RCM Analysis: The Ultimate Guide [one-page infographic]

What is Reliability Centred Maintenance (RCM)?

RCM Analysis is a structured framework for identifying and analysing the functions and potential failures for a physical asset to preserve system functions. It is not a type of maintenance, instead, it is about analysis, development and management of maintenance plans. 

Generally, an RCM analysis has 3 stages:  

1. Prepare and Define stage;  
2. Analyse stage – answer 7 questions;  
3. Act and sustain stage.  

Within these 3 stages, you can proceed through 13 steps to complete a thorough RCM analysis. 

How to Perform an RCM Analysis? 

Prepare and Define Stage

Step 1: Assemble a cross-functional team of subject matter experts. 

Make sure the size of the team is adequate for an effective RCM analysis without wasting resources and/or making the team out of control (usually 4 to 5 people).  

Tips: a core RCM team might include experts from: maintenance, machine repair, machine parts management, operations, system engineering, manufacturing engineering, quality/reliability, equipment manufacturer. 

Step 2: Select the equipment to be analysed.

Answer: 

• What is the scope of the RCM analysis? – i.e., Which level of the asset (e.g., plant, system, subsystem, component or part) should be the starting point of the analysis? Tips: usually starting at the system level to make sure enough visibility in the analysis.  
• What are the system boundaries and the relationships between all major components or subfunctions? – specifying what will be included and not included in the RCM analysis by using a Functional Block Diagram.
• Which equipment is most valuable for you to analyse with RCM first? – Risk Discovery Questions and Risk Discovery Ratings are two commonly employed equipment selection methods.

Step 3: Define ground rules of team management and assumptions of the RCM analysis. 

Step 4: Gather and review relevant documentation that will provide input to the RCM analysis: e.g., system P&IDs, manuals, equipment history, work order summary etc. 

Analysis Stage – Answer 7 questions

The SAE JA1011 standard describes the minimum criteria for an RCM process. The 7 questions need to be asked for each asset: 

1. What are the functions and associated desired standards of performance of the asset in its present operating context (functions)? – Step 5 
2. In what ways can it fail to fulfil its functions (functional failures)? – Step 6 
3. What causes each functional failure (failure modes)? – Step 7 
4. What happens when each failure occurs (failure effects)? – Step 8 
5. In what way does each failure matter (failure consequences)? – Step 9 
6. What should be done to predict or prevent each failure (proactive tasks and task intervals)? – Step 10 
7. What should be done if a suitable proactive task cannot be found (default actions)? – Step 10 

Reference: SAE JA1011 “Evaluation Criteria for Reliability-Centered Maintenance (RCM) Processes,” issued in August 1999. 

Step 5:  Identify functions.

Answer: What does the selected equipment do and what is the acceptable level of performance you want to achieve? 

Function Statement Tips:  

• Start with a verb (e.g., to pump water). 
• Avoid use the equipment names to describe the functions (e.g., “To maintain discharge flow of 500 gpm” rather than “To provide a centrifugal pump that delivers 500 gpm.”). 
• Be as specific and quantitative as possible (e.g., “To produce a target of 25 units with a minimum of 22 units in an 8 hour shift” rather than “To produce as many units as possible”). 

Step 6: Identify functional failures.

Answer: How can the selected equipment fail to fulfil one or more intended function(s) to a standard of performance?  What kinds of failed states they are? 

Failure Statements Tips:

• Avoid talking about equipment. Keep in mind the purpose of RCM is to prevent loss of function, not equipment. 
• Distinguish different failures. One function can have multiple failures which will be related to different failure modes, causes, effects and actions. 
• Define the failures based on the operating context. 

Step 7: Identify failure modes.

Answer: What are the specific causes of the functional failures you have listed in step 6? 

Cause Descriptions Tips:

• Decide the appropriate level of the root cause investigation, identify the causes at the actionable level (i.e. the level at which it will be possible to apply a maintenance strategy to address the potential failure). 
• Consider the time dimension (the exact time at which failure modes have occurred) if you plan to perform statistical data analyses. 

Note: Extensive discussions about failure mode identification will greatly benefit the RCM program. It is what could make a difference between a reactive and a proactive maintenance management plan.

Step 8: Identify failure effects. 

Answer: What happens when failures occur and what are the symptoms of failure?

Detailed questions like:

• What will be observed when the failure occurs? 
• What is the impact on operations/production? 
• What is the impact on the environment/safety? 
• What physical change will occur to the equipment or adjacent equipment? 
• What alarms or indications will be observed? 

Additionally, effects can be defined at three different levels: 

• Local Effect – What is observed at the individual component? 
• Next Level Effect What is observed at the sub-system level? 
• End Effect What will be observed at the system level? 

For example, if you run out of gas in your car, then: 

• Local Effect: Fuel injectors fail to supply gas to the engine. 
• Next Level Effect: Engine stops working. 
• End Effect: Car stops, you are late to work. 

Note: we can also identify effects first, then failure modes. Both approaches yield the same results in the RCM logic diagram analysis. 

Step 9: Identify failure consequence.

Answer: How and why does the failure matter?  What is the likelihood of occurrence and the severity of the failure mode? 

The consequences of every failure mode shall be formally categorized: 

• Hidden verse Evident Failure Modes  
• Safety and Environmental (1st priority) and Economic (2nd priority) consequences.  
• Operational (1st priority) and Non-Operational (2nd priority) consequences.  

This step directs RCM analysis to focus on the maintenance activities which have the most effect on the performance of the organization, instead of those with little or no effect.

Step 10: Select Maintenance tasks.

Answer: Can the failure be predicted or prevented? Is it feasible and worth doing the task(s)? If not, what can be done to deal with the failure?