<p>Understanding fatigue crack propagation behavior in AA7075-T6 aluminum alloy is essential for ensuring structural integrity in aerospace applications. This study presents a comprehensive experimental investigation of crack growth mechanisms using standardized ASTM E647 protocols under controlled conditions: 22 kN cyclic loading at 10 Hz and a stress ratio <i>R</i> = 0.1. Fatigue tests monitored crack evolution from 1 mm initial notches through critical failure dimensions, revealing distinct three-stage propagation behavior. Stage I (0–20 mm) exhibited slow, steady growth at 0.036 μm/cycle, followed by Stage II (20–35 mm), characterized by transitional zigzag crack trajectories at 45°, and Stage III (&gt;35 mm), showing rapid acceleration to final fracture. Microstructural analysis demonstrated consistent transgranular fracture mechanisms across all growth stages. Systematic testing validated the Paris law parameters (<i>C</i> = 1×10^–8, <i>m</i> = 4.05) with a threshold stress intensity factor Δ<i>K</i>_<i>th</i> = 3.2 MPa·m^1/2, providing excellent agreement with the existing literature (<i>R</i>² = 0.96). The quantified critical thresholds at 20 mm (transition onset) and 35 mm (acceleration initiation) serve as fundamental parameters for damage-tolerance assessments. These findings enable enhanced predictive modeling capabilities for fatigue life estimation and provide quantitative criteria for structural health monitoring protocols. The results directly support risk-based inspection strategies and emergency repair decision-making in aerospace applications, thereby improving operational safety and reliability for AA7075-T6 components subjected to complex service loading conditions.</p>