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fuel tank fairing nutplates

kens_cockpit

Well Known Member
I have the RV8 Quickbuild wings and fuel tanks.
I drilled and dimpled the holes for the screws and K1100-08 nutplates on the inboard skin of the fuel tank to attach the wing root fairing. I measured for edge distance of the holes but now the inboard edge of the nutplates sit on the rib of the fuel tank.

If I install the nutplates as is they will be on an angle which I expect will make it difficult to install the screws to attach the fairings. I'm not sure how to fix that.

Can I grind down the nutplate so it misses the rib? To do that will require a lot of the web of the nutplate to be removed taking it close to the thread.

Or do I need to place a shim under the nutplate? If so that will be a very fiddly task. But if that is what is needed I'll do that. What would the shim look like and how will it be secured?

Anyone else come across this issue at this stage? What is the solution?
 
I wonder if you can cut a long narrow strip of 0.025 (or whatever shim thickness needed) and install that along the whole length of that area on the inside surface of the inboard tank skin. Maybe bond it with proseal for drilling and then use the nutplate rivets and screws for the mechanical fastening? If you had built the wings, there's a fab project to make a splice plate that provides the mounting shoulder for the outboard fuel tank screws using a similar process of wrapping a thin sheet around the leading edge shape.

I would attempt to shave down the nutplate first and see how badly that might compromise the threaded barrel where the screw is secured.
 
Assuming you don't actually have to grind away (much of) the threaded barrel of the nutplate, I'd look at using MS21053 single-lug nutplates which you could angle away from the fuel tank rib.
 
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