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 flow checks of the hydraulic pump drain system to ensure that the system is not clogged, and correction of any discrepancy. Additionally, the proposed AD would require replacement of the existing seal of the accessory gearbox with a new, improved seal assembly; this replacement would terminate the requirement for repetitive flow checks. This proposal is prompted by reports indicating that hydraulic fluid had contaminated the engine oil system as a result of failure of the seal of the hydraulic pump shaft. The actions specified by the proposed AD are intended to prevent clogging of the hydraulic pump drain system, which could cause failure of the seal of the hydraulic pump shaft and subsequent contamination of the engine accessory gearbox oil; this condition could result in an in-flight engine shutdown.