Hexa crush, Log file analysis Please

Hi guys,

I’ve been trying to figure out what happened to my hexacopter S900, but with no luck. I had couple flights with no issues, but after updating to APM 3.3.1 my hexa suddenly crushed. Fortunately i was flying very low and only one propeller got broken, but what caused this crush i don’t know. I would appreciate if someone could look at the log files and give me an idea what was wrong.

My gear:
Pixhawk APM 3.3.1
Frame: S900 hexacopter
400 KV brushless motors
40A simonK ESC
15x5.2" propellers
6s 16000mAh battery

dataflash log:

drive.google.com/file/d/0B6GRJS … sp=sharing

Just looked at datalog.
What I see predominantly is Very high Z vibrations. I really think that is your problem.Hope that helps.

Test: Compass = FAIL - Large change in mag_field (50.63%)
Max mag field length (635.25) > recommended (550.00)

Thanks @servoman1, the z vibrations looks quite high, i have missed those ones, because graph of AccZ looks pretty good, so i though that vibrations are ok. and i know i have mag field above recommended value, but i have been trying everything and cant go lower than that, any suggestions?


Without seeing your Drone,it’s hard to say.
But, I highly recommend Kyosha zeal tape.Amazon sells it.I use it on the 4 corners of the FC.
Also,keep all wires(servo cables) and wiring off of the FC.These can vibrate in flight.
Good luck with your drone.

It looks like a failure of motor #4 (back right). The reason I think so is the actual roll and pitch angles suddenly diverge from the desired angles (they were tracking ok before the crash although the tuning, especially on the pitch was not very good). The actual angle shifts back (positive pitch) and right (positive roll). Backing this up is the motor output which shows motor #4 going to full (and it’s opposite motor, #3, going to minimum) which is a classic sign of a motor failure.

I’ve attached the graphs and here’s a link to the motor map in case that helps.
copter.ardupilot.com/wiki/connec … xa_octo_y6