Airworthiness Directives; Hawker Beechcraft Corporation Model MU-300-10 Airplanes and Model 400 and 400A Series Airplanes; and Raytheon (Mitsubishi) Model MU-300 Airplanes

The FAA is superseding an existing airworthiness directive (AD), which applies to certain BEECH Model 400, 400A, and MU-300-10 airplanes. That AD currently requires installation of an improved adjustment mechanism on the flightcrew seats and replacement of the existing aluminum seat reinforcement assemblies with steel assemblies. This new AD would add airplanes to the applicability of the existing AD. This AD results from reports of incomplete latching of the existing adjustment mechanism and cracked reinforcement assemblies, which could result in sudden shifting of a flightcrew seat. We are issuing this AD to prevent sudden shifting of a flightcrew seat, which could impair the flightcrew's ability to control the airplane.