Airworthiness Directives; Rolls-Royce Limited, Bristol Engines Division, Viper Models Mk.521 and Mk.522 Turbojet Engines

This amendment adopts a new airworthiness directive (AD), applicable to Rolls-Royce Limited, Bristol Engines Division, (R-R) Viper Models Mk.521 and Mk.522 turbojet engines, that requires replacement of certain high pressure (HP) fuel pumps with an improved design which is more tolerant of reduced lubricity fuel caused by water contamination. This amendment is prompted by reports of HP fuel pump drive shaft failures resulting in in-flight engine shutdowns. These failures have been attributed to the reduced lubricity properties of fuel which is contaminated by water. The actions specified by this AD are intended to prevent HP fuel pump failures, which can result in an in-flight engine shutdown.