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

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Raytheon Model Beech 400, 400A, and 400T series airplanes; Model Beech MU-300-10 airplanes; and Model Mitsubishi MU-300 airplanes. This action requires repetitive inspections to detect cracking in the radius of the cutout of the aft flange of the left engine forward carry-through mount bracket, and replacement with a new bracket and fitting if necessary. This action is necessary to prevent failure of the engine mount and possible loss of the engine, and consequent loss of control of the airplane. This action is intended to address the identified unsafe condition.