Airworthiness Directives; Eurocopter France Model AS 365 N3 Helicopters

This amendment adopts a new airworthiness directive (AD) for the specified Eurocopter France (Eurocopter) model helicopters that requires installing a tail rotor blade (blade)-to-torsion bar attachment tuning weight assembly on each blade of the Quiet Fenestron tail rotor and replacing each blade attachment bushing. This amendment is prompted by the discovery of tail rotor induced vibrations during flight tests. The actions specified by this AD are intended to prevent vibration in the tail rotor and the pilot's anti- torque pedals, blade pitch control failure, and subsequent loss of control of the helicopter.