This work uses Fuzzy Inference Systems to model the failure modes of the Metrocable (ropeway massive transportation system in Medellín-Colombia) and to this aim, handle the concept of Condition Based Maintenance (CBM) for the automation of maintenance routine.Maintenance procedures in this massive transportation ropeway system have been designed from manufacturer and improved by expert knowledge trough years of operation, so they can be modeled by fuzzy models.The following work is part of the project "Diagnostic system of the interface grip-cable of the Metrocable", developed between the entities COLCIENCIAS, Metro de Medellin and Universidad EAFIT.