Mavic mini crash today - vision sensor error

[zeusfl]

I have a friend that crashed his Mavic Mini this morning. Here is the flying log. The only thing i see is the vision sensor failure but he say the drone went down twice even when he was pulling up until crashed. Never seen that error before in MM.

He recovered the drone partially under water in the weeds. He had to go for his boat to get it.

Now when he plug the battery the lights are flashing red and white without turn on the drone.

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[MS Coast]

Though it's somewhat after the fact, suggest to him that he not try to power it up until it's thoroughly dry. And don't bother with immersing it rice. It's much better to put wet electronics in a warm, gentle airstream to dry them out. The top of a refrigerator on in the cooling fan exhaust from a computer, for example.

This error appears several times - low speeds, no unusual maneuvers. Might he have had something attached to the drone?

"Aircraft max power load reached. Decrease altitude and fly with caution. If this issue persists, land immediately (Code: 30168)."

 

[Deleted member 103366]

It's far too soon to be have a battery plugged in, both the drone and the battery need to be thoroughly dried first and not in rice. Perhaps a couple of days above the hot water tank for the drone, I am not sure if it would be safe to put the battery there.
Can he give you the DAT for the flight? The DAT produced by App ver 1.2.1 is readable.
I see multiple in-flight "max power load reached" warnings, what state were or are the props in? (This is why I am asking about the DAT.)

 

[Meta4]

I have a friend that crashed his Mavic Mini this morning. Here is the flying log. The only thing i see is the vision sensor failure but he say the drone went down twice even when he was pulling up until crashed. Never seen that error before in MM.

At 2:20.9 there was a warning message: Aircraft max power load reached. Decrease altitude and fly with caution.
This is showing that the drone is not providing the thrust that it should when the motors are at full speed.
It was repeated at 2:39.5, 2:51.5 and 3:02.5.
Shortly after 3:02.5 the drone started having difficulty maintaining altitude.

For the rest of the flight the drone's altitude was unstable with uncommanded descent and climbing, and in the later part of the flight it wouldn't climb with full throttle.

The cause is possibly a problem with the propellers.

 

[slup]

The cause to this was the famous "uncommanded descent" which the Mini 1 has been plagued with since the release.

It's very easily seen by the pitch instability already from start in this flight ... all is due to flattened prop-blades that can't generates enough thrust & it's mostly the rear props that are effected due to how they have been put under pressure when the craft is folded & stored. Eventually DJI released a firmware that told the pilot that the motors were spinning to fast & that the props should be changed ... but as this craft was flown with a very old app version I suspect that the AC firmware also wasn't updated.

Easily seen in this instance in the flight ... Even thought full throttle (blue) & full elevator (purple) are applied the craft suddenly pitch up (black) to nearly 15 degrees ... & the craft loses height. When this happens the motors are on max rpm's but the thrust generated aren't enough to keep the craft pitched down properly anyway.

If you share the mobile device .DAT log ending with FLY058.DAT we will certainly see max rpm's when this happens.

In the end of the flight the thrust was so poor from the rear that the craft couldn't be kept airborne any more.
(the vision sensor error is unrelated to the outcome here ...)

 

[Meta4]

This Mini was running Firmware v01.00.0400.
DJI released Firmware 1.0.05 not long after the release of the original Mini to address this issue.

 

[zeusfl]

Awesome. I will call him now to see if he can get the .DAT
That will be by connecting the drone to the DJI Assistant 2 right ?

 

[Deleted member 103366]

Awesome. I will call him now to see if he can get the .DAT
That will be by connecting the drone to the DJI Assistant 2 right ?

No. The DAT should be in the MCDatFlightRecords folder which is in the folder "FlightRecord"? on the phone? where he found the txt log.

 

[zeusfl]

ok I have him on the phone.

 

[zeusfl]

As soon as he plug it to the DJI Assistant 2 it says System Recovery in progress. I never seen that.

 

[Deleted member 103366]

The DAT I am talking about is on the phone and assistant is NOT needed.
If the phone is Android, Windows can find the DAT through the normal Windows Explorer or what ever it is called.
If IOS is involved you might need iTunes. I think Linux finds them in a similar manner to windows.
THe DAT's on the drone are encrypted and can not be read by us mere mortals.

 

[zeusfl]

Now that I can post. I help him for about 4 hours. Turn out that he has a very old version of the DJI Fly app that never offered a firmware update but at the same time when we navigate to the Android folder the flying logs and data files were empty. After upgrading the Fly app and syncing again then they showed up. I have a hard time (over teamviewer) upgrading the firmware in the MM since had many failures in the process. In the end, I was able to do it and then upgrade the RC controller and batteries. The battery that was inside the drone at the moment of the crash is unable to upgrade failing in the 90% and going to recovery mode...

After testing the drone I was getting in the logs motor spinning too fast and I notice a high pitch over the phone. He changed the propellers for new ones and that fixed the issue. The propellers were too flat. The new ones had a better pitch angle and this fixed the drone. By having the propellers too flat non having a good pitch the motors need to overcompensate with too much speed and less lift. All errors went away.

We still need to make sure the vision sensor error never comes back but so far good.

Thanks for the help!

 

[Zbip57]

After testing the drone I was getting in the logs motor spinning too fast and I notice a high pitch over the phone. He changed the propellers for new ones and that fixed the issue. The propellers were too flat. The new ones had a better pitch angle and this fixed the drone. By having the propellers too flat non having a good pitch the motors need to overcompensate with too much speed and less lift. All errors went away.

See these two posts for info on how to avoid such prop deformation.

mavicpilots.com/threads/mavic-mini-crash.109111/page-2#post-1236446

mavicpilots.com/threads/motor-speed-error-mavic-mini.86130/page-13#post-1038101

 

[zeusfl]

Nice information. i will apply the same with my DJI Mini2.

 

[brew99]

Nice information. i will apply the same with my DJI Mini2.

Did they not fix this prop bending issue when they released the mini2? I thought it was only a factor for the mini1

 

[Zbip57]

Did they not fix this prop bending issue when they released the mini2? I thought it was only a factor for the mini1

I only have the Mini-1, so have no way of comparing what's different with the Mini-2.

Do you have a Mini-2? Can you post a couple of photos like these? Are the Mini-2's rear motors canted outboard the same way?

One difference is that the Mini-2 is sold with prop-holders that position the blades more at a ~45° angle, so the tips aren't forced to cross as they are in the Mini-1's flymore case.

Here's my Mini-1.

Rear motors with arms folded.

 

[MS Coast]

The Mini 2 uses the same configuration.

I don't like the way the new propeller holder bends the aft propellers. I don't use it and always store the Mini 2 and the Air 2S unfolded.

 

[Zbip57]

The Mini 2 uses the same configuration.

Are people not experiencing the same propeller deformations with the Mini-2? If not, why not?

If you store with arms folded and the rear propellers crossed, something has to give. If the blades are stiffer it would just twist the arms instead. Or are the Mini-2's blades somehow more forgiving? Can they be bent without twisting and losing pitch angle?

 

[Deleted member 103366]

The mini 2 blades are stiffer than the Mavic Mini blades. The holder does not need the rear blades across the drone, rather, from memory it seems designed to have then pointing backwards but slightly inwards.
I don't use the holder myself as I do not like the way the strap clamps down on the front blades. In the Mini 2 Flymore bag I stand the drone on its nose with the rear motor blade swept rearwards as the drone goes into the bag and the front motor blades are left to hang down their arms.

 

[dozzn]

I had similar problems with the Mini 1 when everyone else did, after the update. I changed the props and try to be more careful when I put the drone away.

Now that I have the Mini 2 I never fold the arms. I have a large case that I use for transporting the drone. If I ever need to, I could use the bag that it originally came with, but right now I don’t.