1. “Faultless to a fault.” - Robert Browning Albert Hsu
Fault Tree Analysis
“Faultless to a fault.” - Robert Browning
Albert Hsu

2. Introduction
Fault identification, correction and tolerance to improve design
Fault Tree Analysis
“A method to decompose it and look for situation that might lead to failure” (Software Engineering)
Displayed the logical path from effect to cause
Fault Tree Analysis, Fall 2006

3. The Fault Tree
Begin Fault Analysis by identifying possible failures in design operation or maintenance
Next build a graph whose nodes are failures
Single contents
System function
Entire system
Edge = relationship among nodes by logical descriptor (AND,OR)
Fault Tree Analysis, Fall 2006

4. The Fault Tree Figure 5.19 Portion of power plant control system
Fault Tree Analysis, Fall 2006

5. Cut-set Tree From Fault tree to cut-set tree
To find single points of failure in complex tree
Figure 5.20 Cut-set tree generated form the fault tree
Fault Tree Analysis, Fall 2006

6. Fixing the Failure Remove it
Add components or conditions to prevent the input condition that cause the fault to be executed
Add components that will recover from the damage the failure will cause
Fault Tree Analysis, Fall 2006

7. Some faults… Time-consuming in constructing the graphs
Many systems involve many dependencies
Difficult to detect inconsistencies
Difficult to focus only on the most critical parts of the design on high coupling systems
Not always easy to spot
Fault Tree Analysis, Fall 2006

8. Reference
Atlee, Joanne, Software Engineering Theory and Practice, Pearson Prentice Hall, New Jersey, ©2006, pg
Fault Tree Analysis, Fall 2006