This paper presents a case study of an economic justification of an expert system in a large maintenance operation. A simulation model was developed to study the failure modes and operating characteristics of the maintenance operation and the potential impact of installing an expert system. The simulation results are used as inputs to the justification process. The justification approach combines conventional economic analysis with multiattribule utility measures. It was found that overall maintenance cost after an expert system installation was much lower than the cost without expert system installation. Thus, the proposed expert system was economically justified.