Pixhawk Full Failure

Really need help. Pixhawk in our QAV 540 has been flying great for months. Until yesterday there was a catastrophic failure on the second flight. Launched in loiter flew up approx. 20 feet, moved left over a cliff, suddenly it just fell from the sky. Looks like power just ended or something, turned over upside down and cash. Total write off. I have attached the last 3 files from the SD card. We are of course very concerned about the unpredictability as we have three other builds underway. Can you please have a look to see if you can see something?

It looks to me like a failure of the left rear motor or ESC. As your troubles start your Pixhawk is requesting more power from the left rear motor. At the same time it’s telling the right front motor to cut back power. The other two motors are sort of holding at midrange. This suggests the APM was attempting to counteract a rolling action toward the left rear motor. It could be a failing ESC (they can go bad for no good reason), possibly a failing motor, or even a bad connection or solder joint for that arm.

It really doesn’t matter that it’s been flying great for X number of flights. This sort of random crap happens all the time, and can do so without any warning.

So…my vote is for mechanical/electrical failure somewhere in the left rear arm. I see no evidence of a problem of a problem with your Pixhawk. The Pixhawk was trying to save it. Something else on your quad let it down. It appears you tripped off a few GPS and radio failsafes as the quad tumbled. But they only happened after the acrobatics began.

Excellent tips otherhand. Can you tell me how you detected the left rear issue from the logs? Did you plot any particular attributes? Would love to learn from you on this diagnosing skill