Huge Quad sudden drop out of sky

Log Analysis -- deprecated Copter Logs -- deprecated
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1

Hello guys, I’ve been making a maiden flight for a big quad (135kv motors, 28" propellers, 6S Lipo, MRO Pixhawk)
I did an autotune on roll and pitch axes, it went perfect, the copter behaved perfectly. After the autotune I did a test flight, after like 10 minutes, the quad started to descend quickly and hit the ground, I switched from loiter to stabilize and hit max throttle, but it didn’t help…
I can’t figure it out what is wrong. Can somebody please look at the telemetry log to see what happened, I couldn’t find anything suspicious.

Telemetry log of the incident

Thank you for the help in advance.

Have a nice day guys.

2

seems like motor/esc fail.
motor 2 failed (maybe thermal throttling? esc fail/motor fail) and goes to max,
other motors try to compensate for yaw and lower throttle. Motor 7 goes to almost zero.

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3

Thank you for the reply aamadeuss, it is a quadcopter, I only have 4 connected motors.
I will try changing the ESC’s and let’s see what happens.

4

I concur. However, it was a partial failure or a throttle back since it did not crash. Btw, pwm 1700 for loitering seems a little bit high, isn’t it underpowered ?

5

Thank you for the response Andras, if you look at CTUN THo param, the Quad hovers at ~35% throttle, the power is ok, I think…

6

hahah sorry for the motor 7 :smiley: it was motor 2 at 100% and motor 1 at 0% (for compensation)
take a close look at motor/esc 2!

7

Hello guys, I’ve finally changed the ESC’s and the problem was an ESC fault, most probably at motor 2, as amadeus suggested.
Thank your for your kind help, love this community.
Regards,
Sarge