Problem Solving using

Root Cause Analysis

Franck Vermet

Why do we need Root Cause Analysis?

Because it works!

Works for all types of problems solving (HSE, Quality, etc.)

Needs a paradigm shift:from “Who” to “Why”

What are problems?

Opportunities

Symptoms

What are problems?

Problem solving

To be efficient:-Systemic analysis -Action

Problem solving time effect

Days WeeksMonths

Years

Untouched 0

Leaf 1

Small Branch 2

Master Branch 3

Trunk 4

Roots 5Time before it grows again

The deeper we cut into the problem, the longer it takes to reappear.

Problem Solving

Solving any complex problem simply.

Solution not guaranteed.

RCA techniques: Level 0Surface understanding

Symptom

Root Cause

Why

Because

RCA techniques: Level 1Linear chain of cause and effect

My car will not start. (the problem)

1.The battery is dead.

2.The alternator is not functioning.

3.The alternator belt has broken.

4.The alternator belt was well beyond its useful service life and has never been replaced.

5.I have not been maintaining my car according to the recommended service schedule.

Symptom

Root Cause

Why

Why

Why

Why

Why

SymptomRCA Worksheet Description

Reference

Who When

Why - 1

Why - 2

Why - 3

Why - 4

Why - 5

Who When1

Wha

tto

exp

lain

5 W

hy's

to u

nder

stan

d1

How

to re

solv

e

GuessOpinion

Fact?

What

5 Why’s example: Manufacturing

1. “Why did the robot stop?”The circuit has overloaded, causing a fuse to blow.

2. “Why is the circuit overloaded?”There was insufficient lubrication on the bearings, so they locked up.

3. “Why was there insufficient lubrication on the bearings?”The oil pump on the robot is not circulating sufficient oil.

4. “Why is the pump not circulating sufficient oil?”The pump intake is clogged with metal shavings.

5. “Why is the intake clogged with metal shavings?”Because there is no filter on the pump. Taiichi Ohno

Symptom

Root Cause

Questioning technique: Design1 Why do we use twin booster rockets for the Challenger space

shuttle? They are made by Thiokol at their factory at Utah. The railroad line from the factory runs through a mountain tunnel which is slightly wider than the railroad track. The US gauge (standard distance between the rails) is 4 feet, 8.5 inches.

2 Why was that gauge used and not something larger?Because that's the way they built them in England, and English expatriates built the US Railroads.

3 Why did the English build them like that?Because the first rail lines were built by the same people who built the pre-railroad tramways, and that's the gauge they used.

4 Why did they use that gauge then? Because the people who built the tramways used the same jigs and

tools that they used for building wagons, which used that wheel spacing.

Symptom

Questioning technique: Design5 Why did the wagons have that particular odd wheel spacing? If they used any other spacing, the wagon wheels would break on some

of the old, long distance roads in England, because that's the spacing of the wheel ruts.

6 Why is it the spacing of the wheel ruts?Imperial Rome built the first long distance roads in England for their legions nearly 2000 years ago. Roman war chariots formed the initial ruts, which everyone else had to match for fear of destroying their wagon wheels. Since the chariots were made for (or by) Imperial Rome, they were all alike in the matter of wheel spacing.

7 Why did Rome choose this spacing for their chariots? The Imperial Roman war chariots were just wide enough to

accommodate the back ends of two war horses. A major design feature of what is arguably the world's most advanced transportation system was determined over two thousand years ago by the width of a horse's ass.

Courtesy of Mark WarrenRoot Cause

SymptomReference (SN, PN, SO, PO, eQ#, Quest #)

Investigator(s)

Date

5 Why'sto understand

Occurrence

Gue

ss

Opi

nion

Fact Root Cause

Identified?5 Why'sto understand

Non detection

Gue

ss

Opi

nion

Fact Root Cause

Identified?

Why - 1 Why - 1

Why - 2 Why - 2

Why - 3 Why - 3

Why - 4 Why - 4

Why - 5 Why - 5

1 Howto resolve

1 Howto resolve

Who When Who WhenWhat + Quest# What + Quest#

ManufacturingProcess Tests

RCA technique: Level 1.2Why why (occurrence and detection)

RCA techniques: Level 2Logic tree

Symptom Why?

Root Cause

Root Cause

Root Cause

Root Cause

Root Cause

• The 5 enablers (5Ms) of a production system are used as a checklist

• Helps brainstorming potential branches of a logic tree• Can be very time consuming• Can be frustrating as only a few branches as picked (usually by the manager)

RCA techniques: Fishbone diagram

Symptom

Man Machinery

Methods MaterialsMother Nature

Key to make it work:

Take action Be Accountable

Not a robust RCA

Key to make it work: attitude• No finger pointing / no blame

culture• from 1 Who• to 5 Why’s + 1 How

• Open communication

• Become a GOFer (Guess, Opinion, Fact:

Validate your answer)

Conclusion: 5 why’s examples

You do not have any good 5 Why’s examples.

1. Your brain just isn't coming up with any ones I've used in the past.

2. Those examples were too long ago, with no current examples.

3. The method is not used consistently in your problem solving process.

4. It is not integrated into your process for handling root cause analysis and problem solving.

5. You have not been trained on how to do so, or it has not been a priority (until now).

From the web

Symptom

Root Cause

Remember these things…• Root cause analysis can be simple and fun• Five-Why’s is quick and efficient• Kill the system’s root – kill the problem tree