The dynamic performance of a turboshaft gas turbine engine is investigated in this paper. The air flows inlet to the engine and to the power turbine, are controlled by means of two guide vanes cascade. The displacement of the inlet guide vanes is controlled by means of two electrohydraulic servo actuators. The fuel flow rate is controlled by another electrohydraulic controller incorporating a series pressure compensated flow control valve. The equation describing the basic system subsystems and controllers were deduced and applied to develop a simulation program. The simulation program of the electrohydraulic servo controllers was validated experimentally. The engine dynamic performance is studied theoretically using the developed computer simulation program. Simulated results are shown for the transient response of the engine air and fuel flow control systems and its effect on the engine performance. The simulation results of engine air flow control show an agreement with the validated experimental results.