Airworthiness Directives; Airbus Airplanes

We are adopting a new airworthiness directive (AD) for all Airbus Model A330-200 Freighter, A330-200, A330-300, A340-200, A340- 300, A340-500, and A340-600 series airplanes. This AD was prompted by the results of endurance qualification tests on the trimmable horizontal stabilizer actuator (THSA), which revealed a partial loss of the no-back brake (NBB) efficiency in specific load conditions. This AD requires inspecting certain THSAs to determine the number of total flight cycles the THSA has accumulated, and replacing the THSA if necessary. We are issuing this AD to detect and correct premature wear of the carbon friction disks on the NBB of the THSA. Such a condition could lead to reduced braking efficiency in certain load conditions and, in conjunction with the inability of the power gear train to keep the ball screw in its last commanded position, could result in uncommanded movements of the trimmable horizontal stabilizer (THS) and loss of control of the airplane.