In modern aviation, gas turbine engines are the main energy source, and their gas-dynamic stability is one of the prerequisites for the robustness, operational lifetime and safety of the aircraft as a whole. Gas turbine engine fans, due to the absence of a bandage, long blades, and wide chord width, are most susceptible to vibrations caused by interaction with the air flow. This paper presents the results of numerical simulation of blade aeroelasticity of aircraft engine fan in off-design mode. The equations of motion of unsteady fluid flow were integrated using the ANSYS Fluent software package, simulation of motion of the blades, as well as two-way coupling between the equations, was implemented in additional software to speed up the simulation process. The blade motion was simulated using the natural mode decomposition method for the first five natural modes of vibration. The aerodynamic damping values were obtained for five modes and four interblade angles, as well as the distribution of damping along the blade length. As a result, negative damping of vibrations was revealed in the first natural mode and synchronous vibrations of the blades. Subsequent modeling of coupled blade vibrations revealed self-excitation of blade vibrations in zero phase shift mode and damping for other vibration modes.