DJI Drone Help Forum

OK, it's another "why did it happen"

I’m new to the forum & new to “why did this happen” … so bear with me.
I’ve had my P3A for just over a year with no crashes or great issues … until a couple of weeks ago.
I was landing (always manually - maybe it’s the control freak bit) & all was good until it landed … & I could not shut one motor down. The other 3 stopped but this didn’t. Of course, everything happens in seconds, so it flipped on one side …yes, prop digging holes!
The only way I could stop it was to pull the battery out.
Yes, the faulty (??) motor was extremely hot & started to melt the mounting place.
Now I’m pretty sure I didn’t do anything wrong here but I’d like to know how I can read the flight log. As I’m new I’m not allowed to upload files as yet.
Drone is at the “hospital” getting analysed first, then fixed up second … I hope.
Appreciate peoples advice here.

You can upload your TXT flight log here. However, you’ll likely need to see the DAT flight log from the Phantom since that’s the only log that contains data for each individual motor.

Ouch. Can you retrieve the .DAT and provide it via a DropBox (or similar) link? Here is some info about retrieving the .DAT
http://datfile.net/DatCon/retrieve.html

OK … I’ll try DropBox to see if you can read them. I’ve loaded the last 2 DAT files.

F…k it! I can’t upload or link files yet!

You should be able to link Dropbox or any other external links here.

I’ll try it another way.


Well, that’s kinda strange. The .DAT shows what you described - that the leftBack motor continued to run although all the motors were being commanded to stop.


But, the ESC temp starts to rise.

So I’m gonna guess that the ESC failed in an “on” state.

1 Like

This may have no bearing on the apparent ESC issue, but did you use a CSC to shut down the motors? This can cause a motor to keep running and flip the aircraft, but granted normally for not long. That’s what it looks like and just wanted to point that out.

Is this a CSC? The rudder and elevator input is neutral.

I did see that, but why else would the aileron be at max along with the throttle? That is the first thing that came to mind. Mainly was just curios as to the reason for it, if there was one.

I’m not sure I understand the question. But, it wasn’t a CSC.

The question being, why the aileron inputs while shutting off the motors. Iv’e never seen anyone do this unless it was in the process of a CSC. The full down throttle is normal. The aileron is not. That was the question.

Righto … thanks for the info. Ah … hmmm … the questions. CSC … what’s that?
Normally - well just about 100% of the time, I land it manually, so it’s just throttles all the way to stop motors - once landed. As you know, all this happens in seconds so I don’t know exaclty what I did on the controller once I saw it wouldn’t turn off. Pulling the battery was the only course of action.

My point was when you took the throttle down to turn off the motors, you also gave full aileron at the same time, which is odd if you are using the standard throttle down only for 2-3 seconds. CSC is how you start the motors on a P3…not stop them, although that will work, it usually results in a flip over.

Just to be clear. CSC is both sticks down and in. Rudder full positive and aileron, throttle, elevator full negative. CSC was not performed here.

Agreed. Maybe I wasn’t clear enough in what I was attempting to say. What I am suggesting, and this may or may not be related whatsoever, is the fact that I have not seen ( Not to say it hasn’t occurred before ) anyone give unnecessary inputs to stop the motors. Either a CSC or a full throttle down ONLY will stop them. Just as a speculation, the timing of the throttle down and aileron inputs in this particular case “might” cause an issue. Unsure of that but the possibility is there. Full throttle down occurred at 605.1 seconds. At the same time the aileron was being moved. Full aileron occurred at 607.4 seconds. Motor shutdown ( Except for the Left Rear ) occurred at 608.3 seconds. Just my thought, but the aileron input during the shutdown process “may” have flipped the aircraft, which in turn “may” have resulted in the OP’s description of the event and the subsequent ESC failure, presumably. Like I said, it is just a thought. I hope that explained better what I was thinking.

Look at the Roll value at the spike in the motor speed. It looks like the aircraft was rolling over from the aileron input.

Zooming in a bit it looks like the roll close to the ground may have caused the left props to strike the ground at 606.525. There was an abrupt decrease in speed but then it recovered.


I suppose it’s possible that a prop strike may have caused the ESC to fail.

Looking at this incident some more I don’t see any evidence that the P3AP actually “flipped”. Did it really flip @Rod ? The data shows it rolled to -58° for about 3 secs then righted itself.

1 Like

That is what I was attempting to explain. The RC aileron input during motor shutdown appears to have caused the hard roll, just as a CSC might do while stopping the motors in that manner. I didn’t see any actual “flip” either. I was using that term generically. I didn’t mean there was an actual CSC, but the results are similar.

No it didn’t flip over.