A framework to qualitatively assess the performance of maintenance policies in electrical production plants is presented. A Monte Carlo simulation scheme is combined with fuzzy logic for modelling the component degradation. The novelty of the work consists in the modelling of the influence of the actual living conditions on the degradation of the specific component under analysis; this is done by using linguistic fuzzy rules which formalize the expert knowledge on the degradation process. An example of application regarding a water-feeding turbo pump is presented to illustrate the potential of the proposed approach.