AP won’t hold alt

[rockitdoc]

HDX or PANEL-AP. Whether in expert or basic modes. Calibrated it twice. If I set it to ALT HOLD at the current altitude with current altitude selected it holds for 30 sec then either starts to climb or descend usually with trim up or trim down indications. I can’t trust it. Sometimes the vetical speed increases significantly to point where I have to disconnect the AP.

Any ideas appreciated. Units are 2022 models.

 

[airguy]

Your trim is wired backwards.

 

[jakej]

The calibration process will fix that - eg when it ask which way the tab moves - there’s the clue
You do not need to reverse the wires with the Dynon system at all.

 

[rockitdoc]

Your trim is wired backwards.

Don’t think so. Calibration moves controls in correct direction. Of course that doesn’t activate trim, so I’ll check to see how trim is wired.

 

[RV7Builder]

Hi, we have the same issue sinc yesterday. Until yesterday it worked fine. Do you think we have to make a nwe callibration ?.

 

[rjones560]

Is your pitch trim wired through the Dynon autopilot control head? If it is then do the trim calibration procedure. It will ask you which way the trim is moving during calibration and electronically change it if it is moving in the wrong direction.
If it is not wired through the Dynon autopilot control head then you will not have auto trim available for the autopilot.
If you have the aircraft trimmed at cruise speed before engaging altitude hold there is some other problem. You can check your autopilot servo settings. There may be an issue there.
It would be helpful to know what aircraft and if you have the autopilot control head.

 

[RV7Builder]

Hi, no pitch trim is not wired through the AP panel. We have manual trim. It is an Rv 7, and it worked all well until yesterday, so there must be anything that changed. Maybe i need a new calibration. In the past the trim Advive message appeared within severeal Minutes. ANd it worked fine.