AD 97-20-03 62 FR 49429

This amendment adopts a new airworthiness directive (AD), applicable to all de Havilland Model DHC-7 series airplanes, that requires revising the Airplane Flight Manual (AFM) to prohibit positioning of the power levers below the flight idle stop during flight, and to add a statement of the consequences of such positioning of the power levers. This amendment is prompted by incidents and accidents involving airplanes equipped with turboprop engines in which the propeller ground beta range 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 when the airplane is in flight.