Cherokee Pilots
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Cherokee Pilots Cherokee Pilots' Association Cherokee Chat Archives Return to Cherokee Chat Main Page Cherokee Chat has become a major source of information for Cherokee owners. Here are some of the archived answers to questions over the past year. They are presented in chronological order, but you can do a word search - to find a particular topic. (Hit Control + F and type in word you are looking for.) Surface Corrosion on Wing Ribs (Not Spars) 1165 April 17, 2008 It would be next to impossible to "scotch brite" both sides of all your wing ribs due to limited access through the tank openings. From what you describe, it sounds like you have relatively benign surface powder corrosion - not all than uncommon in our 40 year old planes, depending on where it has lived. Obviously, you should remove all that you can get to with the scotch pad. The rest can hopefully be neutralized with ACF-50. When you apply it - make sure you use a fogging applicator - otherwise, you will be wasting your time and money. The ACF-50 website has video instructions. IMHO - airframe corrosion prevention/treatment is most neglected aspect of aircraft maintenance and ownership. Sooner or later, it will most likely be what sends our aging planes to the salvage yard. Arrow Gear - Motor Cycles On and Off After Retraction April 6, 2008 2411 file:////Clarabelle/joes/FLYING/Internet/Cherokee%2...d%20Tips/Cherokee%20Chat%20Archives%20-%20Final.htm (1 of 1069) [3/6/2012 11:42:41 AM] Cherokee Pilots The problem with the gear motor going on and off is serious and will ultimatly kill the motor. The system is very simple in that the pump runs to bring the gear up. When the gear is stowed the pump pumps against the cylinders and will pump up the system pressure in excess of 1400PSI. Once the system pressure has exceeded the pressure switch the switch will open the pump will shut off. This is the normal pattern. A pump that is running on and off indicates that the system has some device that is not allowing the pressure to be maintained once the gear is stowed or the pump itself has a failing check valve in it. Your only recourse on the failing valve in the pump is a new pump. About $350 plus about 4 hours labor to R&R it. I'd suggest you get your AP to get the plane on jacks and then cycle the gear, watch the gear and the doors, the pump cycle and then try to observe which one of the gear is not coming up and staying up. I suspect that while you are flying along your pump is probably getting energized for a second or two and you wont know it except to hear a ping in your ears or if you happen to see the load meter the meter bounce. A simple pressure gauge, 0-2000PSI and a T can be purchased. Install the TEE in the pressure switch location the gauge and the pressure switch in the TEE. Cycle the system and watch the pressures. If you cannot locate the problem you can purchacse caps and install them on each of the elbows one at a time to find the troubled actuator. Once you cap all the lines the gear motor should energize, pump up the system and then shut off and HOLD the pressure against the system. If it wont your pump check valves or high pressure relief in the pump has failed...but a new pump. ...And... April 7, 1008 4467 Nine times out of 10 the problem is the emergency extension hydraulic valve under the back set... requires 2 O-rings to rebuild. Do this 1st, and if the problem remains then isolate each actuator one at a time by capping their lines at the manifold, until you identify the one that is allowing leaking from the high to low sides. Lubricant for Pulleys April 6, 2008 1517 I've been using this stuff from McFarlane: www.mcfarlane-aviation.com/Products/? ID=69361872&PartNumber=PULLEY%20OILER%20KT& The extension kit is great and very handy. The oil itself is very long lasting and a tiny bit will do the job. file:////Clarabelle/joes/FLYING/Internet/Cherokee%2...d%20Tips/Cherokee%20Chat%20Archives%20-%20Final.htm (2 of 1069) [3/6/2012 11:42:41 AM] Cherokee Pilots Over-Sized Door Hinge Fork Holes - Loose After Pin Replacement April 3, 2008 1517 The door hinge forks should just be changed. It shouldn't be too hard for an A&P who's good with sheet metal. Drill out the rivets, remove the old hinge fork, fit the door with shims in the door jamb, fit the new hinge(s), drill rivet and install. Alternator Upgrade Where No Plane Power STC Available April 2, 2008 5109 I just went through the same routine with my 67' 140. The alternative, that is STC'd, is the InterAv 50 amp alternator, also available from Aircraft Spruce. I went with it and have had five trouble free flights since coming out of annual. You get it as a kit that includes the alternator, brackets, VR, Over Voltage Relay, and noise supressor. I had to add the 60-amp breaker as well. It is a new alternator and not a rebuilt. The thing that gets me boiling, is that once you do this under the InterAv STC, the Planepower alternator can then be used under their STC as a replacement for the InterAv alternator. It just can't be used to initially replace the generator or to replace the 37-amp Chrysler. My local FSDO would not approve it without an engineering study and they had no 337 records of anyone having done it previously in this area. If you do an arhive search of alternator issues, there is someone on the chat who did it successfully with a 337. I can't recall the member's name, but I recall, too late for my purposes, that he was able to install the Plane-Power with a 337. This is something the local FSDO said would help them in making their decision. So far, I've got nothing bad to say about InterAv. Their product is available, it is a new alternator, not a rebuilt and it works. Rigging Per Manual March 27, 2008 1517 Step 1: Get service manual! Step 2: Fabricate stabilator rigging tool from service manual drawing. (a must have) file:////Clarabelle/joes/FLYING/Internet/Cherokee%2...d%20Tips/Cherokee%20Chat%20Archives%20-%20Final.htm (3 of 1069) [3/6/2012 11:42:41 AM] Cherokee Pilots Step 3: Level airplane. Step 4: Place tool on stabilator per service manual and use an accurate level (digital would be pretty good). The figures in table V-I, letter A refers to upward travel at the chord of the stabilator, C refers to the lower travel of the stabilator chord line. B and D refer to the travel of the trim tab, at least that's how I take it. Interpreting Oil Analysis March 26, 2008 0279 I find it beneficial plug the data into a spreadsheet and look at the ppm/hr of use. I change every about 4 months regardless of use (which tends to eliminate the time factor) - and I definitely fly more hours in the summer than in the winter (highest 4-mo usage was 36 hours and lowest was 10). Iron has ranged from 12 to 61 ppm, but on a per hour basis, it has always been about 1.3 (std dev of 0.4) ppm/hr. Copper has ranged from 1 to 12 ppm, but on a per hour basis, it has been about .38 (std dev of .12) ppm/ hr. I only get concerned it the Analysis company says to get concerned - or if the ppm/hr goes outside 2 std deviations of my past 4 years of data, but I pay attention if it is outside of one std deviation. Oil Leak and Clogged Breather March 25, 2008 1677 I noticed a small bit of oil coming from the top of the cowling. Found the only A&P working on the field, de-cowled and found a very small amount of oil under the spinner indicating a leaking crankshaft seal. Then we noticed more oil along the spine and underneath the engine also. He asked if the oil breather tube had ever been cleaned out. Not to my knowledge. He took it off and found it clogged with gunk. He cleaned it out with pressurized air and solvent. The A&P on the field, my A&P and a respected friend who knows about such things all say the case was pressurized by the clogged oil breather tube causing oil to find easy ways out, including the seals at the front of the engine. The thought it that since we caught it early, the seals are probably still in good shape. file:////Clarabelle/joes/FLYING/Internet/Cherokee%2...d%20Tips/Cherokee%20Chat%20Archives%20-%20Final.htm (4 of 1069) [3/6/2012 11:42:41 AM] Cherokee Pilots Operating Lean of Peak March 8, 2008 2411 www.lycoming.textron.com/support/publications/service-instructions/pdfs/SI1094D.pdf Lycoming explains in detail how they wish for you to operate your engine. In normally aspirated engines, with carbs, you cannot run LOP. If you wish to run LOP in a fuel injected engine it is best done only with the proper instrumentation onboard. A good digital 4 probe EGT would be required to ensure that you not damage your engine.