Thank you @JulianOes, your assmuption seems to be correct. Motor 4 (connected to output3) actually is deat. It cant figure out what way it should rotate. Thus my assumption is that one of the coils is burn down in some reason. Now i have to figure out what was that reason.
I have Sunny-Sky II 980kV motors with 1045 props and TBS Bulletbroof 25A ESCs (BLHeli_S firmware) with default settings. My main concern is that there is Brake on stop enabled by default. If i undrstand correctly this parameter, then it should actively break motor with sudden high current in counter direction. Can it cause too high current peaks to motor, thus burn it?
ESC itself seems to working correctly with spare motor.
EDIT: Did some quick research. Seems that brake on stop feature goes into play when PWM dissapears (with kill switch for example i presume) so it should not have any affect during normal flight. Correct?
Instead it might be damping feature what can cause problems i guess?
Or it was just bad coincidence.
EDIT2: I did one more test flight. Log is here
It was quite ok, with manual, altHold and PosHold mode. Little over reacting for control sticks, but in overall quite stable.
Until it again crashed in manual mode. This time ended with broken arm. Motors are working correctly after crash.
From to log i noticed taht vibration is in in red zone. But i can not figure out is it “bad” red, or “quite ok” red?
EDIT3: Tho i can also see similar wierd patten for Output3 just at the time when crash started. According to 3D view it started to trop at 04:26.200