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Action

Final rule.

Summary

We are superseding an existing airworthiness directive (AD) for all Turbomeca S.A. Arriel 2B and 2B1 turboshaft engines. That AD currently requires checking the transmissible torque between the low- pressure (LP) pump impeller and the high-pressure (HP) pump shaft on high-pressure/low-pressure (HP/LP) pump hydro-mechanical metering units (HMUs) that do not incorporate Modification TU 147. This new AD requires inspection and possible replacement of the HMU. This AD was prompted by three additional cases of uncoupling of the HP/LP pump HMU LP fuel pump impeller and the HP fuel pump shaft, since the existing AD was issued. We are issuing this AD to prevent an uncommanded in-flight shutdown, which can result in a forced autorotation landing or accident.

Document

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