Wobble in FFF but not during normal flight

[Number]

Hi all, I've got my 500X equipped with a Brain2. I'm having a weird issue where it flies great normally but if I do very high speed forward flight I get an oscillation on elevator axis and it doesn't stop until I slow down and go middle collective for a bit. It doesn't do it during flight and doesn't even do it during fast elevator tic tocs.. only during high speed flying. Any ideas?

[Crashalotjoe]

Originally Posted by Number

Hi all, I've got my 500X equipped with a Brain2. I'm having a weird issue where it flies great normally but if I do very high speed forward flight I get an oscillation on elevator axis and it doesn't stop until I slow down and go middle collective for a bit. It doesn't do it during flight and doesn't even do it during fast elevator tic tocs.. only during high speed flying. Any ideas?

I guess it could be a number of things. Possibly gain related. Have you looked at the vibration log to see if that gives any clues? Are there any wires either touching the FBL unit or tight enough to transfer vibes?

Head dampers?

[Number]

Here's quick vid... the tic tocs at the beginning were just showing that it doesnt wobble during elevator-y (?) maneuvers.

wobble (0 min 27 sec)

[OnTheSnap]

Drop the elevator d gain