Abstract: Helicopter torque arm assemblies are subjected to complex alternating loads, making them prone to fatigue crack initiation at fastener hole connections. To address this issue, the effect of the interference level during the cold expansion process on the fatigue life of load-bearing holes in 7050-T7451 aluminum alloy is investigated in this study. Finite element simulations of the cold expansion process for aluminum alloy lug components were conducted. Furthermore, the cold expansion strengthening process was systematically evaluated through both specimen-level and component-level expansion and fatigue life experiments. The results indicate that the fatigue life of load-bearing holes can be significantly enhanced by cold expansion. Under the optimized cold expansion process, the fatigue life of the lug specimens is increased to 1.9 times that of the unexpanded specimens. The effectiveness of the cold expansion is further validated through fatigue testing of anti-torsion bracket assemblies, in which the fatigue life of the load-bearing holes is substantially improved by the expansion process. This work provides guidance and technical support for the fatigue-resistant manufacturing of load-bearing holes in helicopters.