Mavic Pro Crashed - Could it Be Manufacturing error?

[gaboveloz]

Could anyone help me trying to figure out why my MP crashed? There was no collision with any buildings, telephone poles, or birds. My MP simply made a weird sound and fell down. This is how it happened: I took off the drone, started flying up and forward, moved/flew drone to the left, slightly flew upwards, and this is when the drone made a weird sound and started spiraling down.

I've attached the flight record and log for better references. I've sent the drone to DJI Texas repair shop 2 days - and it should be arriving tomorrow. But I am hoping this is a manufacturing error so that DJI can replace it.

Before this flight, I flew the drone perfectly for less than 2 minutes and quickly landed it back to clean up space from memory card.

Please note that I did calibrate the drone before the first flight.

This is a shareable link to the flight record screen-recorded from my iPhone --> IMG_8966.TRIM.MOV

I am not sure if the flight log is the correct one as the flight happened at 6:59am on 2018-10-06. The attached file is set at 6:57am.

Phantom Help Log link: DJI Flight Log Viewer - PhantomHelp.com

Best!

 

[MavicCF]

It has been a while since I've posted on here or analized anything so I'm pretty rusty. It looks beyond me anyway, @sar104.
It does have a lot of compass and speed errors, but I can't tell if they are a caues of the crash or merely the result of the abrupt changes in yaw.
The pitch, roll, and yaw make it look almost like a prop loss, which is about all I could think of to explain the sudden loss of altitude.
OP, what kind of props were you using, and where they all still attached to your Mavic when you got to it?

 

[gaboveloz]

I used the original props. When I recovered the drone I noticed 1 prop was missing but I assumed the prop broke when it hit the ground as I noticed the prop "tooth" was still attached to the motor. Please see attached.
IMG_37711FC40CB9-1.jpeg

 

[sar104]

It was clearly loss of propulsion from one prop - the signature is unmistakeable as mentioned by @MavicCF. The aircraft pitched up, rolled right, and yawed CCW. The first two indicate loss of propulsion rear right, but the CCW yaw is inconsistent with the loss of a CW prop - it more likely suggests that the rear right motor seized or the ESC failed. That would also explain the strange noise, and would be consistent with the ESC errors starting at 84 seconds.



If you want to retrieve the DAT file from your mobile device then the motor data will probably show definitively what happened.

How to retrieve a V3.DAT from the tablet

 

[gaboveloz]

Thank you both for responding to my thread. I did followed the instructions to retrieve the DAT file for this flight. However, the latest DAT file belongs to the flight prior to this (attached in first message). Could you kindly take a look at it and confirm if it belongs to this flight?

Update: I believe I found the file(s). Attached for reference.

 

[sar104]

Thank you both for responding to my thread. I did followed the instructions to retrieve the DAT file for this flight. However, the latest DAT file belongs to the flight prior to this (attached in first message). Could you kindly take a look at it and confirm if it belongs to this flight?

Update: I believe I found the file(s). Attached for reference.

FLY104 was the correct file. The data are actually a bit confusing. Looking at the motor speeds:



There are two unusual features here. Firstly, the front right motor speed goes very high - characteristic of a lost prop. And then the rear left drops to zero (that's not normal and suggests a problem), and the rear right also drops, which is the reason for the pitch backwards.

The motor current and PPM data don't shed much light on this either, so I'm not sure what happened. I guess that the sudden right front overspeed does suggest that the loss of that prop was the primary issue, and that is the missing prop in your photo. The FC response is a bit of a mystery though.

 

[gaboveloz]

@sar104 thanks for taking the time to analyze the data. I find it a bit strange that the drone lost a prop when I made sure all props were secured prior to the first flight. On the flight before this one, the altitude and distance were significantly higher than this flight. Going back to the missing prop on the picture, I did noticed that part of one prop hook was still attached to the motor upon recovering it.

Would losing a prop suggest the strange sound I heard just prior the drone started going down? Would this still be factored as a ESC error? I also wonder why the rear left motor drops to zero as you stated that this is not normal.

All hopes is DJI taking my case as a warranty case.

 

[sar104]

@sar104 thanks for taking the time to analyze the data. I find it a bit strange that the drone lost a prop when I made sure all props were secured prior to the first flight. On the flight before this one, the altitude and distance were significantly higher than this flight. Going back to the missing prop on the picture, I did noticed that part of one prop hook was still attached to the motor upon recovering it.

Would losing a prop suggest the strange sound I heard just prior the drone started going down? Would this still be factored as a ESC error? I also wonder why the rear left motor drops to zero as you stated that this is not normal.

All hopes is DJI taking my case as a warranty case.

I wouldn't expect an ESC error due to a lost prop. My guess is that the ESC error related to the rear left motor, which just stopped if we accept the logged data. All of which is not very satisfying, since those look like unrelated problems even though, obviously, they cannot be.

 

[gaboveloz]

@sar104 @MavicCF

I just heard back from DJI Support team with the following response:

“Dear Gabriel,

Thanks for your patience.

This is Ken from data analysis team, and I will be assisting you on this case from now on for related inquiries about data analysis.

The unfortunate incident that occurred to your aircraft has been confirmed as a warranty case according to our data analysis. We will have our quotation team to follow up on your case soon.

Thanks for your support. Have a nice day.
Best regards,
Ken”


I wonder if DJI will replace the drone as the damages were severe after the fall.

UPDATE #1: According to the invoice email I later received it states the following: “After carrying out the data analysis, we found that your product is qualified for a free replacement.”

However, it also states that “Your product sent back qualifies for repair under warranty. Repair will be finished within three to six business day.” Repairs total up to USD $217.

Just a little confused as to wether they’re replacing the drone or repairjng it.

I still don’t know what was the actual cause of the crash. Updates to follow...

 

[ac0j]

Maybe a little lock tab from the prop broke off and fell into the motor causing it to bind and make noise. If one prop fails, I would think the FC would try to compensate with the motor opposite of the failure. To correct attitude?

 

[MavicCF]

@sar104 @MavicCF

I just heard back from DJI Support team with the following response:

“Dear Gabriel,

Thanks for your patience.

This is Ken from data analysis team, and I will be assisting you on this case from now on for related inquiries about data analysis.

The unfortunate incident that occurred to your aircraft has been confirmed as a warranty case according to our data analysis. We will have our quotation team to follow up on your case soon.

Thanks for your support. Have a nice day.
Best regards,
Ken”


I wonder if DJI will replace the drone as the damages were severe after the fall.

UPDATE #1: According to the invoice email I later received it states the following: “After carrying out the data analysis, we found that your product is qualified for a free replacement.”

However, it also states that “Your product sent back qualifies for repair under warranty. Repair will be finished within three to six business day.” Repairs total up to USD $217.

Just a little confused as to wether they’re replacing the drone or repairjng it.

I still don’t know what was the actual cause of the crash. Updates to follow...

It’s quite probable that the actual cause of the problem may remain a mystery.
It’s good news that it’s a warranty repair though!
In cases like this, they will analyze the damage and see if it will be cheaper to repair it or replace it. It’s almost always cheaper to repair, and they will send you an invoice with the amount it would regularly cost.
This being a warranty case, they will not actually charge you what the invoice shows, but will state the total price owed as $0.00 or something like.