Action
Final rule.
Summary
We are superseding airworthiness directive (AD) 2013-01-07 for all Turbomeca S.A. Arriel 2D turboshaft engines. AD 2013-01-07 required replacing the hydromechanical metering unit (HMU) at a reduced life. This AD maintains that requirement and also requires conducting inspections of the HMU. This AD was prompted by further cases of deterioration of HMU rotating components. We are issuing this AD to prevent an uncommanded in-flight shutdown of the engine and possible loss of the helicopter.