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DJI Mini 3 Pro suddenly dropped to the ground
289 4 10-12 08:49
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GeirViking
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Norway
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I had about ten flights in total with this drone, time equivalent to about an hour in total. I was flying over a parking lot when it suddenly fell out of the skies and down to the ground. The air temperature was about 12 Celcius and the wind averaged 4,7m/s. The height over sea level was about 6 meters.

I flew in sport mode and I was descending from about 107 meters. If I remember correctly I used the 'return to home function', but not sure. The photo showed that everything was normal until about 50 meters when the footage show a small but sudden jerk. Less than a second later it just falls to the ground. Propellers were rotating slowly and the drone was somewhat level which probably slowed down the fall. At 10 meters it fell into a tree next to the parking lot and then down to the grass. Luckily _nothing_ was broken. Just some green marks after hitting the tree. I tried to fly it after and everything seemed to work just fine. Even the camera. All in all, it went well. But now I'm nervous about flying again. What if this happens over water or somewhere where I can't retrieve it??

Why could this happen? Was the decent too fast? Or doesn't it handle wind that well? 5 m/s isn't very strong wind, is it?


No, I didn't fly with the gimbal guard.



10-12 08:49
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DowntownRDB
Captain
Flight distance : 525 ft
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United States
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If you want to learn what your flight data tells of your incident ...

Go to: https://www.phantomhelp.com/LogViewer/Upload/
... where you'll find instructions to upload the data to that site and it will give a report.

For help interpreting the data you can post a link for the report here.  Or just post the .txt file.  Probably BETTER to post in the Products/Mini 3 section as it is much more active.  
10-12 13:23
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DJI Diana
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Flight distance : 2408 ft

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Hi GeirViking. Thank you for reaching DJI Forum. Please be advised that if a crash or collision incident occurs, we recommend sending the unit in for a proper diagnosis. Rest assured that as long as the unit is within the service guarantee period, we can forward an investigation and data analysis can be applied to determine its cause. We'll send you an offer depending on the results and it is also to ensure future flight performance. Please find this link https://dji.com/support?site=brandsite&from=nav helpful in contacting our Product Support team for further assistance on the request. Should you need to contact us for any reason, please know that we are always here to help. Thank you.
10-12 14:11
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GeirViking
lvl.1

Norway
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DJI Diana Posted at 10-12 14:11
Hi GeirViking. Thank you for reaching DJI Forum. Please be advised that if a crash or collision incident occurs, we recommend sending the unit in for a proper diagnosis. Rest assured that as long as the unit is within the service guarantee period, we can forward an investigation and data analysis can be applied to determine its cause. We'll send you an offer depending on the results and it is also to ensure future flight performance. Please find this link https://dji.com/support?site=brandsite&from=nav helpful in contacting our Product Support team for further assistance on the request. Should you need to contact us for any reason, please know that we are always here to help. Thank you.

Thanks for your reply. But it's not good enough. I've searched a lot of similar threads on the forum, but never have I seen any detailed answers. Just "send it in". I'm not expecting a definite cause of the incident, but some possible causes would be nice.

I've extracted the flight data, and to me, it seems like cell 2 had insufficient current to power the motors. It was about 4,7 m/s winds that day, but gusts might have been higher. Voltage data shows that cell 2 voltage fluctuated quite a lot compared to cell 1. The deviation between cells was upwards of 0,056 volts. Voltage continued to drop rapidly during the flight, cell 2 more than cell 1. The max altitude was 107 meters, so there might have been some stronger wind gusts at that height.

Just before it fell to the ground, the voltage of the battery pack dropped by 0,18 volts for a second (cell 1: 3,48v and cell 2: 3,43v). Shortly thereafter, the drone reported another error code. A few seconds later, another voltage drop and another error code, until it reported "motor stuck", and it fell to the ground.

To me, it seems like the battery was faulty and couldn't deliver enough current when the cell 2 voltage dropped below 3,43 volts.

Some inputs on this theory?

And a tip to you at DJI, don't just tell people to send it in. Try to help people to understand what could have happened.
10-13 07:04
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DJI Diana
Administrator
Flight distance : 2408 ft

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GeirViking Posted at 10-13 07:04
Thanks for your reply. But it's not good enough. I've searched a lot of similar threads on the forum, but never have I seen any detailed answers. Just "send it in". I'm not expecting a definite cause of the incident, but some possible causes would be nice.

I've extracted the flight data, and to me, it seems like cell 2 had insufficient current to power the motors. It was about 4,7 m/s winds that day, but gusts might have been higher. Voltage data shows that cell 2 voltage fluctuated quite a lot compared to cell 1. The deviation between cells was upwards of 0,056 volts. Voltage continued to drop rapidly during the flight, cell 2 more than cell 1. The max altitude was 107 meters, so there might have been some stronger wind gusts at that height.

Thank you for the information. I'm sorry if you feel this way. Please be advised that, for us to properly diagnose and assess the root cause of the incident, we will need to send the unit in for a proper assessment and for the unit to undergo quality assurance, it is also to ensure future flight performance. Rest assured that the result of the diagnosis will be provided.
10-13 09:53
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