Two hexacopter fail and crash (EKF_CHECK-2)

ArduCopter Copter 3.5
1

I have the same problem on two drones with different versions and configurations. Versions 3.5.2 and 3.5.3. Several flights working perfectly the two but then the dron takes off and after a few seconds begins to tilt until crash.

https://mega.nz/#!s5VjgbCY!5s_F77_lUh2thMwnTJxcHiC--9qHNW18GeibfmJ6upw

https://mega.nz/#!U51SUCib!s2ahi7BH_nJJr-7hui1U-CYDBgzpw09H8q1ihfczSVU

2

004.BIN : Vibrations grown into insane levels during the flight, something was falling apart as you flew, the data for the autopilot were garbage.
056.BIN : motor/prop/ESC 3 failed, the log is not oblivious about that, maybe due to bad tune, but it’s easy enough to see.