Schematex
rbd·IEC 61078 / ARP4761·engineering, technology·complexity 3/3·since v0.9.5

Fly-by-wire flight control (triple-redundant)

A reliability block diagram of a fly-by-wire flight-control system — 2-of-3 voting flight-control computers, triple-redundant hydraulics, and dual electrical buses, all in series. The engine computes the six-nines-class system reliability the architecture is designed to hit.

For the avionics reliability engineer sizing redundancy

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Fly-by-wire Flight Control Reliability block diagram: 8 blocks. System reliability R = 0.999998. Highest reliability-importance block: AC1. No single point of failure — every block has redundancy in the success path. Fly-by-wire Flight Control System reliability R = 0.999998 2/3 Flight computer 1 R=0.9995 Flight computer 2 R=0.9995 Flight computer 3 R=0.9995 Hydraulics green R=0.998 Hydraulics blue R=0.998 Hydraulics yellow R=0.998 AC bus 1 R=0.999 AC bus 2 R=0.999
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What this shows

A textbook fly-by-wire architecture, the kind certified under ARP4761: 2-out-of-3 voting flight-control computers (a single computer can fail or disagree without losing control), three independent hydraulic systems (the green/blue/yellow split of a modern airliner), and dual electrical buses — all in series because the aircraft needs computing, hydraulics, and power simultaneously.

The architecture's whole point is a number, and the engine computes it. Each subsystem is driven so close to 1 that the product still lands at a system reliability of ≈ 0.999998 — and Schematex prints the nines rather than rounding to "1", because in this domain the nines are the answer. No single point of failure remains, which is exactly the design intent the diagram now proves rather than merely asserts.

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