Airworthiness Directives; Pratt & Whitney Canada Corp. Turboshaft Engines

We are adopting a new airworthiness directive (AD) for certain Pratt & Whitney Canada Corp. (P&WC) PT6B-37A turboshaft engines. This AD requires initial and repetitive inspections until replacement of the No. 10 bearing, and eventual replacement of the No. 9 bearing, both located in the engine reduction gearbox (RGB) assembly. This AD was prompted by reports of incorrect engine torque for PT6B-37A engines. We are issuing this AD to prevent axial migration of the No. 10 bearing in the engine RGB assembly, which could result in engine overtorque, failure of the engine, in-flight shutdown, and loss of the rotorcraft.