Our S76 are C+, they usually fly smoothly and are pleasant to fly at all speed as long as engineers take a carefull and regular care of the vibration level adjustment.
They are not equipped with the upper (5P) bifilar, nor with LVA.
This 4P vibration appeared suddenly on cruising flight, beeing rather worrying.
It feels a bit like a fixed wing post stall buffeting, but not constant, in few seconds sequences in the 135 Kts IAS range.
Last edited by cpt; 29th Jan 2008 at 06:47.
Reason: 5P "upper" bililar