Airworthiness Directives; Beechcraft Corporation Airplanes

We are adopting a new airworthiness directive (AD) for certain Beechcraft Corporation (Type Certificate Previously Held by Hawker Beechcraft Corporation; Raytheon Aircraft Company; Mitsubishi Heavy Industries, Inc. Ltd.) Model MU-300 airplanes, and Beechcraft Corporation (Type Certificate Previously Held by Hawker Beechcraft Corporation; Raytheon Aircraft Company; Beech Aircraft Corporation) Model 400, 400A, and 400T airplanes. This AD was prompted by multiple reports of fatigue cracking in the horizontal stabilizer ribs. This AD requires repetitive inspections of the horizontal stabilizer rib assemblies for cracking, and replacement if necessary. We are issuing this AD to detect and correct such cracking, which could result in the failure of the horizontal stabilizer and loss of pitch control of the airplane.