Airworthiness Directives; Pratt & Whitney Canada Corp. Engines

The FAA is adopting a new airworthiness directive (AD) for certain Pratt & Whitney Canada Corp. (P&WC) Model PW535E and PW535E1 engines. This AD was prompted by a manufacturer design review that indicated certain flange bolts securing the gas generator case and turbine support case are susceptible to cracking at their current low- cycle fatigue (LCF) life. This AD requires repetitive borescope inspections (BSI) of the gas generator case to turbine support case retaining bolts for evidence of bolt cracks, bolt fracture, missing bolts, or loose bolts and replacement, if necessary, as specified in a Transport Canada AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products.