AD NUMBER: 2018-12-01

PRODUCT: All Safran Helicopter Engines, S.A., Arriel 2B and 2B1 turboshaft engines.

ACTION: Final Rule.

SUMMARY:  The FAA is superseding Airworthiness Directive (AD) 2012-03-11, which applied to the products listed above.

AD 2012-03-11 required checking the transmissible torque between the low-pressure (LP) pump impeller and the high-pressure (HP) pump shaft on the HP/LP pump and metering valve assembly, hereafter referred to as the hydromechanical metering unit (HMU).

Since AD 2012-03-11 was issued, the manufacturer determined that incorporating Modification TU 178 is a more effective method to reduce the risk of uncoupling between the LP fuel pump impeller and the HP fuel pump shaft than the prior Modification TU 147.

This AD requires inspection and possible replacement of the HMU. This AD was prompted by three cases of uncoupling of the HMU LP fuel pump impeller and the HP fuel pump shaft since AD 2012- 03-11 was issued.

DATES: This AD is effective September 12, 2018.

COST: The FAA estimates that this AD affects 417 engines installed on helicopters of U.S. registry. The cost of compliance is estimated as follows:

• Remove and replace the HP/LP fuel pump metering unit. Labor - 2 work-hours × $85 per hour = $170; Parts - $17,400; Cost per aircraft - $17,570.

FMI: AD