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Salvage or Start over

Juan

I'm New Here
I bought a partially built RV-7 Empennage and Wing kit. It was first delivered on 2004 and most parts kept stored on the original crating for the past 15 years. Several pieces show light to severe corrosion and rust.

My idea is to build and RV-7 which I can keep and not have issues in the future. My simple question is:

SHOULD I TRY TO SALVAGE THIS KIT OR ORDER NEW KITS AND START OVER FROM SCRATCH???

I tried to treat some of the corrosion with Scotch Brite and you can see the results on the pictures attached.

Thanks,

Juan
 

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send a note to Van's and ask for their corrosion limits and min thicknesses after corrosion removal.
 
Treating corrosion

Stop and ask Vans.
Build on or scrap?
How to remove?
How to treat it?
That spar cap is probably the most important part and most expensive. Hold off with the sander till you hear from Vans.
I wish builders would peel that blue vinyl.
 
While it might be necessary to clean off the corrosion, your aggressive cleaning left scratches in the surface that would all need to be removed. You'd need to have the surface be smooth. While it doesn't need to be polished, it does need to be free of scratches.

And on the before/after photos of the sheet, it appears as if there is still corrosion above the area where you worked on it. If you keep this kit, you've got a LOT of work ahead just getting to the point that you can start building.

If it were me, I'd accept the loss and start anew with a replacement kit, assuming that I could afford that. This said, and that's more of an editorial comment than guidance, Steve's and Larry's suggestions are good if you're up for all the remedial work ahead of you.

Dave
 
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Numbering your photos 1 through 9 top left to right and bottom left to right.

1) Hard to tell but photo #2 is after blend? See below.
2) Where is this? What was the original thickness (0.032?) and final thickness. In general 10% loss of thickness is OK. Some times the stock material was on high side of tolerances, so loss of some thickness is not as critical.
3) & 4) Looks fine. Of course clean, etch, alodine, prime with two part epoxy primer made for aerospace / aluminum. In the old days a rattle can of Chromium spray paint, long ago outlawed
5) That kind of sucks. It is the shop head. The go to repair is drill out and replace. WARNING. That is a really long "spaghetti fastener". "Drilling out" or trying to drive it out not easy and high risk of damaging hole. The fix to that is over size. Is that rivet doing much? It is next to very larger attach bolts. The adjacent rivets are good. The rivets with corrosion on the head are still functional through the stack up. It would be wise to inspect every year. I think it is OK. The rivet is seated and taking shear load despite the shop head corrosion. I would CLEAN the shop head up a little, use care to remove MIN MATERIAL (shop head does not have to look perfect) and take care to not damage finish of spar cap adjacent. If you have some decent* shop head material left I would leave these alone, clean area, spot prime. What is decent*? Use your Mark 12 calibrated eye ball under strong light and magnification, squint and use the German Engineering method: "Gut Un enough".
(Drilling it out and replace rivet - You could drill it out but would do it on a very accurate drill press or CNC and have spar JIGGED accurately and securely. You will have to basically drill full length / depth of rivet out, to almost the full diameter without hitting the spar. Not easy but it has been done. You might be able to bring it to a machine shop. Now you have to get some long rivets and a VERY big squeezer. You can't use a 2x rivet gun and a 1lb bucking bar. Because you are starting with a small diameter drill bit you have to be careful it is not wondering or going off center. For that reason don't start with a too tiny pilot drill bit, may be 1/2 diameter of hole for a drill bit. Then step up diameter slowly. Start on the manufacture side. Shop heads tend to drift off center slightly. Shave off the shop head of BOTH manufactured head and shop head to know where the center of the hole. Jig spar. Drill a little, stop and check and measure progress. If you elongate hole you will have to drill it oversize. Personally I would try to leave it, by all means prime the whole area.
6) This is the elevator steel weldment. It is over built and looks like surface corrosion. Clean up, smooth, and re-prime. HOWEVER use some diligence and estimate material lost you can go 20% may be more for small local areas.
7) Blend and prime. Measure loss in thickness. 10% rule applies. If it is a few more thousands than 10% loss (0.0032 lost assuming base material is 0.032, final thickness 0.0288). If it was 0.027 I would not worry.
8) Low stress area remove damage, prime.
9) See #5.

The parts appear repairable. How you repair them, quality and details of repair will be up to you. If in doubt replace that part or seek help from vans. If you do ask for help you need to MEASURE and draft out detailed damage mapping. What I just said above is good structural advice, but it is based on what I see and GUESS from photos and no measurements. Keep that in mind.

CLEAN IT UP, MEASURE and get back to us. Cheers. :D
 
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I agree with the advice you have received to talk to the factory. My concern would be the corrosion you can't see.
 
Relative saving

Some good suggestions above; assuming the factory provides assurance and guidance for remediating the corrosion (understand that they may not be willing or able to do so and may refer you to AC43.13 instead, which would be reasonable), then you'd need to assess the value of your time and how much you'd really save. There would likely be some disassembly required e.g. to properly strip, clean and recoat the elevator horn.

The general rule of thumb for the total cost to complete is something like 1/3 airframe, 1/3 panel, 1/3 firewall forward. The parts you already have may be half of the airframe, so in overall relative terms the saving by continuing with the current parts is around 15%. I think there's already enough work as it is in a kit, without the extra burden of remediation, but it also depends a bit on your personal situation.
 
Imagine the amount of very old airframes out there with corrosion flying daily?
I’d hate to think!
 
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