Crab/aa77788,
Ref the vibration you are feeling on approach (forget T/O, that you are about in this last couple of posts, are you talking about the Nper rev vibe at about the 45->25KIAS regime on decel/finals? Especially noticeable in the Aw139???
No, I'm talking about an approach in just about any helicopter but particularly in this case light singles and around the 20 Kt IAS mark.