Facilities operations and maintenance encompasses a broad spectrum of services, competencies, processes, and tools required to assure the built environment will perform the functions for which a facility was designed and constructed. Operations and maintenance typically includes the day-to-day activities necessary for the building/built structure, its systems and equipment, and occupants/users to perform their intended function. Operations and maintenance are combined into the common term O&M because a facility cannot operate at peak efficiency without being maintained; therefore, the two are discussed as one.The scope of O&M includes the activities, processes, and workflows required to keep the entire built environment as contained in the organization's Real Property Inventory of facilities and their supporting infrastructure, including utility systems, parking lots, roads, drainage structures and grounds in a condition to be used to meet their intended function during their life cycle. These activities include both planned preventive and predictive maintenance and corrective (repair) maintenance.
Preventive Maintenance (PM) consists of a series of time-based maintenance requirements that provide a basis for planning, scheduling, and executing scheduled (planned versus corrective) maintenance. PM includes adjusting, lubricating, cleaning, and replacing components. Time intensive PM, such as bearing/seal replacement, would typically be scheduled for regular (plant or "line") shutdown periods.
Corrective maintenance is a repair necessary to return the equipment to properly functioning condition or service and may be either planned or un-planned. Some equipment, at the end of its service life, may warrant overhaul. Per DOD, the definition of overhaul is the restoration of an item to a completely serviceable condition as prescribed by maintenance serviceability standards.