Mavic Air Crash??? (Uncommanded Descent into water and then 2 flyaways)

[arunkennedy3]

Hi,
So I went flying at the beach and from the start the Mavic Air was behaving weird. When I powered it up the controller was beeping but there were no error messages on my screen so I just restarted everything and the error was still there with no indication of what it was beeping for.

I foolishly ignored the beeping and proceeded to take off and hover about 5 metres up and the beeping stopped.

So I flew around and took some pictures and went out over the water for the first time. When I proceeded to bring the drone back by pulling back on the right stick the drone also began to descend. I didn't notice this until it was just about to touch the water which can be seen in the video.

Eventually I got it back over to me and hovered and as I tried to land it, it took off on its own and no matter what I did with the remote it didn't respond until I pressed the return to home button. I proceeded to return to home and then hovered 30 metres above the home location and started to lower and then again it took off on its own and flew for a couple seconds and then eventually just dropped out of the sky.

After reviewing the flight Log footage, it displays that the drone was getting a descent input when it was coming back initially which is why it ended up in the water briefly. I was not giving it the command to descend. Would this be due to me not calibrating the compass prior to take-off?????

I got the drone back anyway and the camera and Gimbal are the only things damaged. Everything has been cleaned off with Isopropyl alcohol and I've tested it and everything works fine but the gimbal is in two pieces and the camera lens is cracked so I am going to replace that. I can get a camera and Gimbal on ebay but I'm not sure if it will calibrate correctly with python without the error 3 because it would be a new camera and Gimbal?? Does anyone have more info on this?

Has this ever happened to anyone else and what do you think went wrong? I have attached the flights logs as well if anybody would like to have a look

Any help is greatly appreciated,
Thanks

 

[arunkennedy3]

Link to the video

 

[BossBob]

Constant calibration of the compass does more damage than good!
If you follow the instructions in the stickies at the top of this forum and post the flight logs someone will be along who can probably tell you what was happening.

 

[arunkennedy3]

Link to the Flight Log

 

[slup]

...When I powered it up the controller was beeping...restarted everything and the error was still there with no indication of what it was beeping for.

The beeping from the controller meant that something was wrong ... in this case it indicated just what you experienced later in the flight, that the sticks didn't functioned as they should. The log show several occasions when the throttle stick (left forward/backward) gives erratic inputs very much like "ghost" inputs due to malfunctioning hall sensors in the RC. We have seen this several times before, the pilot gives one stick input & at the same time another is given in a erratic pattern. You should have calibrated the sticks ... that might have solved it, if not a cleaning of the Hall sensors is needed,

...When I proceeded to bring the drone back by pulling back on the right stick the drone also began to descend. I didn't notice this until it was just about to touch the water...

You wasn't just about to hit the water ... in your clip it's obvious that you actually dipped your drone partially in salt ocean water.

Eventually I got it back over to me and hovered and as I tried to land it, it took off on its own and no matter what I did with the remote it didn't respond until I pressed the return to home button. I proceeded to return to home and then hovered 30 metres above the home location and started to lower and then again it took off on its own and flew for a couple seconds and then eventually just dropped out of the sky.

All these problems most probably are direct related to your drones bath in the ocean ... you have the battery on the bottom, a lot of electronics inside & electrical motors out on the arms. When your drone started to behave it most probably was a lot of failures in vital systems that normally keep your drone flying steady... due to salt water.

Furthermore ...

The battery you used in that flight ... it was already from beginning a ticking bomb, massif voltage drops from all cells already on the first ascent after take off ... only a minute into the flight one of the cells were down to 3,17V ... that's 0,17V away from a forced low battery auto landing ... and you being over water ...

A healthy battery have approx 3,5V/cell when the BMS show 0%.

Dispose of that battery in a proper way immediately...

(Click on the chart to make it larger)

 

[arunkennedy3]

Thanks very much for your analysis. It seems you've hit the nail on the head. It was probably the coldest I had ever flown it. 3/4°C which I believe would have probably contributed to the battery and the controller.
Also, yes it did go in the water, sorry if i didn't clarify that properly. I will take apart the controller and clean sensors to be sure it doesn't happen again any time soon.

Thank you very much ))

 

[slup]

...I will take apart the controller and clean sensors to be sure it doesn't happen again any time soon.

Follow this for disassembly & what/how to clean ...

 

[arunkennedy3]

Perfect, in regards to the camera/gimbal. I believe the camera is linked to the motherboard so an authorized DJI repair centre must do the repair. Is this true?

Thanks

 

[slup]

Perfect, in regards to the camera/gimbal. I believe the camera is linked to the motherboard so an authorized DJI repair centre must do the repair. Is this true?

Thanks

Most probably yes ... you probably can get the camera to work by doing it yourself, but you will have an error showing all the time.

Maybe you can get it to work without errors by following this ...

 

[arunkennedy3]

Brilliant, thanks for your help

 

[Dunc's]

This is exactly what my drone is doing, I think it may be an up date problem. I have tried cleaning the toggle, by completely dismantling it, as described, still no resolve, this does seem to be a design floor.