A fuel control system for a gas turbine engine includes a fuel metering valve, a pressure raising and shut-off valve (PRSOV), and a shutoff effector including a first stage unit that is electrically powered and a second stage unit that is controlled by the first stage unit. The second stage unit actuates a valve member of the PRSOV between an open position that allows supply of a fuel to burners of the gas turbine engine and a closed position that prevents supply of the fuel to the burners. Upon loss of electrical power to the first stage unit during operation of the gas turbine engine, the first stage unit is configured to: control the second stage unit to actuate the valve member of the PRSOV to the closed position after a predetermined time duration; or retain the valve member of the PRSOV in the open position.

A fuel system for an aircraft includes a main pump, a servo pump, a servo minimum pressure valve, and a servo pump bypass connection element. The main pump receives fuel from a source. The servo pump also receives fuel from the source. The servo minimum pressure valve receives fuel from the main pump supplied through a first line and the valve receives fuel from the servo pump supplied through a second line. The servo pump bypass connection element connects the first line and the second line.

The present disclosure provides a device for controlling a variable section ejection nozzle of a turbojet engine nacelle of an aircraft. The device includes a calculator adapted to determine a position setpoint of the nozzle and a management system of the servo-control of the position of the variable nozzle depending on the flow rate of the fuel supplying the turbojet engine. The management system includes at least one instantaneous flow rate sensor of the fuel and a management unit which is designed to compare the flow rate measured by the flow rate sensor with a theoretical fuel flow rate depending on the parameters of the flight of the aircraft, to determine a correction value of the position of the nozzle depending on the comparison of the measured flow rate and the theoretical fuel flow rate, and to correct the position setpoint of the nozzle according to the correction value.

A method of modulating cooling flow to an engine component based on a health of the component is provided. The method includes determining a cooling flow requirement of the engine component for each of a plurality of operating conditions and channeling the determined required flow to the engine component during each respective operating condition of the plurality of operating conditions. The method also includes assessing a health of the engine component. The method further includes modifying the determined cooling flow requirement based on the assessed health of the engine component, and supplying the modified cooling flow requirement to the engine component during each subsequent respective operating condition of the plurality of operating conditions.

An engine bleed control system for a gas turbine engine of an aircraft is provided. The engine bleed control system includes an engine bleed tap coupled to a fan-air source or a compressor source of a lower pressure compressor section before a highest pressure compressor section of the gas turbine engine and a motorized compressor in fluid communication with the engine bleed tap. The engine bleed control system also includes a controller operable to selectively drive the motorized compressor to boost a bleed air pressure as pressure augmented bleed air and control delivery of the pressure augmented bleed air to an aircraft use.

An aircraft including lean-burn gas turbine engines operating in pilot-plus-mains mode with a given initial fuel flow W.sub.0, a method of controlling the optical depth of contrails produced by a first group of engines includes the steps of (i) reducing fuel flow to each engine in the first group to change the operation of each engine from pilot-plus-mains mode to pilot-only mode, and (ii) adjusting fuel flow to one or more engines in a second group of engines such that the total fuel flow to engines of the second group is increased, all engines of the second group remaining in pilot-plus-mains mode, and wherein the set of lean-burn engines consists of the first and second groups. Depending on atmospheric conditions, the average optical depth of contrails produced by the engines may be enhanced or reduced compared to when all engines operate in pilot-plus-mains mode with a fuel flow W.sub.0.

A gas turbine engine includes a main compressor section and a main turbine section. A cooling air supply system cools a location in at least one of the main compressor section and the main turbine section. The cooling air supply system includes a tap for tapping cooling air compressed by the main compressor section, connected for passing the cooling air through a heat exchanger and to a boost compressor, and then to the cooling location in the at least one of the main compressor section and the main turbine section. A fuel supply system has a fuel tank for delivering fuel to a fuel pump. At least one valve for selectively returning fuel downstream of the main pump back to an upstream location. At least one return turbine drives at least one fluid moving device in the air cooling system.

A two-gas shaft turbine control system (31) is disclosed. The gas turbine control system comprises a fuel controller (35), which receives a speed error signal, indicating whether the low-pressure turbine wheel (11) of the gas turbine (1) is rotating at the desired target speed. The gas turbine control system (31) further comprises an NGV controller (41), which receives a speed error signal, indicating whether the high-pressure turbine wheel (9) of the gas turbine engine (1) is rotating at the desired target speed. Two cross channel controllers are further provided. On the basis of a gas turbine model, a first cross channel controller (43) provides a fuel control modification signal, which is added to a control signal generated by the fuel controller (35). A second cross channel controller (45) provides an NGV control modification signal. The modification signals are aimed at reducing or canceling the effect of mutual interaction between fuel control and NGV control. A two-shaft gas turbine engine system and a method of operation are further disclosed.

A lean burn combustor includes a plurality of lean burn fuel injectors, each including a fuel feed arm and a lean burn fuel injector head with a lean burn fuel injector head tip, wherein the lean burn fuel injector head tip has a lean burn fuel injector head tip diameter, the lean burn fuel injector head including a pilot fuel injector and a main fuel injector, the main fuel injector being arranged coaxially and radially outwards of the pilot fuel injector; and a combustor chamber extending along an axial direction for a length and including a radially inner annular wall, a radially outer annular wall, and a meter panel defining the size and shape of the combustor chamber, wherein the combustor chamber includes primary and secondary combustion zones. A ratio of the combustor chamber length to the lean burn fuel injector head tip diameter is less than 5.

To prevent or reduce an oversensitive change in the degree of opening of a bleed valve regulating the flow volume of a cooling air used to heat a fuel. A gas turbine includes: a compressor compressing an air; a combustor burning a fuel mixed with the air compressed by the compressor; a turbine configured to be driven by a combustion gas generated by the combustor; a heat exchanger causing the fuel to be supplied to the combustor to be heated through a cooling air bled from the compressor to be supplied to the turbine; a bleed valve regulating the flow volume of the cooling air; a first sensor measuring a fuel state value; a second sensor measuring a cooling air state value; and a control computer controlling the degree of opening of the bleed valve. The control computer stores therein data on reference values and dead bands including the corresponding reference value set for each of the fuel state value and the cooling air state value, and, when a measured value of at least one of the fuel state value and the cooling air state value has changed so much away from the corresponding reference value as to fall outside the corresponding dead band, controls the bleed valve such that the changed measured value is brought close to the corresponding reference value.