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First 2022 crash (not sure, which smiley to use ... ;) )

mucek

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First of all - happy new year! ;) Wishing you safe flights and zero crashes!

But still, today I wanted to rise above the fog level from our house with my Mini 2 and at approx 90 m height I started receiving "Motor error" mesages. Immediatly I started with descending, but already saw from the image that the drone is rotating around Z but it was still partially maneouvrable and not free falling. However, it wasn't controllable and it felt to the grass near my takeoff position.

Gimbal holder is broken, other seems ok. I am disassembling it now to see, if I can fix it.

Some questions:
- Any idea, why this would happen? I flew 2 days ago and did had a small crash (hit some small leaves on a tree and drone fall from 2 m down on a snow), but I already flew it then for like 15 minutes without problems.
- Also wasn't a missed propeller case as drone had them all when "landed"
- Is it possible to get and analyze logs from Mini 2? (if I remember correctly, Mini 2 has encoded logs?)

Regards,
Gregor

Regards,
Gregor
 

Meta4

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- Any idea, why this would happen?
- Is it possible to get and analyze logs from Mini 2? (if I remember correctly, Mini 2 has encoded logs?)
Flying through fog in cold conditions is not safe.
Propellers can ice and lose lift.
We saw a number of crashes caused by that last northern hemisphere winter
The props of the Mini are particularly vulnerable to this.

To get the flight data ...
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file here.
 

mucek

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Just "fixed" the gimbal, it was stuck on landing, but "only" whole gimbal was moved on rubber holders so it was stuck. Now I released it, but still getting gimbal errors (motor overload, gimbal stuck), however after drone is powered, gimbal moves normally to all positions and returns to center afterwards.

Any idea? (unfortunatly my DJI care just expired 14 days ago ... Argh ...)

Regards,
g
 

PhiliusFoggg

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With regards to the 2 day old crash, did you look in to the motors to check for any leaf debris in the motors themselves?
One thing that does occur to me is that some leaf fragments might have got in there and been stuck. If so they might have loosened when they dried out, come free and played havoc with the motor.
 

mucek

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Yap, I did check this right after the incident (as well as replace one propeller pair, as one blade had slight damage on one edge). Don't think this might be an issue. I also tried to hover it now and flies fine (2 batteries) except for gimbal issue now.
 

PhiliusFoggg

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If you download, unzip and open the csv from the PhantomHelp webpage you will see a wealth of information, 170 + columns worth probably. To create the graphs download and install CsvView then use it to process the csv.
 

slup

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Nothing magical will be found in the .TXT log only, when it comes to prop or motor issues ... the .DAT log is needed for that & for a Mini 2 that one is encrypted and can't be read by us.

So it will be a guess work ...

But knowing that incidents like this usually show up during winter seasons ... and that the ambient temps on ground level together with the dew point was just above freezing where you flew ...

1641070674980.png

... make prop icing a likely cause to this.

According to the log the first motor error came at 103m altitude ... at that height the ambient likely was below freezing & the error originated from that the flight controller required more thrust in order to control the AC but the motor was already on max rpm due to a ice build up around the props altering the shape making the prop lose the ability to generate thrust... the motor simply couldn't provide more, that triggers the error.

On the way down the AC show a odd descent behavior which isn't proportional to how you applied throttle ... the decent speed abruptly changed +/-2m/s back & forth ... this indicate ice shredding, the ice around the props crack & fly off & new ice is created again. Anyhow ... the generated thrust is erratic, if only one motor (or prop) had been affected (for another reason than icing) the AC had rotated due to an uneven rotational torque, either CCW or CW ... but here we instead see that the AC sway back & forth on the way down.

Prop icing is a real risk from approx +4C degrees to -20C degrees when the dew point is close to the ambient temperature (free moist in the air).

The risk starts already above freezing, not only because it can be colder later on at higher altitudes ... it's also due to that the props create a pressure zone with higher & lower pressure where the prop slice through the air ... & with higher pressure water goes to ice even above freezing temps.
 
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mucek

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Thanks for your analysis, I did suspect icing too after some thinking.

And I found the problem with gimbal: there is a broken flat cable, probably used for some sensoric from gimbal (as camera works as well as gimbal moves, just causes error).

Any idea, where to get it? I'd really like to avoid cost of new gimbal ;)

Regards,
Gregor
 

PhiliusFoggg

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That is the correct cable, it connects to the circuit board that drives the yaw motor + the IMU ? board & the drone's main board.
Photograph how the various sections are laid before you remove the old one, it needs fairly accurate folding and placement.
Where to get them, ebay etc. as you found, though that seems an expensive one
Be warned it may not fix the problem, I have replaced one with a second hand cable and it did not fix my problem but given that the cable was second hand the replacement cable may be faulty, I haven't got round to trying another cable.
 
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Crashdummytest

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First of all - happy new year! ;) Wishing you safe flights and zero crashes!

But still, today I wanted to rise above the fog level from our house with my Mini 2 and at approx 90 m height I started receiving "Motor error" mesages. Immediatly I started with descending, but already saw from the image that the drone is rotating around Z but it was still partially maneouvrable and not free falling. However, it wasn't controllable and it felt to the grass near my takeoff position.

Gimbal holder is broken, other seems ok. I am disassembling it now to see, if I can fix it.

Some questions:
- Any idea, why this would happen? I flew 2 days ago and did had a small crash (hit some small leaves on a tree and drone fall from 2 m down on a snow), but I already flew it then for like 15 minutes without problems.
- Also wasn't a missed propeller case as drone had them all when "landed"
- Is it possible to get and analyze logs from Mini 2? (if I remember correctly, Mini 2 has encoded logs?)

Regards,
Gregor

Regards,
Gregor
Ice, it has happened to me as well - Fog can be really bad in cold weather. As soon as you get that "motor error" message you need to land immediately. Cold fog is really a no-go even sometimes fantastic visual opportunities..
 

mucek

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Yeah - did try to land as soon as error appear, but ... Well, it sure landed somehow and didn't stay in the air ;)

Lession learnt ... Now I "only" need to fix the gimbal ;)
 

hiflyer201

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Visible moisture and freezing temperature are a perfect recipe for prop ice. Icing is very incidious
 

AVLJMA

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On the 2 rare occasions that I flew up and over fog in cold weather, I sprayed a Q-tip with WD40 and lightly coated the props lift edge. I never had an icing problem but then again, I may not have had the problem regardless.
 

hiflyer201

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Visible moisture and freezing temperature are a perfect recipe for prop ice. Icing is very incidious
 

mucek

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Can anyone tell, if flat cables for MINI and MINI2 are the same?
The reason I'm asking this is, that local dealer has Mini1 cable in stock (and price is really good! :) )

Mini 2:
Amazon.com: PONYRC Original Mavic Mini 2 Flexible Flex Cable, Flat Ribbon Cable, 3 in 1 Cable for DJI Mavic Mini 2 Repair Parts Replacement : Electronics
Mini1:
 

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