What took me down? (mavic mini fell out of the sky)

[Jess--]

I was flying my mini close to home, and a little over 1 min into the flight the drone just tumbled to the left and fell out of the sky and lost connection with the controller.
sticks were centred at the time with a light breeze (just enough to lean the drone)
The only unusual thing at the time is that I was above power cables (they are at 30 feet and the drone was at 50 feet).

The drone remained powered and recording throughout, after it was recovered it still flew perfectly (2 1/2 batteries flown since)

video from crash

logfiles (raw txt & csv via phantomhelp)
DJIFlightRecord_2022-05-08_[08-54-13].csv
DJIFlightRecord_2022-05-08_[08-54-13].txt

First sign of the crash is at 1m 9.8s in the logs where pitch and roll values jump and the gimbal hits the limits.

 

[Meta4]

I was flying my mini close to home, and a little over 1 min into the flight the drone just tumbled to the left and fell out of the sky and lost connection with the controller.
sticks were centred at the time with a light breeze (just enough to lean the drone)
The only unusual thing at the time is that I was above power cables (they are at 30 feet and the drone was at 50 feet).

This had nothing to do with power cables.
The drone maintained connection as it fell.
Your drone was in a stable hover with plenty of battery and at 1:09.8, it started to spin clockwise, tunble and lose height.
The tumbling and spinning, never corrected.
The data indicates loss of the front left prop or motor.

 

[0Kajuna0]

I synced the video with the data in case that helps with the analysis:

I can't spot anything especially revealing, other than the pitch and roll changes maybe suggesting a front left prop malfunction. The satellites and GPS level drop soon after, but that would be a side effect.

 

[Jess--]

It does seem odd that after the crash the drone was able to fly perfectly.
at the time of the crash the drone had around 11 hours flight time on it and about 125km flown (now at 12.1h / 132km)

damage from the crash was a popped cover by the power switch (just clicked back in) and some grass stains on the front legs

 

[Chaosrider]

This had nothing to do with power cables.
The drone maintained connection as it fell.
Your drone was in a stable hover with plenty of battery and at 1:09.8, it started to spin clockwise, tunble and lose height.
The tumbling and spinning, never corrected.
The data indicates loss of the front left prop or motor.

It's not clear how that would be the case, if the drone flew perfectly after recovery. The OP didn't mention that any repairs were needed.

Why do you rule out the powerlines as a factor?

Thx

 

[Chaosrider]

I synced the video with the data in case that helps with the analysis:

I can't spot anything especially revealing, other than the pitch and roll changes maybe suggesting a front left prop malfunction. The satellites and GPS level drop soon after, but that would be a side effect.

What app/technique are you using to get all of that cool information on the screen? Can that be available in-flight on a Mini?

Thx!

 

[0Kajuna0]

What app/technique are you using to get all of that cool information on the screen? Can that be available in-flight on a Mini?

Thx!

Sent info by DM

 

[Meta4]

Why do you rule out the powerlines as a factor?

Because there's nothing about being close to powerlines that would stop one motor from running.

 

[Yorkshire_Pud]

Bearing in mind that you did disturb ducks and some might have chicks did you see any near the drone i.e. I am wondering about a bird strike, but I see nothing in the log to indicate that.

 

[Jess--]

It's not clear how that would be the case, if the drone flew perfectly after recovery. The OP didn't mention that any repairs were needed.

After the crash the only visible damage to the drone was that the plastic cover was popped open around the power button (even the arms were still folded out), the drone was still powered and recording, I stopped the recording once the controller reconnected, put the drone on a flat surface (with the cover still popped open), doing a manual start (down & out) all 4 motors span up and ran smoothly, take off and flight were normal with no warnings.

Bearing in mind that you did disturb ducks and some might have chicks did you see any near the drone i.e. I am wondering about a bird strike, but I see nothing in the log to indicate that.

Nothing seen with the naked eye and nothing seen in frame by frame checking as the drone tumbled.

After a few more flights I do seem to have a fault appearing after the crash, my drone will now intermittently fail to detect ground in close proximity, when descending it will try to go full speed into the ground 75% of the time, messing around if I go to land it will sometimes do it's usual stop at 2 feet off the deck but most of the time it won't try to slow down.

With the drone in a low hover I can bring my hand up underneath it (flat) and pick the drone out of mid-air the motors go down to a ground idle while it's on my hand, if I lower my hand with the drone still on it the motors pick back up and the drone goes back to it's hover.

Since it still has a rock solid low hover I believe the downward camera is working fine but the IR rangefinder has failed (and of course the range finder is part of the main board so not easily replaceable)

In short after an unexplained crash I seem to have a drone that still flies but cannot be trusted.

 

[Yorkshire_Pud]

If you upload a flight with the landing protection problem to phantomhelp then have a look at column i of the csv you should find it is entitled "OSD.vpsHeight [ft]", check the entries in that column to see what value they record when the drone is close to the ground. I think they read 33.1 for every thing over 33.1ft.
One other thing, if you do not sync your flight logs then, if you look in the folder where you found the flight log, you will see another folder named MCDatFlightRecords or similar. In there have a look for the file with the date and time stamp the precedes the crash flight by probably a few seconds and/or whose name contains FLY007.
If you up load that log to here or download and instal CsvView it may be possible to read the DAT and find out what the motor speeds were during the crash flight.
I do not have FLY ver 1.5.10 installed but seem to have been able to open a Mavic Mini DAT recorded by ver 1.5.4.

 

[Jess--]

No dat file as I actually enabled sync the day before the crash (so I have dats for every flight from new until 1 flight before crash).
Winds have been too high here to do a proper test flight for the vps but one of my quick flights from the 8th had the vpsheight stuck at at 5.9 throughout, the flight before & after showed realistic figures (no power off between flights).

Anyway.... new fault found (it may have been present for a long time without me noticing due to the way I use the drone)
If I put a battery in the drone and don't power it up after about 1 min the motors initialize (usual flicks of all 4 motors with the three beeps) but the drone is NOT active (no lights, no gimbal, no connection), trying to power up the drone from this state does nothing.
If I refit the battery and then hit the power button everything seems normal again until I power it off with the button whereupon it wont power up again from the button.
With the way I usually use the drone I could have missed this for a long time, I usually grab a battery, put it in and power up straight away and then walk to where I take off from (hoping it gets gps lock on the walk), after a flight I vary between walking back and dropping the battery back in the charger or switching to another battery and flying again.

My current thinking is to sell this drone for whatever it's worth and put that money towards a new mini se (because that still lets me hijack my partners mini batteries).
now I just need to work out what a mini that still flies with an unhappy main board is worth (complete with everything in the original box)

 

[slup]

No dat file as I actually enabled sync the day before the crash...

As this was a Mini 1 we still have a possibility to see what the motors actually was doing ...

The Mavic Mini maintains the most recent DAT file named fc_log.log on the removable SD card in hidden folder: MISC » LOG » flylog.

Check if you have that fc_log.log file ... if you have, share it. It might be rather large so you perhaps need to put it on some personal cloud service like Dropbox & share a link to it.

 

[Yorkshire_Pud]

what are you thinking it is worth and what would be included?

 

[Jess--]

what are you thinking it is worth and what would be included?

for what would be included it would be everything that was originally in the box
drone, controller, battery, spare props (unopened), controller-phone leads, charging lead & spare sticks (if the spare sticks came with the basic drone package not the fly more)
all put back in the original box for shipping.

Value wise I would be guessing somewhere around the £150 mark shipped in the UK

 

[Yorkshire_Pud]

Thanks.

 

[Jess--]

Thanks.

Do you think I am in the right price area with shipping included?

I have ordered the SE but will continue to test & report on the mini here.
Once I am up to the 30 days I will add it in the classifieds section (I would rather sell it here where the buyer can see this thread and can be fully aware of the drones history / issues)

 

[kidroc]

Bearing in mind that you did disturb ducks and some might have chicks did you see any near the drone i.e. I am wondering about a bird strike, but I see nothing in the log to indicate that.

I don’t thinks chicks can fly!!

 

[Yorkshire_Pud]

I don’t thinks chicks can fly!!

I think you are correct but their presence does tend to cause the adults to be protective of them.

 

[DanMumford]

I synced the video with the data in case that helps with the analysis:

I can't spot anything especially revealing, other than the pitch and roll changes maybe suggesting a front left prop malfunction. The satellites and GPS level drop soon after, but that would be a side effect.

Sorry for being off topic, but what did you use to sync the date over the flight? Thanks!