This paper presents a possible application of the Analytic Hierarchy Process (AHP) in a multi-criteria analysis of components importance to a system reliability structure illustrated by a stern tube sealing system installed on deep sea ships. We used the AHP to determine the relevance of the importance ranks and made an importance analysis for the criteria of reliability, safety and repair costs. We compared our results with the measures analysed and presented in literature before. We also presented some conclusions on using the AHP for multi-criteria analysis of components importance in Complex Technical Systems (CTS). We finished with suggestions for further research on quantitative and qualitative methods of importance analysis.