Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all Airbus Model A330-200 and -300 series airplanes, and Model A340-200 and -300 series airplanes. The existing AD currently requires repetitive inspections to detect discrepancies of the transfer tubes and the collar of the ball nut of the trimmable horizontal stabilizer actuator (THSA), and corrective action if necessary; repetitive inspections for discrepancies of the ball screw assembly, and corrective action if necessary; repetitive greasing of the THSA ball nut, and replacement of the THSA if necessary; and modification or replacement (as applicable) of the ball nut assembly, which would end certain repetitive inspections. Since we issued that AD, we have determined the repetitive inspections of the ball screw assembly (and corrective action if necessary) and repetitive greasing is needed for additional THSA nuts. This proposed AD would remove certain inspections, revise certain actions, andadd airplanes to the applicability. We are proposing this AD to prevent degraded operation of the THSA, which could result in reduced controllability of the airplane.