Airworthiness Directive · Amendment 39-10947 · Rolls-Royce Limited, Bristol Engines Division, Viper Models Mk.521 and Mk.522 Turbojet Engines
Rolls-Royce Limited, Bristol Engines Division, Viper Models Mk.521 and Mk.522 Turbojet Engines
Rolls-Royce Limited, Bristol Engines Division, (R-R) Viper Model Mk.521 turbojet engine with high pressure (HP) fuel pump, part numbers (P/N's) MGBB.167 or MGBB.134 installed, and Model Mk 522 turbojet engine with HP fuel pump MGBB.137, MGBB.145, MGBB.168, or MGBB.169 installed. These engines are installed on but not limited to Raytheon (formerly British Aerospace, Hawker Siddeley) Model DH.125 series and BH.125 series 400A airplanes.
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.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
