Airworthiness Directives; Turbomeca S.A. Arriel 2B Turboshaft Engines

The FAA is adopting a new airworthiness directive (AD) for Turbomeca S.A. Arriel 2B turboshaft engines with Modification TU62A incorporated. This AD results from several reports of the hydromechanical unit (HMU) acceleration controller axle sticking. This AD requires initial and repetitive inspections, cleaning, lubrication, and checks for proper operation of the HMU acceleration controller axle. We are issuing this AD to prevent loss of control of engine fuel flow in manual control mode or mixed control mode, leading to engine overspeed and in-flight engine shutdown, or uncommanded in-flight engine shutdown.