This article relies largely or entirely on a single source. (May 2011)
Planned preventive maintenance (PPM), more commonly referred to as simply planned maintenance (PM) or scheduled maintenance, is any variety of scheduled maintenance to an object or item of equipment. Specifically, planned maintenance is a scheduled service visit carried out by a competent and suitable agent, to ensure that an item of equipment is operating correctly and to therefore avoid any unscheduled breakdown and downtime.
Along with condition-based maintenance, planned maintenance comprises preventive maintenance, in which the maintenance event is preplanned, and all future maintenance is preprogrammed. Planned maintenance is created for every item separately according to manufacturers recommendation or legislation. Plans can be date-based, based on equipment running hours, or on the distance travelled by the vehicle. A good example of a planned maintenance program is car maintenance, where time and distance determine fluid change requirements. A good example of condition-based maintenance is the oil pressure warning light that provides notification that you should stop the vehicle because engine lubrication has stopped and failure will occur.
Planned maintenance has some advantages over condition-based maintenance (CBM), such as:
- easier planning of maintenance and ordering spares,
- costs are distributed more evenly,
- no initial costs for instruments used for supervision of equipment.
- less reliable than equipment with fault reporting associated with CBM
- more expensive due to more frequent parts change
- requires training investment and ongoing labor costs
Parts that have scheduled maintenance at fixed intervals, usually due to wearout or a fixed shelf life, are sometimes known as time-change interval, or TCI items.
- Aircraft maintenance checks
- Condition-based maintenance
- Predictive maintenance
- Preventive maintenance