Airworthiness Directive · Amendment 39-9696 · Sikorsky Aircraft Model S-76B Helicopters
Sikorsky Aircraft Model S-76B Helicopters
Sikorsky Aircraft S-76B helicopters, with engine drive shaft assembly (drive shaft), part number (P/N) 76361-09202- 044, -047, -049, or -051, with either rivet, P/N CR3523P-8-XX, with a washer or balance weight, or rivet, P/N NAS1738MW6-X, with or without a washer, installed, certificated in any category.
This amendment supersedes an existing Airworthiness Directive (AD), applicable to Sikorsky Aircraft Model S-76B helicopters, that requires an inspection of the drive shaft for cracks or loose balance weights. This amendment also supersedes a Priority Letter AD that currently requires repetitive inspections for cracks in the driveshaft in helicopters with certain engine drive shaft assemblies (drive shafts) installed. This amendment is prompted by a report of a fatigue crack found in a drive shaft that was caused by fretting of a balance weight rivet washer. The actions specified by this AD are intended to prevent failure of the drive shaft, loss of power to the rotor system, and a subsequent forced landing 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.
Aircraft
