AC3.5.2 AutoTune Crash

I have recently updated a 600mm class quadcopter (X-666 frame) from an APM 2.6 (It went up in smoke) to a Pixhawk 2.4.8,

This is my 3rd Pixhawk so I’m up on setup, config, and calibrations.

Yesterday I completed the power monitor calibration so this morning I wanted to run AutoTune.

I took the aircraft out, powered it up, waited for GPS lock, armed the motors, waited for the AutoSave LED dance, and took off.
I hovered until the main LED went green and landed to save the trims. (Not that I had any to save…)

I armed the motors, took off and established a hover out of ground effect.

I switched to Loiter. Every thing was fine so I switched to PosHold. Again things were fine so I switched to AutoTune.

Taranis announced “AutoTune Flight Mode” (I’m using C&T Flight Deck), the quad twitched roll left, inverted, and crashed.

The only physical damage was a broken GPS mast…

Here is the hardware list:

X-666 Quad
Dry Weight (no battery) 1545
APM 2.6 w/GPS, telemetry radio
2 4S 5200mAH 15C LiPos in parallel
Generic 5010-530Kv motors
Tall landing gear
1555 CF Props
Hobbywing Pentium 30A ESC
200mW vTX w/CP Antenna
MavLink OSD

I suspect a motor de-synch. I have some Hobbywing Platinum Plus 30a ESCs, so I’ll make the swap and try again.

Any further guidance or assistance will be appreciated.
3DR Telemetry Radio
FrSky X8R RX
CCD FPV Camera

Uploading a data log would enable people to have a look at what happened and offer some suggestions.

I went through the logs and nothing jumped out at me. The flight only lasted about 2 minutes so the logs aren’t very long.

Link to .bin and .log files:!ArOZGChodNsHtCKBQYXz2Dct8Hj-

Seems a motor2 failure for me, copter started to pitch up and roll left, while RC2 went to max…
Autotune did not started yet, at least no DesRoll and DesPitch changes till the crash…

That’s pretty much what I was thinking, so I replaced all of the ESCs with a set of Hobbywing Platinum Pro 30A OPTO ESCs.

I took the aircraft out this evening after dinner and got a successful AutoTune.