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1. Summary

ISO 55001 does not have specific requirements pertaining to failure codes. It does however require nonconformities to be identified, reacted to, dealt with in terms of its consequences, and cause elimination as appropriate. Documented information shall be retained.

This article argues that a highly structured approach to functional failure handling, in line with traditional RCM principles, is an implied requirement of ISO 55001.

2. The nature of functional failure

To develop an understanding of the purpose and nature of “failure codes”, and therefore also the requirements to which it must conform, we will start by summarising the basics of functional failure.

2.1 Functional failure in context

A physical asset, no matter what the physical properties there-of are, was purchased in the first instance to perform one or more very specific production or service delivery functions.

There cannot be the slightest doubt that the clearer the production or service delivery functions are defined, the better the physical asset purchase decisions will be. But clarity of functions and performance standards go way beyond the purchasing decision – because the future maintenance requirements will be driven by the rate of deterioration that will eventually lead to the asset no longer meeting the performance standards associated with the functions.

But unclear performance standards means that a large number of observed / perceived functional failures are subject to interpretation; or even worse – functional failures could go by without being noticed. This last situation is often called “latent failures”. The root causes of failures are present; and in fact one or more small failures might already have occurred without directly or immediately influencing the total asset’s performance.

We find in practice that different asset management practitioners have vastly different ideas of what the term “functional failure” means. For one person, it could mean that the asset is totally shabby, worn-down and has reached the point where it is no longer service-able. This sort of situation is often accompanied with quick fixes, making plans, and performing clever, innovative but temporary repairs. For another person, functional failure could mean a small, superficial scratch in the paintwork of a physical asset.

Nowlan and Heap’s[1] description of the nature of failures is as relevant today as it was in the ‘70’s:

“Each of us has some intuitive notion of what constitutes a failure. We would all agree that an automobile engine, a fuel pump, or a tire has failed if it ceases to perform its intended function. But there are times when an item does continue to function, although not at its expected level. An automobile engine may run powerfully and smoothly, but its oil consumption is high; a fuel pump may pump fuel, but sluggishly; a tire may hold air and support the car, but its bald tread indicates that it will do neither much longer.

Have these items failed? If not, how bad must their condition become before we would say a failure has occurred?  Moreover, if any of these conditions is corrected, the time required for un-anticipated repairs might force a change in other plans, such as the delay or cancellation of a trip. In this event it could still be argued that no failure had occurred?

To cover all these eventualities, we can define a failure in broad terms as follows:

A failure is an unsatisfactory condition.

In other words, a failure is any identifiable deviation from the original condition which is unsatisfactory to a particular user. The determination that a condition is unsatisfactory, however, depends on the consequences of failure in a given operating context.”

“In short, the exact dividing line between satisfactory and unsatisfactory conditions will depend not only on the function of the item in question, but on the nature of the equipment in which it is installed and the operating context in which that equipment is used. The determination will therefore vary from one operating organization to another. Within a given organization, however, it is essential that the boundaries between satisfactory and unsatisfactory conditions be defined for each item in clear and unmistakable terms.

The judgment that a condition is unsatisfactory implies that there must be some condition or performance standard on which this judgment can be based. As we have seen, however, an unsatisfactory condition can range from the complete inability of an item to perform its intended function to some physical evidence that it will soon be unable to do so. For maintenance purposes, therefore, we must classify failures as either functional failures or potential failures.

A functional failure is the inability of an item (or the equipment containing it) to meet a specified performance standard.

A complete loss of function is clearly a functional failure. Note, however, that a functional failure also includes the inability of an item to function at the level of performance that has been specified as satisfactory. This definition thus provides us with an identifiable and measurable condition, a basis for identifying functional failures.

To define a functional failure for any item we must, of course, have a clear understanding of its functions. This is not a trivial consideration. For example, if we say that the function of the braking system on an airplane is to stop the plane, then only one functional failure is possible – inability to stop the plane. However, this system also has the functions of providing modulated stopping capability, providing differential braking for maneuvering on the ground, providing anti-skid capability, and so on. With this expanded definition it becomes clear that the braking system is in fact subject to a number of different functional failures. It is extremely important to determine all the functions of an item that are significant in a given operating context, since it is only in these terms that its functional failures can be defined.”

“The ability to identify either a functional or a potential failure thus depends on three conditions:

  • Clear definitions of the functions of an item as they relate to the equipment or operating context in which the item is to be used.
  • A clear definition of the conditions that constitute a functional failure in each case.
  • A clear definition of the conditions that indicate the imminence of this failure.”

Note that Nowlan and Heap’s work centers on assets, like aircraft. If we consider ISO 55001, then the point of departure is pretty much the organization, organizational context, and stakeholder needs and expectations. ISO 55001 then requires these aspects to be taken into account for purposes of policy development, management planning, organizational arrangements, and various support requirements. The next paragraph puts this in perspective, with a view to sensibly deduct the ISO 55001 implications in terms of failure codes and reporting.

2.2 The relationship between function and physical asset

To give some substance to the relationship between function (as mentioned in the preceding paragraph) and physical assets, the diagram below, loosely based on some aspects of ISO 55001, is useful to consider failure codes and failure reporting in the context of ISO 55001:

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Diagram 1: Relationship between (selected) key elements of an asset management system

 

1.1 Stakeholder needs and expectations:

Stakeholders include both internal and external individuals and groups; and include (but are not limited to) investors, law enforcement organisations and staff to customers or users of the delivered services.

Stakeholders might have very little or no interest in the physical assets – aspects like the price of shares, quality of products or services, cost, profit, image, and risk are more relevant.

These aspects are all sub-ordinates of the basic production or service delivery function. Stakeholder needs and expectations can therefore be embodied in a structured set of production- or service delivery functions; each associated with at least one performance standard, like in the example below:

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The example shows that a specific service delivery function is to be performed, and the associated standard shows that some stakeholders (users) have certain expectations in terms of the level or quality of service. Similarly, multiple standards can be developed for such a function.

Note that at this stage, there is no reference to any specific physical asset. We are dealing purely with service delivery and its associated standards.

1.2 Organisational Context:

Various external issues (for example legal requirements, national and provincial development plans) as well as internal issues might be relevant to the purpose of the  organisation, and also affect its ability to achieve its intended outcomes. It is therefore a requirement to understand the organisational context such that the asset management system is on the one hand aligned with, and on the other hand in full support of the broader organisational characteristics.

The organisational context can also influence the requirements or performance standards that apply to the functions as discussed in the previous point. For example, the municipality used as example could have a very strong desire to display its corporate colours; in which case the function standards can be expanded as follows:

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Once again, here is no reference to any specific physical asset or asset type at this stage.

1.3 Management Structure:

Any organisation can only function and keep functioning if operational and management responsibilities are very clearly designed, assigned and communicated.

Such management structures must create a dynamic link between the stakeholder needs and expectations and organisational context, and the physical assets that are intended to ensure service delivery or production output.

Management structures and other organisational elements must be designed with full cognisance of asset management strategies, objectives and plans. Furthermore, these structures must take the nature of the various asset portfolios into account.

The management structures must also be very clear on accountability and responsibility for both the asset system and the asset management system; with a view to long-term successful asset management.

1.4 Organisational objectives and plans

Organisational objectives stand towards the asset management system in a guiding position rather than being integral to it. But asset-specific properties can influence organisational objectives and plans; for example minimum size of a parking area, demarcation standards etc. On the other hand, organisational objectives have a direct impact on both the asset system and asset management system.

• Firstly, the asset system’s nature and scope is fully determined by service delivery objectives. The on-going requirements for asset care are similarly determined by service delivery plans.
• Secondly, the asset management system forms part of an integrated set of business processes which spans all the traditional disciplines like financials, engineering, human resources, time and attendance etc. System objectives and plans need to take this reality into account.

1.5 Maintain a register of superior references:

Physical assets (and more so in the Public Sector), as well as the organisations managing these assets, are subject to strict governance requirements. Such governance requirements have major implications for general management, financial and performance reporting, and recordkeeping. It follows that all superior references, in particular those that are of a regulatory nature, must be visible, understood and actively provided for in the asset management system.

Such superior references might in fact prescribe requirements or performance standards that apply to the functions as discussed previously, as shown in the example below:

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The standard in this example is, as in the previous examples, generic by nature and not specific to any type of asset or individual asset. It applies more to the function than to an asset.

The requirement for documented information pertaining to legal and regulatory requirements is quite clearly stated in ISO 55001, clause 7.6.1; it is therefore a logical next step to extend such requirements to performance standard level.

2.1 Strategic Asset Management Objectives and Plans:

A set of strategic asset management objectives that is demonstrably aligned with the organisational objectives and plans will be developed and maintained. These strategic asset management objectives and plans are indispensable guidelines for the on-going management of both the asset system and asset management system. Very specifically, the role of the asset management system to ensure that asset management objectives are met, need to be understood. This in turn leads to the development of strategic objectives and plans that relate to the asset management system.

Referring back to point 1.1 “Functional failure in context”, it should be abundantly clear now that strategic asset management objectives and plans can be seen as driven by service delivery or production functions, together with their performance standards.

2.2 Asset management policy:

The asset management policy can be regarded as an instrument to provide on-going leadership (in the sense of the principles by which the organisation intends applying asset management) to the total asset management environment. It therefore addresses two inter-twined but separately identifiable dimensions of asset management:
3.    The management of the asset system.
4.    The management of the asset management system.
The risks associated with the asset system (including safety, service delivery and cost related risk) are high when compared to other areas of risk. Assets systems and the associated risk can only be managed at the hand of well-designed asset management system.

2.3 Asset management system definition:

As for point 2.2 above.

2.4 Asset management plans:

The boundaries between “strategic asset management plans” as discussed under point 2.1 and “asset management plans” are not exact. For the purposes of this policy, the following guideline will be used:

1. Strategic asset management plans: Asset management plans are considered to be strategic if they relate to longer-term service delivery expansion, asset additions, expansion of facilities, or major organisational changes. These plans are associated with capital requirements, and are influenced by stakeholder expectations and the organisational context.
2. Asset management plans: Asset management plans revolve around the operational requirements and levels of performance. They typically include planning for asset performance improvement like RCM studies; improvement of skills, practices, stock levels; and also improvement initiated by sub-standard performance and specific improvement targets. “Routine” maintenance strategies and task plans can be classified as a sub-set of asset management plans as well, and will be called “maintenance strategies”.

All strategic asset management plans and asset management plans will at all times consider the associated risk; and the relevant mitigation and corrective actions will form part of such plans.

2.5 Not shown for purposes of this discussion.

2.6 Asset Management System Plans:

The complex and integrated nature of asset management in the current day makes it a necessity to distinguish between:
1.    The management of the physical assets.
2.    The management of the asset management system.
The management of the physical assets depends fully on a suitable and aligned asset management system. This inter-dependency means that asset management approaches and asset management plans will invariably have some implications on the asset management system. This calls for formal asset management system plans in exactly the same way as asset management plans.
Although not the intent of this paper, it illustrates the far

2.3 Conclusions pertaining to the function / asset relationship

It is possible to create a hierarchy of service delivery or production functions to represent the totality of a municipality or any other business. At the highest level we might have a function like “to ensure the provision of services to communities in a sustainable manner”, and this high level function can be developed to lower levels like:

•    stimulate social and economic development,
•    promote community health and safety, and
•    provide services.

But the functions in the hierarchy need to be performed by somebody or something; namely a physical object. It is often handy to call these physical objects that are intended to perform specific, defined production functions, productive equipment.

Therefore, in order to describe our business comprehensively, we need to understand the hierarchy of functions (functional breakdown), and we need to know which specific physical units (productive equipment) perform these functions.

The preceding discussion points very clearly towards a need to have a complete understanding of the functions and associated performance standards. Failure to meet these performance standards, disregarding the physical asset employed to perform the function, is a functional failure. And these performance standards are influenced by factors like stakeholder needs and expectations, the organisational context, and superior references like statutory requirements.

 

3. Service delivery / production function definition and coding

Let us revisit Nowlan & Heap’s 1978 report, paragraph “Applying RCM theory to aircraft”:

“…The first step in this process is to organize the problem by partitioning the equipment into object categories according to areas of engineering expertise. Within each of these areas the equipment is further partitioned in decreasing order of complexity to identify significant items (those whose failure may have serious consequences for the equipment as a whole), items with hidden functions (those whose failure will not be evident and might therefore go undetected), and non-significant items (those whose failures has no impact on operating capability)”.

Below is a sample system information worksheet taken from the Nowlan & Heap report:

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The approach above, including the system information worksheet, is perfectly all-right for an aircraft as an object which is often employed as a self-contained, totally individual item. It how-ever excludes (at least partially) the impact of factors like stakeholder needs and expectations, the organisational context, and superior references like statutory requirements.  The system requirements implied by ISO 55001 means that the functional failure identification is to be escalated to the level of service delivery or production function, as shown by the logic below:

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The diagram shows the following:

Define service delivery or production functions:

As discussed in previous paragraphs, very close to the totality of the business can be described at the hand of a functional decomposition. For reasons of practicality, this decomposition continues to the level where the function is a single logical function, and can be associated with a single equipment item – although such equipment item can be a discreet asset like a compactor, a network asset like a water distribution system, or a linear asset like a road.

Describe all performance standards:

Once the functions are documented and understood (within the context of the organisation and recognising stakeholder needs and expectations), the relevant performance standards are described. There is no specific asset or asset type involved at this stage – the emphasis is more on “what is required in terms of services / output and the associated standards” than on “what assets do we operate”.

An example of a function definition, as part of a structured cascade of functions, is shown below:

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The associated performance standards (not comprehensively developed) could be as follows:

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We can now start to make some conclusions about numbering:

  1. Individual functions need to be clearly identifiable in order to associate them with specific performance standards.
  2. If performance standards are not exact, there will always be doubt as to our capability to objectively assess actual performance.
  3. It follows that functions need to be numbered, and that performance standards need to be positively associated with these functions. ISO 55001 is quite clear on this requirement, as shown below:
    1. Clause 7.5 (e): the organization shall ensure that there is consistency and traceability between the financial and technical data and other relevant non-financial data, to the extent required to meet its legal and regulatory requirements while considering its stakeholders’ requirements and organizational objectives.
    2. Clause 7.6.1: The organization’s asset management system shall include:
      • documented information as required by this International Standard;
      • documented information for applicable legal and regulatory requirements;
      • documented information determined by the organization as being necessary for the effectiveness of the asset management system, as specified in 7.5.

There two further interesting and valuable implications flowing from the structuring and numbering of functions. The first is facilitating the ISO 55001 requirement for continual improvement – refer clause 10.3. This point will be dealt with in more detail in subsequent paragraphs. The second important implication is about risk management. One can argue that risk management is very much central to ISO 55001, as is illustrated by the following clause:

Clause 6.1: Actions to address risks and opportunities for the asset management system

“When planning for the asset management system, the organization shall consider the issues referred to in 4.1 and the requirements referred to in 4.2 and determine the risks and opportunities that need to be addressed to:

  • give assurance that the asset management system can achieve its intended outcome(s);
  • prevent, or reduce undesired effects;
  • achieve continual improvement.

The organization shall plan:

  1. actions to address these risks and opportunities, taking into account how these risks and opportunities can change with time;
  2. how to:
    • integrate and implement the actions into its asset management system processes;
    • evaluate the effectiveness of these actions.”

Risk management will not be dealt with in more detail in this article, but the importance there-of is such that the systems implications need to be noted. The paramount systems implication is that if we consider the hierarchical breakdown of service delivery or production functions from a functional failure perspective, and all the associated performance standards are clear and documented, then a further analysis of functional failures, failure modes etc is nothing but an auditable, responsible analysis of risk. In corporate environments where a central risk register is periodically reviewed by senior management, such a risk register which is fed or updated from the hierarchy of functions and performance standards will certainly be regarded as authorative, and can hence be actioned in a decisive manner.

The fact that we control less energy than for example a TEPCO at Fukushima, and hence the realization of risk is far less dramatic, does not mean that we are doing better in terms of understanding and mitigating risk. It is merely a matter of visibility.

Prioritise:

Service delivery or production functions are not equal in terms of their contribution towards meeting stakeholders’ requirements and organizational objectives. In the current day and age where every organization is somewhat limited by skills and resource scarcities, it makes a lot of sense to direct skills and resources to where it will maximally impact service delivery, profit and of course sustainability. To conclude the discussion of functions and performance standards, a sample function prioritizing worksheet is shown below:

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Associate productive equipment:

In some cases, arguably more so in the Public Sector and agriculture, there are choices to be made between service delivery / production by means of intensive manual effort, or by means of highly mechanized methods. In case, the functions to be performed and their performance standards should meet the requirements of stakeholders. In the case of asset-intensive functions, the asset(s) employed to perform the function have a major impact on our asset management approaches and systems. ISO 55001 requires (clause 5.2) that an asset management policy shall be established in order to

  • be consistent with the organizational plan;
  • be consistent with other relevant organizational policies;
  • be appropriate to the nature and scale of the organization’s assets and operations;
  • be available as documented information;
  • be communicated within the organization;
  • be available to stakeholders, as appropriate;
  • be implemented and be periodically reviewed and, if required, updated.

Furthermore, clause 6.2.2 requires:

When planning how to achieve its asset management objectives, the organization shall determine and document:

  1. the method and criteria for decision making and prioritizing of the activities and resources to achieve its asset management plan(s) and asset management objectives;
  2. the processes and methods to be employed in managing its assets over their life cycles;
  3. what will be done;
  4. what resources will be required;
  5. who will be responsible;
  6. when it will be completed;
  7. how the results will be evaluated;
  8. the appropriate time horizon(s) for the asset management plan(s);
  9. the financial and non-financial implications of the asset management plan(s);
  10. the review period for the asset management plan(s) (see 9.1);
  11. actions to address risks and opportunities associated with managing the assets, taking into account how these risks and opportunities can change with time, by establishing processes for:
  • identification of risks and opportunities;
  • assessment of risks and opportunities;
  • determining the significance of assets in achieving asset management objectives;
  • implementation of the appropriate treatment, and monitoring, of risks and opportunities.

The organization shall ensure that its asset management related risks are considered in the organization’s risk management approach including contingency planning.

The functional unit is the central hub of any life cycle assessment, benchmarking or comparative study, since it provides the reference to which all other data in the assessment are normalised.

The association of equipment with functions is therefore very much a requirement, which must meet requirements for trace-ability. An example is shown below:

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Develop asset (hardware) hierarchy:

The approach of defining the functions at the hand of hierarchical breakdown down to the level where “productive” assets can be associated with the functions has the intrinsic benefit of putting the specific asset right into its operating context. This is of critical importance when developing the appropriate maintenance strategies, for example a parking area in a warm, windy, high humidity area will display dominant modes of deterioration that differ substantially from a parking area in a mild, moderate climate.

In the particular operating context, the asset is now regarded as a complex assembly of various sub-systems, which include primary production functionality, secondary functions and supporting functions.

Nowlan & Heap suggests the following:

“The first step in the development of a scheduled maintenance program is a quick, approximate, but conservative identification of a set of significant items.

A significant item is one whose failure could affect operating safety or have major economic consequences.

The definition of “major economic consequences” will vary from one operating organization to another, but in most cases it includes any functional failure that has a direct effect on operational capability or involves a failure mode with unusually high repair costs.

…To reduce the problem of analysis to manageable size, it is customary to partition the equipment into three major divisions – systems, power-plant, and structure – each of which involves different areas of engineering expertise. Each division is then partitioned in descending order of complexity, with successive fewer failure possibilities at each level”.

An interesting question which arises now, is what the relationship between asset partitioning and hardware breakdown development for purposes of:

  • Maintenance strategy and failure reporting development, and
  • Traditional configuration management purposes.

Answering this question is beyond the scope of this paper, but this point requires some investigation and consideration when ISO 55001 clauses 7.5 and 7.6 are considered, in particular the following points:

  1. the organization shall specify, implement and maintain processes for managing its information;
  2. the organization shall determine the requirements for alignment of financial and non-financial terminology relevant to asset management throughout the organization;
  3. the organization shall ensure that there is consistency and traceability between the financial and technical data and other relevant non-financial data, to the extent required to meet its legal and regulatory requirements while considering its stakeholders’ requirements and organizational objectives.

A partially developed asset breakdown structure is shown below:

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In the above example, the asset is partitioned, and major sub-items (often referred to as rotables, sub-assemblies, or components) are identified.

Note that this is an area where, in South Africa at least, there are clearly different interpretations of the terms asset and component in the financial management and engineering worlds. ISO 55001 has some requirements in this regard:

Clause 7.5 (d) and (e): ”the organization shall determine the requirements for alignment of financial and non-financial terminology relevant to asset management throughout the organization;

Clause 7.5 (e): “the organization shall ensure that there is consistency and traceability between the financial and technical data and other relevant non-financial data, to the extent required to meet its legal and regulatory requirements while considering its stakeholders’ requirements and organizational objectives”.

Perform conventional RCM study:

With a clear understanding of the service delivery or production functions, their hierarchical relationships, the associated performance standards and the technical make-up of the assets performing those functions, we can perform a traditional RCM study with the confidence that the result will provide a firm departure point for medium-term maintenance planning.  A key point in this regard is that we can now confidently enforce full adherence to the medium-term maintenance plan; with some degree of predictability of asset performance, asset condition and cost.

4. RCM study and failure codes

ISO 55001 deals very specifically with nonconformity and corrective action in clause 10.1:

“When a nonconformity or incident occurs in its assets, asset management or asset management system the organization shall:

  1. react to the nonconformity or incident, and, as applicable:
    • take action to control and correct it;
    • deal with the consequences;
  2. evaluate the need for action to eliminate the causes of the nonconformity or incident, in order that it does not occur or recur elsewhere, by:
    • reviewing the nonconformity or incident;
    • determining the causes of nonconformity or incident;
    • determining if similar nonconformities exist, or could potentially occur;
  3. implement any action needed;
  4. review the effectiveness of any corrective action taken; and
  5. make changes (see 8.2) to the asset management system, if necessary.

Corrective actions shall be appropriate to the effects of the nonconformities or incident encountered.

The organization shall retain documented information as evidence of:

  • the nature of the nonconformities or incident and any subsequent actions taken;
  • the results of any corrective action”.

With these requirements as background, we can investigate some aspects of the Nowlan & Heap RCM process in order to arrive at some useful failure code format recommendations. The subsequent discussion is based on the broad process diagram shown on the next page. Note that the diagram does not represent a comprehensive RCM process; it only serves as guideline for the subsequent discussion:

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4.1 Productive assets, operating context, partitioning

As shown by the preceding paragraphs, the functions to be executed in order to deliver services or produce goods, provided that the associated performance standards are known, will in practice fail. Furthermore, the productive assets that we employ to perform these functions will display their own failure behavior.

4.2 Strategy setting

The standard strategy development process leads to the (amongst other) identification of functional failures, failure modes and failure root causes. The sample below shows such a numbered, cross-referenced set of sample data:

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The details of the analysis process is beyond the scope of this article, but the example above clearly shows that a properly structured, properly numbered and therefore fully cross-referenced hierarchy of service delivery or production function, productive equipment, equipment partitioning and the elements of the subsequent RCM study is both practical and feasible. The real advantage in terms of the ISO 55001 requirements as contained in clause 10 and its sub-clauses “Improvement” will become apparent in the following paragraphs.

4.3 Task planning

Once the appropriate and feasible mixture of preventive, detective, corrective and possible single management intervention tasks have been developed, the contents of these tasks are properly planned. The approach to task optimizing and planning is not discussed further in this article.

The key point is that every function, functional failure, failure mode, failure cause and task is identified, uniquely numbered and clear in the context of service delivery or production function. We are therefore achieving full line-of-sight right through from stakeholder expectation to individual maintenance task. With-in this context, all tasks are pre-defined. This approach also satisfies the requirements of the following ISO 55001 clauses:

Clause 6.1: Actions to address risks and opportunities for the asset management system

“When planning for the asset management system, the organization shall consider the issues referred to in 4.1 and the requirements referred to in 4.2 and determine the risks and opportunities that need to be addressed to:

  • give assurance that the asset management system can achieve its intended outcome(s);
  • prevent, or reduce undesired effects;
  • achieve continual improvement.

The organization shall plan:

  1. actions to address these risks and opportunities, taking into account how these risks and opportunities can change with time;
  2. how to:
    • integrate and implement the actions into its asset management system processes;
    • evaluate the effectiveness of these actions”.

Clause 6.2.2: Planning to achieve asset management objectives

  • actions to address risks and opportunities associated with managing the assets, taking into account how these risks and opportunities can change with time, by establishing processes for:
  • identification of risks and opportunities;
  • assessment of risks and opportunities;
  • determining the significance of assets in achieving asset management objectives;
  • implementation of the appropriate treatment, and monitoring, of risks and opportunities.

The organization shall ensure that its asset management related risks are considered in the organization’s risk management approach including contingency planning.

4.4 Medium-term planning

The on-going improvement of a maintenance strategy means that either the content of a specific maintenance task, the frequency there-of or another activation mechanism like condition is improved.

A critical requirement for on-going improvement of a maintenance strategy is the ability to assess asset performance characteristics like availability, reliability and operating (including maintenance) cost in the light of:

  1. Adherence to preventive task frequencies.
  2. Adherence to detective task frequencies.
  3. Actual rate of failure by functional failure, failure mode and failure cause at the hand of actual MTBO (mean time between occurrences) versus planned MTBO.
  4. Task execution quality.

The above is obviously not possible without a formal medium-term maintenance plan, spanning at least a rolling time horizon of one year.

4.5 Work execution

Once a rock-solid set of maintenance strategies have been developed, the execution of the tasks as generated and activated at the hand of the medium-term plan can (and should) be enforced. The structuring and numbering as discussed now means that a direct correlation can be made between every task that has been executed and the medium-term maintenance plan. This applies not only to the preventive and detective (hard-time) tasks, but also to the corrective and single management intervention tasks.

An aspect of work execution which is often overlooked, sometimes due to the in-ability of our systems, is that work execution poses valuable opportunities to assess the validity of our maintenance strategies. This point will be discussed in some more detail in the following paragraphs.

4.6 Defect analysis

A structured, numbered set of functions, failures, failure modes and failure causes gives significant additional meaning to defect analysis. In the very often typical maintenance environment, failures are tolerated because the effect there-of on service delivery or production is not realized. This is to be expected where performance standards are not clearly defined.

The approach discussed in this article allows for two actions to be taken decisively:

  1. Determining if the failure is to be expected, at the hand of the structured and numbered hierarchical breakdown.
  2. Updating the maintenance strategy right after investigating the failure. This updating can involve any one or more of
    • Updating preventive or detective task content.
    • Updating the frequency of preventing or detective tasks.
    • Adding additional, previously un-identified failure modes or failure causes, with the subsequent addition of the necessary strategies.

4.7 Strategy shortcoming?

The analysis of the failure allows for an authorative updating of the existing maintenance strategies, as discussed in the previous paragraph.

4.8 Work execution history

The positive association of maintenance tasks with functions, asset construction types, asset partitions etc., together with a comprehensive medium-term maintenance plan, allows for the direct comparison of tasks executed with planned execution dates. But importantly, it also allows for the comparison of actual MTBO’s (mean time between occurrences) to planned MTBO’s.

But this level of visibility can only be achieved when each and every maintenance task can be traced back directly to the relevant strategy, failure cause, and failure mode and of course functional failure.

4.9 Compare

Let us consider once again a sample maintenance requirements analysis:

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In the case of a functional failure like “Shade-net torn over parking spaces 48 and 49”, and the failure is reported at the hand of the structured and numbered breakdown, an immediate and direct comparison to the structured maintenance requirement analysis can be made. A sample routine report to achieve this is shown in the next paragraph.

4.10 Maintenance strategy evaluation report

The approach to a structured and numbered set of “failure codes” as discussed in the previous paragraphs culminate in full visibility of the relevance of maintenance strategies, as shown in the sample report below:

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If the month of January is considered as example, the following are evident:

  1. The medium-term maintenance plan is not adhered to.
  2. The maintenance strategies are not complete or accurate because all failure causes have not been pre-identified. Ditto for functional failures.
  3. There could well be issues with work execution quality or even operator skill because significantly more failures occurred than was anticipated.

The knowledge obtained through such a report can obviously be used for an immediate and authorative review of the maintenance strategies, work execution standards, maintainer skill or operator skill.

5.  Conclusions

Full compliance to ISO 55001 requirements entails much more than a number of tick-marks on an audit worksheet. It might in practice take a number of years for companies to fully grasp the asset management system implications of the new standard; but it is clear that visibility and line-of-sight requirements will lead to a number of very specific system requirements.