Last year at the NATS I entered my all foam electric Seafire AMA profile. You might say the construction is somewhat experimental, but I have been building these type planes for some time now. However, the AMA carrier has tougher pull test requirements than sport flying. It pulls about 63 lbs and although it had been pulled before I felt something give. I didn’t examine it closely at the time. I just assumed the mount had given way. I came home, put it on the shelf and sort of forgot about it. I have a new profile for AMA E profile, but with my field closed by the FAA I have been unable to find a place to fly carrier. (CL models are such a threat to full size aviation) so I am behind in testing and trimming.
So this last week I thought I had better repair and have the Seafire available in case things don’t work out on the other model. When I got into the BC issue I found there wasn’t any structural failure. The wing has two ply plates (Top and Bottom of the wing) , the BC is mounted by simply bolting it through the plates. What happened was the 6-32 bolt holding the BC bent. I had three different 6-32’s so I tested them, two bent the socket head broke all this with minimal force. The 4th is a #8 (see picture). I simply chucked the screws in a vice and bent them with a pair of pliers. The # 8 requires a bit more force but not a lot.
The BC is a Sig nylon and I think the problem may be that the thickness puts too much force on the bolt. I will test with a #8 bolt, but I think it will be best to switch to a GS, LR, Brodak crank.