Within the framework of a general policy aiming at the improvement of the services in order to ensure a permanent availability of the production installations, SAMIR opted for a modernization of the modes of management of maintenance by using new techniques like the analysis of the Root Causes (RCA) and the analysis of the modes of failure, of their effects and their criticalities (AMDEC). In order to achieve this objective, we first applied the RCA approach on the electric motors of the critical units of the UPGRADE area. Therefore, we have developed a qualitative study to analyze the root causes of their malfunctions. In a second part, we carried out a Failure Mode, Effects and Criticality Analysis (FMEA) on the most critical equipment, which allowed us to identify their failure modes. Finally, we developed a maintenance plan, while proposing improvement actions.