Fault diagnosis: Engineers and troubleshooters combine forces to create a knowledge-based system for the aerospace industry

A brief description of expert systems is followed by a discussion of a knowledge-based diagnosis system developed to assist in fault isolation on Lockheed´s Baseband Distribution Subsystem (BDS), an electronic device acting as a large signal-switching network. The purpose of the expert troubleshooter is to perform corrective maintenance on the BDS by rapidly isolating a faulty printed circuit board or other chassis-mounted part that has caused a failure. The BDS diagnostic knowledge base is represented in three forms: factual knowledge, heuristic knowledge, and control knowledge. A typical diagnostic session is described, and the results during six months of use are reported. The expanding role of expert systems in maintenance diagnosis of electronic equipment is discussed.