Preface
“Customer Delight” is the Guiding mantra for Maruti Suzuki.
MSIL Strives to provide the best quality products backed up with “Zero tolerance to Defects”
strategy to ensure the lifetime satisfying ownership experience to the customers.
Product Quality plays an important role in achieving this objective. A good Product Quality is
the result of the constant endeavors of MSIL Expert team of Engineers, who always strive
towards upgrading MSIL products as per the customer’s expectations.
A Quality Engineer is said to be the Customer’s Representatives working in plant to ensure,
expectations are met. It is very important that the customer’s requirement in terms of
vehicle performance, features and vehicle behavior under different local conditions are
accurately captured on time.
In order to sustain & upgrade the product quality with volume, it is very critical to sincerely
analyze the quality feedbacks reported in our products at various stages, and close them
with a standardized approach and preventive methodology for the similar scope.
Purpose of this manual is to develop a structured methodology for analyzing all the quality
issues and taking improvement actions, in such a way that it never gets repeated again and
thus to achieve customers delight.
This manual explains in detail the Use of Fault Tree Analysis (FTA), as a Quality Assurance
tool to systematically analyze a quality issue by identifying and validating all the possible
causes leading to the failure and thus improve the quality of Maruti Suzuki Products. The
role of Suppliers in this system is of the utmost importance.
This manual will serve as a guide to use Fault Tree Analysis (FTA) tool effectively.
This collaborative approach between MSIL & its Suppliers will result in continuous
improvement based on Customer feedbacks.
Quality Assurance Division,
Maruti Suzuki India Limited
Copyright @ Maruti Suzuki India Limited. All rights reserved
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Chapter 1
1. Back Ground & Introduction.
1.1
In Current Scenario, MSIL Market Quality is applying various tools to
identify the root cause of the defect received from market. WHY-WHY analysis,
Ishikawa Fish bone diagram, Statistical tools are some example which are being
widely used & with that we are identifying the root cause successfully for most
of the cases. But for some cases we are not able to identify the root cause. So,
FTA (Fault Tree Analysis) is being introduced for identifying the root cause for
cases in which root cause could not be established.
1.2
This draft manual provides an overview & guideline of the basic
concepts in fault tree analysis (FTA) as it applies to root cause analysis where
current tools are not sufficient to identify the root cause.
1.3
Fault Tree Analysis (FTA) is a technique for reliability and safety
analysis. Bell Telephone Laboratories developed the concept in 1962 for the
US Air Force for use with the Minuteman system. It was later adopted and
extensively applied by the Boeing Company. Fault tree analysis is one of many
symbolic "analytical logic techniques" found in operations research and in
system reliability. Other techniques include reliability block diagrams (RBDs).
In MSIL Market Quality we will not use the conventional method of FTA
block diagram, modification is being done to simplify for understanding /using.
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2. When to Make an FTA.
2.1
If Root Cause is not clear by the conventional method (WHY-WHY
Analysis, Ishikawa Fishbone Diagram, 4M, Statistical Tool)
2.2
To identify correct root cause in case of multiple causes of failure
3. How to Make a Fault Tree Analysis Stepwise
Fault Tree Creation
Fault Tree Analysis (FTA) provides a means to logically and graphically
display the paths to failure for a defect/component failure.
One way to manage a complex system (Multiple reason of defect) is to start
with a Block Diagram. Then create a fault tree for each block in the Block
Diagram.
Whether a single block or a top level fault for a defect the basic process to
create a fault tree follows a basic pattern.
3.1 Define the system.
This includes the scope of the analysis including defining what is considered a
failure. This becomes important when a defect/ component may have an
element fail or a single function fails and the remainder of the system still
operates.
3.2 Define top-level faults.
Whether for a defect or single block define the starting point for the analysis
by detailing the failure of interest for the analysis.
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3.3 Identify causes for top-level fault.
What events could cause the top level fault to occur? Use the logic to organize
which causes can cause the failure alone, or require multiple events to occur
before the failure occurs.
3.4 Identify next level of events.
Each event leading to the top level failure may also have precipitating events.
3.5 Identify root causes.
For each event above continue to identify precipitating events or causes to
identify the root or basic cause of the sequence of events leading to failure.
3.6 Add probabilities to events.
When possible add the actual or relative probability of occurrence of each
event.
3.7 Analysis the fault tree.
Look for the most likely events that lead to failure, for single events the
initiate multiple paths to failure, or patterns related to stresses, use, or
operating conditions. Identify means to resolve or mitigate paths to failure.
3.8 Document the FTA.
Beyond the fault tree, graphics include salient notes from the discussion and
action items.
FTA is a convent means to logically think through the many ways a failure
may occur. It provides insights that may lead to product improvements or
process controls.
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4. Basic Block diagram Of FTA
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5. Simple Example of FTA : Battery Power Circuit defective
Defect: Motor does not start when Switch is ON
Specifications for the Battery Power Circuit Fault Tree
Top event of FTA: Motor does not start when switch is ON.
Boundary of the FTA: The circuit containing the motor, battery, and switch.
Resolution of the FTA: The basic components in the circuit excluding the wiring.
Initial State of System: Switch open, normal operating conditions
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