Airworthiness Directives; Dowty Aerospace Propellers Type R321/4-82-F/8, R324/4-82-F/9, R333/4-82-F/12, and R334/4-82-F/13 Propeller Assemblies

This amendment supersedes an existing airworthiness directive (AD) that applies to Dowty Aerospace Propellers (Dowty) Type R334/4-82- F/13 propeller assemblies. That AD currently requires a one-time ultrasonic inspection of propeller hubs, part number (P/N) 660709201, for cracks. This amendment requires initial and repetitive ultrasonic inspections of propeller hubs, P/N 660709201, that are installed on airplanes, and for hubs and propellers in storage, initial ultrasonic inspection of propeller hubs before placing in service. Propeller hubs, P/N 660709201, are installed on Type R321/4-82-F/8, R324/4-82-F/9, R333/4-82-F/12, and R334/4-82-F/13 propeller assemblies. This amendment results from the manufacturer's reevaluation of potential hub failure on Type R321/4-82-F/8, R324/4-82-F/9, R333/4-82-F/12, and R334/4-82-F/ 13 propeller assemblies. We are issuing this AD to prevent propeller hub failure due to cracks in the hub, which could result in loss of control of the airplane.