so i binned my 5inch pretty hard into a tree last weekend, classic case of fpv tunnel vision and misjudging a gap. anyway one of the motors is definitely toast, it spins but there's this grinding noise and you can feel resistance when you spin it by hand. the other three seem fine but im wondering if the adjacent one took any shock damage even if it sounds okay right now.

ive replaced motors before but usually its just a clean swap, never really thought about whether i should be checking the bell for cracks or inspecting the stator after a hard hit like this. the frame took most of it but there was a definite jolt through the whole thing when it went in. anyone have a routine for this kind of thing or do you just replace whats obviously broken and fly?

the grinding is almost certainly the bearings, either they got deformed on impact or debris got in there. you can sometimes press new bearings in if the stator and bell are fine but honestly for a 5inch motor its rarely worth the time unless its an expensive one. just swap the whole motor.

as for the neighboring motor ? spin all of them by hand with props off and feel for any roughness or wobble in the shaft. if it feels smooth and your ESC telemetry isnt showing weird current draw after a short hover test youre probably fine. i usually do a low hover for like 30 seconds and watch temps before trusting any post-crash motor.

yeah same thing happened to me a few months back and i made the mistake of just replacing the one that was obviously dead. flew it twice more and then the one next to it seized up mid-flight because i guess the shaft got slightly bent from the impact and i just didnt catch it. lost it in a cornfield lol. now i just replace any motor that was on the same arm as a hard hit, its like a few bucks and saves the headache.