Autopilot Trim and Altitude Issue Strange autopilot behavior

[RV7Builder]

On the last two flights, the autopilot had issues with pitch and trim. We have manual trim, and during the 1. flight the Dynon constantly displayed "Trim Up" or "Trim Down". Altitude hold still worked at that point. We where flying in Nav Mode. Sot he AP should have maintained track an Altitude.

On the return flight, conditions were strongly thermal. Once again the Dynon message "Trim Down / Trim Up" alerts were very often present . These messages really came in rapid succession — literally one second after a "Trim Up" message, a "Trim Down" would appear. In addition, altitude hold stopped working completely. The aircraft would fly 300 to 400 ft above or below the selected altitude.

Could our servo be defective? We only have about 60 operating hours so far, and until now everything has worked very well. Trim up/down message appeard only when changing the Altitude or Power Setup.

Nice Greetings David

 

[rjones560]

The RV7 has electric trim, not manual trim. I suspect that you mean that the pitch trim is not wired through the Dynon autopilot control head or you did not install it.
Are your servos set to 100% torque? I have been in turbulence (uppers and downers) both in jets and light planes where the autopilot could not hold altitude, but that was quite rare.
More information is required.

 

[RV7Builder]

Yes you are right it is an elecrtric trim but not an Auto trim which is managed with the AP. Yes it has 100 % torque. An it worked until yesterda in thermal situatuons very good. Yesterday was really bumpy, maybe i willl have to try it again. Unfortunatlay we are grounded for two weeks due to our home airport.