You've performed an RCM analysis of your system and the program is underway. You have had an existing condition-based maintenance program in place for years. How do you know your program is effective? What process can be used to determine if it is performing optimally?

The US Military has a concept known as the Maintenance Effectiveness Review (MER) in which maintenance programs are periodically reviewed for effectiveness. It is a continuous improvement opportunity to upgrade and streamline your program without the intensity and costs required to perform continuous RCM. There are several techniques, including the Backfit Process, which we will cover, that provide the necessary rules.

There are a number of benefits to the implementation of a MER which include:

  • It provides a continuous improvement dimension to your condition-based maintenance program;
  • It can be used to identify weaknesses in the program;
  • It can be used to identify new opportunities or methods for condition-testing;
  • It provides a measurement process for the effectiveness of your program;
  • It provides a process 'safety net;' and,
  • It is normally used following the application of RCM.

It is a fact that, regardless of how robust your RCM process is, problems will slip through the cracks and new technologies and processes, not identified during the original process, may come to light. The MER process also keeps the concept of CBM in all stakeholders' minds, following the initial implementation of the program, allowing for long-term success.

Maintenance Effectiveness Review Overview

The MER usually begins following at least one cycle following the implementation of CBM processes. When the cycle is unclear, it should be started after 12 months of the implementation of the program with the exception of a noticed increase in unplanned and/or reactive failures.

One of the first steps in the MER process is selecting systems for review. This is normally done based upon the system's impact on safety and regulatory issues, the impact on production or mission, the expense of repairing or replacing the equipment and the rate of failure. The prioritization of systems for review is based upon the systems low or high availability, RCA reporting, high rate of failures and a pre-set schedule.

A team is assembled that consists of a facilitator, associated system stakeholders, including operators and maintenance, and vendors, as appropriate. Each system should be MER'd in a process that should take about 4 hours to three days, depending upon the size of the system and the personalities involved. Unlike the RCM process, however, the MER can be performed on one system up to a common system across the corporation.

Perform the MER process then assign responsibility for implementing findings and a time-schedule. Follow-up can be performed at the beginning of each MER meeting with feedback that can be as simple as a list of findings assigned on a red-yellow-green chart.

Does the MER Follow the Seven Requirements for RCM?

While the MER is not meant to be a full or rigorous RCM process, it does meet the requirements for RCM. Following are a list of the requirements and a brief explanation:

1. Identify the functions of the system: The first part of the MER process, when used with an RCM program, is to review the functions of the system as outlined in the original RCM process.

2. Identify functional failures: Not only does the MER review the functional failures outlined in the original process, but it is used to identify if the functional failures have actually occurred.

3. Identify failure modes: The MER verifies the failure modes as they have actually occurred.

4. Identify failure effects: The MER verifies the failure effects as they have actually occurred.

5. Identify failure consequences: Same as 3 and 4.

6. Identify methods to identify failure or to reduce consequences: The purpose of the MER, including reviewing the Risk using a Risk Chart.

7. Identify solutions should a proactive task not be identified: The purpose of the MER is to verify that the solutions and proactive tasks are actually identifying the issues that they were selected to identify.

The purpose, of course, is to verify the findings and implementation practices from the original RCM process.


The purpose of the MER process is to provide a continuous improvement step to a Condition-Based Maintenance process. It is not designed to replace the RCM process, but to enhance it and find weaknesses in the original program, as well as to support the program through the implementation of a continuous process. It utilizes the original information, regardless of the type or rigorous-ness of the original process, and meets the requirements of an RCM program.

About the Author

Howard W Penrose, Ph.D., CMRP, is the President of SUCCESS by DESIGN, a reliability and maintenance services consultant and publisher. He has over 20 years in the reliability and maintenance industry with experience from the shop floor to academia and manufacturing to military. Dr. Penrose is a past Chair of the Chicago Section of the Institute of Electrical and Electronic Engineers, Inc. and is presently the Founding Executive Director of the Institute of Electrical Motor Diagnostics. Dr. Penrose may be contacted via phone: 860 575-3087 or email:

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