Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Mitsubishi Model YS-11 and YS- 11A series airplanes. This proposal would require revising the airplane flight manual (AFM) to prohibit positioning the power levers below the flight idle stop. This proposal is a result of incidents and accidents involving airplanes equipped with turboprop engines in which the propeller beta was used improperly during flight. The actions specified by the proposed AD are intended to prevent loss of airplane controllability or engine overspeed with consequent loss of engine power caused by the power levers being positioned below the flight idle stop while the airplane is in flight.