How strange, hookedonrc, but I just ran into the same problem yesterday building a Goldberg Protege for my grandson.

This is a .60 size trainer that usually uses rubber bands but had the option for bolt-on wing. They suggested using 8-32 bolts which I felt were too small for a 6' wingspan, so I changed to 10-32 (should have used 1/4-20 in retrospect).

Anyway, epoxied in the metal blind nuts and went on to other things. Well, yesterday I installed the wing to set the H-stab center and one of the nylon bolts went in fine, the second would pop a thread when only tightened about 1/2 of the other one. Tried others and metal....same thing. So I figured the blind nut is oversize.

Here is how I fixed it (you guys will probably tell me I shouldn't do it!).

I inserted the nylon bolts backward -- with the bolt head facing down and the shaft facing the top of the wing. Placed the wing on, installed two nylon flat washers over the bolt ends and two nuts.

Looks a little strange and not as smooth a set-up as two bolt heads showing on the top of the wing, but I know the bolts won't come out!

Before I did this, I looked seriously at removing the bad blind nut but there is just no way without tearing up the saddle.

I've built about 10 planes and never ran into this before, but I can tell you that I'll check the bolt fit on the next plane before I epoxy the blind nuts down!