Airworthiness Directives; Aerospatiale Model ATR42-200, -300, -320, and -500 Series Airplanes; and Model ATR72 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Aerospatiale Model ATR42-200, -300, -320, and -500 series airplanes; and all Model ATR72 series airplanes. The AD requires revising the Airplane Flight Manual to modify procedures for calculating takeoff performance when Type II or IV de-icing or anti- icing fluids have been used. This amendment is prompted by reports that use of these de-icing or anti-icing fluids may result in an increase in the pitch forces necessary to rotate the airplane during takeoff. This condition could result in a delayed takeoff or even late aborted takeoff. The actions specified by this AD are intended to ensure that the flight crew is advised of the potential effects of Type II or IV de-icing or anti-icing fluids on the airplane's performance during takeoff, and to ensure that the flight crew is advised of the revised performance calculations for takeoff to address these effects.