In pursuit of the ideal power-to-weight ratio， supercritical transmission shaft systems are increasingly used in the design of helicopter structures， which leads to the generation of violent vibrations driving through its critical speed. To suppress the exces? sive transcritical vibration， dry friction dampers are usually employed. In this study， a supercritical transmission shaft system with a dry friction damper is investigated. The governing equations are established and the boundary characteristics of various rub-impact responses of the system under eccentric excitation of the transmission shaft are analyzed. Firstly， the nonlinear governing equations of the damper/shaft system are constructed. Secondly， typical response characteristics are determined using frequency sweep， and the boundaries of impact occurrence and stability conditions for the synchronous full annular rub are solved using analytical meth? ods. Finally， the derived response boundaries are verified by the Runge-Kutta method， and the relationship between the response boundaries and the system parameters is further explored.