I have an APM 2.5 running Arduplane 2.74b. I have the autopilot mounted upside down. I have already changed the relevant setting and re-leveled the plane.
So, my problem is that when I switch to FBWA the rudder centre position offsets to the left. The offset is probably about 40% of the full servo range. That's a lot, almost at the end of the range.
The plane is a rudder-elevator only model. I have set the rudder to aileron mix to 1. The offset doesn't happen in stabilize mode. The rudder stays centered as in manual mode.
I was planning on tuning the pid controllers, but did not dare to fly the plane. Any recommendations?