Preventive maintenance strategy

95% PM compliance. Still breaking down. Here is why.

PM compliance tells you whether preventive maintenance was executed on time. It does not tell you whether the PM tasks were technically capable of preventing, detecting, or controlling the failures you care about.

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The distinction

Compliance measures execution. Effectiveness measures whether the strategy works.

PM compliance

PM compliance answers:

Did we complete the preventive maintenance that was due, inside the completion window we defined?

A common calculation is:

PM compliance = PMs completed on time ÷ PMs scheduled or due × 100

The site must define “on time” consistently. That may mean by the due date or within an approved tolerance based on the task frequency and risk.

PM effectiveness

PM effectiveness asks:

Did the task actually prevent a failure, detect deterioration early enough to act, restore a required condition, or control the failure mode it was designed for?

It is not one universal percentage. It is a body of evidence connecting PM content to asset failure behavior, findings, corrective follow-up, reliability, and maintenance burden.

What high compliance proves

A high PM compliance rate proves one important thing: the team executed the schedule.

That matters. A technically excellent PM program that is never completed cannot protect the equipment. But once execution is under control, the next question has to be whether the work itself deserves to remain in the program.

It can prove

Scheduled PM work is being completed inside the organization’s defined timing rule.

It cannot prove

The task addresses the correct failure mode, uses the correct method, or has a defensible frequency.

It also cannot prove

A completed inspection produced useful findings, corrective action, or a measurable reduction in recurrence.

Why the numbers can disagree

Five ways a plant can have high PM compliance and poor reliability.

1. The wrong failure modes are covered

The PM is executed exactly as written, but the recurring failures are caused by conditions the task never inspects, measures, restores, or detects.

2. The task is too vague

“Inspect motor,” “check conveyor,” and “service pump” can all close on time while giving technicians no consistent inspection point, method, or acceptance criterion.

3. The frequency has no useful basis

A legacy interval can be executed perfectly while being too short, too long, or simply unrelated to the deterioration pattern it is supposed to manage.

4. Findings die inside the PM work order

An inspection finds looseness, leakage, wear, contamination, or abnormal condition, but no corrective work is generated and the defect survives until failure.

5. The PM itself creates burden

Duplicated, overly intrusive, or low-value tasks can consume labor and equipment access without creating enough risk reduction to justify the maintenance touch.

Use both dimensions

The four conditions a maintenance leader should recognize.

Low compliance, low effectiveness

The plant is not consistently executing the program, and the technical content may also be weak. Stabilize work management while identifying the highest-risk PM gaps first.

Low compliance, potentially effective content

The PM strategy may be technically sound, but labor capacity, scheduling, access, parts, production pressure, or reactive work is preventing execution.

High compliance, low effectiveness

This is the dangerous false-positive state. The KPI looks strong, but repeat failures, emergency work, weak findings, or poor failure-mode coverage show the strategy needs redesign.

High compliance, strong effectiveness

The team executes the intended work consistently, the tasks are technically defensible, defects are found early, corrective work follows, and failure behavior supports the strategy.

How to measure PM effectiveness

Do not force effectiveness into one KPI if the evidence needs several.

A stronger PM review combines execution data with failure behavior, finding quality, corrective follow-up, and task-level evidence.

Failure recurrence after completed PM

Are assets continuing to experience the same failure modes even though the relevant PMs were completed on time?

PM finding yield

Which inspection or condition tasks actually identify actionable deterioration, and which repeatedly close with no useful condition information?

Corrective follow-through

When a PM finds a defect, does it create, prioritize, and complete corrective work before functional failure?

Failure-mode coverage

Do credible asset failure modes have an appropriate maintenance strategy, or are important mechanisms uncovered while low-value tasks remain?

Reliability trend

Where the data is trustworthy, are failure frequency, downtime, reactive labor, emergency work, or similar asset-level signals improving after strategy changes?

Maintenance burden

How much labor, access, production interruption, parts consumption, and planning effort does the PM program require for the risk it controls?

A practical PM audit

Ask these questions task by task.

Technical purpose

  • What failure mode or deterioration mechanism is this task intended to address?
  • Is this the right maintenance strategy for that failure mode?
  • What evidence or authority supports the task?
  • What condition should trigger corrective action?

Execution quality

  • Can a technician tell exactly what to inspect, measure, lubricate, test, clean, adjust, restore, or replace?
  • Are method, safety, access, tools, and acceptance criteria clear enough?
  • Is the expected labor realistic?
  • Does the task create a usable record of what was found?

Frequency basis

  • Why is the interval daily, weekly, monthly, quarterly, or annual?
  • Is it based on an OEM requirement, engineering requirement, failure behavior, condition trend, duty cycle, regulation, or another defensible basis?
  • Has operating context changed since the interval was established?

Program value

  • Does another PM already cover the same component or failure mode?
  • Are findings generating corrective work?
  • Do failures continue even when the task is completed on time?
  • Should the task be kept, modified, consolidated, converted, investigated, added, or removed?

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Example

95% compliance can still describe a poor PM system.

A conveyor line completes 95 of 100 scheduled PMs inside its defined completion window. Compliance is 95%.

But the same drive-end bearing continues to fail. The monthly PM says only “inspect conveyor.” Technician notes contain no bearing condition, temperature, vibration, lubrication condition, contamination finding, or acceptance criterion. No corrective work is generated before failure.

The execution metric is strong. The maintenance strategy is not.

The corrective response is not “push compliance to 100%.” The response is to validate the failure mode, determine the appropriate maintenance strategy, rewrite the task, establish the technical basis and acceptance criteria, and verify whether the new strategy changes the failure behavior.

Where MaintenanceAI fits

Use compliance to test execution. Use maintenance history to test the strategy.

MaintenanceAI reviews PM master data against corrective work history, repeat failures, task quality, frequency basis, failure-mode coverage, and available technical evidence. The goal is not simply fewer PMs. It is a more defensible maintenance strategy.

Learn the method

See the full preventive maintenance optimization workflow, including Keep, Modify, Consolidate, Investigate Frequency, Convert Strategy, Add, and Remove dispositions.

Read the PM optimization guide →

See the output

Review a fictional PM effectiveness analysis showing task-level findings, evidence controls, confidence, and human-review requirements.

View the sample PM analysis →

MaintenanceAI

Do not stop at “Did we do the PM?”

The stronger question is: did we do the right maintenance, at a defensible interval, in a way that controls the failures the asset actually experiences?

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