What mechanism positions the VSV by hydraulic fuel pressure?

The Main Fuel Control (MFC) plays a critical role in the regulation of fuel flow in a gas turbine engine, and it is directly responsible for managing the positioning of Variable Stator Vanes (VSV). The MFC adjusts the fuel pressure based on various parameters, such as engine speed and load conditions, to optimize performance and efficiency.

By utilizing hydraulic fuel pressure, the MFC facilitates the actuation of the VSV, which in turn alters the airflow through the engine to improve efficiency and reduce emissions across different operating conditions. This adjustment is necessary to maintain appropriate compressor performance and to prevent stalls.

In contrast, the Power Control Unit (PCU) generally focuses on controlling power output from the engine rather than positioning the VSV directly. The Variable Geometry Control (VGC) is a broader term that refers to systems designed for managing the variable geometry of different engine components, while the Electronic Control Unit (ECU) plays a supportive role in managing various electronic functions within the engine, but it does not directly control the hydraulic fuel pressure responsible for VSV positioning.