Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76B and S-76C Helicopters

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2001-03-51, which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-76B and S-76C helicopters by individual letters. This AD requires, for certain main rotor shafts, initial and recurring fluorescent penetrant inspections. Replacing each affected main rotor shaft (shaft) on or before reaching 1,000 hours time-in- service (TIS) is also required. This amendment is prompted by four reports of shaft cracks. The actions specified by this AD are intended to prevent failure of the shaft and subsequent loss of control of the helicopter.