The FAA is adopting a new airworthiness directive (AD) for Turbomeca S.A. Arriel 2D turboshaft engines. This AD was prompted by a low fuel pressure event caused by deterioration and a loss of the low-pressure drive function within the hydro-mechanical metering unit (HMU).

This AD requires replacing the HMU at a reduced life. We are issuing this AD to prevent an uncommanded inflight shutdown of the engine, and possible loss of the helicopter.