Airworthiness Directives; Gulfstream American (Frakes Aviation) Model G-73 (Mallard) Series Airplanes Modified in Accordance With Supplemental Type Certificate (STC) SA2323WE

This amendment adopts a new airworthiness directive (AD), applicable to certain Gulfstream American (Frakes Aviation) Model G-73 (Mallard) series airplanes, that requires revising the Airplane Flight Manual (AFM) to prohibit positioning the power levers below the flight idle stop, and to provide a statement of consequences of positioning the power levers below the flight idle stop. This amendment is prompted by incidents and accidents involving airplanes equipped with turboprop engines in which the propeller 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.