Preventive Maintenance (PM) is often called the backbone of asset reliability. Yet in reality, many organizations implement PM programs that look impressive on paper but fail to deliver measurable improvements. The gap lies in coverage depth.

Most PM programs cover equipment at a surface level: a few inspection checklists based on recent breakdowns, some lubrication routines, and occasional adjustments. These “shallow” programs may catch obvious issues but rarely prevent major failures. Why? Because assets fail at the component level. A pump does not fail in general — its bearings seize, its seals leak, or its impeller erodes. If a PM program does not reach those specific failure mechanisms, reliability improvements remain elusive.

The principle of rigorous coverage is straightforward: identify failure modes, design PM tasks at the component level, and sustain their execution. Yet in practice, very few organizations reach this level of depth. Even fewer sustain it. The result is a cycle of repeat failures, reactive firefighting, and scepticism about the value of PM.

Why Rigorous Coverage Matters

Rigorous PM coverage aims to address the root mechanisms of failure, not just their symptoms. The logic is simple but profound:

1. Failures always originate at the component level (bearings, seals, valves, sensors).

2. Only preventive tasks linked to these components can interrupt failure progression.

3. Shallow PMs — based only on past breakdowns — are biased and incomplete. They protect against yesterday’s failures, not tomorrow’s risks.

When preventive maintenance is built on detailed coverage, the benefits extend beyond fewer breakdowns. Organizations see:

1. Higher availability and OEE as unplanned stoppages decrease.

2. Improved safety because hidden failure modes are identified before they escalate.

3. Optimized costs as reactive work and emergency spare part purchases decline.

4. Predictable operations that allow production teams to plan confidently.

In contrast, shallow PM programs often become checklist compliance exercises — lots of activity, little impact.

Why Organizations Fall Short

If rigorous coverage is so logical, why do most organizations stop at shallow programs? Several factors combine to create this gap:

1. The Perception of “Unnecessary Detailing”

Leaders may feel that going down to bearings, seals, and sensors is overcomplicating things. On a busy shop floor, component-level PMs can seem academic. As long as equipment appears to run, teams often resist additional detailing.

2. High Effort, Uncertain Gains

Breaking down assets into components, analyzing failure modes, and writing specific PM tasks requires effort from engineers, planners, and technicians. Without visible quick wins, leaders may conclude the effort is not worth it.

3. Effort-to-Gain Ratio Concerns

In resource-limited organizations, the thought of investing 100+ hours of engineering work to improve PM design feels risky. If the payback is uncertain, leaders prefer to stick with familiar shallow checklists.

4. Lack of Methods and Tools

Manual systems and spreadsheets rarely support this level of analysis. Without structured methods like Reliability-Centred Maintenance (RCM), Failure Modes and Effects Analysis (FMEA), or CMMS task libraries, teams simply lack the framework to design component-level PMs.

5. Continuous Operations Pressure

In plants running 24/7, there is rarely downtime to implement deeper inspections. The operational mindset is “keep the machines running,” which deprioritizes analytical redesign of PM programs.

6. Skills and Knowledge Gaps

Planners and technicians may lack training in failure mode analysis. As a result, PM design defaults to generic OEM manuals or past breakdown experiences.

7. Organizational Culture

Some organizations treat PM as a compliance box-ticking exercise rather than a strategic reliability tool. In such environments, the appetite for deeper coverage is low.

The Cost of Staying Shallow

Shallow PM programs create an illusion of control. Teams are busy completing checklists, but the reliability outcomes are stagnant. Common symptoms include:

1. Persistent repeat failures in overlooked components.

2. “Surprise” breakdowns in areas never considered by PMs.

3. High unplanned downtime despite extensive PM hours.

4. Frustration among production staff who see maintenance as ineffective.

Ultimately, shallow PMs are expensive distractions. They consume resources but fail to reduce risk.

How Rigorous Coverage Works

Rigorous coverage means systematically identifying failure modes and linking them to preventive tasks. It often involves structured methodologies:

1. Failure Modes and Effects Analysis (FMEA)

   1. Break the asset into systems, subsystems, and components.

   2. Identify how each can fail, why it fails, and the effects of failure.

   3. Design PM tasks to detect, prevent, or mitigate these modes.

2. Reliability-centred Maintenance (RCM)

   1. Go beyond simple failure listing and consider consequences.

   2. Focus effort on tasks that are technically feasible and worth doing.

   3. Eliminate unnecessary tasks that add cost without reducing risk.

3. Criticality Analysis

   1. Rank assets by criticality and prioritize component-level PMs for high-risk equipment.

4. Use of CMMS

   1. Build asset hierarchies down to the component level.

   2. Store and manage detailed task libraries.

   3. Track compliance and feedback to refine PM design.

A Practical Example

A food processing plant struggled with repeat failures in its packaging line. The PM program consisted of monthly inspections and lubrication tasks. Availability remained low, and breakdowns continued.

When the maintenance team applied an FMEA, they discovered that several critical components — including sensor wiring, small conveyor bearings, and pneumatic actuators — had no preventive coverage. They redesigned the PM program with targeted inspections, lubrication, and condition monitoring.

Within six months, breakdowns reduced by 40%, availability increased, and emergency repair costs dropped. The rigorous coverage at the component level paid off, even though the initial effort seemed excessive.

Why Programs Fail Even When Rigorous Coverage Is Attempted

Interestingly, some organizations attempt rigorous PM design but still fail to see improvements. Common reasons include:

1. Equipment is never taken off the floor. Without scheduled downtime, inspections and replacements cannot be executed.

2. PM overload. Teams add so many tasks that execution becomes unrealistic, leading to poor compliance.

3. Lack of feedback loops. PM effectiveness is never reviewed against asset performance data, so weak tasks persist.

4. Change fatigue. Teams lose momentum after initial enthusiasm, and new practices fade away.

Rigorous PM design must be paired with disciplined execution, validation, and adjustment to succeed.

How to Build Sustainable Rigorous Coverage

1. Start Small, Scale Gradually

   1. Begin with a critical asset or system. Prove the concept before expanding plant-wide.

2. Prioritize by Risk

   1. Focus component-level PMs on high-consequence failure modes first.

3. Use Modern Tools

   1. Leverage CMMS to manage detailed asset structures and PM tasks. Manual systems cannot sustain this complexity.

4. Balance Depth and Practicality

   1. Avoid overloading technicians with hundreds of tasks. Design meaningful, executable PMs.

5. Close the Loop with Data

   1. Compare PM compliance and backlog with asset performance indicators (availability, MTBF). Adjust tasks where necessary.

6. Invest in Skills

   1. Train planners and engineers in RCM/FMEA. Without analytical skills, PMs will remain shallow.

7. Communicate Value

   1. Share results with leadership to justify the effort. Show how rigorous PMs reduce downtime, cost, and risk.

The Cultural Shift

Ultimately, rigorous PM coverage is not only a technical challenge but also a cultural one. It requires shifting the mindset from “just keep it running” to “design reliability into the system.” This cultural change means valuing preparation over reaction, discipline over shortcuts, and long-term reliability over short-term convenience.

Organizations that succeed in this shift find that reliability stops being a lucky outcome and becomes a predictable result of disciplined maintenance.

Conclusion

Preventive maintenance is only as strong as its coverage depth. Shallow programs, designed from recent breakdowns or generic templates, deliver little more than activity without results. Rigorous PM coverage — down to the component level, guided by failure modes — creates the foundation for true reliability.

Yes, it requires effort, structured methods, tools, and discipline. But the cost of staying shallow is far greater: repeated failures, unplanned downtime, wasted resources, and frustrated operations.

For organizations serious about reliability, the path is clear. Build rigor into preventive maintenance. Use structured methods like FMEA and RCM, enable them with CMMS, and sustain them with culture and discipline. Reliability is not a matter of chance; it is the outcome of a well-designed, rigorously executed maintenance system.