Help with Tail Servo

[SPARKY426]

I have a Trex 500ESP set up with a GY520 and a 9257 tail servo. Tx is a Futaba 7C with gain set at 65%. I was hovering today and the heli starting to piro slowly at first and then pick up speed. I put TH on and was looking at the tail and when in HH, which is what I fly in, if I give it rudder input, it follows the command and then the servo horn starts to slowly rotate towards the tail. If I put it into rate mode, it centers perfectly and follows the rudder input without any issues. I put it back into HH mode and it starts to slowly rotate towards the tail again.

Any ideas?????????

Thanks, chris

[Deet]

That is exactly how the gyro should work when on the bench

I would re-check all the settings in the gyro and make sure you don't have any binding in the tail

[SPARKY426]

No binding in the tail, but it never reacted like that before?

[Deet]

it will do that if you have some stick input

check you don't have any trim or sub trim on the tail in the Radio, the gyro will see that as an input and keep going in that direction