Summary
The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), applicable to Dowty Aerospace Propellers 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 proposal would require 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 proposal is prompted by 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. The actions specified by the proposed AD are intended to prevent propeller hub failure due to cracks in the hub, which could result in loss of control of the airplane.