Maintenance & Reliability worked example

Maintenance Backlog with preventive backlog hours of 550 hr: a worked example

What does the result look like when preventive backlog hours reaches 550 hr? The full calculation is worked below with real intermediate numbers. Use it when checking whether the maintenance organization is carrying more work than current staffing can execute.

The inputs for this scenario

  • Preventive (PM) backlog hours: 550 hr (raised for this scenario; the documented default is 220)
  • Corrective repair backlog hours: 160 hr (unchanged)
  • Improvement project backlog hours: 90 hr (unchanged)
  • Deferred work backlog hours: 60 hr (unchanged)

Working through the calculation

  • Applying the documented formula (Total maintenance backlog = PM backlog hours + corrective backlog hours + project backlog hours + deferred work hours) to the inputs above produces each figure below.
  • At this operating point the engine returns 860 hr for total maintenance backlog, the number this scenario is built around.
  • At this operating point the engine returns 550 hr for pm backlog.
  • At this operating point the engine returns 160 hr for corrective backlog.
  • At this operating point the engine returns 150 hr for project and deferred work.

How this compares with the baseline

  • Against the tool's baseline example, where preventive backlog hours sits at 220 hr and the headline result is 530 hr, this scenario comes in 62.26% above the baseline at 860 hr.
  • A figure at this level is achievable when preventive backlog hours is genuinely sustained, not just peaked for a shift. Hours alone do not tell you priority or asset criticality; a small backlog on critical equipment can be riskier than a large one on spares, so read it alongside criticality and ready-backlog metrics.

Results at a glance

  • Total Maintenance Backlog: 860 hr (headline result)
  • PM Backlog: 550 hr
  • Corrective Backlog: 160 hr
  • Project and Deferred Work: 150 hr

Run it with your numbers

  • Every input above is editable in the live Maintenance Backlog calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.