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#1
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consumer report
I have recently found myself in need of a skin repair to the trailing edge of the elevator. It's a long story having to do with a snow plow and a hangar door that I won't go into here. I retained the services of Airframe Components in Kendallville, Indiana to do the work. Attached are links to two short video clips of the part that I got back after some 3K in labor, materials and transportation. I do not believe that this represents a satisfactory, workman like repair but I would be interested in the opinions of this community. Most especially any airframe mechanics among us who consider themselves knowledgeable in sheet metal work. I have made known to A.C. my concerns but they will not admit to any problem or deficiency whatsoever. Now trying to ascertain where to go from here. So far I have only managed to trade one small ding in the trailing edge plus a lot of money for an elevator that now oilcans on half the rib bays. Thanks for your collective consideration.
https://www.dropbox.com/s/iyqlyqe48c..._0767.MOV?dl=0 https://www.dropbox.com/s/tnj4nwc4yp..._0768.MOV?dl=0 
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#2
12-08-22, 04:55 PM
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Sorry to hear about your troubles. I can't answer your question, but would like to know more about the work done. Was a replacement skin purchased from Cessna to replace the damaged one, or was a skin manufactured by replicating the damaged one?
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#4
12-09-22, 09:55 AM
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I have never done a sheet metal repair, nor did I stay at a Holiday Inn Express last night, but if a factory-built, non-damaged elevator doesn't exhibit the same "oil canning" properties as the repaired elevator, I would suspect the repair is not up to snuff. Perhaps a call to your local FSDO would be in order, as you suspect you've been sold a repair that doesn't meet airworthiness standards? If the FSDO won't play, call a Designated Airworthiness Representative (DAR). He will charge you, but his word is like that of the Oracle, so the shop and the FAA would have to respond. Just the threat of getting a DAR involved may cause the shop to reconsider it's position regarding the repair. Or, on the other hand, you may find out that "oil-canning" is perfectly acceptable. Either way, you'll know. Even if it is acceptable, I wouldn't want to hear it every time I went flying!
Here is an engineering forum where actual aircraft engineers discuss oil-canning. According to what I see there, no oil-canning is permitted as it negatively affects the flight control: https://www.eng-tips.com/viewthread.cfm?qid=248639 There are many mentions of oil-canning on the Vans RV builder's forum, and the solutions range from re-skinning to "don't worry about it". So a definitive answer may be hard to find without a DAR or DER getting involved... Last edited by mshac : 12-09-22 at 10:17 AM.
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#5
12-09-22, 12:21 PM
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Thanks for the well reasoned reply. Noise is certainly one element of the issue. Every time the surface pressure transitions from positive to neutral or negative the affected skin segments will "pop". But in addition to the noise this constant flexing will result in paint failure, smoking rivets and eventual stress cracking of the work hardened material.
Interestingly the linked thread makes the observation that maintenance manuals do not address the question of "acceptable oil-canning" because there is no such thing. I have several other feelers out for additional input but so far there is unanimity of opinion that this is not a satisfactory condition.
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Linear Mode
