In this paper we study the steady state availability of main k-out-of-n: F and secondary subsystems having general repair time distribution. When more than k units of main subsystem fail, then the main subsystem shuts off the secondary subsystem. The life time distributions of the main units and that of secondary subsystem are exponentially distributed. A repair facility having single repairman is facilitated to restore the failed unit. Failure of the main unit shuts off the operation of secondary subsystem, but not vice versa. Failure of the main unit or the secondary subsystem initiates the system shut down. The steady state availability is obtained by solving the linear ordinary differential equations governing the model by using supplementary variable technique.