X8 coaxial heavy lift crashed in automode

X8 coaxial 20kg airframe loaded with AC 4.0.4

Yesterday i have tried auto mode with 6m/s waypoint speed & everything went well up to 20min of flight and suddenly there was immediate crashes .i don’t know what could be the reason.
Bin file attached here.

parameter file
2020-10-05 14-55-05.log.param (18.5 KB)

motor out graph shoeing that there is a issue with motor 2 and 5 .

Hello! I think the problem were motors 1 and 6 because they were at maximum while 3 and 8 were at minimum. So it seems you had an electric problem in the connection of those two motors (1 and 6) because it would be strange that two ESC or motors burned at the same time.

Check those connections and see if there is something strange in those two motors.

Hi i am having problems with the same poss set up as you. two or three motors spin down at flight settings. i am using the pixhawk 4,
mine weighs 14Kgs, what settings are you using set up any help would be fantastic to get this flying. so far not had much help from the guys on here.
i did what one guy said just get it flying and it will sort its self out. hmmm that nearly cost me a very very expensive copter lucky I had it tethered, only 2 ft off the ground.

What was the fix you came up with?

Thank you David .

But we were seen in the air that front left arm (motor 2& motor 5 but not sure ) broken in the mid air.

So can you relate with pwm out and justify which arm or where is the problem occuried?.

I agree that it looks like Motors 1&6 lost thrust (RC out command to max) and the opposite arm motors (3&8) dropped to attempt Stabilization. Overall lack of thrust to fly and Return To Earth.

On that log file time is around 11:27; on your RCOU graphs around 15:17.

Refering to the log:

Vibration starts, CTUN.ThO goes to 1, and even oscillates.