Hi all,

I'm working on my Stits SA6B project, and have turned my attention to the wings. This was obtained as a partial project, and I've just noticed a possibly serious error on the part of the original builder. The right rear wing attach fitting is located too far forward on the fuselage, and so isn't aligned with the rear spar as it should be. See pictures below.


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Correct (forward) fitting

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Incorrect (rear) fitting

I would say the discrepancy is 1/4-3/8". Mostly what concerns me is how far off the fitting the aft-most spar strap is. The forward one is adjacent to the fitting, albeit "inside" the bracket rather than in front of it, but at least the bolt is only loaded in shear through this part. The rear strap is cantilevered off the fitting by the bolt.

My thoughts are:
1. Cut and relocate the fitting, which is all but impossible without serious reconstructive surgery to a major cluster of structural members.
2. Weld a shim to the aft face of the fuselage fitting to relieve the bending on the bolt. This still leaves the forward strap of the rear spar on the wrong side of the bracket, but very close to it. Here is an illustration of the idea.

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Proposed fix.

Any thoughts? It's a deviation to a critical structural component, but I don't have a lot of options. I don't like that the fuselage-side bracket won't be "captured" by the spar straps as per design, but I don't know how big a deal that is. I could put a bushing on the bolt, captured in the middle of the fitting, which would effectively transfer any longitudinal loads into the rear half of the fitting without putting the loads on the nut.


-Tony