Airworthiness Directives; Pratt & Whitney Canada Corporation Turbofan Engines

The FAA is adopting a new airworthiness directive (AD) for certain Pratt & Whitney Canada Corporation (P&WC) PW308A and PW308C model turbofan engines. This AD is prompted by a manufacturer's design review, which identified that the combustion chamber outer case (CCOC) to rear compressor case (RCC) flange bolt low cycle fatigue life was inadequate and that those flange bolts may develop cracks resulting in flange bolt fracture. This AD requires replacing all CCOC flange bolts and modifying the CCOC and inner bypass ducts. This AD also prohibits installation of certain flange bolts on any affected engine, as specified in a Transport Canada AD, which is proposed for incorporation by reference (IBR). The FAA is issuing this AD to address the unsafe condition on these products.