Fault Tree Analysis is a commonly used technique for assessing the rel
iability and safety of engineering systems at the design stage but it
is tedious and time-consuming to apply. A reconfigurable program is pr
esented which utilizes a library of qualitative component models to en
able fault tree type analyses of arbitrary hydraulic circuit configura
tions. It is applied to the analysis of failures of an experimental ri
g and a complex industrial system, and some features of its design and
performance are discussed.