What factors drive aircraft systems architecture selection?

Systems architecture encompasses power generation, distribution, and major system configurations. Selection factors: Reliability and safety - Redundancy level (dual, triple), failure modes, and certification requirements; Weight and efficiency - More electric architectures reduce bleed but add generators; Maintenance - Accessibility, line-replaceable units, and fault isolation; Technology readiness - Proven vs. novel systems, development risk; and Commonality - Fleet/family commonality, spares inventory. Major trade-offs: Hydraulic vs. electric actuation (787 uses more electric), Bleed vs. bleedless architecture (787 eliminated bleed air), Centralized vs. distributed systems. Architecture types: Conventional (hydraulic actuation, engine bleed for ECS/ice protection), More Electric Aircraft (electric ECS, electric actuation), and All Electric (still developing). Selection influences weight, fuel burn, maintenance cost, and development risk. System architecture decisions made early due to aircraft-level integration.