Airworthiness Directives; Airbus Airplanes

We are adopting a new airworthiness directive (AD) for all Airbus Model A330-300 series airplanes and Model A340-200 and -300 series airplanes. This AD was prompted by reports of corrosion found on certain trimmable horizontal stabilizer actuators (THSA), affecting the ballscrew lower splines between the tie bar and the screw-jack. This AD requires repetitive detailed inspections for corrosion of certain THSAs, ballscrew integrity tests if necessary; and replacing any affected THSA with a serviceable or new and improved THSA, if necessary. We are issuing this AD to detect and correct corrosion of the THSAs, which could lead, in the case of ballscrew rupture, to the loss of transmission of THSA torque loads from the ballscrew to the tie-bar, prompting THSA blowback, and possibly resulting in loss of control of the airplane.