Hi Guys, I’m very close to my maiden flight and just trying to work out a few bugs. I’ve noticed that in FBW mode if I hold the stick to roll left, the elevons will jump back to neutral after a few seconds. This doesn’t happen when I push the stick to the right, and it doesn’t happen in manual mode at all.
This is probably the anti-stall code. There is an open issue on this
github.com/diydrones/ardupilot/issues/1892
Basically because the plane isn’t moving the APM thinks your going slow and reduces the throw of the surfaces to prevent stalling. Great during flights - not helpful on the ground when testing 
Thanks, Grant.
Easy way to rule it out though. Change STALL_PREVENTION to 0, write paramaters and try the bench test again
I want to revisit this issue. I thought it went away when I updated to the latest version, but I was wrong. The problem was masked by my dual rate setup. It turns out that this happens in manual mode too. If I roll to left and hit 901ms the autopilot will jump back to center. If I reduce my rates, so I never hit 901ms, it won’t happen. So I have a work around, but I’d really like to know the root cause. It’s not related to anti stall, any other ideas?
If it’s happening in manual then it implies it’s your transmitter or receiver having an issue as in manual mode the FC does nothing.
Do you have any log’s of this happening in manual? it sounds as if the tx is moving too far in it’s range and defaulting to a neutral (midstick) output.