Fueldraulic heat management system

A method of operating a gas turbine engine for an aircraft, the engine comprising:

• an engine core comprising a turbine, a combustor, a compressor, and a core shaft connecting the turbine to the compressor;
• a fan located upstream of the engine core and arranged to be driven by the core shaft, the fan comprising a plurality of fan blades;
• a nacelle surrounding the fan and the engine core and defining a bypass duct located radially outside of the engine core, where the bypass ratio, defined as the ratio of the mass flow rate of the flow through the bypass duct to the mass flow rate of the flow through the core at cruise conditions, is at least 4;
• an engine heat management system;
• a plurality of actuators, comprising an actuator configured to actuate a valve within the engine heat management system, wherein the actuator configured to actuate the valve within the engine heat management system is configured to actuate the valve so as to enable non-binary position adjustment between an open valve position and a closed valve position;
• and
• a fuel supply system;
• wherein
• the method comprises:
• supplying, using the fuel supply system, fuel for combustion in the combustor;
• supplying, using the fuel supply system, fuel to fueldraulically drive at least the engine heat management system valve actuator of the plurality of actuators, wherein the fuel comprises sustainable aviation fuel with up to 100% of the fuel being the sustainable aviation fuel;
• and
• controlling the non-binary position adjustment based upon calorific value of the fuel.

A gas turbine engine for an aircraft comprising:

• an engine core comprising a turbine, a combustor, a compressor, and a core shaft connecting the turbine to the compressor;
• a fan located upstream of the engine core and arranged to be driven by the core shaft, the fan comprising a plurality of fan blades;
• a nacelle surrounding the fan and the engine core and defining a bypass duct located radially outside of the engine core, where the bypass ratio, defined as the ratio of the mass flow rate of the flow through the bypass duct to the mass flow rate of the flow through the core at cruise conditions, is at least 4;
• an engine heat management system;
• a plurality of actuators, comprising an actuator configured to actuate at least one valve within the engine heat management system;
• and
• a fuel supply system, wherein
• the fuel supply system is arranged to supply fuel for combustion in the combustor, and to supply fuel to fueldraulically drive the actuator configured to actuate the at least one valve within the engine heat management system,
• the actuator configured to actuate the at least one valve within the engine heat management system is configured to actuate the valve so as to enable non-binary position adjustment between an open valve position and a closed valve position based upon calorific value of the fuel,
• the fuel comprises sustainable aviation fuel with up to 100% of the fuel being the sustainable aviation fuel, and
• the valve controls the fuel.