Airworthiness Directives; Turbomeca Arrius 1A Series Turboshaft Engines

This amendment adopts a new airworthiness directive (AD), applicable to Turbomeca Arrius 1A series turboshaft engines, that requires installation of module TU63, which provides a separate supply of fuel for one of the 10 main injectors of the fuel injection system. This action is prompted by reports of unexpected power loss during test flights. The actions specified by this AD are intended to prevent unexpected power loss, which could result in an uncommanded in-flight engine shutdown, autorotation, and forced landing.