield entirely and the only lapse between crash and arrival of freezing temperatures and severe visibility was from the side window fire apparatus. As a consequence a icing conditions. The changing of which the pilot was able to open great deal of the physical evidence altitude from 9,000 feet to 7,000 and could look out from; although was destroyed by fire, as were all feet early in the flight because of unable to see the airport, we had records being carried. It was not at this time contact conditions and possible, for example, to determine icing appears to have been the start could see the ground. I remember the position of the wing flaps, nor of his trouble. He could safely have passing over a highway and car was it possible to determine why gone elsewhere; landing in the pan­ lights being visible below. Fuel sup­ the windshield de-icers were nof handle section of Texas or a diver­ ply by this time was so low that the effective. Wing de-icers apparently sion to the east would have been gauges could hardly be regarded as were functioning and testimony of reliable. the carrier's maintenance personnel an understandable and safe course indicates that they should have of action. "The pilot decided to make a been in good condition. The land­ second attempt at an approach but ing gear was up. Certainly there was nothing lack­ rather than follow recommended ing in ground help; personnel of . -_· j approach altitude maintained his Air Route Traffic Control went to contact Vl'ith the ground rather than the greatest possib!e lengths in help­ climb bllck into the overcast. ing and in getting others to help. Somewhe1e during the second ap­ ANALYSIS NOT TOO OLD TO BITE proach au.empt the pilot made his Three pilots had exceeded the decision to bring the plane in for regulatory limit of flight duty upon When landing at an aerodrome in Northern growth which surrounds it. Nevertheless, other a wheels up belly landing rather arrival at Boise. Even at that time CONCLU&ION Queensland, in the course of a regular public than an inspection of the undercarriage, there was than risk the possibility of the fuel a degree of pilot fatigue must have transport flight, a DC.3 skidded from the end of no inspection made for damage and it was not until running out during blind condi­ set in. Pilot fatigue, which may This accident was a considerable the strip and struck a boundary fence when turning the aircraft had flown to the next stopping point, tions in the overcast, the re-entry engender a decrease in competence length of time in the making and at the end of the landing run. where the captain requested a further inspection of which would be necessary if we and diligence, could have been a was fully preventable. The facts The strip, which has a grass surface, is 4,850 of the undercarriage, that the mechanics discovered were to go throug!l a normal ap­ factor in an overweight take-off a hole measuring 12 inches by 6 inches in the tail show that operational supervision fee t long with a downgrade of I : 323 in the direc­ proach procedure. When he had from Boise. cone and damage to the trailing edge and several made that decision, I went to the demanding compliance with regu­ tion which was used. As the result of continual rain over a period of three months up to and in­ ri bs in the port elevator which necessitated its rear to warn the passengers to keep The time on the ground at lations was completely lacking replacement. their seat belts tightly fastened and· cluding the day of the accident, the surface was Pueblo was relatively short and it and that the captain demonstrated slippery although firm Since this particular airfield's surface is known at the first sign of any emergency may reasonably be expected that disregard for the Civil Air Regula­ to be slippery when wet, the captain should· have to put their heads in their laps. I re­ an increased level of pilot fatigue There was a low overcast with light continuous tions. The flight went to and be­ rain, the visibility was 2 to 3 miles and the wind ensured that the aircraft touched down within 900 turned forward and the pilot was prevailed upon departing Pueblo. feet of the threshold which is a close approximation was light and variable. still searching for a spot to set The reason for the overload upon yond its point of safe diversion de­ of the distance to the touchdown point from a down. About this point one of the departing Pueblo may have been spite exemplary efforts by F.A.A. The all-up-weight of the aircraft was 4,400 lb. height of 50 feet over the threshold in the conditions engines sputtered and was out of an anticipation of added and un­ personnel to help. This captain less than the maximum permissible for the landing. prevailing. Had the height over the threshold been fuel. A few seconds later we were forseeable flight time because of the pressed on to complete a mission Following a low level circuit and a full flap ap­ reduced to 25 feet, as would have suited the con­ making our forced landing. I had questionable weather ahead or an proach, the aircraft to uched down on the main long after good judgment called for ditions, the aircraft should have touched d·own taken a seat on the floor facing the indifference to regulations. wheels at a point 1,790 feet beyond the threshold. within an approximate distance of 600 feet. rear just behind the bulkhead at discontinuing the flight. Moderate braking was promptly applied and the the rear of the pilot." By executing the approach in such a manner that Economics could have been a fac­ tail wheel lowered after a ground run of 1,260 feet. the ai rcraft touched down 1,790 feet from the thres­ tor in departing Pueblo in the face When nearing the end of the strip, braking proved hold, the pilot erred in his judgment of the action It was subsequently found that of a critical weather picture rather ineffective on the slippery surface so power was required in the circumstances and as a result was at the time of first contact with than remaining overnight. Laying PROBABLE CAUSE used to turn the aircraft whereupon it skidded side­ deprived of the use of some 1,000 feet of strip. A the ground the aircraft was heading over would have obligated the car­ The Board determined that the ways beyond the end of the strip and, unknown to more carefu l assessment of the conditions obtaining about 75 degrees true; left wing rier to furnish lodging and two ad­ probable cause of this accident was the crew, the tail cone and the port elevator struck was warranted and had it been carried out there Jow by about 10 degrees and de­ ditional meals to 25 persons. the boundary fence. is little doubt that the aircraft could have been the captain's poor judgment in con­ scending at approximately a 10- Although the captain was not aware that the tail safely brought to rest in the distance available, degree angle. These figures are The captain was highly ex- tinuing into known and dangerous of the aircraft had struck the fence, he was aware despite the fact that the surface was slippery and readily reconciled with the co-pilot's perienced with 15,0QO hours of icing conditions. that it had swung through the tall dense under- the landing was down the slope of the strip.

2·0 AVIATION S AFETY DIGEST SEPTEMBER. 1960 2 t exists regarding the serviceability of a vital service. pilot has failed to appreciate the significance of an PILOT'S DILE MMA D £ . . Until this has been done, the pilot cannot be sure intermittent and/or apparently minor malfunction­ - eiect 0 iagnos1s that a recurrence, or even more serious troubles, ing. will not develop under circumstances that jeopardise the safety of the aircraft. Although aircraft accidents Sometimes a ferry flight has been undertaken with On take-off from an airfield remote from technical flight then proceeded and was completed without emanating from mechanical causes rarely occur an undiagnosed defect. Such a flight under these facilities an engine of a transport aircraft oversped further incident. without some prior warning, reports from aviation circumstances has not reduced the chances of an beyond the maximum permissible r.p.m. T he pilot authorities throughout the world show that this accident, but has merely limited the exposure to the immediately abandoned the take-off. After com· The propeller governor unit was changed, but type of accident frequently happens because the crew. pleting a ground run, during which the r.p.m. did could not be faulted on test. Other ground and not rise beyond the normal take-off figure, a second air tests at that time failed to establish a reason take-off was a ttempted. Again the r.p.m. rose be­ for the above normal r.p.m. experienced. Two days yond the permitted maximum, and again take-off later sluggish pitch control was reported and an Maintenance Hazard - was abandoned. electrical component changed. T his may have had some bearing upon the circumstances first describ­ , As maintenance personnel were not available, and ed, but a precise reason for the malfunctioning ex­ Inadvertent Gea r Retra ct io n • a visual examination of the engine and control perienced on either occasion was not established. linkages did not reveal any abnormalities, the pilot " Disciplinary a ction has been taken ••. and doing a cockpit check to make certain the The circumstances surrounding these two in­ carried out further ground running tests but was those in charge • . . ordered to ensure . . . all selector was in the down position. We have unable to establish the reason for the malfunction­ cidents are published for the purpose of introducing no report on the supervisor's whereabouts all the problem that faces transport pilots where there superviso.ry personnel exercise m 01·e personal ing. Operation during a third take-off was norma l, this time. and the flight continued. However, as the flight pro­ are indications of unserviceability at airfields remote control ova· proceedin gs . . . " from maintenance facilities. These two incidents gressed, high oil temperature and· low oil pressure This is a quote from a ground accident report (iii) In the third case the crew left an aircraft on became evident on this same engine. The propeller have been chosen because they illustrate two dif­ jacks while they went for lunch. While they was feathered and the flight terminated at a suitable ferent approaches to a similar situation. It is not concerning an inadvertent undercarriage retraction that cost $6,000 and 60 man-hours of work. were away someone lowered the nose jack and aerodrome. intended to discuss rights or wrongs, or attempt to took the jacking pad. The crew returned and deal with the many aspects that the pilot-in-com­ This is what had happened. A mechanic was de­ wi thout checking they pressurized the system. Examination of the engine revealed failure of mand must consider under these circumstances. The sole purpose of this article is to invite attention tailed to jack the aircraft for a retraction test. Wing The nose wheel folded. They had not noticed No. 1 piston and cylinder barrel, due to detonation. jacks were used to lift the main wheels clear of the that the nose jacking pad had been removed It is believed a faulty magneto which had been re­ to the nature of the unserviceability experienced, fl oor, but contrary to established procedures the and the jack lowered. And the supervisor moved the previous day was the source of this how it was caused, and the possible effects of con­ nose wheel was not jacked. When an "up" selection had not noticed that the crew was shortcutting trouble. It was also concluded that the overspeed­ tinued operation. By doing so, we hope that safety ing experienced· during the attempted take-offs was considerations will be carefully weighed against the was made the nose wheel retracted - proving the procedures. (l ncidentally, the "thief" should due to metal particles in the oil system causing the other factors which influence a pilot in hi s decision adage, "There is never enough time to do it right; have been strung up three times, once for propeller governor to stick in one position, thus pre­ whether to continue with a flight or not where there but always enough time to do it over". tampering with another crew's work, and again are indications of mechanical malfuncti oning. for not leaving some obvious, unmistakable in­ venting the governor from maintaining constant H ow many accident reports like that have you dication that the work had been tampered with, r.p.m. seen? Accidents of this type have been amazingly A lthough overspeeding of a propeller may occur and finally for impersonating a mechanic.) during the early take-off stage on almost any con­ commo n: They can be attributed chiefly to lack of stant speed propeller it is a condition which cannot supervision, shortcuts and carelessness. And be­ This is the pattern. It reveals mechanics who In another incident involving a transport air­ be mistaken by an experienced pilot and therefore ca use they follow a pattern they should not be take short cuts and who either do not know or will­ craft, the pilot experienced propeller malfunction­ not likely to be confused with the conditions as­ ing, again at an airport where technical assistance hard to stop. fully disobey established procedures. And they also sociated with some mechanical defect. In the case reveal supervisors who do not supervise. was not available. On take-off the r.p.m. was in where metal was present in the engine lubrication Most inadvertent gear retractions correspond excess of the normal figure and did not reduce on system, the contaminated oil could have resulted in closely to one o~ another of these three typical T he answer seems relatively simple: operation of manual propeller control. Take-off the governor pilot valve sticking in a manner that cases. (a) Supervisors to spend more time "on the floor" was immediately abandoned. Because of the re· neither feathering nor full power would be possible; latively short time the r.p.m. was above the pre­ as it was, the engine failed, and an unscheduled (i) An aircraft was given a retraction test and then so the mechanics may have the benefit of the scribed take-off maximum, the pilot was uncertain landing was necessary. parked on the flight line with the undercarriage supervisor's experience and example. whether there had been a genuine overspeed con­ selector in the up position. When the engine (b) Better instruction. A refresher for supervisors dition, or if it was a momentary surge frequently was started the nose wheel retracted. Anyone Operational experience has shown there is a might help, with emphasis on the fact that experienced on take-off. The field length had pre­ of three people- the mechanic who made the definite relationship between malfunctioning of con­ " paper work" is not the supervisor's main job, vented him from continuing with the take-off for stant speed propellers and contamination of the retraction test, the supervisor, or the man in sufficient time to establish whether the r.p.m. would but only the report of how his job is being engine lubrication system. · This symptom is ap­ the cockpit when the engine was started-could stabilise at normal. After carrying out various preciated by experienced aircraft engineers, and has cond ucted. ground checks, he contacted his base by telephone, have prevented this accident. frequently led to detection of engine failure in its Obviously some mechanics can use instruction discussed the symptoms experienced , and obtained (ii) After a retraction test an aircraft was taken early stages before serious secondary damage occur­ too. It is particularly important that they learn approval to carry out a test flight without pas­ red. Proper inspection by qualified persons, is essen­ off the jacks before the landing gear locking the economics of shortcuts and of the avoidance of s engers. tial when mechanical malfunctioning occurs. pins were installed. When the hydraulic system time consuming procedures. You have to save an was pressurized the gear collapsed. T he men On this flight the r.p.m. stabilised at a figure in awful lot of minutes to pay fo r a six thousand Jn all cases where a defect remains undiagnosed who lowered the aircraft did not follow estab­ excess of the take-off setting, but was fully con­ and uncorrected, a serious hazard may exist and lished· procedures. The men who pressurized dollar accident. trollable by manual means. All other engine and advice should always be sought from properly propeller functions were normal. The scheduled trained and qualified persons whenever a doubt the system could have averted the accident by (Extract for Aviation Mechanics Bulletin)

S E PT E M BER . 1960 23 22 AVIATIO N S A F ETY DIGES T • the vicinity of Hurn was on or mately 2,000 feet and not 12,000 by a failure on the part of both the Error Ill Reading Al ti meter near the surface. feet as reported and that con­ captain and first officer to establish sequently some 10,000 feet was lost the altitude of the aircraft before The final descent was commenc­ prior to 1135 hours without either and during the final descent. leads to Britannia Accident ed some time after 1155 hours with pilot appreciating it. It might be' the inboard engines at "flight idle" of some significance in this respect The height presentatipn afforded power and at an airspeed of about that when the climb to 18,000 feet by the type of three-pointer alti­ CHRISTCHURCH, HANTS, U.K. 180 knots with the dump chutes in was concluded the subsequent air meter fitted to the subject aircraft the extended position. Under these tests were not of a kind which re­ was such that a higher degree of (Summary based on the report of the Ministry of A viation, U.K.) conditions the associated rate of quired the crew to focus attention attention was required to interpret descent would be about 750 feet on the altimeters. it accurately than is desirable in so per minute. It has been established vital an instrument. This, when (All times G.M.T.) that the aircraft struck the ground CAUSE taken in conjunction with the at approximately 1158 hours. It The accident was the result of nature of the flight on which the On 24th December, 1958, a Britannia engaged in a test would seem therefore that at 1153 the aircraft being flown into ground aircraft was engaged was a con­ flight was cleared to descend from 12,000 to 3,000 feet. hours the aircraft was at approxi- obscured by fog. This was caused tributory factor. About three minutes after commencement of the descent, the ai.rcraft struck the ground which was obscured by fog. The captain and eight occupants were killed, while the first officer and two engineer officers suffered serious injuries. .- -~ . I

THE FLIGHT to 3,000 feet. We're VMC on top An inspection of the wreckage fllie at 13,000 feet just above a cloud established that the flaps and under­ The aircraft took off from Lon­ layer, we will come over Hurn and carriage were retracted and that the don Airport into a cloudless sky ' have clearance from there." A fuel dump chutes were in the ex­ VITAL LINK .I ! at 1010 hours for a test flight in . ... •. _ J course was steered towards Hurn tended position. The engines were i....---···- -...• • ' . connection with the renewal of the for about 18 minutes and during running under power at the time of Certificate of Airworthiness. The Seeking to establish the - cause of looseness in his disconnected, due to a clevis pin falling out. The pin this flight the fi rst officer believed impact. A number of flight test captain was at the controls in the was found lying in the engine cowling with no sign they were 3,000 feet above a cloud forms, completed during the flight, engine throttle controls prior to flight, the owner/ left-hand seat and the first officer layer. At 1153 hours, the first were recovered and they provided pilot of a private ultra-light aircraft disconnected of it having been properly secured. in the right-hand seat where he various joints in the throttle linkage. This involved officer reported over Hurn at 12,000 details of temperature and altitude operated the R./T. and was re­ The obvious reason for this accident was that the feet VMC on top and requested logged during the aircraft's climb. the removal of a number of clevis pins. Eventually, sponsible for the navigation. he ascertained the cause of the apparent looseness, so owner/pilot overlooked securing of the split pins at descent clearance to 3,000 feet. As Subsequent examination of the proceeded to reassemble the control linkage. As each the time of completing the adjustments prior to fli ght The aircraft was climbed towards there was no IMC traffic in the area, wreckage failed to reveal any pre­ clevis' pin was installed, he loosely inserted a retain­ Although he firmly believes that he inserted and Woodley and on levelling out at the aircraft was requested to ad­ crash defects in the airframe or ing split pin, . but did not bend out the ends to secure secured all split pins and thoroughly checked the 3,000 feet the first officer cross­ vise when descent to 3,000 feet had engines. these pins. At this stage he was called away from the linkage prior to flight, there is no doubt that this checked the captain's altimeter been completed. During the descent. job. belief is in error. with his own. At 1015 hours the which was made at an airspeed of Comparison of the outside air 180 knots, the aircraft entered· haze temperatures logged during the It seems obvious that the owner/pil ot's error arose aircraft left the airways, the pro­ Some time later he completed the work required climb with the upper air tempera­ from an unsound procedure in performing simple peller of No. 4 engine was feather­ and the First Officer expected, on and prepared his ·!_ aircraft for flight. He then took-off tures provided by the Meteorolo­ maintenance work. By inserting a split pin without ed for test purposes and the air­ passing through it, to see a second to practise circuits and landings. Turning onto base craft was climbed to 18,000 feet. layer below, but to his surprise the gical Office confirmed that an alti­ securing it immediately, he ignored one of the basic tude of approximately 18,000 feet leg on his first circuit the pilot reduced engine r.p.m. principles of aircraft maintenance that whenever a After the completion of the climb, ground suddenly appeared. An at­ from the cruising setting for an engine assisted ap­ tempt to check the aircraft's descent was attained. locking device is installed, it must be secured at the when all four engines were running proach. On final approach, at a height of about 150 normally, a series of handling tests was too late to prevent it striking time of positioning. This principle rightly supposes At 1135 hours the First Officer feet, he applied· throttle to correct for undershooting that if the device is not installed, its absence will be were commenced. the ground. T he aircraft broke up but the engine failed to respond. progressively and isolated fires reported to Air Traffic Control apparent during a final inspection whereas loosely On completion of the tests, the broke out. that the height of the aircraft was positioning the item can easily conceal the fact that first officer called Hurn approach, 13,000 feet and at 11 53 hours Realising he would not reach the aerodrome the it has not been properly secured. requested a clearance to descend to 12,000 feet, i.e., a descent of 1,000 pilot attempted a landing in an open field outside the T he fact that the owner's attention was distracted 3,000 feet, and sought information feet in 18 minutes. Between these aerodrome boundary. The field was being ploughed JNVESTIGATION by being called away at a vital stage of this work was, as to the height of the tops of the times, according to the First Officer, and formed into wide furrows which proved to be too under the circumstances, considered a factor which lowest cloud layer. Hurn approach The aircraft struck the ground the aircraft flew towards Hurn ap­ much for the undercarriage and inevitably the aircraft contributed in this error. Provided the proper pro­ replied "I haven't got an estimate with its starboard wing while flying proximately 3,000 feet above a ended up on its back. Although the pilot was not cedures are employed and a thorough final inspec· here but in the Southhampton area approximately longitudinally level. cloud layer. From a consideration injured, his aircraft suffered major damage. tion of all points concerned is carried out however, they are VMC at 2,000 feet". At After this, considerable break-up of the meteorological conditions, Examination of the engine a short time after the this type of interruption should not, in itself, result 11 35 hours, the first officer replied, occurred as it traversed level ground however, it would seem that the accident revealed that the throttle linkage had become in maintenance errors. "We'd like permission to descend for a distance of some 600 yards. only cloud layer which existed in

SEPTEMBER. 1960 25 :24 AVIATION SAFETY DIG EST • Carbon Monoxide IS Lethal

The deadliness of carbon monoxide is widely1 it does diffuse upwardly and, even if it enters an authorities throughout the world introduced strict In everyday life, danger begins if exposed to known as a result of publicity on accidental deaths aircraft near the floor, may soon rise to pilot head pressure-testing requirements for exhaust-muff type 0.025% for prolonged periods, and deafu is likely and suicides involving inhalation of automobile ex­ level. cabin heaters soon after they came into general use. after exposure to 0.040% for four hours. H owever, haust gases. In an aircraft, death or serious injury Local requirements are contained in Air Navigation for the crew of an aircraft, the hazard appears at can result from exposure to a much lower con­ In aircraft, carbon monoxide d·erives from in­ Orders Part 105. which requires that the heat ex­ an earlier stage. Headache and• nausea caused by centration of this gas as it may rapidly reduce the complete combustion of hydrocarbon fuels. The changer must be pressure tested at each engine relatively slow build-up of carbon monoxide can mental capabili ties of the pilot to a state where he principal potential source of contamination is the change period. Defects in the system may escape a reduce the most competent crew member to a state loses control; the resulting accident does the rest. engine exhaust, but petrol-burning cabin heaters, visual inspection, but they will not elude detection of inability to fly or navigate safely. In the case of where used, may be an additional source. under a properly conducted pressure test. The fuel­ more severe contamination, useful consciousness can In the early days of closed cockpit aircraft, acci­ burning cabin heater, also, will not provide a hazard be lost with very little in the way of premonitory dents d ue to carbon monoxide poisoning were not The percentage of carbon monoxide in piston­ if it is maintained as laid down by the manu­ symptoms. infrequent. These led to design requirements in­ engine exhaust fumes is related directly to the fuel­ facturer. tended to ensure that the concentration of carbon air ratio used. R ich mixtures, in which the amount of monoxide reached in cockpits and cabins as a result air and hence of oxygen available to support com­ of entry of exhaust gases would be held below a­ bustion is relatively inadequate, result in high carbon monoxide outputs; conversely, operation on lean specified limit. A newly designed aircraft is now Data from Bureau of Stondgrd1 Ta,hnicgl Paper 212. routinely tested to determine the concentration of mixtures r ~duces carbon monoxide generation. Even What Can It Do? - (To You) in cruise settings, however, where the fuel-air ratio carbon monoxide in the cabin or flight deck during Being colourless, odourless and tasteless, carbon the type certification fl ight tests. This must not ex­ is as near as possible to the ideal, complete com­ monoxide is liable to be most insidious in its physio­ bustion of fuel is not achieved, and carbon mon­ ~eed 0.005%, which can be tolerated indefinitely logical effects; it can produce unconsciousness with­ oxide is still present in the exhaust gas. without any significant effect. out any clear recognisable warning. The gas turbine engine under normal circum­ It would seem reasonable from this to expect all stances does not produce significant concentrations Toxic effects result chiefly from the strong affinity new aircraft to be free from dangerous carbon of carbon monoxide. This is due to a high degree of of haemoglobin, the oxygen-carrying component of monoxide contamination but such is not the case. fuel combustion resulting from the relatively very the red cells of the blood, for carbon monoxide. This Even minor modifications, whether made in pro­ large quantities of air taken in. Only in military air­ affinity is stronger than the normal affinity of duction or in service may introduce a hazard. A craft where air for cabin pressurisation is bled off haemoglobin for oxygen, so that the presence of typical case was that of a si ngle-engined cabin type from the engine compressor itself, rather than being carbon monoxide in the lungs embarasses the uptake in which a small camera installation hole had been supplied by an accessory compressor, is there any of oxygen, and its transport to the tissues of the cut through the floor in proximity to the exhaust real risk of cabin contamination. body. L ess importantly, the presence of carbon slack. T his mod·ification had no influence on the monoxide in the red blood cells binders the release In addition to its intrinsic carbon monoxide aircraft structure or performance, but it did allow from tb.~iu to the tissues of such oxygen as has ob­ 4. entry to the cabin of carbon monoxide in dangerous problem resulting from high fuel/air ratio, the tained transport. Thus the symptoms and signs of () .020 1--- -1-- amounts. Jn another case, an aircraft type which fuselage-nose locati on of the piston engine in most carbon monoxide intoxication are in fact mainly f... had been in service for many years was modified contemporary light aircraft adds to the possibility of those of oxygen-lack in the body tissues, of which ~ . 0101---t---t---J--"'-'!:....-t---'==t"-"'--l~~~~...J cockpit carbon monoxide contamination. It is usual the brain is the most vulnerable in this regard. T he ~ - OOSl----+---+--+-----+---+---11----+----I for agricultural use. The additional equipment below ~ . OOOOL---'---'---l...--~2--.1...--~3..___...... __ _., the fuselage affected the flow of exhaust gases in to find that the amount of gas entering the aircraft entry of carbon monoxide to the bloodstream is H O U R S E XPOSURE such a way that they entered the tail-wheel aperture will progressively increase over the period between entirely through th~ lungs. producing a hazardous concentration of carbon engine overhauls, for reasons not associated with The toxic effects of carbon monoxide in terms of monoxide within the fuselage. T he route of con­ fu el combustion efficiency. These reasons include a falling-off in effectiveness of sealing throughout the concentration and exposure-time are shown graphic­ tamination was discovered only after extensive in­ ally below. This graph should however be accepted vestigation. exhaust system, and· between the engine nacelle and the interior of the aircraft. Thus routine in-service with some reserve in the high-concentration case, in What Can You Do About It? which symptoms occurring before the development These two examples will show why the Depart­ checking of the various firewall seals for correct In flight, development of headache, drowsiness or of serious incapacity may be transient and vague. ment, in addition to calling for carbon monoxid·e function is highly desirable. Changes of engine vent­ mental sluggishness, or even the smell of exhaust As has a lready been stated, actual loss of conscious­ determinations prior to issue of initial Certificates of ing or cabin ventilation arrangements may, of fumes, is good enough reason to suspect the p re­ ness may occur without any real warning, if the con­ Airworthiness, requires that similar tests be made course, drastically influence the entry of exhaust gas sence of carbon monoxide. The immediate action is centration of carbon monoxide breathed is high. after any modification to an aircraft in service to the enclosed area. to get rid ot contaminated air by introducing fresh which could conceivably result in gas contamination. The exhaust-muff type of heat exchanger, in use It will however be seen that the healthy body can, air. The recommended drill is:- on many types of light aircraft, can be Pilot Enemy and, in all probability, frequently does tolerate low Where Does It Come From ? No. I in the carbon monoxide field. This system is concentrations of this gas without any significant (I) shut off any heating system, whether it be ex­ very good - provided the muff is properly main­ effect. This physiological tolerance makes it possible haust-muff or combustion heater type; Carbon monoxide is a colourless, odourless and tained . If, however, the assembly is not maintained to lay down that, allowing an operational safety tasteless gas. As its vapour density is only slightly in a sound condition, exhaust gases can feed directly factor, 0.005% carbon monoxide is permissible in (2) open all windows or other fresh air sources im­ Jess than that of air it diffuses slowly. Nevertheless, into the aircraft. It was for this reason that aviation an aircraft interior. mediately;

26 AVIATI ON SA FETY D I GEST SEPTEMBER. 1960 27 (3) land as soon as possible, and have your aircraft This equipment, which utilises quantitative carefully inspected by a qualified engineer, en­ "colour-change" of silica gel crystals impregnated suring that he is fully advised of the circum­ with potassium pallado-sulphite, is sensitive and stances and the symptoms experienced. If no accurate. Kits are held at various centres through­ cabin heater is fitted, pay particular attention to out the Departmental network, and tests can be ar­ the entire exhaust and general sealing of the ranged by contacting the Regional Aircraft Surveyor cabin area. at your nearest Regional Office. There is no charge for this service; the only cost involved is that of the If no defect can be located, despite thorough in­ relatively short flight time required for the necessary spection, it is not necessary to freeze during flight tests. to make sure that you are not being poisoned by carbon monoxide. The Department has test equip­ U in doubt, have your aircraft checked. An ounce ment available that will soon establish whether you of prevention is better than a ton of cure-in fact, have a carbon monoxide problem and, if you have, with this gas, if prevention is ignored cure may not its nature and extent. be possible.

BEWARE 0 F EXHAUST FUMES

How Considerate are YOU?

Incidents have recently been reported where pilots have been flying below 500 feet in other than authorised low flying areas and, as a result, have caused considerable financia l Joss to poultry farmers in the outer Sydney metropolitan area.

At the sound of approaching aircraft, birds have panicked, crowded into the corners of their sheds, and suffocated. One farmer alone lost poultry valued at over £300 in three separate cases of low flying.

The witnesses to these incidents ctid not take steps to identify the aircraft and for this reason the Department has been unable to approach the pilots concerned. The farmers have now been advised of the need to obtain aircraft registration markings in any future case of low fl ying over their properties.

Clearly these incidents have been caused by a few pilots only and this article is published m the hope that those responsible will in future show more consideration for people on the ground.

Remember, low Hying below 500 feet is permitted only in low flying areas designated by the Director-General under Regulation I l 7B. At all other times, pilots must strictly observe the height requirements of Regulation 133.

Even at 500 feet birds may be disturbed and take fright, particularly in those areas where air­ craft seldom operate or pass over. As a poultry farm is usually easy to recognize every endeavour should be made to fl y round the area or to climb the aircraft to a height of at least 1,000 to 1,500 feet.

.28 AVIATION SAF ETY DIGEST