Trad Heli Users,
I am writing to warn you of the higher probability for an in-flight motor shutdown in Auto or Guided flight modes. This is occurring because the autopilot declares land complete in flight which initiates the auto shutdown and disarm sequence. The root cause of this was determined to be due to the new integrator management implementation. That PR changed the landing detector logic which overrided the suppression of the land complete declaration when the aircraft was not in a landing state in auto or guided modes.
The best way to guard against this other than reverting back to AC 4.0.5 is to set the H_COL_MID parameter as low as possible to prevent the current collective from going below the H_COL_MID value (which is used to determine land complete). Suggest making the H_COL_MID value equivalent to - 2 deg of collective pitch which should be acceptable for extended ground runs with rotors turning in Loiter or althold modes. If you experience any issues with rotors turning on the ground, raise this value as needed but -2 deg should be safe. If you are using the collective to yaw mixing (H_COL_YAW non zero) then you may choose to revert back to AC 4.0.5 or turn off the collective to yaw mixing by setting H_COL_YAW to zero. The reason I say this is that the collective to yaw mixing feature uses the H_COL_MID parameter to set the zero thrust point(minimum torque) for the collective to yaw feedforward.
I am working to implement a fix to this bug as soon as possible. Planning to get it into 4.1.0 before it gets released as stable and potentially providing a point release to 4.0.7.