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Ataytis Assurance documentation.

Generate fault trees, bow-ties, event trees, reliability block diagrams, GSN arguments and Markov models from Power BI data with the Ataytis Assurance visual.

Ataytis Assurance · Fault Tree Analysis

Fault Tree Analysis

What the fault tree analysis (FTA) diagram type draws, what it does not calculate, the standards that describe it, and its defaults.

What it draws

Fault Tree Analysis draws how a top event can occur. The top event can be any outcome you want to explain, such as a service outage, a product defect or a safety incident. It is developed through logic gates into intermediate events, and down to basic, undeveloped and house events that are not developed further. The tree is drawn top to bottom by default.

A fault tree in Ataytis Assurance with OR, voting, spare and AND gates, probabilities under each node, and nodes coloured by status.
A fault tree with OR, voting, spare and AND gates, probabilities on a secondary line, and nodes coloured by status. The page title and industry tabs belong to the sample report.

What it calculates

Nothing. Probabilities, failure rates, repair rates and mission times are displayed and checked as your data supplies them. The visual does not calculate a top-event probability, minimal cut sets or importance measures, and never converts a failure rate into a probability. A probability on a top or intermediate event is shown exactly as the data states it.

Standards

The default profile is designed with reference to IEC 61025:2006, Fault tree analysis (FTA). Fault tree analysis also appears in IEC 31010:2019, IEC 60300-3-1:2003, IEC 62740:2015, IEC 61508-6:2010, IEC 61511-3:2016, SAE ARP4761A:2023, ISO 26262-10:2018, MIL-STD-882E, ISO/TR 24971:2020, EN 50126-2:2017 and ECSS-Q-ST-40-12C, which adopts IEC 61025 for space projects. Notation standards lists what each one covers.

Defaults

SettingDefault
Notation profileIEC 61025:2006. Traditional / NUREG-0492 and Custom are also available.
OrientationTop to bottom
Connected node is read asThe parent: the node directly above the row
Node type when no Node Type column is mappedIntermediate event
Relationship type when the cell is blankGate/event input
Probability displayTooltip only
Voting criterionDrawn on the gate as k/n

In this section

Preparing fault tree dataThe table format, column names, and a complete worked example.Fault tree events and gatesEvery node type and relationship type, and how to write them.Gate inputs and valuesInput counts, voting, priority, spare, house and zero events.Transfers and large treesContinuing a tree in another diagram.Probabilities, labels and symbolsWhat is drawn on each node, and the symbols under each profile.Fault tree validationRules by profile, messages and fixes, and advisories.
Fault Tree Analysis — Ataytis Assurance | AtaytisTech