Airworthiness Directives; Raytheon (Beech) Model 400, 400A, 400T, and MU-300-10 Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Raytheon (Beech) Model 400, 400A, 400T, and MU-300-10 airplanes, that currently requires a revision to the Airplane Flight Manual (AFM) to provide pilots with special operating procedures during icing conditions. This amendment adds a requirement to modify the airplane ice protection system. This amendment also removes Model MU-300 airplanes from the applicability of the existing AD. This amendment is prompted by the development of a modification that will positively address the unsafe condition. The actions specified by this AD are intended to prevent uncommanded nose-down pitch at certain flap settings during icing conditions.