Sudden shutoff mid-air

[eligri]

Hey'a!

Bought and refurbished a M2P. Ran good for 3 flights, but on flight 4 it shut off at 200ft and fell into the ground. Was decending from 300ft, and once reached aprox. 200ft all motors shut-off and it just dropped.
Now it won't bind to remote again.

And no, didn't do the emergency shutoff movement (sticks to center or outwards).

70%+ battery, and newest firmware.

Any idea what could have caused this?
I'll transfer flight log when home tomorrow.

Cheers

 

[Thomas B]

Sounds like a swelled battery disconnected from the drone… —> no power or signal.

not sure about the binding issue… can you post the flight record for our experts to analyze?

 

[eligri]

Sounds like a swelled battery disconnected from the drone… —> no power or signal.

not sure about the binding issue… can you post the flight record for our experts to analyze?

I'll tear apart the battery and check for swelling. No visual swelling on the outside though.

I'll post flight records tonight.
Thanks!

 

[eligri]

So tore it apart. A ribbon cable "core" was disconnected. Reconnected it and all is working fine by some miracle; other than the front right sensor (which already was broken).

Will post flightlogs soon

 

[eligri]

DJI Assistant 2 won't show any flight logs. Just blank loading page.

 

[eligri]

Ok so got flight records off my phone. Attached here.

Need the DAT file also?

EDIT: Also, didn't pull apart the battery. No visual swelling, and app shows voltages at 3.91, 3.9, 3.89, 3.89.
So doesn't look like any faulty cells.
Also status shows; "connection OK".

 

[GFields]

I am surprised that there is anything left after a 200' fall.

 

[Arnold LeVine]

I am not surprised, I am SHOCKED there is anything left after a 200' fall.

 

[eligri]

Same. What really surprises me is that the props, covered in dirt, simply washed clean. No cracks, dents or bends on them. Couple little scratches, but surface level only.

Small crack to the gimbal mounting base, but that's a simple glue fix. Clean break in a non-stress spot.
Arm joint/axis bent; but simply bended straight and still feels strong. All landing gear fine, gimbal fine, motors fine, sensors fine, camera fine, etc.

Miracle.

 

[slup]

Ok so got flight records off my phone. Attached here.

Need the DAT file also?

EDIT: Also, didn't pull apart the battery. No visual swelling, and app shows voltages at 3.91, 3.9, 3.89, 3.89.
So doesn't look like any faulty cells.
Also status shows; "connection OK".

Yes ... your AC lost all thrust midair. No typical signs from a thrust problem on either corner is found, so this isn't one lost prop or motor. The log records the whole way down so it isn't a power loss either ... battery on 66% with healthy cell voltage levels.

At 350sec into the flight up on 58m height, while you were descending with 3m/s the AC suddenly starts to free fall & tumbling down reaching a speed of nearly 20m/s ... at 353sec a "NotEnoughForce" error is shown in the log (the light blue background color in the chart).



The mobile device DAT log ending with FLY080.DAT is needed to pinpoint this further ...

 

[eligri]

Yes ... your AC lost all thrust midair. No typical signs from a thrust problem on either corner is found, so this isn't one lost prop or motor. The log records the whole way down so it isn't a power loss either ... battery on 66% with healthy cell voltage levels.

At 350sec into the flight up on 58m height, while you were descending with 3m/s the AC suddenly starts to free fall & tumbling down reaching a speed of nearly 20m/s ... at 353sec a "NotEnoughForce" error is shown in the log (the light blue background color in the chart).

View attachment 130687

The mobile device DAT log ending with FLY080.DAT is needed to pinpoint this further ...

Thanks!
Requested file attached

All props were, and are, fine. All attached after crash. No odd sounds while decending, just free fall. Believe the motors started once while falling, but I'm not certain (went so fast). Battery was next to craft, but think it flopped out upon impact.

Could this have been the lower PCB that disconnected from the mainboard? Noticed that the ribbon cable marked 'core' was off after teardown. Not sure if caused by crash, or the cause for the crash.

 

[Kilrah]

Log shows all 4 ESCs being disconnected at 52m height, so seems like the latter.

 

[slup]

Thanks!
Requested file attached...

Log shows all 4 ESCs being disconnected...

Yep, that's the case ... something broke the link to the ESC's



All motor data in the log flat-lines after 349,9sec ... oddly the FC continues to command some of the motors for a short period after ... the right front goes to 96% at 350,05sec & stops, the rest continue to get commands to 350,87sec then also stops. This could indicate that the ESC for the right front was the initial culprit.

 

[eligri]

Yep, that's the case ... something broke the link to the ESC's

View attachment 130690

All motor data in the log flat-lines after 349,9sec ... oddly the FC continues to command some of the motors for a short period after ... the right front goes to 96% at 350,05sec & stops, the rest continue to get commands to 350,87sec then also stops. This could indicate that the ESC for the right front was the initial culprit.

View attachment 130691

If the ribboncable dropped, wouldnt all 4 DC at once?

 

[slup]

If the ribboncable dropped, wouldnt all 4 DC at once?

What we see in the log is a 3 step time separated event ... At 349,9sec ALL motor side data goes flat



0,103sec later the FC commands the right front motor to 96% ... & goes flat



And 0,812sec after that the rest of the motors gets their last command from the FC ... and goes flat.



This is maybe a coincident & doesn't mean anything ... I'm not familiar on how the electronics in a M2P is designed so can't say for sure. What's for sure though ... is that the ESC's got disconnected & that meant a sudden end of the communication between the motors & the FC.

If that ribbon cable had something to do with this it should be easily tested ... connect it & try to arm the motors with the CSC command, if they start to idle fine. Then disconnect the cable & do the same ... if they don't start you have found the reason.

 

[Kilrah]

If the ribboncable dropped, wouldnt all 4 DC at once?

Well in the report they all show disconnected within 20ms, and there being any difference is likely more of a matter of the logging/detection than an actual difference in when they actually disconnected.

 

[eligri]

Happened again twice now, during test flights.
Checked all cables, all are seated well. No visible damage to Core/Main board nor ESC. All motors re-boot after aprox 30 seconds.
Error shown in app is:
"ESC status error".
No motor specified.

 

[eligri]

I believe these are the correct logs.

 

[eligri]

I believe these are the correct logs.

Sorry forgot to tag you, @slup

 

[slup]

Same incident as the earlier one... all motor side data freezes at 511,773sec with the messages in the DAT event log about disconnected ESC's. At 569,287 the ESC links are reestablished for a unknown reason.



DAT events at the time when the ESC's disconnect:


And when they reconnect:



So no more to go on this time either ... perhaps time to get it in for a repair before something more catastrophic happens.