Maintenance backlog

The maintenance backlog is all the work that has been identified and approved but not yet done. Every team has one. The question is whether it is the right size, whether it is growing, and whether it is real.

Formula

Count the backlog in labor hours, then divide by the hours the crew has for this work each week:

Backlog (weeks) = estimated labor hours of open work / crew hours available per week

Crew hours available means hours for backlog work, after breakdowns, meetings, and other time are taken out. Use a realistic figure, not paid hours.

Worked example

A team of six technicians works 40 hours a week each. On average, 25% of their time goes to emergencies and 10% to meetings, training, and travel inside the plant. That leaves 65% for planned work: 6 × 40 × 0.65 = 156 hours a week.

Open work orders:

• 320 hours of work ready to schedule,
• 180 hours waiting for parts,
• 120 hours waiting for a planned shutdown.

Total backlog: 620 hours, or 620 / 156 ≈ 4 weeks. Ready backlog: 320 / 156 ≈ 2 weeks.

Reading the numbers

Size. A backlog of a few weeks gives planners enough work to fill schedules efficiently without letting jobs sit for months. Many planners use a rule of thumb in that range; the right figure depends on your site and work mix. A very small backlog can mean the team is overstaffed, or that problems are not being reported. A very large one means work is waiting too long.

Trend. The trend matters more than the size. A backlog that grows every month means more work arrives than the team can finish. Eventually, deferred work turns into breakdowns, which adds even more work.

Age. Look at how old the oldest jobs are. Work that has been open for a year is either not needed or is being avoided. Both need a decision.

Ready or blocked. Split the backlog into work that can be scheduled now and work waiting for parts, shutdowns, approvals, or contractors. A large ready backlog is a capacity problem. A large blocked backlog is a planning or supply problem.

Pitfalls

Dirty backlog. Duplicate requests, jobs done but never closed, and work that is no longer needed inflate the number. Review the backlog regularly, for example monthly, and clean it.

Missing estimates. A count of open work orders treats a five-minute adjustment and a three-day overhaul the same. Estimate hours, even roughly.

Ignoring unreported work. If operators have stopped reporting problems because nothing happens, the backlog looks small while the plant gets worse. A sudden drop in new requests is a warning, not good news.

Mixing in preventive work too early. Some teams count PM work orders only once they are due. Others include all future PMs. Pick one approach; including the whole PM calendar makes the backlog look permanently huge.

Using it as a target. A team told to reduce the backlog can do it by closing or rejecting requests. Look at what was closed and why.

What to do about it

A growing backlog has a few possible responses: add capacity with overtime or contractors, reduce incoming work through better preventive maintenance and root cause analysis, or decide that some work will not be done and close it. The worst response is to let it grow without a decision.

Backlog data comes from work orders. It is only as good as their estimates, status, and closing discipline. See The life of a work order.