Comparison of digraph and fault tree based approaches for system fault diagnostics

The issue of fault diagnosis has become ever prevalent in engineering systems. Information concerning possible failures within a system can help to minimise the disruption to the functionality of the system by allowing quick rectification. Traditional approaches to fault diagnosis within engineering systems have focused on sequential testing procedures and real time mechanisms. Both methods have been predominantly limited to single fault causes. Latest approaches also consider the issue of multiple faults in reflection to the characteristics of modern day systems designed for high reliability. The bases of these approaches are the fault tree analysis technique and the method of digraphs. Both use a comparative approach to consider differences between actual system behaviour and that expected. This paper focuses on reviewing the developments with these methods to diagnose faults within an aircraft fuel system and to compare their effectiveness and future potential.