Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Short Brothers Model SD3-30, SD3-60, SD3-SHERPA, and SD3-60 SHERPA series airplanes. This proposal would require revising the Airplane Flight Manual (AFM) to modify the limitation that prohibits positioning the power levers below the flight idle stop during flight, and to provide a statement of the consequences of positioning the power levers below the flight idle stop during flight. This proposal is prompted by incidents and accidents involving airplanes equipped with turboprop engines in which the ground propeller beta range was used improperly during flight. The actions specified by the proposed AD are intended to prevent loss of airplane controllability caused by the power levers being positioned below the flight idle stop while the airplane is in flight.