Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Airbus Model A330 and A340 series airplanes. This proposal would require a one-time inspection of the hydraulically operated valve of the parking brake of the main landing gear to identify the part and serial numbers, and follow-on actions, if necessary. This action is necessary to prevent leakage of the valve, which could result in failure of the "blue" hydraulic system and consequent failure of alternate parking brake and emergency braking systems. This action is intended to address the identified unsafe condition.