Uncommanded Pitch Down when AP engaged

[Fly4fude]

Greetings,

When I engage the autopilot in "ALT/TRK" simplified mode it initiates an increasing pitch down command until I disengage. (It does this in any mode I select. . . thoughts?)

I have searched the forum and found a somewhat similar discussion involving the setting of the IAS bug. Not sure it is relevant when I am trying to simply hold level altitude.

 

[dynonsupport]

Did it work in the past and is now not, or has it never worked?

Two possibilities (but not the only ones):

1) Failed G-meter in the ADAHRS. Check that it reads 1G on the ground.

2) Reversed servo calibration. Run the servo test and make sure it moves the pitch in the correct directions.

 

[Fly4fude]

It has done this everytime I've attempted to engage AP. I'll check gmeter tomorrow.

 

[DBRV10]

Are you on later software?

I used to get this randomly, and a later version plus some trim speed changes and sensitivity changes, so make sure the software is current and check your settings. If the trim speed is too slow it might be an issue.

 

[Dynon]

One more outside possibility is that your low airspeed limit is set very high, and you're below it when you engage. Then, SkyView would pitch down to try to attain the minimum airspeed. You'd see that annunciated in the AP status area though.

 

[DBRV10]

That is a good point.

Unfortunately that was not ever a problem I had.

But worth checking in any case!