13 templates
Fault tree (FTA) templates
Quantitative fault-tree analysis in the IEC 61025 notation. Build the tree from AND / OR / k-out-of-n / INHIBIT gates over basic events carrying probabilities, and the engine computes the top-event probability exactly rather than by the rare-event approximation, ranks each basic event's Birnbaum and Fussell-Vesely importance, and enumerates the minimal cut sets. The safety analysis a boxes-and-lines drawing cannot perform.
Fault Tree — Reactor Decay Heat Removal
Loss of decay heat removal after a reactor trip: two redundant paths, a two-of-three auxiliary feedwater vote and an INHIBIT gate for the fouled service-water strainer, quantified over a one-year mission.
Risk & ReliabilityFault Tree — Triple Hydraulic Loss
Total hydraulic power loss on a three-system narrowbody over a five-hour leg, where a single common-cause fluid contamination event sits in all three branches and dominates a picture that looks fully redundant.
Risk & ReliabilityFault Tree — Data Centre Power to IT Load
Tier III power path from utility through a two-of-three generator vote and an N+1 UPS pair, exposing the transfer switch and the final rack circuit as order-one cut sets no amount of upstream redundancy touches.
Operations & OpsFault Tree — Piped Medical Oxygen
Loss of ward oxygen at an acute hospital: bulk evaporator and emergency manifold in parallel, with the manifold gated by an INHIBIT on unreplaced reserve cylinders, plus three pipeline faults that bypass the redundancy entirely.
Risk & ReliabilityFault Tree — Total Loss of Vehicle Braking
Dual diagonal hydraulic circuits backed by an electric park brake over 300 driving hours, showing how the shared master cylinder and reservoir turn two independent-looking circuits into one, and the 12 V supply into a common mode.
Risk & ReliabilityFault Tree — Blowout Preventer on Demand
Subsea BOP failing to seal a well over one section, with the blue and yellow control pods feeding BOTH the shear rams and the annular preventer — a shared gate drawn once and transferred, and the reason the two seals are not independent.
Risk & ReliabilityFault Tree — Wrong-Side Signalling Failure
A conflicting movement authority issued at a junction: interlocking logic, a two-of-three train-detection vote and the downstream protection layer, quantifying how much of the residual risk sits with the signaller rather than the equipment.
Operations & OpsFault Tree — AV Pedestrian Detection
An automated vehicle failing to detect a crossing pedestrian across 1000 urban hours: camera, lidar and radar pipelines must all miss AND the fusion layer must fail to recover, ranking sensor modality against software by Fussell–Vesely.
Research & AcademicFault Tree — Regional Cloud API Outage
A month of a three-zone regional service, where one shared datastore sits inside all three availability-zone branches: the exact evaluation shows the two-of-three vote buys far less than the architecture diagram promises.
Operations & OpsFault Tree — Batch Reactor Overpressure
A runaway exotherm meeting a failed relief path in a batch reactor: cooling loss, charging error or agitator stop on one side, relief valve and bursting disc in series-to-fail on the other, over a one-year campaign.
Scientific PlotsFault Tree — Metro Signalling Loss
Loss of movement authority on a CBTC metro line over a year, where a shared trackside radio segment sits inside both the primary and the fallback branch and is the tree's only single-point failure.
Risk & ReliabilityFault Tree — Vaccine Cold Chain Excursion
Temperature excursion of a pharmacy vaccine fridge over a year, gating the alarm-response branch by an INHIBIT on out-of-hours cover and exposing the door-ajar cut set that no compressor redundancy touches.
Risk & ReliabilityFault Tree — Offshore Turbine Unavailability
Loss of export from a single offshore wind turbine over a year, combining drivetrain and converter faults with an array cable branch and a two-of-three pitch system vote that keeps the rotor controllable.
Risk & Reliability