Abstract: To investigate the nonlinear response characteristics of rotor-stator impacts under time-varying inertial loads during maneuvering flight, this paper derives the system equations of motion using the Lagrangian method. A four-degree-of-freedom lumped-parameter mathematical model is established to accurately simulate the dynamic response induced by nonlinear rotor-stator rub-impacts. A dimensionless gravity parameter is introduced, and the system stability is quantitatively evaluated via Lyapunov exponents. The parametric study focuses on how the dimensionless gravity parameter critically alters the nonlinear behavior of the system. Research results indicate that at high rotational speeds, the rotor exhibits periodic, quasi-periodic, and chaotic motions. At low speeds with specific internal resonance frequencies, an increase in the dimensionless gravity parameter triggers a transition from a quasi-periodic motion to a chaotic one. As the gravity parameter increases further, the full contact between the rotor and the stator occurs, leading to a sharp rise in contact stiffness and to significantly amplifying both forward and backward whirl frequencies in the rotating coordinate system. This study provides a theoretical foundation for understanding and preventing complex nonlinear faults caused by rotor-stator impacts in aero-engines under variable inertial loads.