Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to adopt a new airworthiness directive (AD) for all Airbus Model A330-300 series airplanes and Model A340-200 and -300 series airplanes. This proposed 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 proposed AD would require 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 proposing 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.