Preventative maintenance programs are described as one thing and are three genuinely different arrangements depending on what the site is. A building services programme, a production plant programme and a fleet programme differ on the two questions that decide everything else: what drives the interval, and who controls the window in which work can happen. Recognising which one you are running saves you from copying a structure that was designed for a different constraint.
The building: calendar-driven, occupant-constrained
Air handling, boilers, chillers, lifts, fire systems, water systems. Intervals are seasonal or annual and the calendar is the driver, because a building runs at a fairly constant duty. The constraint is occupancy: work happens out of hours or in the quiet season, so the programme is planned around the year rather than around availability.
The plant: runtime-driven, production-constrained
Machines wear by use, so intervals follow hours, cycles or units produced rather than dates. The constraint is the line: work can only happen in a window production grants. That makes the programme a queue of due work waiting for a shutdown, and the planning effort goes into assembling what fits the next window rather than into the calendar.
The fleet: distance-driven, availability-constrained
Miles or engine hours drive the interval, the vehicle has to be off the road to be serviced, and the person who knows something is wrong is the driver rather than the planner. That makes the daily report a real input to the programme, which is a channel neither of the other two shapes has, and ignoring it is the commonest fleet mistake. A fourth shape exists at some sites: the mixed estate, where a building, a small plant and a handful of vehicles sit under one person. That is not a fourth structure so much as running all three at once, and the thing that makes it workable is keeping the interval driver on the asset rather than on the programme, so a vehicle can be on mileage while an air handler beside it is on the calendar and neither arrangement has to be argued about again.
Questions people ask about preventative maintenance programs
Can one programme cover a site with all three?
Yes, and many sites have all three. What must differ is the interval driver per asset; forcing vehicles onto a calendar or a building onto runtime is where the programme starts feeling wrong to the people running it.
Which shape is hardest to keep going?
The plant one, because the window is somebody else's decision. Programmes there survive on visibility to production rather than on discipline inside maintenance.
Is preventative the same as preventive?
Yes, they are the same word with two accepted spellings, and both are used interchangeably across the trade. Nothing about the programme changes with the spelling.