I just finished my elevators and was proudly showing them off to my wife - especially the trim tabs. I'm not particularly proud of the trim tabs, but they represent the first visible moving parts in my build. As I moved the trim tab from full up to full down on my left elevator, I noticed a small flexing action in the top skin just forward of the rear-spar on the outboard side of the trim tab. The right elevator doesn't have this flex.
As I investigated more closely, it seems that the most likely reason for this is that the hinge attachment on the elevator is not 100% aligned and the motion of the trim tab causes a very small warping or flex in the flange of the rear spar which in turn causes the skin to react. In fact, if I pull the hinge pin out about 4 links-worth, the flexing disappears altogether. It isn't very much - barely noticeable, but it's there and I don't like it.
I drilled out the last 8 rivets and put in clecos then replaced the trim tab and found that there is no skin flexing with the clecos. I replaced each rivet in turn, putting the trim tab back on after setting each rivet and found that the flexing occurs only when the two outboard-most rivets are set (no issue with clecos in these holes). So, I drilled out those last two rivets again and opened up the hole to a #30 and put in a couple of oops rivets, hoping that the hinge would align better through the process of opening up the hole. But no dice. As soon as those rivets were set and I put the hinge pin back in place, the little flex in the top skin was back.
I would share a picture, but it's impossible to see this flexing in a picture. I hope this description might ring a bell with somebody who has had a similar issue and you might have some advice on how to fix it.
Thank you,
As I investigated more closely, it seems that the most likely reason for this is that the hinge attachment on the elevator is not 100% aligned and the motion of the trim tab causes a very small warping or flex in the flange of the rear spar which in turn causes the skin to react. In fact, if I pull the hinge pin out about 4 links-worth, the flexing disappears altogether. It isn't very much - barely noticeable, but it's there and I don't like it.
I drilled out the last 8 rivets and put in clecos then replaced the trim tab and found that there is no skin flexing with the clecos. I replaced each rivet in turn, putting the trim tab back on after setting each rivet and found that the flexing occurs only when the two outboard-most rivets are set (no issue with clecos in these holes). So, I drilled out those last two rivets again and opened up the hole to a #30 and put in a couple of oops rivets, hoping that the hinge would align better through the process of opening up the hole. But no dice. As soon as those rivets were set and I put the hinge pin back in place, the little flex in the top skin was back.
I would share a picture, but it's impossible to see this flexing in a picture. I hope this description might ring a bell with somebody who has had a similar issue and you might have some advice on how to fix it.
Thank you,
