ABSTRACT
E. Systems Maintenance Maintenance, as the activity o f restoring the failed system to its nominal operating conditions, can be:
• Preventive maintenance • Emergency maintenance or maintenance on failure
Preventive maintenance is system restoring according to a regular schedule o f servicing wi th the objective o f preventing unexpected system failure. In com puter aided automated systems preventive maintenance is a predictive mainte nance, based on condition monitoring and on-line diagnostics. Thus, in the case that the system elements are subject to continuous or periodic monitoring so that their degradation is detectable early, such elements can be replaced before they fail. This simplifies the planning and execution o f preventive maintenance.
