Airworthiness Directives; Sikorsky Aircraft Corporation Model S-92A Helicopters

This amendment adopts a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-92A helicopters. This action requires replacing the main gearbox (MGB) lubrication/scavenge pump vespel spline adapters (vespel spline adapters) before further flight, and thereafter, replacing them at certain intervals. This amendment is prompted by a reported incident of an in-flight loss of oil pressure. The actions specified in this AD are intended to prevent loss of lubrication to the MGB, which could cause failure of one or both engine input drives, or planetary gear to sun gear tooth mesh failure, resulting in loss of power to the rotor system and subsequent loss of control of the helicopter.