Airworthiness Directives; Lockheed Model L-188A and L-188C Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to all Lockheed Model L-188A and L-188C series airplanes. This amendment requires revising the Airplane Flight Manual (AFM) to prohibit the positioning of the power levers below the flight idle stop during flight, and to provide a statement of the consequences of positioning the power levers below flight idle stop. This amendment is prompted by incidents and accidents involving airplanes equipped with turboprop engines where the propeller ground beta was used improperly during flight. The actions specified by this AD are intended to prevent loss of airplane controllability, or engine overspeed and consequent loss of engine power caused by the power levers being positioned below the flight idle stop while the airplane is in flight.