To enable the engine to be controlled during all operating conditions it is sometimes necessary to provide a system that can modify the airflow through the engine during transit operation such as acceleration and deceleration. These systems require actuators to change the position of the stator blades within the engine to prevent any possibility of engine stall.

The position of the actuator is determined by an electronic control, and the high pressure power source to move the actuator is provided by the fuel pump.

VSVA Variable Stator Vane Actuator

The FADEC also measures several parameters such as pressure, temperature and speed and from these measurements it calculates the required position for the Variable Stator Vane Actuator.