Reliability Centered Maintenance (RCM) is a method for developing maintenance concepts. It is based on the ideas of Stanley Nowlan and Howard Heap, who published the RCM report in 1978.
RCM report 1978
From the beginning of the 1960s until the end of 1978, they researched the mechanisms behind interference behaviour and how this can be managed. This development of RCM originated in the aircraft industry. Together with Nowlan and Heap, John Moubray has made the start of RCM2. This was the industrial successor of RCM. But RCM2 was too static for a dynamic industry like production processes. So many factors play a role here, that failure behaviour keeps changing. In such dynamic environments, dynamic maintenance plans must be used, so that the current failure behaviour remains under control. RCM2 was further developed to Dynamic RCM in 2005.
Reliability Centered Maintenance methodology
Reliability Centered Maintenance (RCM) is a method that makes use of ready knowledge and available data. Experience shows that ready knowledge is more topical than data. Only 20% of this data turns out to be up-to-date. The RCM approach is aimed at putting the right steps in the right order. A total of 7 steps are completed.
Step 1. Describe the Operational Context and the functions defined on that basis.
Step 2. Describe the functional failures. These are states that do not comply with the functions.
Step 3. Describe types of interference. These are the causes including the underlying reasons that lead to a functional failure.
Step 4. Describe interference effects. These describe what happens if a malfunction occurs.
Step 5. Select which type of interference effect applies to the type of interference (including the interference effect).
Step 6. Evaluate which proactive task the interference form can prevent.
Proactive tasks are:
1. On Condition tasks
2. Discard tasks
3. Restoration tasks
4. Combination tasks
If no proactive task could be found, step 7 offers the following solutions:
1. Failure Finding Tasks
2. Compulsory or desirable modifications
3. Corrective tasks
Steps 1-2-3-4 are performed in a Process FMEA (Failure Mode Effect Analysis). RCM does not use a FMECA (Failure Mode Effect Criticality Analysis). This is also laid down in the International RCM standard. FMECA is better applied to low-critical systems and not to highly critical ones. This seems contradictory, based on the word “Criticality”. But there are decisive reasons for this choice.
FMEA (Failure Mode Effect Analysis)
The FMEA is a way to generate a complete list of real possible forms of interference and effects. With the help of the RCM Process FMEA, very complete and detailed overviews of interference behaviour can be generated.
Because the FMEA has to describe the current failure behaviour, it is necessary to have this done by a working group led by an RCM facilitator. The working group must master the terminology of RCM in order to understand the questions of the RCM facilitator and to record the right information at the right places in the methodology.
Steps 5-6-7 develop the maintenance concept. A decision strategy is used for this. The criteria for maintenance tasks differ considerably, depending on the category of failure consequences. That is why step 5 is so important. In step 6, a proactive task is sought, based on the criteria. If it is found, step 7 is not necessary. If no proactive task is found, the working group will look for an appropriate fallback task that can minimise the consequences.
The end result is a maintenance concept that can manage the current failure behaviour in a way that effectively prevents failure forms or minimises the consequences. This concept is a theoretical model that has yet to be nested into a practical maintenance plan. This maintenance plan is put in a CMMS and planned in a diary. This is how the maintenance programme is created.
Overview of our RCM training courses:
RCM Level 1: training to become an RCM workgroup member. This level is supervised by an RCM Level 2 (RCM Facilitator). In this 3-day course participants get acquainted with the ideas behind RCM. This partly consists of the terminology that is needed to be able to apply the ideas. In this training the participants learn which RCM steps are taken to make maintenance concepts.
RCM Level 2: training to become an RCM Facilitator. This level has the final responsibility for the composition of working groups, choices of analyses and system boundaries, execution and quality of RCM analyses and the continuous improvement of maintenance plans that have to manage the current failure behaviour.