Summary
We propose to adopt a new airworthiness directive (AD) for certain Pratt & Whitney Canada Corp. (P&WC) PT6B-37A turboshaft engines. This proposed AD was prompted by reports of incorrect engine torque for PT6B-37A engines. This proposed AD would require 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. We are proposing this AD to prevent axial migration of the No. 10 bearing in the engine RGB assembly, which could lead to engine overtorque, failure of the engine, in-flight shutdown, and loss of the rotorcraft.