Why did my Mavic Air 2 fall out of the sky after 1 minute of flight?

[MNewman]

Hi Everybody,

I'm a real estate photographer/videographer and have been flying drones for several years. Today, I was using my Mavic Air 2 for a real estate shoot. About 1 minute into the flight, I got the following message:

"Image transmission signal may be blocked. Position remote controller to face aircraft and adjust antennas for optimal signal strength or fly at higher altitude (Code: 80004). Weak signal. Adjust antennas.; Image transmission signal may be blocked. Position remote controller to face aircraft and adjust antennas for optimal signal strength or fly at higher altitude.; Aircraft not connected to RC.; RC not connected to mobile device.; Target flight area is a Warning Zone. Fly with caution.

My monitor went blank and the drone was nowhere to be seen in the sky at its last location. After thirty minutes of searching, I finally discovered that it had apparently fallen out of the sky and crashed into someone's backyard. It's now smashed to bits, and the lithium battery has a bulge in it.

My question is -- what exactly happened to cause this? Is it possible some neighbor used a jammer to knock it out of the sky? I've flown nearly one hundred flights with this particular aircraft and my battery was fully charged before I started. Here's the flight log:

DJI Flight Log Viewer - PhantomHelp.com

Please let me know if you can figure out what caused this. I should add that I did crash the drone into a tree branch during the previous flight I was on, but it managed to dislodge from the tree and continue to fly without any problem for the rest of the shoot (another 10 minutes or so). A few of the propellers were a little scratched, but obviously not badly enough to compromise it.

Any and all advice and suggestions would be much appreciated!

~M

 

[MNewman]

And here's the .DAT file (attached below)

 

[thispilothere]

Just a guess based on how suddenly this happened, is the battery bulged in a way that could cause the connection points to dislodge?

 

[MNewman]

I attached a few pics of how the battery looks at present. It is bulged towards the top and not at the bottom where the connection points are. I should add that I found the battery a good distance away from the rest of the drone. The drone was found crashed upside down on a sloping hill. The battery was found about fifty feet away from it much further down the hill, and at a little bit of an angle away. My guess is once it hit the ground it popped out and rolled down the hill.

But it was not this misshaped when I first put it in. Are you thinking maybe it started to warp mid-flight, and this caused it to pop out of the connection points?

And on another note, does anybody know how to properly dispose of this battery?

 

[Yorkshire_Pud]

I haven't looked at the DAT yet but I am a bit puzzled that it is smaller than the .txt flight log. With my fly app drones, minis, the DAT is normally several times the size of the .txt.
Is there another DAT or where did this DAT come from?
I am also puzzled as to why the Phantomhelp csv is smaller than the .txt, again, for me, they are generally several times the size of the txt.
For reference, on my hard drive the DAT is 773kb, the .txt 1.2Mb and the csv 635kb, could you check the size of the original txt please?


With regards to

After thirty minutes of searching, I finally discovered that it had apparently fallen out of the sky and crashed into someone's backyard.

was it not under the lost point of connection? If not could you post a map showing where you found it?

 

[MNewman]

I haven't looked at the DAT yet but I am a bit puzzled that it is smaller than the .txt flight log. With my fly app drones, minis, the DAT is normally several times the size of the .txt.
Is there another DAT or where did this DAT come from?
I am also puzzled as to why the Phantomhelp csv is smaller than the .txt, again, for me, they are generally several times the size of the txt.
For reference, on my hard drive the DAT is 773kb, the .txt 1.2Mb and the csv 635kb, could you check the size of the original txt please?


With regards to

was it not under the lost point of connection? If not could you post a map showing where you found it?

I double checked and the DAT file is indeed only 756kb. You're right -- most others I have are bigger than the .TXT file but that's the only one that showed up, I'm afraid. It's not the first time, though. In looking through all the other .TXT and .DAT files, I have a bunch of .DAT files that are less than 1MB and smaller than the .TXT.

Below are two pics that show specifically where the drone's last signal was, where it crashed, and where the battery was found.

 

[thispilothere]

But it was not this misshaped when I first put it in. Are you thinking maybe it started to warp mid-flight, and this caused it to pop out of the connection points?

That's my guess. There aren't any other warnings, it was flying great, then just fell like the battery disconnected.

 

[mobilehomer]

The distortion is NOT swelling. That is from contact with the ground. Are you sure you had it locked in fully?

 

[Yorkshire_Pud]

O

I double checked and the DAT file is indeed only 756kb. You're right -- most others I have are bigger than the .TXT file but that's the only one that showed up, I'm afraid. It's not the first time, though. In looking through all the other .TXT and .DAT files, I have a bunch of .DAT files that are less than 1MB and smaller than the .TXT.

Below are two pics that show specifically where the drone's last signal was, where it crashed, and where the battery was found.

Oh I think your photos and annotations answer why it fell, the battery came out. I see no other possible explanation for the distribution of the disconnection point, battery location and drone location.
That leaves the question of why did it come out and I can't help with that, its production date might be 20-Aug-2020( Airdata, battery info) and the charge count is/was 46 ( Ph csv) so it has had reasonable regular use.

 

[MNewman]

I mean, I've flown the thing over 100 times, so I'm pretty sure it was in. If it wasn't, how could it even take off and fly at all?

 

[Yorkshire_Pud]

A slight un-noticed swelling has been thought to prevent clips from not properly engaging but I associate that more with m2p batteries but that is probably because I own and m2p so pay more attention to comments about them..

 

[MNewman]

Assuming the battery was in correctly and then it started to warp mid-flight, what would case it to do that? Or is the only explanation that it just wasn't in properly and somehow popped out during the flight?

 

[Yorkshire_Pud]

Assuming the battery was in correctly and then it started to warp mid-flight, what would case it to do that? Or is the only explanation that it just wasn't in properly and somehow popped out during the flight?

I imagine significant swelling could pop it out but that is imagination-only or vaguely remembered hearsay.
I don't think batteries warp, to me warp means bend/twist. I think they swell/inflate.

 

[Yorkshire_Pud]

As a totally unrelated comment, those houses and that stone wall look very European/British-Isles-ish in nature, I had to zoom the flight track out to check the location lol.

 

[rjwmorrell]

That's my guess. There aren't any other warnings, it was flying great, then just fell like the battery disconnected.

This would be my preliminary conclusion as well, especially with the battery separation on the ground. Thanks to the OP's photographs of the scene - something I recommended in any crash - it seems batterybseparstion occurred mid-flight. The configuration of the drone probably meant it did not fall straight down, and the battery being dense and heavy probably did fall more or less in the direction of travel.

I would classify this as spontaneous in flight separation of LiPo battery. At 10mph, and 200+ ft altitude, a math whiz.could probably calculate the probably trajectory and I'd bet it would be close to this.

The first collision may have cause battery damage that was not apparent on inspection.

 

[rjwmorrell]

I mean, I've flown the thing over 100 times, so I'm pretty sure it was in. If it wasn't, how could it even take off and fly at all?

How many cycles has the battery been through? 100 flights, that's a lot of recharges, and with the earlier tree collision it's possible like this battery was at the end of its useful life. Given your photographic and log evidence, the most apparent cause is mid-flight separation of the battery due to swelling.

 

[rjwmorrell]

The distortion is NOT swelling. That is from contact with the ground. Are you sure you had it locked in fully?

It's possible that's true, the battery could have hit the retaining wall while falling. But that just reinforces the fact that the battery separated during flight. The battery and aircraft fell to the ground separately, no question, based on their positions relative to the disconnection point, and the external damage to the battery.

The separation could still have been caused by bulging, it's hard to say based on the pictures what damage could be from the fall and what could be from internal swelling that caused the fall.

 

[Yorkshire_Pud]

How many cycles has the battery been through? 100 flights, that's a lot of recharges, and with the earlier tree collision it's possible like this battery was at the end of its useful life. Given your photographic and log evidence, the most apparent cause is mid-flight separation of the battery due to swelling.

46 charges, column DM of the Ph csv, "BATTERY.timesCharged"

 

[samysys]

May the OP also share the photo of the drone after crash? I wonder why it would bulge. The “lock” of the battery seems intact and didn’t suffer damage from the crash, but yet the “head“ of the battery was bulged….

My hypothesis is that the obvious damage to battery was caused post-crash. That can be better confirm when pair with the damage of the drone.

 

[WanderLost]

The first collision may have cause battery damage that was not apparent on inspection.

That was my take as well. A slight twist in the body from the previous crash might have made the battery connections (electrical and mechanical) more tenuous and prone to fail.