I was flying my Trex 450 trad heli with an APM 2.6 running 3.0.1. I was doing auto takeoffs. 20% of the time these result in uncontrolled climbs so I was trying to tune out the throttle.
This time it took off and I let it go. It hit the 85ft altitude fence and kept going to about 160 ft.
Then, the motor quit. As it fell, I noticed the lights were still on but no motor power and no control.
When it hit, the APM was still receiving power but still no GCS contact. I had to recycle the power to get the system to respond. (worked normally)
As I looked at the logs, both the GCS and onboard logs show the climb and then nothing. Neither show the descent. Neither show a throttle down. The only error was two alt fence breaches. I've ruled out any power problem. Good volts all around on a fresh battery.
I can find nothing that indicates a problem except the Nlon count was climbing during the flight to a max of 85 before failure.
Good news is that the damages were limited to blades and nothing a little glue can't fix.