Root Cause Analysis (RCA) is a vital tool utilized daily in the realm of reliability. Properly understanding problem-solving methods and the analytical tools that function within it are key in aiding a facility's journey to world-class maintenance.

Identifying the root of the problem can lead to minimized downtime, defect elimination, and an optimized workforce. The objective of this session is to distinguish, review, and comprehend multiple methods to approach root cause analysis problems.

What is Root Cause Analysis? 

RCA is a continuous improvement process with multiple avenues for uncovering the root cause of a problem or unexpected event. This process looks at the identified problem as a whole, helping facilities to treat the underlying issue rather than just the immediate symptoms, preventing unexpected downtime and costly repairs.

While RCA often begins as a reactive process because of knee-jerk reactions to plant failures, if nurtured over time, this process can become a proactive tool for driving results with overall equipment reliability.  

RCA works to improve the overall quality of a product or process and, as such, merits a certain organized approach to be effective and drive real results. There are several iterations to this methodology, but the seven key steps to consider are:

1. State and clarify the specific problem or concern.

2. Collect data and information related to the problem.

3. Categorize likely and potential causes.

4. Identify what causes need to be removed to eliminate recurrence.

5. Detect effective, potential solutions.

6. Establish a plan for implementation.

7. Review and document changes made to ensure the issue has been properly corrected.

It is worthwhile to note that while these actions and analyses can be completed by an individual, RCA works best when a group of peers with varying levels of experience, job duties, and perspectives are involved.

Root Cause Analysis Methods

With a baseline understanding of what RCA is established and general processes outlined, it's time to examine some common, yet effective, RCA methods that can be applied during this process.

It is imperative to note that each method has a varying level of complexity, and the nature and effectiveness in which each technique is deployed depends on a facility's active involvement in its continuous improvement initiatives.

Some methods are quick processes, while others can require a long and arduous journey. Certain methods are utilized proactively during installation and while equipment is in service. Others rely heavily on the process of reviewing a noted postmortem failure or problem with the asset.

Fishbone Diagrams

There are several names for the first method being covered. Some refer to this exercise as a Fishbone Diagram, Ishikawa, or, sometimes, a Cause-and-Effect Diagram. The idea behind this RCA method is to draw the failure or problem on a box with a long, straight line leading from it. Off this long line there will be several branches or bones that divide off the primary line.

Each line will have a header and act as a specific category failure mechanism in identifying possible reasons for the root cause problem. The number of categories will vary depending on the specific failure, but common category headers include:

• Manpower: The operational and/or functional labor of people engaged in the design and delivery of a product.
• Method: A production process and its contributing service delivery processes.
• Machine: Systems, tools, facilities and equipment used for production
• Material: Raw materials, components and consumables needed to produce a desired end product.
• Mother Nature: Environmental factors that are unpredictable and uncontrollable like weather, floods, earthquakes, fire, etc.
• Measurement: Manual or automatic inspections and physical measurements (distance, volume, temperature, pressure, etc.).

As an example, under the manpower category, the RCA team would identify all notable individuals or positions that would have had a possible impact on the outcome of the problem. The team would continually carry out this process for all reasonable categories and work to identify a common theme of realistic root causes based on one or more categories.

The Fishbone Diagram is one of the most commonly used RCA methods available for identifying root causes after failures or problems occur.

Barrier Analysis

Barrier Analysis can be both a reactive or proactive RCA technique for discovering why a problem occurred and eliminating it from recurring. The idea behind this methodology is that the problem can and should be avoided by having proper barriers established. The RCA team works to recognize the target and hazard, and then tries to identify a means to create barricades between the two.

In some cases, more than one barrier is utilized. This case is referred to as layers of protection or depth in defense. These barriers, depending on the problem, can be engineering or administrative controls.

Barrier Analysis is most commonly used in safety-based incident evaluations.

FMEA

Failure Modes and Effects Analysis (FMEA) is primarily a proactive RCA tool for determining potential failures, risks, and causes. This process is largely a practical application of quantitative traits based on a calculated matrix and is often considered the first step in practice root cause analysis.

When applying FMEA, a team will investigate equipment before a problem occurs to understand the related concerns based on a weighted ranking system. This ranking system will help prioritize the facility's plans and strategies for implementing necessary solutions to concerns identified during the FMEA process.

FMEA most commonly occurs during any installation, design change, or production number increase. 

Fault Tree Analysis

Fault Tree Analysis is a method similar to FMEA in that is often considered to be a proactive approach to RCA. This technique establishes a waterfall or top-down logical analysis of causes shaping event rates and leading to specific root solutions.

This methodology is generally used in process concerns or safety-related incidents.

Eight Disciplines

Eight Disciplines is an RCA approach developed to correct recurring defects or problems by establishing long-term corrective actions based on statistical analysis. Eight Disciplines was initially applied in the automotive industry, but now has many practical applications within RCA.

This process is implemented using eight steps, which includes:

1. Creating a team
2. Describing the problem
3. Developing short-term containment plans
4. Determining and confirming the root cause
5. Verifying long-term resolution
6. Executing corrective actions
7. Preventing recurrence
8. Recognizing success

Five Whys

Is/ Is Not Method

The Is/ Is Not Method is another somewhat simplified approach to RCA. The idea is to create who, what, where, when, and why rows with “Is” and “Is Not” columns influencing the problem or concern based on collected data. 

This practice is often utilized after the problem has occurred and the RCA team needs to narrow the scope, establish solutions based on common themes, and establish priorities.

Pareto Analysis

Pareto Analysis is a great visual presentation of RCA. This method uses data to track and trend root cause concerns. Pareto charts typically appear in bar graphs that display values in descending order totaling the whole charge of the problem. As Pareto is commonly referred to as the 80/20 rule, it often lives up to its name in regard to identifying failures.

Once these critical few items are addressed though Pareto Analysis, the majority of cause for concern will be eliminated. This technique is most commonly applied with quality-control concerns and generally conducted while the failures are occurring.

Scatter Plot Diagrams

Much like Pareto charts function well in other areas of industry, the same can be said for Scatter Plot Diagrams. These diagrams can be a useful RCA tool when working to correlate one or more paired variables. Variables are separated on an "X" and "Y" axis of a chart to establish if the noted variables are related.

This particular method is typically used in conjunction with other methods as a means of validation.

Conclusion

In conclusion, identifying the root of the problem, understanding the RCA process, and knowing how and when to deploy certain analysis methods can lead to minimized downtime, defect elimination, and an optimized workforce. Properly deploying these practices proactively and reactively as well as driving the discoveries to fruition are key in aiding your site’s journey to world-class maintenance.