is this covered by the warranty? i have had no crashes or anything to cause such damage.  it has only happened on one arm of the drone.  please advise.

I think DJI will replace the stress cracks,  If it was done due to a crash no.

I just noticed cracks under one of my motors and on the top shell near one of the other motors. I emailed DJI support with pictures and they sent me an RMA # and shipping label. So they have it now. Mine was 6 weeks old and only about 20 something flights. No crashes or hard landings.

Thanks.  I'll give dji acall.  Good thing I have 3 ...