Airworthiness Directive · Amendment 39-13523 · Eurocopter France Model AS 365 N3 Helicopters
Eurocopter France Model AS 365 N3 Helicopters
Model AS 365 N3 helicopters, with a Quiet Fenestron tail rotor (tail rotor gearbox, part number (P/N) 365A33- 6005-06, and tail rotor hub, P/N 365A33-3500-02), tail rotor hub attachment bushings, P/N 365A33-3530-20, and a reinforced control shaft, P/N 365A33-6214-20, on the tail rotor hub control shaft assembly, installed, certificated in any category.
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.
