First project-need opinions on corrosion

[Conundrum]

Good Afternoon all,

I have been lurking here for a while, learning what I could before starting into my first project, a '62 Colt-N5605Z-complete with a 1200 hour O-235. The previous owner had just stripped the fabric for an A&P supervised recover and lost his medical. It sat for ten years and finally ended up in my shop. Aft of the door frame, the fuselage has already been stripped and primed. One of the elevators needs to be repaired and the rudder replaced per the new Piper AD.

After about an hour of solvent work today and another 3 minutes with 1000 grit sandpaper the following pictures are just inboard of the landing lights on the left wing.20240314_135950.jpg
20240314_140036.jpg
Similar surface corrosion seen on the spars.
20240314_140415.jpg
So the first question is, Are these skins and spars salvageable or am I better off to save the time and effort with new? With the exception of a few small rib repairs, everything else on the wings is sound, even the fuel sending units.

Aaron

[Steve Pierce]

There is no AD on the rudder, just a proposal.

I use Scotch-brite and etch when I encounter something like that. In the second picture there appears to be dents in the leading edge. They will show in your new fabric.

I would clean the spar very well and then measure the depth of the corrosion and refer to AC 43.13 for depth parameters.

[JPerkins]

What Steve said. I just did a J3 wing that looked just like that. Once the spar was cleaned the damage was less than a thousandth deep with no even fence of intragranular corrosion.

[Conundrum]

In the second picture there appears to be dents in the leading edge. They will show in your new fabric.

Thanks for the input. I am considering pulling the entire wing down to sand and treat the spars, bead blast the excess glue off other parts as needed and repair a couple ribs. Log books show 4 ribs replaced during the last recover (1999) which was done very poorly. Lots of excess glue, poor fabric work, and a strip of aluminum screwed to the false spar over the top of the fabric work. Looks like an apprentice panel beater worked that leading edge over but in the end used automotive grade body filler. Bondo has a unique smell when sanding. The logbook notes read like an on-the-ground accident. Hopefully, the English Wheel and I can work those out quickly. At least 3 colors of paint on the fuselage .

[JPerkins]

Careful with the bead blaster, you can warp sheet metal pretty quick.
I’ve dealt with 40+ year old fabric jobs and found paint stripper works well to get rock hard glue,polybrush, or dope off pretty readily.
The leading she skin is fairly thin and a lot of the dents you can rub out with a screwdriver handle.
Polypadding (lot of people call felt) can cover ripples and little dings leaving a smooth clean looking leading edge.

[Steve Pierce]

a strip of aluminum screwed to the false spar over the top of the fabric work.

Piper did that but put a finish tape over the strip. The fabric probably pulled away from the concave false spar and they reattached it.

I just replace the leading edges, they are thin and when I have tried to work out dents in thin aluminum it just grows. The tip bow skins are easily worked out since they are 1100 aluminum and dead soft.