About Lynx vibrations, I remind myself flying at approx 120 Kts and being unable to read accurately the speed due to severe vivrations during the early years of 1980.
In front of such vibrations leading to cracks around the intermediate gear box, the French navy decided to create a track and balance team dedicated to the lynx. Using equipments such as Shadwick, Rotortuner and so on, that team succed in a very short period in a important reduction of vibrations both from the tail rotor and the main one.
This achivement makes me feel that the aircraft concept is not in fault. The vibrations and subsequent cracks came due to an lack of knowledge from the maintenance team. When they got the knowledge, the phenomenon went away.
DO