Crash Analysis II

Hi Forum

Would really appreciate some help analyzing my latest crash. The quad seems to have lost power, causing it to descend and crash-land. I assumed it was a loose spinner again (despite my precautions), and the spinner on motor 3 was indeed loose when I found the quad. However, according to the log it is motor 2 that gets maxed out in the lead up and during the descent. Motor 2’s prop was tight.

Also, motor 3’s carbon prop had a chip out of the end, the only damage from the crash. Indicating that it hit the ground hard. If it had already been loose, this damage would surely not have happened.

I’m really confused. The only conclusion from the current state of the log is that motor 2’s power unit semi-failed. Causing it to lose enough power to descend the quad, but not a catastrophic failure of the kind that would flip the quad. The motor and ESC seem fine, and the quad flies fine in stabilize. Any feedback on what is going on here would really be appreciated.

BTW this is a 3DR PixHawk (3.1.5) based quad with HobbyWing (unflashed) 30A 6s ESCs, 380kV motors and it was flying with 12x38 SF Carbon props.

I think I’ve solved this myself. It wasn’t a prop or power unit failure, it was a basic thrust insufficiency. The quad was flying into wind and trying to maintain a mission speed of 10m.s. The wind on the ground was about 4m.s, aloft it could have easily been 6m.s. Assuming APM’s mission code prioritises waypoint attainment/RTL over altitude hold, this crash landing would make perfect sense.

I’ve posted a new question here: viewtopic.php?f=10&t=10056

The answer should clarify my situation.