Diagnostic reasoning technology for the on-board maintenance system

The authors describe On-board Maintenance System (OMS) developed by Smiths Industries Aerospace and Defense Systems, Inc. which includes inflight diagnostic and prognostic analysis of engines and mechanical systems. This on-board system is designed to enhance the data collection and recording function by providing the pilot with real-time system health information, on-board system and subsystem diagnosis, system performance prediction, and to assist ground maintenance personnel in diagnosing system malfunctions, and scheduling required maintenance actions. Ground maintenance crews have access to on-board diagnosis results while the aircraft is in flight via data link so they can be prepared when the aircraft lands to quickly repair failed units. In addition to the real time system health monitoring, the on-board system allows ground crews to perform maintenance on demand rather than performing maintenance based on time in service, thus tailoring the maintenance performed to the individual needs of each aircraft. A technology demonstration of the application of a hybrid reasoning system called the Diagnostic Reasoning Demonstrator (DRD) has been built which integrates a number of different knowledge sources and reasoning methods to demonstrate the diagnostic and prognostic analysis of mechanical failures trends and events in a gas turbine engine. The diagnostic reasoning technology is centered around hypothetical reasoning. The DRD consists of an engine model and simulator, a failure scenario builder, and the hybrid diagnostic reasoner. The demonstrator is implemented on a color laptop workstation