Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76 Series Helicopters

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2000-11-52, which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-76 series helicopters by individual letters. This AD requires determining the serial number (S/N) of each main rotor blade and removing certain serial numbered main rotor blades. This AD also requires visually inspecting and replacing, if necessary, other certain serial numbered main rotor blades. This AD is prompted by a report of a crack in a main rotor blade and three reports of root end pocket separation from main rotor blades during flight. The crack and the main rotor blade root end pocket separation were due to improper manufacture of certain main rotor blade skins. The actions specified by this AD are intended to prevent main rotor blade root end pocket separation, impact with main rotor or tail rotor blades, and subsequent loss of control of the helicopter.