Motor obstructed after crash

[Emmediemme]

Hi everyone.
This afternoon, after a couple of flights, I landed my drone on my garden. Don't know really how (I was far from my Mavic) but when I did take off my drone again, the Mavic went up and crashed from about less than 2 meters (3ft).

I found my Drone on the soil at the border of grass and when I tried to restart it the left-back motor was obstructed.

I tried to move the motor with my hand and I noticed there was resistance, caused by soil. I forced a little bit the motor and sprinkled compressed air and all went (apparently) good. But when I move the motor by the hand, sometimes (when I make several laps to the engine) I can feel a little noise and a slight resistance, but it is easily overcome, like there were a little grain of soil that doesn't want to go out from. It's as if it moving from one side to the other, but the perception is that it is really very small, almost a grain of sand sandwiched.

The motor apparently work good and the drone seems to fly and mantain its position as ever, but my fear is that it can fail in every moment while I'm flying over a road.

What can I do? How can I fix it removing the dirt?

Thanks in advance and sorry for my bad english.

 

[dmyers7]

Here is my bigger concern, the motors have very strong magnets and the finest of metal debris (from the garden) could be now in there and no amount of compressed air will blow it out. It can abrade the copper wire insulation in the very tight gap between the magnets and stator which can then lead to a short and motor / esc failure. Yes you have reason to be concerned. Only disassembly of the motor can provide access to clean the surface of the magnets. Or replace the motor.

 

[Emmediemme]

Thanks for the reply.

Is it something I can do by my self or I have to send it to DJI?

 

[dmyers7]

Of course if your just over sensitive because of the incident and you did get everything out, it could be as good as new. Fly it 20hrs over a safe area and call it good.

 

[Emmediemme]

Thank you! Is it safe to remove the 3 screws from the motor?

 

[dmyers7]

I think someone with the handle @Thunderdrones has spare parts. He should caught this and respond shortly.

 

[dmyers7]

Thank you! Is it safe to remove the 3 screws from the motor?

Thunderdrones can tell you the exact steps.

 

[Emmediemme]

Thank you very much!

 

[Former Member]

OP I would not blow anything including compressed air into the motor because it will just push the dirt further into the motor and make it worse. The best you can do is turn the Mavic on its back and bang the left rear arm to get the dirt out of the top of the motor.

If you want to use compressed air, you need to blow air up out of the motor instead of in to it. You can take off the plastic piece on the bottom of the arm, remove the motor, and try to blow the dirt out.

I would suggest for $49 to buy a new rear left arm including motor and install it yourself. Once a motor has gotten debris into it, anything can happen, and usually does (Murphys law)

 

[Big Fil]

I've never had the Mavic motors apart but most brushless outrunner motors are mechanically very simple and easy to take apart. Once you have the motor out of the aircraft it usually it involves removing a cir-clip where the motorshaft enters the motor on the outside of the bearing. From there it's just a matter of sliding the rotor and stator apart. Hardest part is probably not losing the circlip as it tries to fling itself into the abyss of your carpet. While it's apart check that the bearings are running smoothly with no roughness.

 

[Emmediemme]

Ahahah thank you @Thunderdrones. My Drone is only 5 days old
Are the non-original arms safe to use?

@Big Fil to be honest the roughness is very rare, and I can feel it only one time when this little piece of sand moves. When I do another motor round I can't feel it.

The thing that most scary me is that I live in a place with one of the greatest wonders of the world: the volcano Etna. And he's full (very very very full) of sand. I will destroy all motors, I guess.

 

[Former Member]

I've never had the Mavic motors apart but most brushless outrunner motors are mechanically very simple and easy to take apart. Once you have the motor out of the aircraft it usually it involves removing a cir-clip where the motorshaft enters the motor on the outside of the bearing. From there it's just a matter of sliding the rotor and stator apart. Hardest part is probably not losing the circlip as it tries to fling itself into the abyss of your carpet. While it's apart check that the bearings are running smoothly with no roughness.

Yes getting the circlip out is challenging, not losing it is another challenge, and then getting it back in without bending it is the last part.

 

[geigy]

I would not run it with debris in the motor. Might cause further damage to the motor, and crash your Mavic in the process.

 

[Former Member]

Ahahah thank you @Thunderdrones. My Drone is only 5 days old
Are the non-original arms safe to use?

@Big Fil to be honest the roughness is very rare, and I can feel it only one time when this little piece of sand moves. When I do another motor round I can't feel it.

The thing that most scary me is that I live in a place with one of the greatest wonders of the world: the volcano Etna. And he's full (very very very full) of sand. I will destroy all motors, I guess.

I would not use any arm not made by DJI. I sell DJI only parts, and trust them to be reliable. Some companies sell copies, but its not worth saving a few dollars for the sake of reliability.

 

[Emmediemme]

I made a video to let you hear the problem. I disassembled the motor and it seems something got down from it (a very little sand) but now I think the motor is noisy.

Dropbox - IMG_1237.mp4

 

[Emmediemme]

Thank you @Thunderdrones. Just a question, why DJI doesn't sell its original spare part on its sit and you have it? Where do you take them? Sorry for my (probably) stupid question.

And just for information: do you send spare parts out of US? 'Cause I'm from Italy

 

[Former Member]

I made a video to let you hear the problem. I disassembled the motor and it seems something got down from it (a very little sand) but now I think the motor is noisy.

Dropbox - IMG_1237.mp4

Yes it sounds like something is in there and it could stop the motor in an instant if it gets caught in the wrong place.

 

[Former Member]

Thank you @Thunderdrones. Just a question, why DJI doesn't sell its original spare part on its sit and you have it? Where do you take them? Sorry for my (probably) stupid question.

And just for information: do you send spare parts out of US? 'Cause I'm from Italy

DJI has a short supply of spare parts to its own repair shop, so getting parts out to the general public is probably not important to them right now.

I have a few new and used Mavics that I use for parts.

 

[Emmediemme]

Ok thanks,
So you suggest me to change that arm, I guess.

Is it simple to do by my self? Do you send to Italy too and what is the cost in this case?

 

[Former Member]

Ok thanks,
So you suggest me to change that arm, I guess.

Is it simple to do by my self? Do you send to Italy too and what is the cost in this case?

You can try it. Do you have a good soldering iron? Have you repaired electronics before? Changing the rear arm is the easiest repair I do on the Mavic. Take off the top cover (12 screws), remove 2 screws holding on the arm. Remove 2 screws inside the arm. Unsolder 3 motor wires from the main board. Install the new arm.