Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Model A318-100 and A319-100 series airplanes; Model A320-111 airplanes; and Model A320-200, A321-100, and A321-200 series airplanes. This proposed AD would require repetitive detailed inspections of the trimmable horizontal stabilizer actuator (THSA) attachments for proper clearances, and any crack, damage, or metallic particles; related corrective actions if necessary; and a report of the inspection results to the manufacturer. This proposed AD results from a report that during lab testing to verify the performance of the THSA's secondary load path with a simulated failure of the THSA's primary load path, the secondary load path's nut did not jam (as it was supposed to do.) We are proposing this AD to ensure the integrity of the THSA's primary load path, which if failed, could result in latent (undetected) loading and eventual failure of the THSA's secondary load path and consequent uncontrolled movement of the horizontal stabilizer and loss of control of the airplane.