Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

We are adopting a new airworthiness directive (AD) for all Turbomeca S.A. Arriel 2E turboshaft engines. This AD requires removing the pre-TU 193 adjusted high-pressure/low-pressure pump and metering valve assembly and replacing it with a part that is eligible for installation. This AD also requires replacing the constant delta- pressure (delta-P) diaphragm of the fuel metering valve. This AD was prompted by reports of fuel flow non-conformities found during acceptance tests of Arriel 2E hydro-mechanical metering units (HMUs). We are issuing this AD to prevent failure of the delta-P diaphragm, which could result in an uncommanded in-flight shutdown and damage to the helicopter.