I'm at a loss here and need help. Lately, my trex450sa looses tail authority and wants to pitch backwards to the left when the nose is facing away from you. Everything will be going fine and suddenly I have to give it more and more right tail imput. I can be giving it full right stick and it still doesn't respond. At first I thought it might be the batteries, wrong. All the linkage seems fine and is adjusted correctly and the servo is mounted properly. I'm using a hitec hs-81 or hs-85 servo for the tail (I'm at work at the moment). I have the tail servo mounted to the servo brackets using the rubber gromets with the brass piece going through, should I have it mounted a different way? Also, I'm using the disc instead of a servo arm but it seems to have the full range of motion. The one thing I noticed was that one of the tail rotor blades was looser than the other, I'm thinking that that could be what's causing it. I'm not doing any 3D flying, mainly just hovering and straight and level flight. Has anyone had this problem or have a clue as to what's going on? Please help, I'm tired of crashing because of this. Thanks!

Is it pitching backwards or pirouetting left?

If you have done nothing and mid flight you have to input tail control to maintain nose direction, one culprit that I can think of is a slipping pulley.

Those servos are not recommended tail servos. You should get a servo rated for tail control. Maybe your servo is overheating and letting the tail go.

Blades should be tightened similarly, but a looser tail blade will not exhibit these characteristics.

Rafael

It is pirouetting left. Now that I think about it, it also pitches to the left at the same time. That could be due to me not being quick to adjust to the different heading.

i would check the servo and see if it has indeed overheated, i had a servo do that to me - would work for 1 min, then overheat and stop...

and yes the pulley is known to slip on the tailshaft.. i ca'ed mine to the otherside of the pulley that is stuck to the shaft