Enhanced diagnosis of faults using the digraph approach applied to a dynamic aircraft fuel system

Malfunctions within commercial aircraft can considerably increase both the financial cost of downtime and the disruption caused to passenger travel. For this reason prompt detection, diagnosis, and rectification of faults is imperative to the successful operation of such a system. In this paper the fault diagnostic problem is tackled based on the application of the digraph procedure. Digraphs model the information flow, and hence fault propagation, through a system. A computational method has been successfully developed to conduct the fault diagnostics process and produce a list of the fault combinations determined. The scope of the method has been demonstrated by consideration of two modes of operation to the application of a commercial aircraft fuel system, namely that of a Boeing 777. In addition the paper highlights the contribution of the development of a reduction method to enhance the likelihood of identifying the possible failure causes in three ways from different viewpoints. The three methods provide the option of determining the component at fault, the most probable failure mode cause, and also evidence for a particular component fault.