AD FAA-2021-0137

The FAA proposes to supersede Airworthiness Directive (AD) 2014-04-06, which applies to all Safran Helicopter Engines, S.A. (Safran Helicopter Engines) Arrius 2B1, 2B1A, 2B2, and 2K1 model turboshaft engines. AD 2014-04-06 requires initial and repetitive inspections of the hydro-mechanical metering unit (HMU) high pressure pump drive gear shaft splines, cleaning and inspections of the sleeve assembly splines, and replacement of the sleeve assembly on the affected high pressure pump drive gear shaft or replacement of the HMU if the HMU fails inspection. Since the FAA issued AD 2014-04-06, the manufacturer has published new service information that revises the inspections for certain HMUs and reduces compliance times for initial inspections. This proposed AD would require revised inspections and continue to require cleaning of the sleeve assembly splines, and replacement of the sleeve assembly on the affected high pressure pump drive gear shaft or replacement of the HMU if the HMU fails an inspection. The FAA is proposing this AD to address the unsafe condition on these products.