P3 Pro Crash log file

[Astfagl]

Hello,


I am looking into second opinion on an issue of one Phantom 3 falling from the sky.

We are repair shop working with drones and other RC’s for almost a decade now. Of course we also sell drones primarily DJI and we provide training.

One part of our job is determining the cause of crash by inspecting the aircraft and reading and inspecting the flight log files.

Now we have case that, according to the owner, the Phantom 3 Pro was normally flying around and then just fell from the sky by itself a couple of minutes after the takeoff. Of course we all know that Phantoms do just drops from the sky without the PIC having anything to do with it

We would like to hear second opinion on certain part of log file for which we believe may indicate that something went wrong with one propeller. We believe that the aircraft lost a propeller during the flight or had seriously damaged the propeller.

The part that interests us the most are rows 4747-4749 of column motorcmd:Rback – what can cause for motor to go to maximum of 10000?
And rows 4195-4218 of column motorload:Rback – what can cause such sudden load change on all motors?

Here is the link for the log file



We know how much time it takes to read the read the log and get to the conclusion so we really appreciate your help.

We would like to hear your opinion before sending the aircraft to DJI.

Regards,

A.

 

[With The Birds]

Link to log file?

 

[Astfagl]

Dropbox - P3pro log.xls

 

[Meta4]

Dropbox - P3pro log.xls

That flight record only goes from line 0-1379 or 0 - 2:23 so it doesn't show the crash.
The important thing it does show is the flight started with the battery at only 43%.
By the time it's been in the air for only 2 minutes, the voltage has dropped to 14.2V.
It's very likely that the crash is due to flying with a partially discharged battery which gives a false % indication in the app.

It would be easier to analyse if you could go to DJI Flight Log Viewer
Follow the instructions to upload theflight record.
Come back and post a link to the report it provides.

 

[Astfagl]

I am sorry, that was the wrong log.

Here is the log from the aircraft

Dropbox - Log aircraft.xls

Also thank for the advice we will upload it also to the DJI Flight Log Viewer

 

[Astfagl]

Here is the link from DJI Flight Log Viewer

DJI Flight Log Viewer - PhantomHelp.com

 

[Meta4]

Here is the link from DJI Flight Log Viewer
DJI Flight Log Viewer - PhantomHelp.com

The dropbox link is for the longer flight but this Phantomhelp file is for the same short flight.
If you could upload the longer flight to Phantomhelp and provide a link it would help.

 

[Astfagl]

We are pulling out the *dat file from the aircraft through Ipad "Enter flight data" mode, which we to convert with Datcon in CSV. It doesn't have feature to convert in *txt. Do you have advice how to convert dat to txt?

 

[stones]

....
It's very likely that the crash is due to flying with a partially discharged battery which gives a false % indication in the app.

Is there a known reason why this occurs in the app? Does the app assume when starting the AC that the battery is 100%? Just trying to wrap my head around the issue. Thanks.

 

[Meta4]

Is there a known reason why this occurs in the app? Does the app assume when starting the AC that the battery is 100%? Just trying to wrap my head around the issue. Thanks.

To see a genuine case of launching with a partially discharged battery and why you shouldn't do it, read this thread: Water Loss
And see the numbers in the flight record here: DJI Flight Log Viewer - PhantomHelp.com

The big problem is that when launching with a partially discharged battery the % indicator is not reliable at all.
The Phantom needs a minimum of 3.3 volts per cell to be able to fly.
Look at the voltage the battery was able to deliver.
Some cells were already below 3.3 V under load at 49%, after only 30 seconds in the air.
That is what triggered the Critically Low Power autolanding.

Never launch with a battery that has been sitting around and has partially discharged

 

[Meta4]

We are pulling out the *dat file from the aircraft through Ipad "Enter flight data" mode, which we to convert with Datcon in CSV. It doesn't have feature to convert in *txt. Do you have advice how to convert dat to txt?

That one might be a case for @BudWalker or @sar104 .
If you upload the .dat file to Dropbox and provide a link, they are good at analysing those.

 

[sar104]

That one might be a case for @BudWalker or @sar104 .
If you upload the .dat file to Dropbox and provide a link, they are good at analysing those.

The DAT file data show that at 140.4 seconds all four motors stopped almost simultaneously and the aircraft fell to the ground. Superficially looks like a CSC, but it wasn't - the sticks were not moved to that position and the motor command signals did not tell the motors to stop.

I can see no apparent cause in the log. The battery was at 34% and looks fine. Power was not interrupted. I would guess some kind of hardware failure on the main board.

 

[BudWalker]

And, the motorVolts for each motor went to 0.0. I'm not a motor guy but it seems this is the reason the motors stopped.