MODERN ON-CONDITION MAINTENANCE CONCEPT OF AIRCRAFT ENGINES

Dragoljub Vujić

Abstract
A new maintenance technology of aircraft engines, based on significant usage diagnostic equipment and sophisticated diagnostic systems, is presented. The technology is applied in engines of combat or civil aircraft. A new maintenance concept is based on monitoring state and calculating real engine life in service instead of maintenance with fixed prescribed number of engine operating hours. Besides traditional method of quantitative measuring and particles analysis of the wear parts containing in lubrication oil, for state determing, it is presented a modern monitoring system enables to detect automaticlly a start of the failure. It pointed out a logic defining problem in failure detection and warning threshold for maintenance personnel. A modern on-condition maintenance concept is explained on the RB199 engine  installed on Italian Air Force TORNADO aircraft. A model of complex automated diagnostic system for state evaluating, failure locating and state forecasting, especially of engine and airframe as subsystems which have the most influent to the aircraft reliability and pilot security, is explained on the MIG-29 aircraft.

Key words: aircraft, aircraft engine, turbojet engine, aircraft maintenance, engine maintenance, maintenance according to state, diagnostics, state estimation.