Game of Drones - Mavic crash

[MML]

So do you guys think this is a faulty aircraft, or is this something common to all Mavics? Is this something that DJI is aware of?

Would it be a good idea to use my DJI Refresh on a replacement? As it stands, the rear arm seems looser than it should. Plus the fact that the shock of impacting a rock face can't have done the aircraft any good.

 

[sar104]

Yes, but this is even more interesting. @MML had submitted a FLY131.DAT back in June. Pretty much the same problem. The eventLog says that compass #1 is stuck and the flight uses compass #2. Towards the of the flight problems with Mag:X(2) get large enough that a switch to ATTI occurs.
View attachment 24089

Here's the Dropbox link for FLY131
Dropbox - FLY131.DAT

The compass had been calibrated at the beginning of FLY131. And, it's also been calibrated since FLY131.

So that's the same aircraft? If so then the similarities between the magnetometer discrepancies would suggest to me that that the aircraft needs new magnetometers. It doesn't seem reasonable that it would be a calibration problem suddenly occurring in the middle of a flight.

 

[BudWalker]

@MML is there an external device mounted on the top rear where the GPS/Compass1 is located? I'm sure you would've mentioned it, but I had to ask.

I agree with @sar104 , There is something odd about this. First, compass #1 gets stuck, then compass #2 operates OK for a while and then starts to have problems. These are separate pieces of HW.... Anyway, if it were mine I would send it to DJI repair. If you don't want to do that then @Thunderdrones is a good guy to repair your Mavic.

I've collected about 500 .DAT files related to various incidents. I automated looking through them all. There are a few cases where a switch to compass #2 occurred and the flight continues without incident. But, there is one like yours that I'm looking at.

 

[MML]

No, nothing mounted there; the only attachments I ever fly with are the little plastic leg extensions, apart from that, it's completely standard, not even stickers, skins etc.

Am I right in saying the DJI Repair and DJI Refresh are two separate entities? Or does a Refresh mean a repair? (As opposed to a replacement.)
Or would it be best to let DJI make the judgement call?

 

[BudWalker]

.......
Am I right in saying the DJI Repair and DJI Refresh are two separate entities? Or does a Refresh mean a repair? (As opposed to a replacement.)
Or would it be best to let DJI make the judgement call?

I like to think my forte is analyzing flights and writing software that helps with that. Determining how to deal with DJI - not so much.
Good luck.

 

[MML]

Thanks for everything you have done Bud, this forum would be a heck of a lot worse off without guys like you! Keep up the good work!

 

[MML]

And of course thanks to everyone that has contributed to finding an answer... it is hugely appreciated!

 

[f3honda4me]

The switch into ATTI seems to be related to large discrepancies between the yaw values computed by the FC from the IMU sensor fusion data and the yaw based on magnetometer data alone. That has nothing to do with GPS per se, but often seems to trigger a switch to ATTI.

Correct if the discrepancy becomes too great, the craft will go into ATTI since it has to throw away that data.

 

[f3honda4me]

By the way super jealous that you get to film where game of thrones is filmed.

 

[MML]

Update:
I just got an email from DJI's Repair department. They're replacing the following, free of charge:

• Middle Frame Module
• Battery
• Propellers
  
• Rear Left Motor Arm

What is the middle frame module? Is that part of the internal chassis?

No mention of what caused the crash... or is that something they tell you?
I'm concerned it will happen again.