ABSTRACT
Complex systems need maintenance to remain in working order. In time components wear out, fluids become depleted, and critical elements fail. Maintenance prevents these from adversely affecting system operation, and repairs systems when component failures or malfunctions occur. Systems generally undergo two types of maintenance, scheduled and unscheduled. Scheduled maintenance is preventive, intended to inspect and replace components, fluids, belts, etc., before they wear out or fail. Unscheduled maintenance repairs the system after an equipment anomaly.
