Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. This proposed AD would require modifying the main gearbox (MGB) tail rotor (T/R) drive flange installation. This proposed AD was prompted by several reported occurrences of loss of tightening torque of the Shur-Lok nut, which serves as a retainer of the T/R drive flange. The actions of this proposed AD are intended to address an unsafe condition on these products.