Arducopter 3.5.7 Crash

X- Quadcopter running Arducopter 3.5.7 had an unusual crash. Fresh build and performing well first 2 hours of flight time on the airframe.

Was flying, flew up to ~18 meters in altitude when the drone flipped towards motor 3 after being switched into stabilize mode.

My initial reaction is to think there was an ESC failure on motor 3 but I’m unsure at this time, any help would be appreciated.

I must note, propellers were undamaged and not loose on copter.

log_40_2018-8-23-12-49-08.bin (719.0 KB)

I have to ask, how is your Pixhawk mounted, your vibrations are so small…

the log confirm what you say. Why it happened, is not clear, what is clear is that flight controller commanded more thrust on #3 , but did not receive.

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It is quite clear that your # 3 motor failed. At the same time as #3 goes full power, the opposite motor, #4, goes to zero and the copter losses attitude control consistent with this. Why it failed, esc, connector, or motor winding is for you to determine.

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Thanks for responding, I have confirmed that #3 ESC is demonstrating odd behavior upon any little bit of heat is induced to it.

I contacted the manufacturer to confirm that it is indeed a faulty ESC. Will do a final update.

Hi Kenneth,

The Pixhawk is actually hard mounted, and the airframe in general is extremely rigid, but extensive care was taken to balance out the motors and propellers, prior to mounting them.

My experience with soft mounted motors mostly lead to fatigued grommets which only make vibrations worse. (DJI S1000).