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Plane 3.9.10 Pixhawk reboot in flight

Hi everyone, as the title said, I had a in flight Pixhawk reboot, resulting in a forced landing… sort off.

I have CUAV Pixhack v3, external mag and airspeed sensor, mounted in a tri motor Vtol.
I had already done about 5 short testing flights on this without incidents, until today when the midair reboot happened.
I was lucky enough to have the plane rather close when I noticed the motors stopping in FBWA mode. Not knowing what happened, I switched to Qstab to save it, since it was about 5m high. It switched modes and the motors started, allowing me to bleed off speed and to get it closer to the ground. This did not lasted long, at about 2m high the motors stopped again and I heard on the telemetry “Throttle Disarmed”. Of course it plunged nose down but it’s not too bad, just the tilt servo mounts and a prop broke.
Checking the logs I see the log stopped and than another one started getting the data from the quick descent.

So, let me attach the logs, maybe someone have a better idea about why this happened.


It clearly rebooted, “why” is harder to explain.
The watchdog picked it up, and it’s handling, despite logging “Ground start complete” saved the day.
You have very fine VPP, (5v) supply, and the servo rail is too high to be useful for backup power.
I see no reason to suspect your voltage regulator, but it could be one obvious reason to a brownout.
Can you confirm that you supply two 5v sources to the (not counting servo rail) - and both are still ok? (try to pull one at a time).

Thanks for checking, while it is true that I don’t have power redundancy due to the servo rail set too high, I think that if the VPP supply would go bad we should see a glimpse of voltage going down before reaching the point of brownout.
Anyway I’ll lower the servo rail bec voltage to have it working as backup power as well.

@Romeo_E Out of curiosity, did you find the problem?

It seems it was the dreaded I2C storm that rebooted the FC.
Since then I have installed the newer firmwares and had not encountered any more inflight reboots.

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