Airworthiness Directives; Beech Model 400, 400A, and MU-300-10 Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Beech Model 400, 400A, and MU-300-10 airplanes, that requires installation of an improved adjustment mechanism on the flightcrew seats and replacement of the existing aluminum seat reinforcement assemblies with steel assemblies. This amendment is prompted by reports of incomplete latching of the existing adjustment mechanism and cracked reinforcement assemblies, which could result in sudden shifting of a flightcrew seat. The actions specified by this AD are intended to prevent such shifting of a flightcrew seat, which could impair the flightcrew's ability to control the airplane.