This research conclusively proved that fixed interval overhaul or replacement is technically not the right action to take when failure is not a function of operating age. In fact, in most cases, scheduled over-haul and replacement hurt reliability. Because most Failure Modes occur randomly, the failure rate could not be controlled by performing more scheduled overhauls and replacements. Armed with these facts, a new way of deriving scheduled maintenance tasks needed to be developed, setting the stage for the birth of RCM principles.
1.6 The Development of RCM Principles
From this research, RCM principles were first conceived within the commercial airline industry. MSG-1, Handbook: Maintenance Evaluation and Program Development was prepared by the 747 Maintenance Steering Group and published in 1968. This document contained the first use of decision diagram techniques to develop a prior-to-service scheduled maintenance program.
Improvements to MSG-1 led to the development of MSG-2: Airline/Manufacturer Maintenance Program Planning Document, which was published in 1970. MSG-2 was used to develop the scheduled maintenance programs for the Lockheed 1011 and the Douglas DC-10. It was also used on tactical military aircraft McDonnell F4J and the Lockheed P-3.
In the mid-1970s, the Department of Defense was interested in learning more about how maintenance plans were developed within the commercial airline industry. In 1976 the Department of Defense commissioned United Airlines to write a report that detailed their process. Stanley Nowlan and Howard Heap, engineers at United Airlines, wrote a book on the process and called it Reliability-Centered Maintenance. Their book was published in 1978. To many, Stanley Nowlan and Howard Heap are considered two of the most significant pioneers of the RCM process. Their book remains one of the most important documents ever written on equipment maintenance.
Using Nowlan and Heap’s book as a basis for update, MSG-3, Operator / Manufacturer Scheduled Maintenance Development was published in 1980. Since then, MSG-3 has gone through many updates. MSG-3 continues to be used within the commercial airline industry today, but is still intended to develop a scheduled maintenance program for prior to service aircraft.
Since Nowlan and Heap’s book was published, there have been various updates to the RCM process, namely the identification of environmental issues. The late John Moubray was another great pioneer of the RCM process; he did a great deal to advance RCM throughout commercial industry. His book RCM II was first published in the United Kingdom in 1991 and in the United States in 1992.
Streamlined RCM and SAE JA1011
Although RCM is a resource intensive process, analyses can be completed efficiently if the process is used correctly with the right people. However, in the mid 1990s, streamlined versions of RCM started to appear. These versions often omit key steps in the process and differ significantly from what Nowlan and Heap originally intended. As a result, the Society of Automotive Engineers (SAE) published SAE JA1011, Evaluation Criteria for Reliability-Centered Maintenance (RCM) Processes in 1999. This internationally-recognized standard outlines the criteria that any RCM process must embody in order to be called RCM. SAE JA1011 was updated in 2009.
The RCM process defined in this book complies with SAE JA1011. More important, it remains true to what the original pioneers of the process, Stanley Nowlan and Howard Heap, originally intended. Therefore, this books details True RCM.
RCM is a remarkable process and can be defined as follows. The terms zero based, failure management strategies, and operational environment bear further explanation.
 | Reliability Centered Maintenance is a zero-based, structured process used to identify the failure management strategies required to ensure an asset meets its mission requirements in its operational environment in the most safe and cost effective manner. |
Zero-based
Each RCM analysis is carried out assuming that no proactive maintenance is being performed. In other words, Failure Modes and Failure Effects are written assuming that nothing is being done to predict or prevent the Failure Mode. In this way, consequences of each Failure Mode can be assessed and solutions can be formulated with no bias towards what is currently being done.
Failure Management Strategies
Notice that the definition states that RCM is used to identify failure management strategies, not maintenance tasks. As explained earlier, managing assets requires more than just scheduled maintenance. Therefore, RCM provides powerful tools for developing other solutions, as detailed in Figure 1.2.
Operational Environment
How an asset is maintained depends on far more that just what an asset is. When solutions for assets are formulated, the following issues regarding the operational environment must be considered.
•Physical environment in which the asset will be used (e.g., cold weather, desert climate, controlled environment)
•Operational tempo (e.g., 24 hour operation, system runs 6 hours each day)
•Circumstances under which the system will be operated (e.g., stand-alone, one of four systems runs at one time but is rotated every month)
•Redundancy (e.g., the system or any of its components operate in the presence of a backup)
These issues can greatly influence not only what maintenance tasks are identified and how often they are performed, but also other solutions such as equipment design and training programs. Therefore, the operational environment must be clearly defined.
1.8 Defining Performance in the Context of RCM
In the context of RCM, there are two features regarding equipment performance that responsible custodians must carefully examine: design capability and required performance.
Asset owners perform RCM to determine what actions must be taken to ensure that equipment meets mission requirements. A mission could be towing a piece of equipment to the construction site, launching an aircraft from an aircraft carrier, or ensuring that there is adequate plant air for the downstream manufacturing process. But when it comes to defining performance, equipment custodians must be specific about what their assets can do (design capability) and what they need them to do (required performance). The following discussion illustrates this point.
Take, for example, a water tube steam boiler. As illustrated in Figure 1.13, the design capability is a Maximum Allowable Working Pressure (MAWP) of 500 psi. However, the required performance is 650 psi. Is this scenario acceptable? Absolutely not, because what the organization requires (650 psi) exceeds