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My Mavic Pro dropped off the sky
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4135 59 2017-7-12
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fans6b14fc11
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My Mavic Pro fell off the sky on the 9th, after owning the drone for only 2 weeks.


It was only less than 10 minutes into the flight. It was at 300ft , flying stable with good RC, GPS and compass signals. Weather condition was also very good. No obstacles were seen in that area.


It lost control suddenly and dropped like a rock, there wasnt any RC input before the drop as I was trying to take some stable shots over the shore. Lucky it dropped on heavy bushes so no major physical damage can be seen outside. (I got more scratches myself trying to recover the drone.) . Inside, tho, I think is totally ruined as the DJIGo4 app is showing a long list of defects.


More detail of my flight can be found here. http://app.airdata.com/main?share=pqPNbm


I have lost confident to the Mavic totally.




2017-7-12
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DroneFlying
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I'm sorry to hear about your crash. The really useful information is in the DAT file for that flight that's stored on the Mavic. If you retrieve it using these instructions, upload it to DropBox or something similar, and provide a link to it here someone may be able to give you some more insight into why this happened. The correct file will have a timestamp that corresponds to when the flight occurred and will probably be at least tens of megabytes in size.
2017-7-12
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SteWong
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DroneFlying Posted at 2017-7-12 04:37
I'm sorry to hear about your crash. The really useful information is in the DAT file for that flight that's stored on the Mavic. If you retrieve it using these instructions, upload it to DropBox or something similar, and provide a link to it here someone may be able to give you some more insight into why this happened. The correct file will have a timestamp that corresponds to when the flight occurred and will probably be at least tens of megabytes in size.

Thanks so much, there are 2 .DAT file with the same time stamp.

FLY058 https://www.dropbox.com/s/642uhowx2gtb96e/FLY058.DAT?dl=0
FLY057 https://www.dropbox.com/s/tm8s6mkifllb4rm/FLY057.DAT?dl=0

Some other files created on the same day can also be found here.
https://www.dropbox.com/sh/chw3w ... oD9BhMucWeRGba?dl=0


Many thanks in advance
2017-7-12
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ephektz
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DroneFlying Posted at 2017-7-12 04:37
I'm sorry to hear about your crash. The really useful information is in the DAT file for that flight that's stored on the Mavic. If you retrieve it using these instructions, upload it to DropBox or something similar, and provide a link to it here someone may be able to give you some more insight into why this happened. The correct file will have a timestamp that corresponds to when the flight occurred and will probably be at least tens of megabytes in size.

You are one of the most helpful individuals on this forum.
2017-7-12
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DroneFlying
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SteWong Posted at 2017-7-12 05:09
Thanks so much, there are 2 .DAT file with the same time stamp.

FLY058 https://www.dropbox.com/s/642uhowx2gtb96e/FLY058.DAT?dl=0

FLY056.DAT is the correct file and it shows that your right front motor abruptly stopped during the flight, as shown in the graph below, where the gold line is your Mavic's height and the blue the right front motor's speed. That's also why you see the "Warning: Motor Obstructed" message in the flight log on AirData.

I can't say for certain what would have caused this, though it's typically attributed to debris getting inside the motor. Are you able to turn the right front propeller by hand and by any chance does it make a grinding sound when you turn it? A mechanical issue is always a possibility, but it looks like you've flown a number of times before this, so I'd guess that some sort of obstruction in the motor is what caused the problem.

MotorStopped.png
2017-7-12
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ephektz
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DroneFlying Posted at 2017-7-12 05:53
FLY056.DAT is the correct file and it shows that your right front motor abruptly stopped during the flight, as shown in the graph below, where the gold line is your Mavic's height and the blue the right front motor's speed. That's also why you're seeing the "Warning: Motor Obstructed" message in the flight log on AirData.

I can't say for certain what would have caused this, though it's typically attributed to debris getting inside the motor. Are you able to turn the right front propeller by hand and by any chance does it make a grinding sound when you turn it? A mechanical issue is always a possibility, but it looks like you've flown a number of times before this, so I'd guess that some sort of obstruction in the motor is what caused the problem.

Do the log files indicate the status of the ESC?
2017-7-12
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Tviscomi
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I'm curious to see what DJI say's about this in regards to warranty coverage
2017-7-12
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SteWong
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DroneFlying Posted at 2017-7-12 05:53
FLY056.DAT is the correct file and it shows that your right front motor abruptly stopped during the flight, as shown in the graph below, where the gold line is your Mavic's height and the blue the right front motor's speed. That's also why you see the "Warning: Motor Obstructed" message in the flight log on AirData.

I can't say for certain what would have caused this, though it's typically attributed to debris getting inside the motor. Are you able to turn the right front propeller by hand and by any chance does it make a grinding sound when you turn it? A mechanical issue is always a possibility, but it looks like you've flown a number of times before this, so I'd guess that some sort of obstruction in the motor is what caused the problem.

Wow. Thanks so much for the information.

I can turn the props like usual, and there isn't any noise coming for it either.

Your advice reminds me that days before the crash, there were two times that the HD images got transmitted back turn sideways suddenly, no response to RC control but then the drone Gaines back stability and everything got back normal. I thought it was interference to RC signal, but seems it is somehow related to this crash.
2017-7-12
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DroneFlying
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ephektz Posted at 2017-7-12 05:59
Do the log files indicate the status of the ESC?

The only property explicitly related to the ESC is the temperature, which spiked along with current when this happened. That might imply some kind of short circuit, but it could also just be a failed attempt by the FC to increase the motor speed, though it did appear to immediately cut the motor commanded (PWM in the graph). The truth is that I haven't seen enough of these to be confident of what happened except to say that the right front motor stopped working during the flight.
2017-7-12
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DroneFlying
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Tviscomi Posted at 2017-7-12 06:01
I'm curious to see what DJI say's about this in regards to warranty coverage

I am too. It's very possible this is a defect / warranty issue but ultimately I think that'll need to be determined by someone physically examining the Mavic.
2017-7-12
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ephektz
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SteWong Posted at 2017-7-12 06:05
Wow. Thanks so much for the information.

I can turn the props like usual, and there isn't any noise coming for it either.

When you turn your motors you should feel "bumps." Do all of your motors feel roughly the same?
2017-7-12
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DroneFlying
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SteWong Posted at 2017-7-12 06:05
Wow. Thanks so much for the information.

I can turn the props like usual, and there isn't any noise coming for it either.

Regarding that previous problem, there have been a lot of reports of what I refer to as "gimbals gone wild", where the gimbal appears to "reset" (or something) during the flight. It's understandably very disconcerting to see via FPV during flight, but if what you experienced was the same thing then it was really just the gimbal moving around and not the aircraft itself, though I'm obviously only speculating here.

Anyway, you're very welcome. I hope this turns out to be a defect problem that's covered under warranty and that you're flying again soon. Please let us know how it turns out.
2017-7-12
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ephektz
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SteWong Posted at 2017-7-12 06:05
Wow. Thanks so much for the information.

I can turn the props like usual, and there isn't any noise coming for it either.

Just a quick follow up question: You said your app is reporting numerous errors. Does one of those errors mention an ESC?
2017-7-12
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SteWong
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ephektz Posted at 2017-7-12 05:59
Do the log files indicate the status of the ESC?

Yup, one of them is ESC status error
2017-7-12
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SteWong
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Tviscomi Posted at 2017-7-12 06:01
I'm curious to see what DJI say's about this in regards to warranty coverage

I have made an appointment to bring it back, hope I can get a replacement/ :/
2017-7-12
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SteWong
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ephektz Posted at 2017-7-12 06:11
When you turn your motors you should feel "bumps." Do all of your motors feel roughly the same?

Yup, all 4 are turning the same, smooth with bumps, and no noise.
2017-7-12
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SteWong
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DroneFlying Posted at 2017-7-12 06:14
Regarding that previous problem, there have been a lot of reports of what I refer to as "gimbals gone wild", where the gimbal appears to "reset" (or something) during the flight. It's understandably very disconcerting to see via FPV during flight, but if what you experienced was the same thing then it was really just the gimbal moving around and not the aircraft itself, though I'm obviously only speculating here.

Anyway, you're very welcome. I hope this turns out to be a defect problem that's covered under warranty and that you're flying again soon. Please let us know how it turns out.

Sure, I will keep this topic updated. I am have an appointment to bring the Mavic back on the 14, hope I can get a replacement soon.

I bought this drone for a family trip to Vietnam and Taiwan for August, hope I can get back flying beforehand.

Thanks so much again for the information.
2017-7-12
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SteWong
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This is what I got after I took the drone back from the wild.
IMG_4315.PNG
2017-7-12
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Griffith
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DroneFlying Posted at 2017-7-12 05:53
FLY056.DAT is the correct file and it shows that your right front motor abruptly stopped during the flight, as shown in the graph below, where the gold line is your Mavic's height and the blue the right front motor's speed. That's also why you see the "Warning: Motor Obstructed" message in the flight log on AirData.

I can't say for certain what would have caused this, though it's typically attributed to debris getting inside the motor. Are you able to turn the right front propeller by hand and by any chance does it make a grinding sound when you turn it? A mechanical issue is always a possibility, but it looks like you've flown a number of times before this, so I'd guess that some sort of obstruction in the motor is what caused the problem.

DroneFlying,  did the other motors also stop, or did they try (without success) to compensate?

One possibility thought is bird collision causing overcurrent and shutdown in one motor.

However, I'm betting on a motor driver failure,  Can't tell if the internal damage is due to crash or electronics failure without taking a look inside.  It's interesting that the drone was still communicating after the crash.
2017-7-12
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Griffith
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Here's another curiosity from Airdata 09m 49s        224.4 ft        1,860 ft        Warning        Attitude too Large. Exit Forward Obstacle Sensing..  This was 3 seconds before the Motor obstruction warning.  Just speculating that at this point the prop had already stopped and the FS had begun trying to compensate.
(At first glance I thought it said Altitude to large,  which made no sense at all) :-)
2017-7-12
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SteWong
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Griffith Posted at 2017-7-12 07:18
DroneFlying,  did the other motors also stop, or did they try (without success) to compensate?

One possibility thought is bird collision causing overcurrent and shutdown in one motor.

Yup, I was impressed that I could still "talk" to the drone till I found it.
Lukyily that teh drone landed onto tall brushes, or else I will be badly disintegrated.
2017-7-12
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SteWong
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Griffith Posted at 2017-7-12 07:30
Here's another curiosity from Airdata 09m 49s        224.4 ft        1,860 ft        Warning        Attitude too Large. Exit Forward Obstacle Sensing..  This was 3 seconds before the Motor obstruction warning.  Just speculating that at this point the prop had already stopped and the FS had begun trying to compensate.
(At first glance I thought it said Altitude to large,  which made no sense at all) :-)

I have a feeling that it dive hard after losing one motor that caused that warning.
2017-7-12
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DroneFlying
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Griffith Posted at 2017-7-12 07:18
DroneFlying,  did the other motors also stop, or did they try (without success) to compensate?

One possibility thought is bird collision causing overcurrent and shutdown in one motor.

The other three motors were still working after the initial event and yes, they appeared to try to compensate but of course it was a lost cause. As far as the bird strike theory I can't really say, but I did check the accelerometer data and didn't see anything that would suggest any sort of impact or other abrupt change prior to the motor failure.

As far as the "Attitude too Large" error, that appears to be a side effect of the motor failure: roll and pitch were nominal leading up to the failure, and although there was some change in yaw present around that time it appeared to be normal and caused by the pilot's rudder input.
2017-7-12
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AndyP.
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ephektz Posted at 2017-7-12 05:55
You are one of the most helpful individuals on this forum.

DRONEFLYING is bae
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AndyP.
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DroneFlying Posted at 2017-7-12 06:10
I am too. It's very possible this is a defect / warranty issue but ultimately I think that'll need to be determined by someone physically examining the Mavic.

I second this
2017-7-12
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Griffith
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DroneFlying Posted at 2017-7-12 08:01
The other three motors were still working after the initial event and yes, they appeared to try to compensate but of course it was a lost cause. As far as the bird strike theory I can't really say, but I did check the accelerometer data and didn't see anything that would suggest any sort of impact or other abrupt change prior to the motor failure.

As far as the "Attitude too Large" error, that appears to be a side effect of the motor failure: roll and pitch were nominal leading up to the failure, and although there was some change in yaw present around that time it appeared to be normal and caused by the pilot's rudder input.

Yes,  That was what I expected. Thanks for checking the accelerometer data,    Sounds to me like hardware failure.  Ill be interested to hear DJI's analysis - hope we do :-)
2017-7-12
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Griffith
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SteWong Posted at 2017-7-12 07:54
I have a feeling that it dive hard after losing one motor that caused that warning.

Agree - since other motors were functional and trying hard to compensate.
2017-7-12
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BudWalker
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DroneFlying Posted at 2017-7-12 05:53
FLY056.DAT is the correct file and it shows that your right front motor abruptly stopped during the flight, as shown in the graph below, where the gold line is your Mavic's height and the blue the right front motor's speed. That's also why you see the "Warning: Motor Obstructed" message in the flight log on AirData.

I can't say for certain what would have caused this, though it's typically attributed to debris getting inside the motor. Are you able to turn the right front propeller by hand and by any chance does it make a grinding sound when you turn it? A mechanical issue is always a possibility, but it looks like you've flown a number of times before this, so I'd guess that some sort of obstruction in the motor is what caused the problem.

There is an experimental filed called Motor:Status:<MOTOR> You can turn on experimental fields by going to the main CsvView window and Preferences->Show Experimental Fields. Check out the Motor:Status fields and you can see the change in the RFront status.

I'll change the Motor:Status fields to non experimental next release. Now that I know what to expect in the way of values.
2017-7-12
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ephektz
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Griffith Posted at 2017-7-12 07:18
DroneFlying,  did the other motors also stop, or did they try (without success) to compensate?

One possibility thought is bird collision causing overcurrent and shutdown in one motor.

That ESC error is pretty telling, though. They do and can fail. I bet it was simply an ESC failing that brought him down from the sky. I wouldn't think a temporary obstruction should have caused the failure. It sounds to me, from his reports, that the motor is fine, too.

2017-7-12
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ephektz
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ephektz Posted at 2017-7-12 11:58
That ESC error is pretty telling, though. They do and can fail. I bet it was simply an ESC failing that brought him down from the sky. I wouldn't think a temporary obstruction should have caused the failure. It sounds to me, from his reports, that the motor is fine, too.

So, digging through some pictures, it appears that the Mavic integrates the PDB, ESC's, and at least part of the flight controller package onto a single board. The electronics that handle the vision system are directly below it. It's possible that by toasting an ESC it took out some of the vision components as well.
2017-7-12
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Griffith
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ephektz Posted at 2017-7-12 18:30
So, digging through some pictures, it appears that the Mavic integrates the PDB, ESC's, and at least part of the flight controller package onto a single board. The electronics that handle the vision system are directly below it. It's possible that by toasting an ESC it took out some of the vision components as well.

I think your analysis is spot on!  DJI should find some some scorched parts/boards which should make the incident a warranty repair.
2017-7-13
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SteWong
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Thanks for all the advice and information guys. I am going to bring the drone to DJI today, hopefully I will bring in some good news today.
2017-7-13
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ephektz
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SteWong Posted at 2017-7-13 19:56
Thanks for all the advice and information guys. I am going to bring the drone to DJI today, hopefully I will bring in some good news today.

Please keep us updated. Good luck! This seems like a fairly clear cut warranty case.
2017-7-13
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SteWong
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I took it in today and am waiting for their reply. One good news is that I should be able to get a drone back in around 7 working days. yay...

2017-7-14
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SteWong
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Hello Everyone

I got a replacement Mavic Pro yesterday free of charge. They told me it was the ESC that failed that caused the crash.

The replacement unit fly well but the camera gimbal seems not level, I need to adjust the gimbal roll to around 1.4 to get it align to her horizon. Anyone know if it is normal?

Thanks so much for the help guys.
2017-7-25
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CuaC
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SteWong Posted at 2017-7-25 00:34
Hello Everyone

I got a replacement Mavic Pro yesterday free of charge. They told me it was the ESC that failed that caused the crash.

You can try to:

-Remove the gimbal adjustment
-Calibrate on a surface as flat as possible
-Check the status and see if it's better

If that doesn't fix it, a cold IMU calibration would probably the best option. Mine is compensated -0.3, more than a degree seems odd...        
2017-7-25
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DroneFlying
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SteWong Posted at 2017-7-25 00:34
Hello Everyone

I got a replacement Mavic Pro yesterday free of charge. They told me it was the ESC that failed that caused the crash.

You're welcome. I'm glad that it turned out to be a warranty case and that you're back to flying again.
2017-7-25
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BumblerBee
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Found this thread as a follow-up read on ESC fail: https://forum.dji.com/thread-4170-1-1.html
Now I am nervous!
Very tempted to buy guards for outdoor flying and cages for indoor flying.
2017-7-25
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SteWong
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CuaC Posted at 2017-7-25 00:52
You can try to:

-Remove the gimbal adjustment

I have tried to reset and to calibrate, but seems it is still the same. I think I might need to bring the Mavic back again ;(
2017-7-25
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SteWong
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DroneFlying Posted at 2017-7-25 02:26
You're welcome. I'm glad that it turned out to be a warranty case and that you're back to flying again.



Thanks so much again, may I ask, what software do you use to read the .DAT files? Wanna have a go
2017-7-25
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