Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Airbus Model A310 and A300-600 series airplanes. This proposal would require a functional flow test and leak test to verify if the pressure reducing valve in the cargo fire extinguishing system is in a serviceable condition, and replacement of any faulty valve with a new valve prior to extended range twin-engine operations of the airplane. This proposal is prompted by a report that, during a scheduled maintenance check, an inoperative pressure reducing valve was found in the cargo fire extinguishing system. The actions specified by the proposed AD are intended to ensure that a faulty pressure reducing valve is not installed, which could result in reduced fire protection of the cargo compartment of the airplane.