Complete Shutdown at high alt. Can't figure out why.

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.

Any clues?

Good news is that the damages were limited to blades and nothing a little glue can't fix.




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  • Hi Ray,

    I had a look, unfortunately I can't see any reason for the brown-out at all.  Not saying it didn't happen, clearly it did as the log just stops.  But I just don't have any data to tell you what the cause was.  Vcc is slightly noisy, and slightly low (how are you powering it?) but nothing that should cause a failure.

    As for the flyaway altitude... I'm not sure what's going on there yet.  You have a sonar plugged in?

    Have you ever looked at the vibration on this heli?

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