A AshToolbox / Maintenance & Reliability Suite
Advanced Category: Reliability Analysis • ~7 min read

Fault Tree Analysis (FTA)

Identify critical minimal cut sets and compute system top-event failure probability.

Q:

What is a Minimal Cut Set in Fault Tree Analysis (FTA)?

A Minimal Cut Set (MCS) is the smallest combination of basic component failures that, if they occur simultaneously, guarantees the occurrence of the Top Event (system failure). Single-element cut sets represent catastrophic single points of failure.

100% In-Browser Computation — Zero Server Storage.

Top Gate Logic

Primary Power Grid Blackout0.05
Emergency Diesel Generator Fails to Start0.02
UPS Battery Bank Depleted0.01
Top Event Failure Probability (Q_top)
1.0000e-3
0.1000% probability of catastrophic event

Minimal Cut Sets (MOCUS)

Cut Set 1:Primary Power Grid Blackout AND Emergency Diesel Generator Fails to Start

Fussell-Vesely Risk Reduction Worth

Primary Power Grid BlackoutI_FV = 1.0000
Emergency Diesel Generator Fails to StartI_FV = 1.0000
UPS Battery Bank DepletedI_FV = 0.0000
Advertisement

Deductive Failure Modeling (IEC 61025)

Fault Tree Analysis is a top-down deductive methodology used in aerospace, nuclear power, and hazardous chemical processing. Starting from an undesired top-level mishap, Boolean logic gates (AND / OR) trace down through subsystems to root initiating events.

Fussell-Vesely Importance Metric

Fussell-Vesely Importance: IFV(i) = [ Qtop - Qtop(q_i = 0) ] / Qtop
Engineering & Regulatory Notice: The calculations, projections, and failure models provided in this suite are for engineering estimation and educational purposes. Verify all calculations and assumptions independently before making operational, equipment replacement, safety-critical, or regulatory compliance decisions.

Recommended Next Steps in Reliability Workflow

Reliability Analysis

Reliability Block Diagram (RBD)

Calculate total system reliability and identify single points of failure.

 Root Cause & Risk

FMEA / FMECA Risk Worksheet

Rank system failure modes by risk priority and assign mitigation actions with XLSX/PDF exports.

 Root Cause & Risk

5-Why Root Cause Tree

Drill past superficial symptoms to uncover systemic and management process root causes.