DJI Mavic Mini lost connection - Failsafe RTH not working - crashed into the water.

[BogdanCr]

My DJI Mavic Mini crashed into the water for no reason - 25 january 2020. I've found this video in the cache of my smartphone. The first error was about sd card malfunction and 5 seconds later an error about losing connection appeares. Failsafe RTH didn't work, a sudden movement in the air and it dropped in the water. The water was about 20 cm tall so i managed to get it out easily.

I bought the drone 2 weeks ago and this was its 3rd flight. I even have the DJI refresh care for it.

What really happened back there ?

 

[xspwhite]

What does your flight logs say?

 

[FoxhallGH]

Check out this post to show you how to post your flight logs for analysis ... Flight log retrieval and analysis guide
The abilities of several members of this Forum may help a lot with your warranty claim!

 

[slup]

Hi Bogdan,

We will need the flight log to diagnose this event ... you should attach the .TXT log at a minimum but it doesn't hurt to also attach the .DAT log as you already are into your phone.
Below to make it easier for you to find what we are after, but do follow @FoxhallGH link to @sar104 eminent analysis guide & read it through, always good to know how thing's work.


LOG FILE RETRIEVAL

Mobile device DJI TXT logs

The log naming convention, based on the date and time of the start of the flight, is: DJIFlightRecord_YYYY_MM_DD_[hr-min-sec].txt.

With iOS devices running DJI GO 4 you need to access the app files via computer, either using iTunes or with a file system browser such as iExplorer. The TXT logs are in Apps » DJI GO 4 » FlightRecords. The same method can be used to access DJI Fly files in DJI Fly » FlightRecords, but with DJI Fly they are also accessible using the iOS Files app by selecting Browse » On My iPhone » DJI Fly » FlightRecords.

With Android devices the file system should mount when plugged into a Windows machine, or via various software options on a Mac. With DJI GO 4 the TXT logs are in DJI » dji.go.v4 » FlightRecord. With DJI Fly they are in DJI » dji.go.v5 » FlightRecord.

Retrieve the logs and post them here directly, or upload them to PhantomHelp or AirData and post the link back here.


Mobile device DAT files (DJI GO 4 & DJI Fly)

The DAT file naming convention, based on the date and time of the start of the file, is: YY-MM-DD-hr-min-sec_FLYXXX.DAT., where XXX is the flight recorder file index from the HOME_dataRecorderFileIndex field in the txt log.

These are retrieved by the same method as the TXT logs. Under both iOS and Android they are in a subfolder, MCDatFlightRecords, in the folder that contains the TXT logs.

 

[Prismatic]

My DJI Mavic Mini crashed into the water for no reason - 25 january 2020. I've found this video in the cache of my smartphone. The first error was about sd card malfunction and 5 seconds later an error about losing connection appeares. Failsafe RTH didn't work, a sudden movement in the air and it dropped in the water. The water was about 20 cm tall so i managed to get it out easily.

I bought the drone 2 weeks ago and this was its 3rd flight. I even have the DJI refresh care for it.

What really happened back there ?

The good news here is that you had the foresight to get DJI Refresh. Even in the worst case, your mini will be replaced without delay.

Unfortunately the log files on the mobile device will end at the moment the connection was lost, so they may not contain the data necessary for analysis of the final moments of the flight.

You can try drying it out completely--the old "put it in a bag of raw rice" trick--and see if it will power up. (Don't use the battery that got wet for this!) If it successfully powers up, you should try to get the log files from it, as those would be conclusive. If it was an aircraft failure you might get a new MM on warranty and save your Refresh option.

Best of luck. That was a very nice video you were taking before "the swim", so don't be discouraged! You'll soon be airborne again!

 

[sar104]

The good news here is that you had the foresight to get DJI Refresh. Even in the worst case, your mini will be replaced without delay.

Unfortunately the log files on the mobile device will end at the moment the connection was lost, so they may not contain the data necessary for analysis of the final moments of the flight.

You can try drying it out completely--the old "put it in a bag of raw rice" trick--and see if it will power up. (Don't use the battery that got wet for this!) If it successfully powers up, you should try to get the log files from it, as those would be conclusive. If it was an aircraft failure you might get a new MM on warranty and save your Refresh option.

Best of luck. That was a very nice video you were taking before "the swim", so don't be discouraged! You'll soon be airborne again!

But the connection was not lost - the video shows the aircraft descending into the water and so the log files will include the descent data.

 

[slup]

But the connection was not lost - the video shows the aircraft descending into the water and so the log files will include the descent data.

Yeah ... as the cache video were recorded on the phone so was the log.

...If it successfully powers up, you should try to get the log files from it ...

Not necessary to have the AC powered up ... it's the log from the phone we need (and can read)

 

[Prismatic]

Yeah ... as the cache video were recorded on the phone so was the log.



Not necessary to have the AC powered up ... it's the log from the phone we need (and can read)

I misunderstood the sequence of events. Reason? Hadn’t had my coffee yet! ?

 

[Stupest]

You can try drying it out completely--the old "put it in a bag of raw rice" trick--and see if it will power up. (Don't use the battery that got wet for this!) If it successfully powers up, you should try to get the log files from it, as those would be conclusive. If it was an aircraft failure you might get a new MM on warranty and save your Refresh option.

Sorry that bag of rice thing is never a solution. People say rice absorb the moisture?? Yeap nup! The corrosion starts straight way and that is what kills electronics when it comes to water. The only hope you have is to clean away the corrosion and hope the components did not get fried from all the short circuits. Just have a look at how water damaged phones are repaired properly, no rice involved at all. That rice thing is based on someones theory but never really works and never results in a reliable repair because you are not fixing the corrosive damage that exists and for a drone reliability is critical. If it returned to DJI they will more than likely toss it in the bin and send a new one if the circuit motherboard has been exposed to water damage.

 

[Simmo]

DJI will never repair a water damaged drone. FACT.
Rice does fix stuff. It attracts many Asians, that are familiar with the damage, and the surplus of rice.... FALSE.

 

[Stupest]

DJI will never repair a water damaged drone. FACT.
Rice does fix stuff. It attracts many Asians, that are familiar with the damage, and the surplus of rice.... FALSE.

Sorry but id like to see how rice can fix stuff. The device will be destined for failure

 

[netsonic]

I do not know why, but one of the solutions to repair a drone and a remote that do not want to pair over wifi was to remove the SD card as this one got corrupted. This being said, I can understand somehow the connection loss, but not the drone falling from the sky. Bogdan please post your logs, as this is very interesting.

 

[sar104]

Sorry but id like to see how rice can fix stuff. The device will be destined for failure

Dry rice does absorb water. However, that doesn't mean that it will prevent corrosion or damage that occurs before the water has been removed.

 

[netsonic]

The picture as well as the video point toward a dive in sea water. Moisture is the least of problems. Corrosion is much worse, regardless how it will dry.

 

[Amadis]

Interesting article on the rice trick: Putting your wet phone in rice probably won’t save it. But do it anyway

 

[BogdanCr]

Hey guys, sorry for the late reply.
This is the flight record found on my iphone in files, hope it is the right one.
I have some other files but i can't upload them here.
Also i have to mention that on other 2 video from the sd card, the gimbal was moving the same as in the video where the drone crashed.
I already sent a message to DJI and to F64 Studio Bucharest (the importers for DJI) so tommorow i will ship it to them.

 

[BogdanCr]

And about corrosion, well, she fell in the Black Sea, really salty water.. the drone turned white on the gimbal and the battery turned white at the connection point. Really messy. If you shake it you can hear the sand in it.

 

[BogdanCr]

What does your flight logs say?

You can find it in a reply. Thanks.

 

[netsonic]

The first thing you had to do was to clean it with plenty fresh water o submerge it in the bath tub and keep it there for 60 seconds to dissolve the salt. Too late for that now, it will be replaced via care refresh.

Stay tuned as the experts will take a look.

 

[BogdanCr]

I do not know why, but one of the solutions to repair a drone and a remote that do not want to pair over wifi was to remove the SD card as this one got corrupted. This being said, I can understand somehow the connection loss, but not the drone falling from the sky. Bogdan please post your logs, as this is very interesting.

So the drone took a left and dived into the water. The same movement i got in other 2 videos that i was able to get from the SD card: