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Definition
Fault Tree Analysis (FTA) starts with a particular undesirable event and provides an approach for analyzing the cause of the event. The undesired event constitutes the top event in a fault tree diagram and generally represents a complete or catastrophic failure of the product. The FTA focuses on a select subset of all possible system failures, specifically those that can cause a catastrophic “top event.”
General/Information/Narrative
Fault Tree Analysis (FTA) involves using deductive logic to determine the possible causes of a defined undesired operational result. Fault trees provide a convenient symbolic representation of the combination of events resulting in the occurrence of the top (main) event being analyzed. The results of an FTA are expressed either qualitatively or quantitatively. Qualitative results include minimum cut-sets (combination of element failures capable of causing system failure), qualitative importance (qualitative rankings of various contributions to system failures) and common cause potentials (minimum cut-sets vulnerable to a single failure cause). Quantitative results consist of numeric probabilities associated with system failure.
Fault Tree Analysis can be used for:
- Functional analysis of highly complex systems;
- Observation of combined effects of simultaneous, non-critical events on the top event;
- Evaluation of safety requirements and specifications;
- Evaluation of system reliability;
- Evaluation of human interfaces;
- Evaluation of software interfaces;
- Identification of potential design defects and safety hazards;
- Evaluation of potential corrective actions;
- Simplifying maintenance and troubleshooting; and
- Logical elimination of causes for an observed failure.
Fault Tree Analysis provides the following benefits:
- It provides a superior depiction of system functions that lead to mishaps or undesired events.
- It provides the ability to analyze complex systems.
- It can identify single point, multi-point or common mode failures.
- It can be used to guide design to reduce vulnerability.
- It can help identify system weaknesses and prioritize hazard mitigation measures.
- It can quantify system failure probability.
When properly applied, an FTA is extremely useful during the initial product design phases as an evaluation tool for driving preliminary design modifications. Through an FTA, a product can be evaluated from both a reliability and fault probability perspective.
In addition to driving preliminary design changes, FTA data provides the logistician with valuable information regarding potential maintenance, support equipment, and spare and repair parts necessary to support the design.
Policies, Directives, Regulations, Laws
Best Practices, Lessons Learned, Stories, Guides, Handbooks, Templates, Example Tools, Communities of Practice, LEC Tools
DoD Guide for Achieving Reliability, Availability, and Maintainability: http://www.acq.osd.mil/dte/docs/RAM_Guide_080305.pdf
U.S. Nuclear Regulatory Commission NUREG-0492, Fault Tree Handbook: http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0492/sr0492.pd...
Training Resources
LOG 200 – Intermediate Acquisition Logistics
SAM 101 – Basic Software Acquisition Management
IRM 101 – Basic Information Systems Acquisition
CLE 009 – System Safety in Systems Engineering
CLE 301 – Reliability and Maintainability
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Definition General Info Policies Guides Communities Training Related