AD FAA-2021-0032

The FAA proposes to supersede Airworthiness Directive (AD) 2020-12-07, which applies to certain Hamilton Sundstrand Corporation (Hamilton Sundstrand) 54H model propellers. AD 2020-12-07 requires initial and repetitive eddy current inspections (ECI) of certain propeller blades and replacement of the propeller blades that fail the inspection. Since the FAA issued AD 2020-12-07, the manufacturer determined that all propeller blades installed on Hamilton Sundstrand 54H model propellers with a 54H60 model propeller hub are susceptible to intergranular corrosion cracking in the blade taper bore. This proposed AD would require initial and repetitive ECI of all propeller blades installed on Hamilton Sundstrand 54H60 propeller hubs and replacement of any propeller blade that fails inspection. The FAA is proposing this AD to address the unsafe condition on these products.