My first crash, what happend? Help please

[adam_nasrri]

Hello people!
Location : Lelystad | The Netherlands.
I had my first mavic drone back in 2016 and i never had any crach during my flight times. I got lately the dji mavic 2 zoom drone and i flown with it multiple times before something happened in the 23th of February 2021. It was a nice sunny afternoon and there was a little bit of wind. I decided to fly my drone in a haven nearby my place. The first flight went good, i descended near the home point to give the drone another task to follow a big ship (active track) but when i just did give it a Go to start its task, the drone behaved weirdly and kept going to the right side and before it falls into the water, i saw a last warning message on the screen, which was saying that the motor reached the maximum speed!. Which i am not familiar with such a warning sign. Two ladies were working on a ship they saw what's happened and reported that to me. The missing aircraft last coordinators show that its 20 meters from the harbor sidewalk. The depth is 4 meters and there are waves because of the big ships in the area, so retrieving the drone is not that easy or almost not possible for a inexperienced like me.

My interaction with the dji support was not that pleasant, neither what i was expecting from them. They said since my drone is out of warranty they can't check the data free of charge, also they told me straight forward that even if i pay for the paid data analysis they won't send me a new unit and i have to pay for it if i want a new drone. It's unfair to lose your drone and then to get such a disappointing support from dji.

I told them that I am not not agreed and my case doesn't seem to have such an importance to them and instead they are just inviting me to purchase another service which is going to be worthless even if it shows that it was a drone error.
So i am still in contact with them trying out my luck and hoping that they may handle my case differently. In the meantime i thought of telling my story here and see if any drone expert members will help me figure out what went wrong, as i am willing to upload the flight data and other information as well.

If any of you want to help me out, please write to me.


Kind regards,
Adam

 

[slup]

...i am willing to upload the flight data and other information as well.

Yeah, you do that ... without logs it will only be a session full of speculations which will not gain you a bit.

Start by sharing the mobile device .TXT log ... if unsure on how to retrieve, check this out --> Mavic Flight Log Retrieval and Analysis Guide (read under section 3.) then attach it here in a new post.

 

[adam_nasrri]

Yeah, you do that ... without logs it will only be a session full of speculations which will not gain you a bit.

Start by sharing the mobile device .TXT log ... if unsure on how to retrieve, check this out --> Mavic Flight Log Retrieval and Analysis Guide (read under section 3.) then attach it here in a new post.

Thank you for your reply, I'll upload them asap!

 

[adam_nasrri]

Here are TXT & DAT files, I hope they work!

DJI_ASSISTANT_EXPORT_FILE_2021-03-07_23-58-39.DAT

 

[Meta4]

It's unfair to lose your drone and then to get such a disappointing support from dji.
So i am still in contact with them trying out my luck and hoping that they may handle my case differently.

That's normal if your drone is well out of warranty and to expect more would be unrealistic.

Here's what that flight data looks like:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Your Mavic was flying normally until just after 10:13.2 when you gave it some positive- throttle to climb from -0.5 metres.
Despite the throttle input the drone descended to -7.4 metres.
At 10:14.7 the pitch and roll data indicates the drone is in trouble.
It shows the drone pitching and rolling around 50° and at the same time, the motors at maximum speed/not enough force warnings start appearing.
With 1.5 seconds of throttle at 10:18, it started climbing and kept going until it reached 32 metres at 10:24.2.
But it failed to hold altitude and descended into the water.

The drone had a problem with the motors or props that caused altitude instability and inability to hold altitude.
If conditions near freezing and the air was moist, propeller icing could have been the cause.

 

[elborak]

Online weather sources show the afternoon temperature on 23 February at around 10 °C. Given the relatively low altitudes on this flight, I would think icing is unlikely as the cause.

 

[slup]

It's highly unlikely that this had anything to do with prop icing considering the ambient temp, the dew point & the clear weather ...


After looking into the log I think it's also fair to say that this couldn't have been something related to props or motors either ... too many odd thing's going on that instead points towards a IMU or FC failure.

If we start up by looking into the vertical movements & relating speed directions ... in below chart.

Red is the height relative the HP measured by the barometric sensor
Green is the vertical speed ... positive values is speed for descent, & negative for ascent
Blue is your throttle stick commands ... left stick forward in this chart.

It's here easy to see that something isn't handled correctly by the IMU, where I've placed the marker in the chart the AC is ascending according to the red height graph ... but at the same time the green vertical speed graph shows big positive values & instead indicates a descent.



Also note the green & especially the yellow bar in the satellite picture above at the time where the marker in the chart is placed ...

The green bar is into the direction the AC points
The Yellow bar is into the direction the AC tilts ...

That tilt direction is usually impossible if the direction of flight is the opposite as indicated by the orange arrow ... this can only happen if the AC is blowing away.

If we then look at the horizontal speeds in below chart & see what they indicate ...

The red is again height
The blue is your elevator input (right stick forward/backwards) ...you didn't input any though
The green is the aileron inputs (right stick left/right) ...you didn't input any though
The purple is horizontal speed relative North (positive values towards north, negative towards south)
The light blue is horizontal speed relative East (positive values towards east, negative towards west)

As it's indicated that the AC is travelling in a north/west direction ... the purple should show positive & the light blue negative ... but they don't, instead the opposite.

So again a clear indicator that the IMU isn't working ...



And lastly ... a comparison between the GPS & IMU velocities, which in normal cases should shown very small deviations of perhaps 0,1-0,5 m/s.

Here instead we see huge deviations starting exactly where the AC started to fly away ...

The black is deviations towards north
The brown is deviations towards east



All of the above give clear signs of a IMU failure ... can't say if it was permanent or a intermittent hiccup ... but as your AC is out of warranty it's very likely that DJI will not do anything for free in this case unfortunately.

 

[Yogi053]

Another terrific analysis slup!
I do sympathise with Adam on the loss of his drone, but I agree if out of warranty I fail to see any other option than that which Dji specify. For the remaining 9 months warranty left on mine, here's hoping I don't have occasion to call on your services.

 

[Squidinc]

It's highly unlikely that this had anything to do with prop icing considering the ambient temp, the dew point & the clear weather ...

View attachment 125346
After looking into the log I think it's also fair to say that this couldn't have been something related to props or motors either ... too many odd thing's going on that instead points towards a IMU or FC failure.

If we start up by looking into the vertical movements & relating speed directions ... in below chart.

Red is the height relative the HP measured by the barometric sensor
Green is the vertical speed ... positive values is speed for descent, & negative for ascent
Blue is your throttle stick commands ... left stick forward in this chart.

It's here easy to see that something isn't handled correctly by the IMU, where I've placed the marker in the chart the AC is ascending according to the red height graph ... but at the same time the green vertical speed graph shows big positive values & instead indicates a descent.

View attachment 125347

Also note the green & especially the yellow bar in the satellite picture above at the time where the marker in the chart is placed ...

The green bar is into the direction the AC points
The Yellow bar is into the direction the AC tilts ...

That tilt direction is usually impossible if the direction of flight is the opposite as indicated by the orange arrow ... this can only happen if the AC is blowing away.

If we then look at the horizontal speeds in below chart & see what they indicate ...

The red is again height
The blue is your elevator input (right stick forward/backwards) ...you didn't input any though
The green is the aileron inputs (right stick left/right) ...you didn't input any though
The purple is horizontal speed relative North (positive values towards north, negative towards south)
The light blue is horizontal speed relative East (positive values towards east, negative towards west)

As it's indicated that the AC is travelling in a north/west direction ... the purple should show positive & the light blue negative ... but they don't, instead the opposite.

So again a clear indicator that the IMU isn't working ...

View attachment 125348

And lastly ... a comparison between the GPS & IMU velocities, which in normal cases should shown very small deviations of perhaps 0,1-0,5 m/s.

Here instead we see huge deviations starting exactly where the AC started to fly away ...

The black is deviations towards north
The brown is deviations towards east

View attachment 125349

All of the above give clear signs of a IMU failure ... can't say if it was permanent or a intermittent hiccup ... but as your AC is out of warranty it's very likely that DJI will not do anything for free in this case unfortunately.

Wow! What an analysis! The forum is very fortunate to have an expert like you on hand to provide this level of flight analysis. ???

 

[adam_nasrri]

Online weather sources show the afternoon temperature on 23 February at around 10 °C. Given the relatively low altitudes on this flight, I would think icing is unlikely as the cause.

I agree, I took my drone on a trip to Switzerland vacation and I photographed and took many videos in freezing temperature and snow fall, the drone did just good and had no issues because of the cold weather.

Here is a video i took with some cold/snow weather condition.

DJI_0673.mp4

drive.google.com

 

[couplands]

I agree, I took my drone on a trip to Switzerland vacation and I photographed and took many videos in freezing temperature and snow fall, the drone did just good and had no issues because of the cold weather.

Here is a video i took with some cold/snow weather condition.

DJI_0673.mp4

drive.google.com

I wonder if the failure was related to the earlier flight in freezing temperatures in Switzerland. I dont know what the operating temp range of the Mavic Pro is, but if you were below that it may have stressed the electronics to the point where failure could occur and it just happened to be on the flight over water.

Just a thought, as I know from experience the operating temp limits on electronics can have an impact down the line.

EDIT: I just looked and the

Operating Temperature Range

-10°C to 40°C

 

[adam_nasrri]

It's highly unlikely that this had anything to do with prop icing considering the ambient temp, the dew point & the clear weather ...

View attachment 125346
After looking into the log I think it's also fair to say that this couldn't have been something related to props or motors either ... too many odd thing's going on that instead points towards a IMU or FC failure.

If we start up by looking into the vertical movements & relating speed directions ... in below chart.

Red is the height relative the HP measured by the barometric sensor
Green is the vertical speed ... positive values is speed for descent, & negative for ascent
Blue is your throttle stick commands ... left stick forward in this chart.

It's here easy to see that something isn't handled correctly by the IMU, where I've placed the marker in the chart the AC is ascending according to the red height graph ... but at the same time the green vertical speed graph shows big positive values & instead indicates a descent.

View attachment 125347

Also note the green & especially the yellow bar in the satellite picture above at the time where the marker in the chart is placed ...

The green bar is into the direction the AC points
The Yellow bar is into the direction the AC tilts ...

That tilt direction is usually impossible if the direction of flight is the opposite as indicated by the orange arrow ... this can only happen if the AC is blowing away.

If we then look at the horizontal speeds in below chart & see what they indicate ...

The red is again height
The blue is your elevator input (right stick forward/backwards) ...you didn't input any though
The green is the aileron inputs (right stick left/right) ...you didn't input any though
The purple is horizontal speed relative North (positive values towards north, negative towards south)
The light blue is horizontal speed relative East (positive values towards east, negative towards west)

As it's indicated that the AC is travelling in a north/west direction ... the purple should show positive & the light blue negative ... but they don't, instead the opposite.

So again a clear indicator that the IMU isn't working ...

View attachment 125348

And lastly ... a comparison between the GPS & IMU velocities, which in normal cases should shown very small deviations of perhaps 0,1-0,5 m/s.

Here instead we see huge deviations starting exactly where the AC started to fly away ...

The black is deviations towards north
The brown is deviations towards east

View attachment 125349

All of the above give clear signs of a IMU failure ... can't say if it was permanent or a intermittent hiccup ... but as your AC is out of warranty it's very likely that DJI will not do anything for free in this case unfortunately.

I am fortunate to get this well detailed and clear analysis, thank you for dedicating your time. I really appreciate you dear.

I think now it is obviously a the drone failure, and it is very disappointing that Dji won't offer me much, it is indeed a sad tragedy to me which i hope that no one else will go through.

Just a question: Maybe I should try to pay for their service (paid data analysis) to see what it is going to lead to? Is it worth the effort?

 

[slup]

...took many videos in freezing temperature and snow fall, the drone did just good and had no issues because of the cold weather.

Even though prop icing wasn't a factor in your crash in this thread ... it's in general not enough with only cold ambient temps to cause prop icing.

You risk prop icing when the dew point is (the RH is 100%) near a ambient temp close or near freezing when you fly. So seeing moist in the air like fog & at the same time having a ambient temp below/near freezing is a good recipe for a disaster.

Just a question: Maybe I should try to pay for their service (paid data analysis) to see what it is going to lead to? Is it worth the effort?

It's really rare that DJI will pay anything when the warranty have expired... at most they might offer you some few percent off if you buy a new one.

 

[adam_nasrri]

I wonder if the failure was related to the earlier flight in freezing temperatures in Switzerland. I dont know what the operating temp range of the Mavic Pro is, but if you were below that it may have stressed the electronics to the point where failure could occur and it just happened to be on the flight over water.

Just a thought, as I know from experience the operating temp limits on electronics can have an impact down the line.

EDIT: I just looked and the

Operating Temperature Range

-10°C to 40°C

No it isn't the case.

I made other flights after that trip as well, all went fine.

 

[peterc4]

DJI customer services are very good until you loose your drone then unfortunately you have had it, i did get 30% off a new one out of warranty, good luck

 

[BossBob]

I am fortunate to get this well detailed and clear analysis, thank you for dedicating your time. I really appreciate you dear.

I think now it is obviously a the drone failure, and it is very disappointing that Dji won't offer me much, it is indeed a sad tragedy to me which i hope that no one else will go through.

Just a question: Maybe I should try to pay for their service (paid data analysis) to see what it is going to lead to? Is it worth the effort?

Your drone is out of warranty so it would have to be a goodwill gesture from DJI for you to get anything from them which is not likely seeing as they want you to pay for analysis in the first place. If it wasn’t for the increasing restrictions on our hobby, I’d put the money towards a new drone. As it is I’d find something else to spend it on. Sorry for your loss.

 

[skunky1]

Sorry for your loss. But why would DJI replace the drone for free out of warranty even though the AC failed and it was not pilot error?
There’s no point of a warranty period then.

Unless you had care refresh, then it’s a different story

 

[Meta4]

DJI customer services are very good until you loose your drone then unfortunately you have had it

This is incorrect.
The forum is full of examples of flyers who received replacement drones as warranty replacements.
But the drone has to be within the warranty period and there has to be evidence to show that the incident was caused by a DJI issue.

 

[adam_nasrri]

Sorry for your loss. But why would DJI replace the drone for free out of warranty even though the AC failed and it was not pilot error?
There’s no point of a warranty period then.

Unless you had care refresh, then it’s a different story

I understand that having warranty gives you some privileges, but then it sounds like dji products does have value and made to last only as long as there is a warranty, so instead of surprising their customers with their bad support, i suggest they must tell it frankly that we will do nothing to help you dear customers even if it is our products fault.

 

[Meta4]

I understand that having warranty gives you some privileges, but then it sounds like dji products does have value and made to last only as long as there is a warranty, so instead of surprising their customers with their bad support, i suggest they must tell it frankly that we will do nothing to help you dear customers even if it is our products fault.

That's how warranties work.
They have a stated time period but outside that, there's no warranty.
Any other company would be the same.