Post crash diagnosis

[Liv3rman]

Hi guys.
I misjudged the height of a tree yesterday and clipped a branch with my front left (no.2) propeller. I managed to shut off the engines and hand catch my Mavic before it hit the ground. However, one of the tabs broke off the propeller and jammed the motor. I have now removed this, motor spins freely again but I get an ESC error on startup. The motor in question ‘twitches’ on startup as normal, but when activated in DJI assistant it doesn’t spin, all the others do. Is it likely to be a damaged motor or a fried ESC on the board do you think? Just strange that it moves briefly on startup indicating to me that the motor itself is ok. ? Any help/advice would be greatly appreciated.
many thanks.

 

[Starz]

Spin the other three motors by hand to get a feel for what they are doing. Then spin the one with the problem. If it doesn’t feel the same, probably a good indicator. Also watch the thin gap at the bottom of the outer case of the motor as you rotate it to see if it wobbles. That would indicate a bent shaft.

 

[Liv3rman]

Thanks for the reply. To be honest it does feel ever so slightly ‘stiffer’ than the others but only just. So would this be enough to throw up the ESC fault?

 

[Starz]

Any sign of a bent shaft on the motor?

 

[Liv3rman]

Any sign of a bent shaft on the motor?

I will give it a thorough visual inspection when I get home and report back! ?

 

[Liv3rman]

No visible signs of damage and shaft definitely not bent ?

 

[Liv3rman]

Just removed the motor and there is one copper winding wire broken. I guess this is the issue! However, I still can’t understand why it twitches with the other motors on startup if anyone can enlighten me?
im not fully informed on the workings of brushless motors.

 

[Thomas B]

Just removed the motor and there is one copper winding wire broken. I guess this is the issue! However, I still can’t understand why it twitches with the other motors on startup if anyone can enlighten me?
im not fully informed on the workings of brushless motors.

It still twitches as a complete revolution is blocked. Think of electricity as a fluid coating moving on the surface of a conductor.

 

[Skyflyer129]

Spin the other three motors by hand to get a feel for what they are doing. Then spin the one with the problem. If it doesn’t feel the same, probably a good indicator. Also watch the thin gap at the bottom of the outer case of the motor as you rotate it to see if it wobbles. That would indicate a bent shaft.


[/QUOTE
“Mind the Gap”, sorry... just had to say it since you’re in the UK. Sorry to hear about your mishap, I’m glad you caught it so it didn’t get more damaged. I hope you found my comment funny to add some levity to the situation.
Blue Skies from SoCal (soon to be Idaho

 

[Liv3rman]

New number 2 motor/arm fitted and all is well with the world and I’m back in the air! ?
Many thanks for all the help and suggestions.