Airworthiness Directives; Airbus Model A310 and A300-600 Series Airplanes Equipped With Pratt & Whitney Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A310 and A300-600 series airplanes, that requires flow checks of the hydraulic pump drain system to ensure that the system is not clogged, and correction of any discrepancy. Additionally, this amendment requires replacement of the existing seal of the accessory gearbox with a new, improved seal assembly; this replacement terminates the requirement for repetitive flow checks. This amendment 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 this 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.