14 Fault trees
Fault trees are a top down, deductive failure analysis tool (FTA) where an top-level failure is decomposed to basic events using Boolean logic. FTA was first introduced by Bell Laboratories and is one of the most widely used methods in system reliability and safety analysis. It is a deductive procedure used to determine the various combinations of hardware and software failures and human errors that could cause undesired events. Basically formalized by WASH1400 as part of a risk assessment, FTA can also be used as a debugging process in software engineering too.
Public Domain
Applications and uses
- Understand logic leading to the top event.
- Show regulatory compliance.
- Prioritize contributions leading to the top event.
- Monitor and control safety performance of a complex system.
- Minimize or optimize resources.
- Assist system design.
- Diagnose causes of the top event
- Identify the causes of a failure.
- Identify weaknesses in a system.
- Assess a proposed design for its reliability or safety.
- Identify effects of human errors.
- Prioritize contributors to failure.
- Identify effective upgrades to a system.
- Quantify the failure probability and contributors.
- Optimize tests and maintenance.
Methodology
- Define undesired event.
- Resolved into immediate causes.
- Continue resolution until basic events are identified.
- Construct fault tree to demonstrate the logical relationships.