A numerical analysis of asymmetric vibrations of an aircraft has been conducted. The present paper contains a discussion of theoretical and numerical analysis of asymmetric natural vibrations of structures with concentrated masses (such as bombs, rockets, fuel tanks, containers with photographic equipment etc. ) suspended below the wing and the fuselage. The equations of motion of the rigid parts of the fuselage are derived, as well as the kinematic and boundary conditions in the assembling sections of attachment.