Maintenance & Reliability worked example

Maintenance Availability at 99% pm execution factor: a worked example

What does the result look like when pm execution factor reaches 99%? The full calculation is worked below with real intermediate numbers. Use it when you need a plant-level view of how maintenance downtime affects true calendar availability.

The inputs for this scenario

  • Available calendar hours after maintenance downtime: 700 hr (unchanged)
  • Total calendar hours: 720 hr (unchanged)
  • PM execution factor: 99 % (raised for this scenario; the documented default is 98)
  • Startup recovery factor: 97 % (unchanged)

Working through the calculation

  • Applying the documented formula (Base maintenance availability = available calendar hours after maintenance downtime ÷ total calendar hours × 100) to the inputs above produces each figure below.
  • At this operating point the engine returns 93.36 % for achieved maintenance availability, the number this scenario is built around.
  • At this operating point the engine returns 97.22 % for calendar-time availability.
  • At this operating point the engine returns 99 % for pm execution factor.
  • At this operating point the engine returns 97 % for startup recovery factor.

How this compares with the baseline

  • Against the tool's baseline example, where pm execution factor sits at 98% and the headline result is 92.42 %, this scenario comes in 1.02% above the baseline at 93.36 %.
  • A figure at this level is achievable when pm execution factor is genuinely sustained, not just peaked for a shift. It assumes maintenance downtime is already captured in the available-hours input; if some unplanned downtime is logged elsewhere, the result will overstate true availability.

Results at a glance

  • Achieved Maintenance Availability: 93.36 % (headline result)
  • Calendar-Time Availability: 97.22 %
  • PM Execution Factor: 99 %
  • Startup Recovery Factor: 97 %

Run it with your numbers

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

Last reviewed 2026-05-12.