Unusual octocopter crash

ArduCopter Copter 3.5
1

Hi guys,

Our customer had a crash with one of our large copters.
Customer reported normal flying in auto mode until there was a large oscillation in pitch/roll. He took over in loiter mode but had to bring it down since there was not much control.

I would like to get a second opinion on the data attached. I noticed a lot of vibration and suspect that one of the motors may have twisted in flight. I also see that there was a GPS glitch before the crash.

https://drive.google.com/file/d/1x3ciN8-Wm6DvaowwEg8WgfOvEUANwTD9/view?usp=sharing

Any input will be appreciated!

2

Looks like Y vibes and RX errors increased right before the oscillations started and Loiter by Radio. The GPS glitch might just be a symptom of the oscillations since HDOP was rising fast once the craft was getting out of control.
In my inexperienced opinion, looks like a mechanical issue, something coming loose.

3

The vehicle was certainly yawing when it didn’t want to. That supports
your theory.

And yes, those vibrations are Not Good. And the magnetic innovations are
constantly climbing.