FAA: Fuel Regulators Must Be Replaced Earlier

     WASHINGTON (CN) – The Federal Aviation Administration has adopted a new airworthiness directive (AD) that requires replacing the Hydromechanical Metering Unit (HMU) in the Turbomeca Arriel 2D helicopter engine more frequently.
     The move comes following an engine test that ultimately uncovered a breakdown in the fuel flow regulation device.
     “During an Arriel 2D endurance test, the illumination of the low fuel pressure warning light was observed,” the FAA explained. “The investigation of the high pressure/low pressure (HP/LP) pump assembly within the hydromechanical metering unit, removed following this occurrence, revealed a deterioration and loss of the LP pump drive function.”
     The FAA said a loss of fuel pressure can lead to engine failure.
     “The AD requires replacing the HMU at a reduced life,” the FAA said. “We are issuing this AD to prevent uncommanded in-flight shutdown of the engine and possible loss of the helicopter.”
     The FAA estimates the AD will affect about 27 engines in the U.S., according to service information, with the cost to U.S. operators comes to a total of $390,407.
     Safran Turbomeca is a helicopter design and manufacturing company based in Bordes Cedex, France. The company’s Arriel 2D is an engine based partly on proven technology, but which also benefits from new industry technology, particularly the engine’s axial compressor and blade material. The Arriel version 2E was recently certified by the European Aviation Safety Agency and will be used to power the Eurocopter EC 145T2 helicopter.
     To learn more click the document icon for this regulation and others.

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