Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
A number of occurrences of an incorrect installation of the trimmable horizontal stabilizer actuator (THSA) have been found and reported during the accomplishment of the AIRBUS Service Bulletin (SB) A320-27-1164 mandated by EASA AD 2006-0223.
These issues could lead to a degradation of the integrity of the THSA primary load path and to secondary load path partial or full engagement.
Degradation of the THSA primary load path could result in latent (undetected) loading and eventual failure of the THSA secondary load path, with consequent uncontrolled movement of the horizontal stabilizer and loss of control of the airplane. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.