US Patent 10961865 Gas turbine engine structure with integrated actuation features

A casing assembly for a gas turbine engine includes a case having an outer case wall extending around a central axis, an inner case wall radially offset from the outer case wall, and one or more hydraulic fluid passages embedded in the case between the outer case wall and the inner case wall. A variable pitch stator vane system includes a plurality of stator vanes are located radially inboard of the inner case wall. Each stator vane is rotatable about a central vane axis. An actuation unit is operably connected to the plurality of stator vanes and driven by hydraulic fluid through the one or more hydraulic fluid passages to urge rotation of the plurality of stator vanes about their respective central vane axes.