Phantom 4 crash

[aerodave3]

Is there an appropriate forum where I can post crash data from my drone and have some expert tell me what went wrong?

Yesterday I took off to fly my normal route with the phantom 4 which I have done many times before. 12 seconds into the flight it started spinning, lost control and slammed into the ground. I downloaded the flight data to the air data sight and it says that 13 seconds into the flight it gave a warning as follows:
“Detected side shock / possible collision, aircraft is rolling sharply to the left (repeated 3 times)”
It took 2 seconds to fall from 100 feet altitude to the ground. The propeller that hit first was broken by the wreckage while the other 3 were still on and intact. Battery was still in and lights were still flashing on the aircraft. It was overcast and getting dark, close to sunset. It was barely sprinkling rain. It was a wide open field with no trees or obstructions.
With that i formation, does anyone have an idea of why this crash happened?
Just trying to figure out what went wrong. Can anyone help?

 

[BigAl07]

WELCOME to the forum

I moved this thread to Crash & Fly Away

 

[Yorkshire_Pud]

I believe the Phantom 4 writes DAT flight logs to the MCDatFlightRecord folder. That folder should be in folder where you found the txt flight log.
Assuming the naming structure is similar to that used with a Mavic 2 the relevant DAT file name will contain something like FLY0114 or FLY114 etc.
If you can post that DAT file here it should contain motor speeds which may show an anomaly.

 

[zeusfl]

Looks like a bird strike for me or a motor failure.

 

[zeusfl]

Also, I never saw an M2P using more than 25.9 Amps under normal circustances. Looks like something happened in that full power.

 

[slup]

...anyone have an idea of why this crash happened?

The messages in the Airdata view about side shocks & collisions are usually auto generated due to excessive craft movements & doesn't necessarily mean that it happened.

Looking into the telemetry your P4 rapidly pitched front down (green graph), rolled over to the left (blue graph) & started to rotate CW (purple graph)... all while losing height.

All this correlate well with loss of thrust from the front left corner ... that the P4 starts to rotate CW is due to that the left front is CCW torquing, losing that means 2 sides CW torqing + 1 CCW torquing = starts to rotate CW.

All relevant telemetry here below ... the incident starts at 12sec where I've placed the chart marker (pink background = Sport mode, white stripes = RC/P4 connection interference).

This is most probably due to a prop or motor failure ... in order to say which we need the mobile device stored DAT log ... the correct one ends with FLY114.DAT. Retrieve that & attach it in a new post here.

(Click on the chart to make it larger)

Also, I never saw an M2P using more than 25.9 Amps...

This was a Phantom 4, not a M2P ...

 

[aerodave3]

There are some DAT files stored associated with this flight but they are not labeled as you indicated and is describes those files as VCD video files.

 

[slup]

There are some DAT files stored associated with this flight but they are not labeled as you indicated and is describes those files as VCD video files.

The correct DAT log is stored in the same place in your mobile device as the TXT log you shared in your first post ... but in a subfolder there named MCDatFlightRecords.

 

[old man mavic]

welcome to the forum
wish it could have been under better circumstances
have you tried to get help on the Phantom pilots forum

 

[aerodave3]

The correct DAT log is stored in the same place in your mobile device as the TXT log you shared in your first post ... but in a subfolder there named MCDatFlightRecords.

Yes I see that folder but it is "empty". There is no data in that file. Maybe because the flight was so short?

 

[Yorkshire_Pud]

Do you sync your logs with DJI? With some drones syncing removes the DAT/s.
Recording of the DAT starts at drone switch on and lasts until the drone is switched off, so most times it covers a greater period of time than the txt flight log. I have Go4 DATs from 1kb upwards and they have some data in them, admittedly very little, but some.

There is also another possiblility, and this is speculation. The controller might not create one, this is based on the behaviour of the controllers for the mavic 2 pro / zoom. There are two types on normal controller for the M2P/Z, an RC1A and an RC1B. The RC1A creates a DAT the RC1B does not, are there different versions of the controller for the P4, if so might the same thing happen there?
You might find .DAT file for the P4? useful or at least interesting

 

[eEridani]

I'm going with prop failure - mainly due to the multiple vibratory reports out of Airdata's algorithms. Something was shaking the drone as if fell, and an imbalance from a broken prop fits that data. What caused the failure, bird strike, age, shotgun skeet practice, other; who knows.

 

[slup]

@BudWalker ... can you give us all secrets regarding DAT logs from a P4, do we have one craft+one mobile device? Where are they stored? And are they readable for us?

 

[BudWalker]

@BudWalker ... can you give us all secrets regarding DAT logs from a P4, do we have one craft+one mobile device? Where are they stored? And are they readable for us?

The on-board .DAT is retrievable and readable. Look here to see how to retrieve an on-board .DAT
How to retrieve a V3 .DAT File from the AC

There is also a .DAT that resides on the mobile device running the Go 4 App.

 

[slup]

@BudWalker ... & the mobile device one, is it stored in the same place as for Mavic's?

 

[BudWalker]

@BudWalker ... & the mobile device one, is it stored in the same place as for Mavic's?

Sorry, I don’t know.

 

[slup]

Yes I see that folder but it is "empty" ...

So if it's empty we instead can use the craft stored DAT log ... it's retrieved through the DJI Assistance 2 program for Phantom 4, download it from here --> Phantom 4 - Download Center - DJI (scroll down there a bit).

Follow then the procedure from the link in post #14 to retrieve it ... the file will be rather large so you need to store it on some cloud service of your own & then come back here & share a link to the log.

 

[aerodave3]

I'm going with prop failure - mainly due to the multiple vibratory reports out of Airdata's algorithms. Something was shaking the drone as if fell, and an imbalance from a broken prop fits that data. What caused the failure, bird strike, age, shotgun skeet practice, other; who knows.

The broken prop theory may be correct since playing the last couple of seconds of video frame by frame I came across this picture before it hit the ground. It appears to have a broken prop. But it may have been spinning so fast it just appears that way. Who knows.

 

[slup]

The broken prop theory may be correct...

Well... in this stage it's equally correct with a motor failure I'm afraid.

The incident starts 12,7sec into the flight... at 14,9sec with the P4 still 13,9m above the homepoint with a heading speed of 11,3m/s a "motor is Blocked/Obstructed" message is issued & it's repeated until the P4 have hit the ground.

This message isn't the usual one when a prop have failed... instead it usually is what it say.

Both a prop or a motor failure in one of the corners generate the same craft movements like them we see in your log... in order to say which of these 2 reasons that is the cause we need to take a look at the motor rpm's & current draw & that data is in the DAT log. Without that log we can only speculate...

 

[aerodave3]

Well... in this stage it's equally correct with a motor failure I'm afraid.

The incident starts 12,7sec into the flight... at 14,9sec with the P4 still 13,9m above the homepoint with a heading speed of 11,3m/s a "motor is Blocked/Obstructed" message is issued & it's repeated until the P4 have hit the ground.

This message isn't the usual one when a prop have failed... instead it usually is what it say.

Both a prop or a motor failure in one of the corners generate the same craft movements like them we see in your log... in order to say which of these 2 reasons that is the cause we need to take a look at the motor rpm's & current draw & that data is in the DAT log. Without that log we can only speculate...

I inspected all 4 props and they were fine. Prop break was not it.
Is it common for a motor to fail? Should I sent the unit to DJI repair to see what it would cost? Anyone had a good experience doing that? I have had this Phantom 4 for I guess 6 years now and it has performed beautifully until this happened. My inclination is to buy another Phantom 4 but I have nothing to compare it to.
Thanks for all the thoughtful input from everyone.