Why this book matters
Every maintenance department measures something. Very few measure things that connect. The planner tracks backlog, the manager reports cost variance, the reliability engineer trends MTBF on the crushers - and none of those numbers talk to each other or to the business. When budget season comes, maintenance can't prove its value, so it gets cut, PMs get skipped, and eighteen months later everyone acts surprised when availability tanks.
Terry Wireman spent decades benchmarking maintenance organizations, and this book - part of his Industrial Press maintenance management series - is the standard text on doing indicators properly. His starting point is blunt: an indicator that doesn't drive a decision is decoration. And a plant-floor metric that can't be traced to a financial outcome will not survive its first budget review.
One warning before you build a single dashboard: numbers only mean something once the work management basics exist. If jobs aren't planned and scheduled, schedule compliance is a random number generator - get the foundation from our Palmer summary first.
Core idea
Indicators form a hierarchy, not a shopping list. Corporate goals cascade down into things a crew can turn with their hands this week; floor metrics roll up into money the CFO recognizes. If you can't draw that line for a metric - in either direction - delete the metric.
The KPI pyramid
Wireman organizes indicators into tiers. At the top, corporate and financial measures the business steers by. Below them, efficiency and effectiveness measures of the maintenance function. Then tactical measures of the work management process, and at the base, functional measures of daily execution. Each tier exists to explain the one above it.
Try the cascade on something concrete. The site's corporate goal is cost per tonne. That is driven by crusher and conveyor availability (efficiency tier), which is driven by how much work is planned and scheduled versus reactive (tactical tier), which is driven by whether PMs actually get done on time and whether failures get recorded properly in the CMMS (functional tier). Now the Tuesday PM route on the conveyor gearboxes has a provable connection to the number the general manager answers for. That's line of sight - and it works in reverse when you need to defend the maintenance budget.
Leading vs lagging: manage with one, report with the other
Lagging indicators tell you what already happened - availability, cost per unit, MTBF. Useful for reporting, useless for steering: by the time MTBF on the pump fleet drops, the damage is months old. Leading indicators measure the behaviours that produce those results - PM compliance, schedule compliance, planned-work ratio, backlog. Wireman's rule of thumb: you manage with leading indicators and report with lagging ones. Sites that manage with lagging indicators are driving by the rear-view mirror.
| Metric | Type | What it tells you | Healthy range | Classic way sites game it |
|---|---|---|---|---|
| PM compliance | Leading | Are you doing the failure-prevention work you committed to? | >90%, with the 10% rule: no PM slips past 10% of its interval | PMs closed from the office chair without the machine ever being touched |
| Schedule compliance | Leading | Does the weekly plan survive contact with the plant? | >85-90% of scheduled hours executed | Under-loading the schedule so the percentage looks safe |
| Planned work ratio | Leading | How much work is prepared before anyone touches a bolt? | >80% of hours on planned work | Relabeling reactive jobs as "planned" after the fact |
| Backlog | Leading | Is there enough identified, ready work - and not a graveyard? | 2-4 crew-weeks of ready backlog | Mass-closing old work orders the week before the review |
| Emergency work | Leading | How much of the week the plant steals back from you | <10% of hours | Downgrading priority codes so nothing officially counts as an emergency |
| Availability | Lagging | Did the assets run when operations needed them? | Context-specific - trend it, don't worship a number | Creative reclassification of breakdowns as "planned downtime" |
| MTBF | Lagging | Is reliability actually improving on the bad actors? | Trend by asset class, e.g. the compressor fleet | Only counting failures that happened to get a work order |
| Maintenance cost per unit | Lagging | What the business ultimately pays for maintenance | Benchmark against your sector, trend over years | Cutting PMs - the number looks great for 18 months, then the bill arrives |
Notice the pattern in the last column: every metric can be gamed by managing the number instead of the work. That's not a reason to skip measurement - it's the reason each leading indicator needs a partner that exposes the cheat. Schedule compliance pairs with schedule loading. PM compliance pairs with PM-generated corrective work (a PM program that never finds anything isn't being done). Backlog pairs with work order age profile.
How KPI programs actually fail
Wireman's book is full of formulas, but its sharpest content is about misuse. Three failure modes account for most dead KPI programs.
- Chasing one KPI in isolation. Wrench time used as a stick turns technicians into actors. Cost-per-unit chased alone kills the PM program - the cheapest maintenance department this quarter is the one that stopped maintaining. Wireman's hierarchy exists precisely so no single number is read alone: every indicator is interpreted through its neighbours above and below.
- KPIs without data discipline. If technicians close work orders with "fixed it" and no failure code, no hours and no parts, then your MTBF, backlog and cost numbers are fiction with decimal places. Garbage in - dashboard out. Data discipline in the CMMS is a functional-tier indicator in its own right, and it comes before the fancy metrics.
- Measuring before managing. A site with no planner and no weekly schedule can still buy a dashboard. It will dutifully display random noise. The work management system generates the signal; the KPIs only read it.
Field tip
Start with the 10% rule - it's the highest-value habit in the book. A weekly PM on the crusher may slip by 17 hours at most; a monthly PM by 3 days. Past that, it's overdue and it shows in red. This one rule kills the "we'll catch up on PMs next month" culture, and it costs nothing to implement in any CMMS.
Using it in 2026
The 2005 edition predates cheap dashboards, IIoT and AI. The logic survives; the plumbing should not.
| Keep as-is | Update with modern practice |
|---|---|
| The pyramid and line of sight. Still the best defense against both dashboard sprawl and budget-season amnesia. | Metric definitions. Don't hand-roll formulas from any single book. SMRP's best practice metrics (harmonized with the European EN 15341 indicators) give you audited definitions your corporate team and your benchmarking partners already speak - see our SMRP Body of Knowledge summary. |
| Manage with leading, report with lagging. No amount of AI changes which direction the causality runs. | Reporting cadence. Monthly spreadsheet rituals made sense in 2005. A live dashboard reading the CMMS directly costs almost nothing now - the effort moves from compiling numbers to acting on them. |
| The control ratios as sanity ranges - >90% PM compliance, >80% planned work, 2-4 weeks backlog, <10% emergency. | Data quality enforcement. The weakest link is still the work order close-out. AI can now validate failure codes, flag "fixed it" closures and reconcile downtime hours at entry - fixing the garbage-in problem Wireman could only warn about. |
Bottom line
Pick 5-7 indicators with a provable line of sight, define them by the standard, automate the collection, and review them weekly with the crew that can move them. That beats every 40-widget dashboard ever built - and it's exactly what Wireman was arguing for, two decades before the tooling made it easy.
References & further reading
This summary is original explanatory writing. All concepts belong to their authors - go to the sources.
- Wireman, T. Developing Performance Indicators for Managing Maintenance, 2nd edition. Industrial Press, 2005. ISBN 978-0-8311-3184-5. Book page
- SMRP. Society for Maintenance & Reliability Professionals - best practice metrics with harmonized definitions (aligned with EN 15341). Our summary · smrp.org
- Palmer, R.D. Maintenance Planning and Scheduling Handbook, 4th edition. McGraw-Hill Education, 2019 - the work management system your KPIs measure. Our summary · Publisher page (McGraw Hill)
- Moubray, J. Reliability-centred Maintenance (RCM II), 2nd edition. Butterworth-Heinemann, 1997 - the strategy layer that decides which work is worth measuring. Our summary
Disclaimer. This page is an independent educational summary written entirely in Rob Reliability's own words. It is not affiliated with, sponsored by or endorsed by Terry Wireman or Industrial Press. No text from the original book is reproduced; all diagrams are our own original illustrations of engineering concepts that are part of the public technical literature. Book titles, trade names and trademarks remain the property of their respective owners and are used solely to identify the work being discussed. If you are a rights holder and have any concern about this page, contact us at hello@robreliability.com and we will address it promptly.
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