Summary
We propose to revise an existing airworthiness directive (AD) that applies to the products listed above. The existing AD currently requires initial and repetitive ultrasonic inspections of propeller hubs, part number (P/N) 660709201. Since we issued that AD, Dowty Propellers introduced a new hub assembly P/N. This proposed AD would revise that AD by introducing as an optional terminating action for the initial and repetitive ultrasonic inspections of that AD, replacement of propeller hub P/N 660709201 with a new propeller hub, P/N 660717226. We are proposing this AD to prevent that same propeller hub failure due to cracks in the hub, which could result in loss of control of the airplane, and to introduce an optional terminating action.