There was an incident at PHI on a 222UT where the one of the drive/pitch link attachments failed in flight causing loss of pitch control on one blade. The pilot (Frenchy, don’t remember full name) very quickly found a collective angle (as he lowered it in response) where the vibration was “tolerable” and flew the aircraft back to shore and did a successful run on landing. Basically he was setting the pitch on the blade he could control to “match” the angle of the “free” blade.