Action
Notice of proposed rulemaking (NPRM).
Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2018-03-13, which applies to certain General Electric Company (GE) CT7- 5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 model turboprop engines. AD 2018-03-13 requires initial and repetitive visual inspections and fluorescent penetrant inspections (FPIs) of the main propeller shaft. Since the FAA issued AD 2018-03-13, the manufacturer detected two additional cracks on a main propeller shaft during its ongoing investigation and subsequently published service information that introduced reduced inspection thresholds for initial and repetitive visual inspections, FPIs, and added initial and repetitive ultrasonic inspections (USIs) of the main propeller shaft. Additionally, the manufacturer revised the airworthiness limitations section (ALS) of the maintenance manual (MM) to incorporate initial and repetitive USIs to inspect for cracks on the main propeller shaft. This proposed AD would require initial and repetitive visual inspections, FPIs, and USIs of the main propeller shaft. Depending on the results of these inspections, this proposed AD would require replacement of the main propeller shaft. As an optional terminating action to these inspections, this proposed AD would require revising the ALS of the existing MM and the operator's existing approved maintenance program or inspection program, as applicable, to incorporate the tasks and reduced inspection thresholds for the main propeller shaft. The FAA is proposing this AD to address the unsafe condition on these products.