How do you plan and execute a full-scale fatigue test for aircraft certification?

Full-scale fatigue test planning involves: Test article specification (representative of production, any preconditions); Load spectrum development (design life simulation, typically 2-3 lifetimes to demonstrate scatter factor); Load introduction fixtures replicating flight load paths; Control system for multi-actuator coordination (120+ channels for large aircraft); Instrumentation plan (strain gauges, crack gauges at predicted critical locations); Inspection intervals mirroring or accelerating operational program; Teardown inspection after test completion; and Correlation with analysis predictions. Test demonstrates compliance with FAR 25.571 for fatigue evaluation, supports inspection program development, and validates damage tolerance analysis. Test modifications may simulate repairs or modifications. Cost typically $50-200M for major programs.