What are the design considerations for fly-by-wire flight control system architecture?

FBW replaces mechanical linkages with electronic signaling and actuation. Architecture considerations: Redundancy level - Fail-operational requires minimum dual command paths, quad redundancy typical, dissimilar backup; Hardware - Primary flight control computers, actuator control electronics, sensors (rate gyros, accelerometers, air data); Software - Flight control laws (normal, alternate, direct modes), envelope protection (AOA, speed, load factor); Sensors - Multiple sources with voting/averaging, sensor consolidation logic; and Actuators - Dual tandem, active-active or active-standby, jam-tolerant designs. Safety: FAR 25.1309 (<10^-9 catastrophic failure rate), Dissimilarity (different processors, software teams), Common mode failure analysis. Benefits: Weight reduction, improved handling qualities, envelope protection, reduced pilot workload. Development: Extensive simulation, hardware-in-loop testing, iron bird testing, and flight test. Certification requires proving continued safe flight after failures. Control law tuning requires pilot-in-loop evaluation for handling qualities.