How do you know if a motor or esc is failing?

Hi I have a pixhawk on a Tarot 650 Ironman with Multistar 4822-690Kv motors and MultiStar 30A BLHeli-S Rev16 V3 ESCs.

I’ve just rebuilt it after a largish crash, which broke one of the arms.

On first flight it needed a lot more thrust than usual to take off and it seems from the flight log that one esc/motor is receiving a lot higher power commands from the FC.

Thus it seems that this pair have suffered damage in the crash - should I replace them both or is there some way of telling if it is the motor or esc failing (other than rebuilding and test flying in a different combination)?

The motor seems spin freely by hand and in a motor test with the props off and doesn’t seem to be getting any hotter than the others.

I’ve worked with a 650 and got similar symptoms due to un-leveled arms / motors mounts. Did you re-level them after the crash?

Otherwise it could definitely be the motor / esc bieng broken. Will get back to you on checking which it is…

Thanks, yes I leveled the motors to be perpendicular in 2 dimensions to the fc.

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Interesting. Any luck yet? It could be anything. TBH I’m not really sure, as I am not too familiar with this type of issue. I wouldn’t recommend plugging your suspected motor into a good esc to check it as it could damage the good esc. I’m not sure if fixing the suspected esc to a new motor will cause any harm though… still better not, unless you are okay with it.

I will do some poking about and see!

Hi there, well I’ve confirmed it’s not the motor or ESC.

I did some more log analysis and noted the Z axis vibration was very high, due to new tarot retractable landing gear I’d fitted with a fair bit of slop in the servos and thus wobble in the legs.

Using the high tech method of using two rubber bands to hold the legs together, the vibration has been damped to below 10G in all axes and no more problems.

Just goes to show - if you have control issues always think vibe first!