Airworthiness Directive · Amendment 39-12095 · Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C Helicopters
Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C Helicopters
Superseded. A later AD replaced this one: AD 2001-10-06. Comply with the one in force.
Model S-76A, S-76B, and S-76C helicopters, with main rotor shaft assembly (shaft), part number (P/N) 76351-09030 series or 76351-09630 series, installed, certificated in any category.
This document publishes in the Federal Register an amendment adopting superseding Airworthiness Directive (AD) 2000-23-52, which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, S-76B, and S-76C helicopters by individual letters. This AD requires, before further flight, performing a fluorescent penetrant inspection of the main rotor shaft assembly (shaft). Also required are recurring fluorescent penetrant inspections and visual inspections for any crack. If any crack is found, the shaft must be replaced with an airworthy shaft before further flight. This amendment is prompted by the discovery of two in-service cracked shafts, one with 477 hours time-in-service (TIS) and one with 313 hours TIS. A third shaft, that had been rejected from the manufacturing process for other reasons, was also discovered to have a crack. The actions specified by this AD are intended to prevent failure of the shaft and subsequent loss of control of the helicopter.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
