I have just taken delivery of two new Piper flap brackets as both of my inner brackets are getting rusty. I had a bare metal respray 18 months ago but rust on these steel brackets is coming through again. (They were rusty before the respray and at the time they were cleaned and primed with zinc chromate primer).
Does anybody know how the OEM Piper parts are protected? If you look at the photo it seems like they are just powder coated with a green paint – one can see the orange peel in the paint. I live in a marine environment and I would really like to zinc plate it then paint it in some way – either powder coat it of put in layers of paint in some way?
Does anybody know how this OEM part is finished? I am tempted to put it in chemical paint stripper and see what is underneath. I am guessing plain steel? Does anybody know?
This is a well known problem with Piper aircraft and as far as I can see the paint is nothing particularly special.
The fact that to install these brackets requires them to be drilled and riveted in place with aluminium rivets and against aluminium structure rather leaves them open to corrosion.
My best advice would be to get a high quality paint job done on the whole flap structure and then use a corrosion inhibitor ( CorrosionX , ACF50 or the like )
My question is have you been inside the flap yet ? If the brackets are corroded the problem has gone further.
The rest of my flaps are in good condition. They were removed for the bare metal respray and get treated with ACF50 . This is light surface rust on an otherwise fairly newly resprayed aircraft.
Somebody mentioned it might be an epoxy primer. I am tempted to strip it off, have it zinc plated, and then epoxy primed. At least this provides a sacrificial anode.
I believe when they are installed a layer of squishy paint like material is put in the joint between the bracket and the flap to try to fill the gap and stop electrolytic corrosion. Why they don’t make them out of stainless steel I will never know? I know this is still a dissimilar metal but surely better than steel?
“ The rest of my flaps are in good condition. They were removed for the bare metal respray and get treated with ACF50 . This is light surface rust on an otherwise fairly newly resprayed aircraft.”
I thought the same when I bought a PA28-180. During the annual a year later, we got a boroscope inside the flap and the nose ribs where the steel brackets attached were completely shagged – it was a wonder we didn’t lose a flap in flight.
I am tempted to strip it off, have it zinc plated, and then epoxy primed. At least this provides a sacrificial anode.
I have made good experience with AkzoNobel 463-12-8 Epoxy primer and with MIPA 100-20. 436-12-8 is best sprayed, but for 100-20 you can buy roll/brush hardener. For spraying the primer, you don’t need a too expensive spray gun though.
All epoxy primers I have ever used were not UV resistant and after a few months in the open the stuff just cracks up. One needs to at least UV lacquer it; same with almost all paint systems.
Stainless steel is not the answer, it is very bad news when in contact with aluminium and I have almost given up using it.
I too had a similar experience with my PA28 as wigglyamp did……… just see the photos
I’m about to experiment with cerakote on some of my vehicle parts and to see how it fares.
Stainless steel is not the answer, it is very bad news when in contact with aluminium
We’ve done this one before. Not sure it is completely as simple, because Socata use SS rivets extensively and mostly they don’t corrode or cause corrosion.
But sometimes they do although the trigger is not clear – apart from some owners tying the yoke to the seat to lock the controls, which prevents the drain holes working
All epoxy primers I have ever used were not UV resistant and after a few months in the open the stuff just cracks up
They are primers. You’re not supposed to use them without a top coat on outside applications. Within the structure, there is barely any UV lighting, so they’re fine there.