i don't know how to say... my arducopter fly very well but sometimes it spin up motors for 1/2 seconds when hovering and i don't know why. I made a video, check the sound and the movement at 49 seconds. I check all connection between motors esc and so on.
What i can do or check?
(i use firmware 2.7 but it does the problem with 2.6 also)
anyone can help me?