Loiter crash // root cause?

Log Analysis -- deprecated Copter Logs -- deprecated
1

My copter crashed in loiter mode.

  • APM1
  • 500mm motor distance
  • 1100kV motors
  • 9x4,7 props
  • 2200mAh 3s
    With previous firmware 2.7 loiter behaved absolutely stable.
    Now, at the first flight after update to 3.1 I had problems.
    First I observed pitch oscillations during forward flight in loiter mode.
    Then I applied yaw. The copter became instable. I tried to switch to stabilize, but the copter crashed. No big damage, only the landing skid.
    Can someone give me a hint, what is wrong with the copter? See log at line 10400.
2

Mediatek GPS?

3

No, I have equipped the copter later with a 3DR LEA 6H GPS.

4

X or + frame? If it is an X frame, I would say you lost your back right motor.

5

The solution is quite simple.
ESC calibration has not been complete.
Apperrently the motor output signal fell below zero baseline of ESC input during attitude control.
Consequence: Delay of power increase and stability problems.
So the advice to check Motors and ESCs was correct.
Thanks for your help,
Jens