Last weekend at the field during the IMAC contest I lost one of the cams and the washer on the port wing of my Slick. No big deal really… I have clips on my anti rotation pins on each wing so I needed a click of aileron trim and all was fine. After the flight when I went looking for the reason I spotted the wing gap and on investigation found that the cam and washer were gone and the stud had rotated out a bit. I didn’t have my spare so that wing went back to the nylon bolt for the rest of the day.
So what happened? While it is impossible to tell for sure, I believe the problem was rooted in not seating the wing down snug against the body. So when I locked the cam down it pulled the wing in a bit but not enough to put pressure against the cam and therefore with some vibration the cam escaped. Maybe the stud rotated enough to further loosen as well. Possibly contributing to this is that I have not glued the washers down inside the body either… perhaps if I had the slack in the system would not have been enough to allow the cam to escape??
The only other issue I can see is that perhaps the stud managed to pull out of the blind nut embedded in the wing root. I am really not fond of blind nuts in any case. I find most of them to be ill fitting/loose. When used in conjunction with a standard bolt there just seems to be a lot of play and I have seen a bolt manage to walk itself out a thread or two before without rotating at all because of vibration and slop.
I have continued to use the system through another 6 flights or so and so far have not had a sign of any movement. I may add some plumbers tape to the studs to cut down on “rattle” between the studs and the blind nuts before my next trip to the field. Otherwise I will keep with it and see how it goes.
(Don’t recommend these anymore… see part 3)