Learn how to strategically prevent system failure with this visual problem-solving technique
Published 28 Apr 2022
Fault tree analysis is a top-down approach to problem-solving wherein the starting point of analysis is the undesired event. Events leading to the undesired event are then evaluated based on their relationship with their immediate effect, which is either another event closer to the undesired event or the problem itself.
Fault tree analysis is primarily used in safety and reliability engineering. Though FTA is essential and known in the aerospace industry, any business that aims to assess the vulnerabilities of their system to failure-causing events can use fault tree analysis.
A fault tree diagram is a key feature of FTA and is best used to explain the relationship between events. Though the FTA diagram is not the intended end result or purpose of fault tree analysis, it helps safety and reliability engineers spot and address issues that could lead to multiple undesired events.
Easily conduct a fault tree analysis with the following steps:
Below is an example of a fault tree analysis in an electric power system:
Top event: short-circuit fault
[OR gate connecting top event to 1A and 1B]
The above fault tree analysis example in a visual format:
Note: The events at the bottom have been labeled as basic events to show a “complete” fault tree analysis. However, the events can still be broken down further and are not the “true” root causes of a short-circuit fault problem.
Disclaimer: Since the focus of this example is to show a fault tree analysis, other technical elements relating to a short-circuit fault may be incorrect.
The most critical part of fault tree analysis is the evaluation of the fault tree diagram. Using the diagram as a visual representation of failure paths, safety and reliability engineers can better identify which elements need to be removed or modified to prevent failure.
Beyond simple identification of failure hazards, the gate and event symbols also help safety and reliability engineers strategically plan for how best to attack failure. They are able to know when and where they should add failure control measures and prioritize and allocate resources accordingly.
Another benefit of fault tree analysis is the ability to get Common Cause Failures (CCFs) when comparing the events of multiple fault trees within a single system. CCFs can be described as the highest priority risks to a system’s safety and reliability.
Since these elements are the most likely to cause failure within a system, CCFs should be closely monitored to help prevent them from going further up failure paths and causing overall system failure.
How do you fix a system if you don’t know the exact problems that need fixing? While most teams already have an idea of the problems they need to solve, some teams may still have difficulty in identifying the problems that are harming their system.
For those who want to ensure that they start their fault trees with the right problems and not waste their time making fault tree diagrams for random issues, consider using iAuditor by SafetyCulture.
Using iAuditor, you can see which undesired events have the largest negative impact on your system and spot trends in system failures. You can do the following and more with iAuditor:
Book a demo to see how iAuditor works, get started for free, or take a look at some of our featured templates for root cause analysis below.
This general root cause analysis template can help you do the following:
You can use this 5 Whys template to support fault tree analysis by doing the following:
To try out the reverse of fault tree analysis, perform FMEA using this template:
Safety committees can use this JSA template to do the following:
System engineers can use this HAZOP template to identify the system’s functional flaws by doing the following:
Zarina is a content writer and researcher for SafetyCulture. She enjoys discovering new ways for businesses to improve their safety, quality, and operations. She is working towards helping companies become more efficient and better equipped to thrive through change.
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