Synergy between Reliability-Centered Maintenance and Root Cause Analysis
Which would you prefer: Prevention or Cure? If you work at an organization that observes the Directive on Risks and Severe Accidents (in Dutch: BRZO), then you would almost certainly say, “Prevention!”. Preventing equipment from failing is obviously a good thing. No one is just sitting around waiting for a radiation contamination incident at a reactor or for a cloud of chemicals to start leaking. But we cannot predict everything. The best preventative efforts still fail sometimes. Wouldn't that suggest that the better answer would be “Cure!"?
The examples I described above commonly come up in discussions about maintenance methods, particularly when it comes to applying Reliability Centered Maintenance (RCM) or Root Cause Analysis (RCA). The biggest problem about these types of conversations is that there is this notion that you have to choose between RCM and RCA, between prevention and cure.
A lack of clarity about what both of these terms actually mean, as well as advisors who tend to be strong advocates for one method above the other, have led to confusion in the industry. There is this perception that you can only choose one. But why should you choose? Wouldn't it be far more effective to use good methods that both prevent and cure? Synergy between preventing and curing can actually make it easier for you to get more out of your assets!
To clarify, RCM is a maintenance method that was developed in the 1960s. This is a method for determining what maintenance activities are required in light of the possibility of system and/or equipment failure, given the impact that such failure would have on safety, operations and costs throughout the entire life cycle [US DoD, 2001].
RCM is used to analyze assets and equipment which are subject to failure mechanisms. The changing odds of failure over time is an important factor in defining the correct maintenance strategy [Nowlan & Heap, 1978], for example failure due to an “aging asset” or “random failures”. It is important to emphasize that the consequences of failure, as opposed to failure itself, should be the determining factor in your choice of maintenance strategy. With that in mind, you can determine the appropriate inspection/prevention measures, or the corrective and contingent measures.
This is then further defined in maintenance concepts which will form the basis of your knowledge of what needs maintenance and which measures you will take. RCM is a powerful mechanism to combat failure mechanisms and thereby prevent failure.
Applying RCM is no one-off project. If you want to ensure that your concepts will remain relevant for aging assets, modifications and adjustments to your business strategy, you will need to re-run your RCM analysis from time to time. In doing so, you can make sure that the most up-to-date knowledge about failure mechanisms are incorporated into your maintenance concepts. By regularly conducting these analyses, RCM can not only prevent issues, but also cure them.
When applying RCM, time and budgetary limitations have to be taken into account. This is one challenge for RCM. The higher costs involved in developing relevant maintenance concepts can stand in the way of effectively deploying RCM. That often results in it becoming a one-time thing, or only partial implementation. Failure to follow through with it means that it is less effective than it could have been if it were to be conducted regularly. RCM also focuses on developing and adapting maintenance concepts. As such, it is less suited to coming up with an immediate solution when something does fail.
But that is where RCA shines. RCA is a method that can be used to identify the root causes of failures or problems [US DoE, 1992]. In the event of a failure of some sort, this method is well suited to not only find the root cause but also the appropriate solutions. From simply asking “why?” five times to an in-depth analysis: RCA is an outstanding way to cure what ails your assets.
Another less direct application of RCA is to use it to improve maintenance concepts. If it becomes apparent that increasing the frequency of inspections could have prevented failure, then this approach can be used to improve the maintenance concept. In that same vein, it can also prevent equipment failure. However, without existing maintenance concepts, RCA can only add or adapt individual measures. That can limit RCA's capacity to prevent failure.
While RCM and RCA have limitations on their own, combining them creates a strong synergy. Applying RCM will result in increased reliability, cost efficiency, availability and improved management of risks that pose a threat to your assets. It is a powerful method that helps to prevent your assets from failing.
Should failures still (unintentionally) occur or should performance continue to lag, applying RCA can lead to better results. The proposed changes which you can generate cost-efficiently, can be used to effectively modify your assets or to improve the maintenance concepts, thus closing the improvement cycle and leaving you with an effective method to continually improve.
DOE Guideline (1992). DOE-NE-STD-1004-92 Root Cause Analysis Guidance Document. US Department of Energy: Washington DC.
Department of Defense (2011). MIL-STD-3034 Reliability Centered Maintenance (RCM) Process. US Department of Defense: Washington DC.
Nowlan, F. S., & Heap, H. F. (1978). Reliability-centered maintenance. United Air Lines Inc San Francisco Ca.