I just got done putting together a Great Planes Avistar Elite, and was going through all my checks and setting my control throws and noticed when I'm working my elevator up and down I see a slight movement in the tip ends of the horizontal stab. I don't really think it's enough to affect flight, but haven't ever noticed this in any other arf's that I've assembled? Has anyone ever had this problem? And might know what the cause is? There doesn't seem to be any binding, and I've made sure that the space between the stab and elevator is clear of any glue. The hinges were installed from the factory and the hinge line is not prefectly straight, but I've seen this before and not had this issue. Any input will be helpful.

If I'm understanding your question correctly, you've got to really crank the 2 plastic screws that secure the stab and the rudder together. After tightening you'll have to keep an eye on them and periodically tighten them during your pre-flight

Originally Posted by eric1313

If I'm understanding your question correctly, you've got to really crank the 2 plastic screws that secure the stab and the rudder together. After tightening you'll have to keep an eye on them and periodically tighten them during your pre-flight

I assure you the screws are cranked down. No movement there, the stab is actually flexing on the tip end a bit... not going to worry about it because I won't be working elevator in a up & down motion while flying, looks like it's just a thin weak stab to me? But I put a OS 55AX on it so I will give it a test with some mild aerobatics.... that is if these high winds die down by the weekend...

It's a warp in either the stab, or the elevator... probably minor at best if you didn't notice it prior to installing... and what might be amplifying it is both surfaces could be warped slightly in opposing directions... Either that or a hinge or 2 wasn't centered exact enough in the surface. Any of these conditions will cause the tips/ends of the stab/elev(or whatever surfaces) to warp when operated.

It's probably nothing that will affect flying at all. Keep an eye on it, and double check it when preflighting the plane... also double check the relationship of stab to elevator to make sure those are in fact true... If those look true to the eye... I do believe its just a small warp.

If your hinge line is not perfectly straight but the gap is even all the way. And the tips go up and down when operating the elevator you probably have a factory oops. With a tight curved hinge line this is unavoidable. You can have one of two situations. The two parts that have matching curves will operate smoothly when testing movement by hand with the linkage disconnected. Depending on the direction of the curve, the tips will move in the same or opposite direction of the elevator. The other is if one part was curved and the other straight. One part has been stressed to achieve that constant hinge gap. In this situation, testing movement will not be even. It will feel like its trying to snap past center. In either case case, hinge stress should be a concern and more so with the latter situation: breakage or pull out. Consistent centering of the elevator trim in the latter case could also be a problem depending on the amount of slop in the linkage.

In either case, flight characteristics should not be affected. But I would have a concern about the life of the CA hinges. If I intended to have this airframe to have a long life, I think I would prone to rehinge the elevator with pin hinges.