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LECTURE-6

-ROOT CAUSE ANALYSIS-

15FMCE214: PREVENTIVE MAINTENANCE TECHNIQUES

Eng. Meryem Kanzari

By the end of this chapter you should be able to:

❑ Define Root Cause Analysis ❑ Identify the basic steps of Root Cause Analysis ❑ Implement Root Cause Analysis method using

different qualitative and quantitative techniques ❑ Identify the benefit of Cause Analysis method

Learning Outcome

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DEFINITION

Root Cause Analysis (RCA):

A technique used to identify the conditions that initiate the occurrence of an undesired activity or state.

US Government Accountability Office (GAO)

The process of problem solving used to identify the underlying or initiating source of a nonconformance.

American Association of Veterinary Diagnosticians (AAVLD)

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DEFINITION

“A tragedy of this magnitude has to be somebody's fault, …”

George Wilson, (Character) Dennis the Menace (1993)

https://www.youtube.com/watch?v=HRHL0ksUH2k Root Cause Analysis with Examples:

Root Cause Analysis allows you to figure out what’s causing the overall problem

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BASIC STEPS OF RCA

❑ By trying to find the root of the problem, this will fix many symptoms that might be going wrong. This will also give you a better understanding of what caused this problem, and how to prevent it in the future. There are five steps to properly conduct a root causing analysis:

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What is specifically happening?

“The computer won’t turn on.” “My car won’t start.”

What proof shows this exist?

“The computer is plugged in, but

nothing is coming up on the screen”

BASIC STEPS OF RCA

1 2 3 4 5 6

Identifying Possible Casual Problems

“Why is there nothing turning on when I

plug it in the outlet”

Identify your root problem

Find the solution to the problem

“My computer is plugged in, my outlet isn’t working, so I will

charge it with a different outlet and make sure to test it

beforehand.”

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TOOLS USED FOR ROOT CAUSE ANALYSIS (RCA)

❑ 5 Whys

❑ Fishbone Diagram

❑ Fault Tree Analysis

❑ Paretto Analysis

Below mentioned are some of the common tools of Root Cause Analysis:

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5 WHYS

❑ Five whys (or 5 whys) is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem.

❑ The primary goal of the technique is to determine the root cause of a defect or problem by repeating the question "Why?". Each answer forms the basis of the next question.

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❑ Example: Let’s think about the football concussion example. First, our player will present a problem: Why do I have such a bad headache? This is our first WHY. First answer: Because I can’t see straight.

Second why: Why can’t you see straight? Second answer: Because my head hit the ground.

Third why: Why did your head hit the ground? Third answer: I got hit tackled to the ground and hit my head hard.

5 WHYS

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Fourth why: Why did hitting the ground hurt so much? Fourth answer: Because I wasn’t wearing a helmet.

Fifth why: Why weren’t you wearing a helmet? Fifth answer: Because we didn’t have enough helmets in our locker room.

After these five questions, we discover that the root cause of the concussion was most likely from a lack of available helmets. In the future, we could reduce the risk of this type of concussion by making sure every football player has a helmet.

5 WHYS

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5 WHYS

❑ Example:

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❑ A Fishbone Diagram is a structured brainstorming tool designed to assist improvement teams in coming up with potential root causes for an undesirable effect. Its name derives from its resemblance to the bones of a fish. It is also known as a Cause and Effect Diagram or an Ishikawa Diagram after its creator.

FISHBONE DIAGRAM

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❑ The system failure is described in a box to the right of the diagram.

❑ Bones • Categories (4 M’s):

▪ Man Power (Personnel) ▪ Machines (Equipment) ▪ Materials (Reagents and Supplies) ▪ Methods

• Primary Causes • Secondary Causes

FISHBONE DIAGRAM

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FISHBONE DIAGRAM

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❑ Example:

FISHBONE DIAGRAM

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❑ Example:

FISHBONE DIAGRAM

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A refrigeration and heating company has asked your advice on how to analyze their service quality . They have logged customer complaints. Here’s recent sampling. Use the supplied template to construct a conventional Fishbone diagram (cause and effect diagram)

❑ Practice

FISHBONE DIAGRAM

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FISHBONE DIAGRAM

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FAULT TREE ANALYSIS

❑ Fault Tree Analysis (FTA) helps determine the cause of failure or test the reliability of a system by stepping through a series of events logically.

❑ A fault tree diagram is used to conduct fault tree analysis.

❑ Fault tree analysis templates provide you lots of special shapes, AND gate, OR gate, Inhibit gate, priority gate, exclusive OR gate, combination, intermediate event, basic event, undeveloped event, etc.

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FAULT TREE ANALYSIS

Fault Tree Symbols

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FAULT TREE ANALYSIS

❑ Example:

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FAULT TREE ANALYSIS

❑ Example:

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PARETO ANALYSIS

❑ Pareto Analysis is a statistical technique used for the selection of a limited number of tasks that produce significant overall effect. It uses the Pareto Principle (also known as the 80/20 rule) the idea that by doing 20% of the work you can generate 80% of the benefit of doing the entire job.

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PARETO ANALYSIS

Here is a simple example of a Pareto diagram, using sample data showing the relative frequency of causes for errors on websites. It enables you to

see what 20% of cases are causing 80% of the problems and where efforts should be focused to achieve the greatest improvement. In this case, we can see that broken links, spelling errors and missing title tags should be

the focus.

❑ Example:

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PLAN-DO-STUDY-ACT CYCLES

❑ The final steps of the RCA aims to identify and implement necessary solutions.

❑ Once a team has mapped a process, set a goal, developed measures and a data collection plan and selected changes, the next step is to test those small changes using the Plan- Do-Study-Act (PDSA) cycle. It's a quick way to improve work processes that allows teams to rapidly test a change on a small scale.

❑ The PDSA cycle brings data, learning, and action together into one process. It should be noted that improvement often requires multiple PDSA cycles.

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PLANS-DO-STUDY-ACT CYCLES

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PLANS-DO-STUDY-ACT CYCLES

The four stages of the PDSA cycle are: Plan – the change to be tested or implemented Do – carry out the test or change Study – based on the measurable outcomes agreed before starting out, collect data before and after the change and reflect on the impact of the change and what was learned Act – plan the next change cycle or full implementation

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ADVANTAGES OF ROOT CAUSE ANALYSIS (RCA)

▪ It helps to understand the exact source of the problem and also the measures to fix the bug is that it doesn’t get repeated in the future.

▪ Is a systematic investigation which checks each and every process and system to form an opinion about the core of the issue.

▪ It offers a long-lasting solution since the principal defect is been eliminated at the preliminary stages thus helping the company to run its processes and systems smoothly without any hick-ups.

▪ It provides a safer workplace for the employees working in the company.

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