Reliability HotWire: eMagazine for the Reliability Professional
Reliability HotWire

Issue 71, January 2007

Hot Topics
The RCM Perspective on Maintenance

Maintenance has gained momentum and is now at the heart of many companies activities due to its vital role in the areas of safety, liability, productivity, quality, system reliability, regulatory compliance, profitability and environment preservation. With this new paradigm, new awareness, realities, challenges and opportunities are being presented to maintenance and operations specialists in various industries. In the center-stage spotlight of maintenance, there is a strategy called Reliability Centered Maintenance, or RCM.

This article provides some background on the RCM perspective on maintenance along with a brief introduction to the major principles.

A Fresh Perspective
Traditional thinking holds that the goal of maintenance is to preserve equipment. On the surface, we might not see a problem in that mindset, but in fact it has been proven to be flawed at its core. The blind quest to preserve equipment has produced many problems, such as being overly conservative in our maintenance actions (which could cause damage due to intrusive actions and increase the chances of human error), thinking that all failures (or parts) are equal or performing maintenance activities simply because there is an opportunity to do so.

Recent decades have brought in many initiatives and management strategies aimed at reducing cost, optimizing the use of resources and becoming sensible about the effect on the bottom line of any action we take. The preserve equipment mentality consumed resources quickly, put maintenance plans behind schedule and overwhelmed even the most experienced maintenance personnel. What is worse, it sometimes caused maintenance actions to become totally reactive. Budget cuts made the scene even uglier and many people simply lost control of their maintenance management.

The development of the Reliability Centered Maintenance approach has provided a fresh perspective in which the  purpose of maintenance is not to preserve equipment for the sake of the equipment but rather to preserve system function. At first, this might be a difficult concept to accept, because it is contrary to our ingrained mindset that the sole purpose of preventive maintenance is preserving equipment operation. But in fact, in order to develop an effective maintenance strategy, we need to know what the expected output is and the functions that the equipment supports; that is, the real purpose of having the equipment in the first place.

What is RCM?
Reliability Centered Maintenance (RCM) was first documented in a report written for United Airlines by F.S. Nowlan and H.F. Heap to transform aircraft maintenance as the Boeing 747 was being introduced. The report was published by the U.S. Department of Defense in 1978 and was then adapted to industrial maintenance. RCM is a process used to determine what must be done to ensure that any physical asset continues to do what its users need it for in a certain operating context. RCM analysis provides a structured framework for analyzing the functions and potential failures of physical assets (such as an airplane, a manufacturing/production line, an oil refinery, a telecommunication system, etc.) in order to develop a scheduled maintenance plan that will provide an acceptable level of operability, with an acceptable level of risk, in an efficient and cost-effective manner.

According to the SAE JA1011 standard, which describes the minimum criteria that a process must comply with to be called "RCM," a Reliability Centered Maintenance Process answers the following seven essential questions:

  1. What are the functions and associated desired standards of performance of the asset in its present operating context (functions)?
  2. In what ways can it fail to fulfill its functions (functional failures)?
  3. What causes each functional failure (failure modes)?
  4. What happens when each failure occurs (failure effects)?
  5. In what way does each failure matter (failure consequences)?
  6. What should be done to predict or prevent each failure (proactive tasks and task intervals)?
  7. What should be done if a suitable proactive task cannot be found (default actions)?

Unlike some other maintenance planning approaches, RCM results in all of the following tangible actionable options: maintenance schedules (which could include on-condition tasks, scheduled restoration tasks, scheduled discard tasks, failure-finding tasks), revised operating procedures for the operators of the asset and a list of recommended changes to the design of the asset that would be needed if a desired performance is to be achieved.

RCM shifts the emphasis of maintenance from the idea that all failures are bad and must be prevented to a more broad understanding of the purpose of maintenance. It seeks the most effective strategy that focuses on the performance of the organization (which might include not doing something about a failure or letting failures happen!). The RCM approach encourages us to think of more encompassing ways of managing failures.

Concluding Remarks
Great success lies ahead of maintenance and operations specialists if they can change another common misconception about maintenance. Maintenance has been mostly considered a "necessary evil"; instead, we could correct this idea and think about maintenance as a profit generator! Like other functions in a business (design, marketing, production, etc.), maintenance incurs costs for its activities. These activities, when properly performed, can significantly help achieve or exceed targeted production output or function. Maintenance should have its treasured place in a companys global strategy.

RCM is not just another empty buzzword or repackaged way of doing things the same old fashioned way. Many things set it apart from other maintenance planning processes used today. It is a simple approach, but requires some very basic changes in attitudes. Future articles will expand on this introduction to RCM and provide discussion and applications of the software tool, RCM++. RCM++, in addition to relying on the standard RCM philosophy described above, provides enhancement by incorporating statistical analysis for life data analysis, optimization of maintenance scheduling based on costs of scheduled and unscheduled repairs and simulation techniques for availability and life cycle cost analysis.

References

Moubray, John, Reliability-centered Maintenance, Industrial Press, Inc., New York City, NY, 1997.

SAE JA1011 "Evaluation Criteria for Reliability-Centered Maintenance (RCM) Processes" issued in August 1999.

SAE JA1012 "A Guide to the Reliability-Centered Maintenance (RCM) Standard," issued in January 2002.

Smith, Anthony and Hinchcliffe, Glenn R., RCM - Gateway to World Class Maintenance, Elsevier Inc, Burlington, MA, 2004.

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