Airworthiness Directive · Amendment 39-12232 · Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C Helicopters
Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C Helicopters
Model S-76A, S-76B, and S-76C helicopters with main rotor shaft assembly (shaft), part number 76351-09030-all dash numbers, installed, certificated in any category.
This amendment supersedes an existing airworthiness directive (AD) that applies to Sikorsky Aircraft Corporation (Sikorsky) Model S- 76A, S-76B, and S-76C helicopters and currently requires, before further flight, performing a fluorescent penetrant inspection (FPI) of the main rotor shaft assembly (shaft). Also, a recurring FPI and visual inspection for a cracked shaft are required by that AD. That AD also requires replacing the shaft with an airworthy shaft before further flight if a crack is found. This amendment requires replacing certain serial numbered shafts with an airworthy shaft before further flight. This amendment is prompted by further investigation and a determination that the inspections can be safely eliminated if certain serial- numbered shafts are removed from service before further flight. 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.
