What is Maintenance?

July 22, 2021
Photo by Jakub Nawrot on Unsplash

You might think this question has an obvious answer. Many say maintenance is about preserving machinery, keeping it working, or fixing it if it breaks. This view of maintenance focuses on the machinery and the maintenance management system. But does this go far enough?

In recent decades the complexity of machinery has been transformed. For example, we have evolved from analogue to digital full-authority control, sensing, protection alarms and warnings. We can no longer maintain our cars without electronics.

Photo by Anne Nygård on Unsplash

At the same time expectations have increased with a wider set of stakeholders who have both power and influence over how machinery is used and maintained. The stakeholders not only include the obvious internal and customers, but other external stakeholders; such as, government, regulators, media, community, the general public and perhaps entities like the environment.

Stakeholders have increasing expectations of safety, environment, sustainability, social responsibility and creating wealth with fewer resources. The result, is that wider considerations have to be taken into account and we must think about maintenance in a more systematic way.

Using systems terminology, we need to think about maintenance holistically. The implications of meeting this wider set of requirements is that maintenance is strategic and a vital component of achieving operational excellence.

What is the purpose of Maintenance?

We put forward Moubray’s statement for the purpose of maintenance:

“Preserve functions that stakeholders expect from their physical assets in defined operating contexts”

Using this definition, we can identify the wider group of stakeholders and identify their requirements for maintenance activities. We initially focus on stakeholder functions, followed by how these impact our operations and maintenance of machinery.

Preserving functions may be a subtle change of words from preserving machinery, but the ramifications are surprisingly profound. Let us take a really simple example to illustrate this point:

What would be the primary functional requirement of an F1 racing car during its time racing on the circuit?

Photo by Goh Rhy Yan on Unsplash

Most would answer ‘to win races’.

If the same car had an outstanding racing performance and reliability record, it may become a star static exhibit in a museum. What is the race car’s primary function now, in the museum?

The answer may be “to leverage its historical record to enhance the manufacturers brand, and to attract more visitors to the museum”.

It’s the same physical car that raced. What are the differences in the maintenance needed for the same car to preserve its functions when used in different contexts?

A wider perspective

Taking a wider perspective of maintenance, we may discover that we need to think about activities that previously weren’t considered as maintenance and that are not managed in a CMMS system.

Photo by Pandu Agus Wismoyo on Unsplashv

Consider safety and functional checks. We may conduct functional checks to uncover hidden failures; or in some industries to ensure the statistical safety case is valid by ensuring things work and resetting the statistical baseline. Would anyone regard a pilot walking around an aircraft doing pre-flight checks as maintenance? Well it is.

A growing trend of good practice in maintenance is defect elimination, which seeks to find common causes of failures from operating and maintaining assets. This is done either with historical failure data and root cause analysis, or if there is a lack of data, by taking a risk view in determining well known causes of operational or maintenance quality issues. Sometimes this defect elimination process is referred to as proactive maintenance. The improvements may be correcting low quality operational and maintenance processes, as well as introducing modifications to machinery. Would anyone regard the statistical analysis and causality investigations as being maintenance? Well it is.

Another relative newcomer to maintenance is predictive maintenance, which is a specialisation in on-condition maintenance. It uses the availability of times series and state data from asset sensors to diagnose incipient failure and prognose remaining useful life before we have to initiate corrective maintenance. Much of the process should be automated, using computing and machine learning to automate the analysis. Predictive maintenance techniques are typically used to monitor machinery performance, efficiency and emissions, warning us when these go out of acceptable limits. Would anyone regard the data analysis as being maintenance? Well it is.

Photo by Aaron Barnaby on Unsplash

These maintenance practices imply that a machine does not necessarily have to be broken to be functionally failed. Not all maintenance work has to involve spanners or screwdrivers. Not all maintenance transactional work is managed in a maintenance management system.

Work which may primarily come under the umbrella of maintenance, is split across organisational boundaries. I have observed many organisations’ planned maintenance managed separately from scheduled vibration analysis. Specialisation might make this appropriate; however, is the output data merged, and are the tasks rationalised between the two functions to maximise efficiency?

Understanding the purpose of maintenance, and the widely varied scope of activities maintenance encompasses, provides a holistic understanding of how it works. We can now start to think about maintenance effectiveness and efficiency from the wider perspective.

Do you know of instances when preventative scheduled maintenance is separated from safety checks, vibration or oil/debris analysis — organisationally and with separate management systems?

I served on nuclear submarines, the nuclear reactor safety checks were separated from planned maintenance, both using different governance and management systems. I would like to hear your experience in the comments!

In the next blog we will build on stakeholder functions to discuss functional failure and build a picture of how and why things fail, and what the major failure influences are.

If you missed the introductory blog you can find it here.

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