Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Airbus Model A310 and A300-600 series airplanes, that currently requires, among other things, repetitive inspections to ensure correct synchronization of the hydraulic control valves of the trimmable horizontal stabilizer (THS) actuator; replacement of the horizontal stabilizer actuator motors with new or serviceable motors and resynchronization of the valves, or adjustment of the synchronization, if necessary; and a functional test of the THS. This proposed AD would add a requirement to replace the hydraulic motor of the THS with an improved motor, which would constitute terminating action for the repetitive inspections. This proposal also would expand the applicability to include additional airplanes. This proposal is prompted by the issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent desynchronization of the hydraulic control valves, which could result in runaway of the horizontal stabilizer to its full up or down position, subsequent reduced maneuvering capability, and potential pitch upset.