Mini 2 crash

[ukando]

I owned MM before, and replaced it for Mini 2. Completely new, flew it 2-3 times. Charged 2 times. So here's the story:
0 Celsius, slightly foggy, 3 minutes in the sky, ~40 meters height, then message popups "Motors error. Check propellers and fly with caution". Started to land immediately, noticed that it doesn't lower the height, switched to the Sport mode, continued to land, but it just stopped motors, so it crashed from ~35 meters of the height. Didn't look damaged, fell in a soft mug, so it was all in the mug. Dried, cleaned a bit, turned on, but IMU could not get calibrated.
Brought it to the local DJI store for a warranty check. Today received the email: estimation ~300 eur for its repair - Gimbal Axis Arm module should be replaced they say.
Isn't it a firmware problem to handle that there's a problem with motors, to tell earlier that you should land? I am not even sure that this was a flight condition problem it was a very slight fog and 40 meters wasn't very high, it just fell down in few seconds after that warning popped up. Also, why it just turned off the motors?
And in the service protocol, they stated:
Warranty status: No warranty. Assessment result: Physical damage. The Gimbal Axis Arm Module
was malfunctioned, which caused gimbal stability related issue. (Flight data was analyzed.) Reminder: After repair/replacement, faulty unit orp partswill not be returned.

I'm attaching flight data file. Also going to call that shop in the morning. Should I contact DJI directly about this? I am really not sure about the "No Warranty" message. I bought it in the end of November. Flew it just few times, almost new drone. We should have normal 2 year warranty on the EU. I suspect faulty motors/firmware in the beginning of their production? Could you please advise what to do? Upset
UPD: Uploaded txt to airdata: UPD2: Uploaded DAT file: fc_log.DAT
UPD3: PhantomHelp: DJI Flight Log Viewer - PhantomHelp.com

 

[elborak]

0 Celsius, slightly foggy... icing perhaps?

 

[Lastrexking]

So, it was -2oC and foggy (probably colder 40m up too). It sounds like it iced up. That’s why the motors just stopped. The manual clearly states not to fly in fog, and you did anyway, so they’re not going to deal with it as a warranty claim, but as pilot error unfortunately.

 

[slup]

Yeah ... all was set for a prop icing case again (think this is the third or even fourth case this winter?).

With the air temp below freezing & so close to the dew point with fog on top of that, it's no good to get airborne. This as all moist in the air will form ice around the prop edges & totally destroy the geometry & make the motors go harder and harder until they can't generate enough lift anymore ... or/and generates an overly high amp draw that eventually shut the system down.



The normal signs of prop icing is like what's shown in your case, motor errors & a rapidly increasing amp draw with a sudden motor stop.

Here's the increased motor amp draw ...



So all in all ... a bad choice to fly that day & agree with DJI unfortunately, this was a clear pilot error.

 

[boblui]

Yeah ... all was set for a prop icing case again (think this is the third or even fourth case this winter?).

Prop icing is definitely one of the possible causes because the current started to increase and voltage decrease quite rapidly after about 90 seconds into the flight and the warning "Motor error, check propeller" was issued at 110 sec. Then without any further warnings or notifications, the motor shut off in the air 20 seconds later at a height of 35m.




Such behaviour is quite different from this recent case of prop icing although that craft was an MA2 : Mavic Air 2 crash, can an expert check my logs? In that case the motor did not shut down in the air despite the fact that the current was extremely high and warning messages about the motors being blocked were issued continuously until the craft crashed.

That led me to look into another possibility : may be the craft thought that it has landed so it shut down the motors ?



As can be seen from the chart above, the fog made the craft believe that the ground was just 0.6 meter beneath it so even when full throttle-down stick input was applied in sport mode, it descended at a very cautious speed of 0.4 m/s ( max speed is 3.5 m/s ). Normally this should continue until the craft touches the ground before motor shutdown follows. Is it possible that there were some glitches in the sensor ( e.g. accelerometer ) making the craft believe that it has already touched down when it was actually still in the air ?

 

[ukando]

Thank you guys for all the replies.
I have read all of them in the morning, understood that all that happened due to the pilot error.
So here's the continue of the story:
I called the store today where I bought the Mini 2, it's DJI authorised.
Specifically I asked "What does it mean "No warranty" there?"
They said "DJI didn't recognise it as a warranty case, perhaps you just smashed it or something, but they analysed the flight data". So I understood that they have no clue about the exact reason, BUT when I asked if after the repair I'll receive a completely clean drone, due to that it was all in the mug? And he said: "No, you will receive a completely new unregistered drone for that price (~300 eur), they don't solve such big repairs, they just send a new one". Regardless my drone was almost new, I thought it might be a good solution then, also considering that most probably it was just my fault flying in the iced fog, which I didn't realise, as it was around 0 or +1 C on the ground.

But whatever, I agreed, also they emailed that they applied to DJI already, there's gonna be replacement in 6-9 days, also they asked for a better price due to that it's just Mini 2. So fingers crossed. Seems like the problem is going to be solved. Then I'll need to pass the exam for the license according to the new EU rules and back in the sky!!

Again, guys, thank you very much for every your reply.
@boblui This is was my first complain about the late warning and slow decrease altitude issue and it just smashed onto the ground. But considering that they say "Don't fly in the fog", I don't think I would have this argument valid anymore. I just can say to everyone here - "Don't fly in the high humidity and low temperature!" ;-)

 

[hiflyer201]

I flew three years on a weather modification project. I would fly for hours at the -5 degree in IMC conditions to monitor the ice accumulation and whether it was rime, clear or just frozen precip.. We all flew at that level be science says that is the level where ice is most likely to occur. Guess what you can be ice free...sometimes. Visible moisture..freezing temps equal ICE

 

[eaglesurfing]

It is always the fog....
Several post about this but not many are catching them.
Oh by the way....
Welcome to the forum and enjoy.

Please use one of the best forum search options.

Please share your pictures, videos and knowledge about your drones.

 

[Whitefalcon]

Thank you guys for all the replies.
I have read all of them in the morning, understood that all that happened due to the pilot error.
So here's the continue of the story:
I called the store today where I bought the Mini 2, it's DJI authorised.
Specifically I asked "What does it mean "No warranty" there?"
They said "DJI didn't recognise it as a warranty case, perhaps you just smashed it or something, but they analysed the flight data". So I understood that they have no clue about the exact reason, BUT when I asked if after the repair I'll receive a completely clean drone, due to that it was all in the mug? And he said: "No, you will receive a completely new unregistered drone for that price (~300 eur), they don't solve such big repairs, they just send a new one". Regardless my drone was almost new, I thought it might be a good solution then, also considering that most probably it was just my fault flying in the iced fog, which I didn't realise, as it was around 0 or +1 C on the ground.

But whatever, I agreed, also they emailed that they applied to DJI already, there's gonna be replacement in 6-9 days, also they asked for a better price due to that it's just Mini 2. So fingers crossed. Seems like the problem is going to be solved. Then I'll need to pass the exam for the license according to the new EU rules and back in the sky!!

Again, guys, thank you very much for every your reply.
@boblui This is was my first complain about the late warning and slow decrease altitude issue and it just smashed onto the ground. But considering that they say "Don't fly in the fog", I don't think I would have this argument valid anymore. I just can say to everyone here - "Don't fly in the high humidity and low temperature!" ;-)

Hi, sorry about the loss of your drone,
It's a good idea to do your exam and get a qualification as you say in your post. I did the UK CofC course and the effects of weather, temperature and dew points is well covered along with other important points that I did not know when I bought my drone.
The effects of flying in Fog and mist can not only include icing but also moisture accumulation on the electronic components which is not a good idea.

Hope your new drone comes soon.

 

[boblui]

They said "DJI didn't recognise it as a warranty case, perhaps you just smashed it or something, but they analysed the flight data". So I understood that they have no clue about the exact reason....

This would not be a satisfactory answer for me .....

The fact is the drone shut down by itself in the air without any warning messages in the last 20 seconds. Prop icing is just a possible but not definitive cause. Exactly why the motor shut down should have been indicated by the log inside the drone. DJI owes you a better explanation.

 

[ukando]

Hi, sorry about the loss of your drone,
It's a good idea to do your exam and get a qualification as you say in your post. I did the UK CofC course and the effects of weather, temperature and dew points is well covered along with other important points that I did not know when I bought my drone.
The effects of flying in Fog and mist can not only include icing but also moisture accumulation on the electronic components which is not a good idea.

Hope your new drone comes soon.

Thank you my friend!

 

[ukando]

This would not be a satisfactory answer for me .....

The fact is the drone shut down by itself in the air without any warning messages in the last 20 seconds. Prop icing is just a possible but not definitive cause. Exactly why the motor shut down should have been indicated by the log inside the drone. DJI owes you a better explanation.

You are right! Thing is - I did not speak directly to DJI but through their authorised store where I bought the drone from. The guy didn't have a clue about what caused exactly, so had no sense to ask him questions. I could move forwards with that directly to DJI, but considering that I broke the warranty rule about the fog, I didn't.
But your investigation here actually proved that there's same question - why did it shut the motors off when it's high in the air without warning to land?
Also the warning I received was "Motors error. Check propellers and fly with caution", which didn't even tell me to land.
I checked the price of the gimbal arm, the cheapest found was around ~200USD. Wasn't sure if I would replace myself and make a calibration without any other problems. Also the store wants around $35 for the shipping/administrative fees if I wouldn't agree on the repair price, so I decided to go with the way they offered 300eur and completely new drone, not activated (so I'll be able to get a DJI care).

 

[JAW]

For 300 EUR do you get a complete package or just the drone?

 

[ukando]

For 300 EUR do you get a complete package or just the drone?

Not sure. They told me, that it's gonna be a completely new drone, not activated. So let's see.

 

[ukando]

Ok, so few days ago received a completely new drone (not refurbished or anything). Not activated, with stickers and new battery inside. Just drone, I think the remote controller I received is mine. No boxes or cables.
Also got a discount of ~75 eur.
So all this problem costed me exactly 230 eur. Additionally I purchased Care Refresh, which became cheaper now plus it's covering fly-aways now.
So in the latest repair protocol they stated the following:

Dear customer, the analysis result is as follows:

1. The aircraft worked under GPS mode, and there was fog affecting the performance of the aircraft;
2. Flight Time T=140 s, Relative Height H=42.7 m, Distance to Home Point D=4.5 m, the Infrared Height was 0.8 m, which indicates there was fog in the flight environment;
3. The fog affected the downward sensors and the propellers were frozen due to the cold and humid weather condition;
4. T=161.8 s, H=34.4 m, D=5.4 m, the main controller regarded the motors as stalled and turned them off since the motors were unable to responded to the pilot’ s commands well due to the frozen propellers.
   *Flight Time here started when the aircraft was powered on.
   We always strive to provide you with more professional, safer and more reliable air protection to keep every flight safe. At the same time, we would like to remind you to pay attention to the flight environment and to fly with caution.

I think I should agree with everything stated above and be happy about the price for a completely new bird.

Also I would like to thank everyone here in this group!!!

Now I need to pass that exam and get the license

 

[Whitefalcon]

Ok, so few days ago received a completely new drone (not refurbished or anything). Not activated, with stickers and new battery inside. Just drone, I think the remote controller I received is mine. No boxes or cables.
Also got a discount of ~75 eur.
So all this problem costed me exactly 230 eur. Additionally I purchased Care Refresh, which became cheaper now plus it's covering fly-aways now.
So in the latest repair protocol they stated the following:

Dear customer, the analysis result is as follows:

1. The aircraft worked under GPS mode, and there was fog affecting the performance of the aircraft;
2. Flight Time T=140 s, Relative Height H=42.7 m, Distance to Home Point D=4.5 m, the Infrared Height was 0.8 m, which indicates there was fog in the flight environment;
3. The fog affected the downward sensors and the propellers were frozen due to the cold and humid weather condition;
4. T=161.8 s, H=34.4 m, D=5.4 m, the main controller regarded the motors as stalled and turned them off since the motors were unable to responded to the pilot’ s commands well due to the frozen propellers.
   *Flight Time here started when the aircraft was powered on.
   We always strive to provide you with more professional, safer and more reliable air protection to keep every flight safe. At the same time, we would like to remind you to pay attention to the flight environment and to fly with caution.

I think I should agree with everything stated above and be happy about the price for a completely new bird.

Also I would like to thank everyone here in this group!!!

Now I need to pass that exam and get the license

Thanks for sharing this. I didn't realise that foggy conditions could fool the downward sensors. Interesting: as they say "every day is a school day".
Glad you have a new drone now.
One thing I learned from my course about flying in the cold was to do a short test flight. Not high or far. Land and check the props for icing etc before continuing to fly if all OK.

Happy flying.

 

[boblui]

....the main controller regarded the motors as stalled and turned them off ....

This must be a new logic implanted into the firmware of the Mini2 because in the other cases seen here the motors kept spinning despite the occurrence if prop icing and increase in current. Such logic is kind of hard to understand because the craft will free fall if the motors were turned off. It can be expected that both the drone and things hit by it will likely suffer from bigger damage.