Maintenance planning
Reliability guides / Practical method
How to run a preventive maintenance gap analysis
A PM gap analysis compares evidence sources rather than declaring a programme complete. It gives a review team a structured list of omissions, conflicts, and weakly specified tasks to decide on.
Published August 19, 2026 · Practical engineering guidance
01 / Method
Choose a clear asset boundary and source set
Start with one asset, system, or consistent equipment family. Assemble the current PM programme, relevant OEM manuals, approved FMEA or risk review, work-order history, and any statutory or site requirements.
Record the version and scope of each source. A comparison is unreliable when one document applies to a newer configuration or a different duty than the PM list being judged.
02 / Method
Compare more than task titles
Map each source by component, action, interval or trigger, procedure quality, and intended failure mode where known. A title match alone can hide a weak task: “inspect motor” may not cover a specified insulation resistance test, lubrication condition, or alignment check.
Classify findings as missing work, interval conflict, unclear procedure, missing control, or evidence to retain the existing approach. Each finding should name the source and the reason it was raised.
03 / Method
Prioritise decisions, not just gaps
Review high-consequence and recurring issues first, then consider implementation effort, access, downtime, and monitoring capability. Some findings will be accepted risks or deliberate run-to-failure decisions. Capture that decision rather than treating every difference as an automatic new PM.
After changes are approved, update the programme and retain the evidence trail. Revisit the comparison when equipment, duty, failure history, or OEM guidance changes.
Example
Worked example: an overlooked inspection criterion
A current PM task says “monthly inspect belt drive.” The manual specifies belt tension and alignment checks, while work orders show repeated belt failures.
- Map the current task against the manual's specific actions and interval.
- Review whether the existing procedure includes a measurable tension and alignment method.
- Use the failure history to prioritise the review, then define the revised task, criterion, tools, and response—not simply a new title.
Takeaway: The gap is the missing coverage detail, not merely the absence of the word “belt” in the PM list.
Engineering boundaries
Bring your equipment evidence into the review.
- A gap analysis cannot certify that a PM programme is complete.
- A source conflict needs engineering judgement; the newest or most detailed document is not automatically correct for every site.
- Do not add work solely to improve a coverage score.
- Critical equipment may need formal change control and specialist review.
Common questions
Bring your equipment evidence into the review.
What counts as a PM gap?+
It can be a missing task, a missing failure-mode control, an unclear procedure, an unsuitable interval, or a difference between evidence sources that has not been reviewed.
Should work-order history override OEM guidance?+
Not automatically. It provides operational evidence that should be considered with OEM guidance, duty, condition data, safety obligations, and engineering judgement.