Abstract: A bypass valve (22) and vent valve (24) are connected in parallel with the normal flow path between a low-pressure fuel pump (12) and a high-pressure fuel pump (16). When a low fuel inlet pressure is detected the bypass valve (22) and vent valve (24) are opened. Gas is vented out of the fuel system and bypasses a heat exchanger (14) between the low and high-pressure pumps (12 and 16), thus avoiding the need to overcome vapor lock between the two pumps. The vent valve (24) passes gas to a drain tank (26) and then closes to prevent the escape of fuel as the high-pressure pump (16) primes.

Abstract: A high pressure fuel system includes tapped high pressure flows (22,24) with restrictors (44,46) to provide low pressure flows with which, via a valve (50) to enable either a low pressure flow to bias a main, high pressure fuel cut off valve (16) to close at a steady given rate, or a high pressure flow across a further valve (30), to close the valve (16) at a faster rate.

Abstract: The amount of fuel supplied by a low pressure pump and a high pressure pump to combustion means is controlled by a control unit. If most of the fuel delivered by the pumps is required by the engine a clutch engages to provide a direct mechanical drive between the pumps so that they are driven at the same speed. However if the combustion equipment requires a reduced flow of fuel the clutch disengages and the excess fuel is diverted by a valve to a turbine. The turbine drives the low pressure pump at a higher speed than the speed of the high pressure pump. The energy of the diverted fuel is converted to mechanical energy to drive the turbine so that the temperature rise of the diverted fuel is reduced.

Abstract: A gas turbine engine heat exchange apparatus comprises a first heat exchanger (12), which is arranged to receive oil from a lubricating oil system of the engine and put the oil in heat exchange with either a cooling or heating medium (17, 21), and a second heat exchanger (26), which receives the oil from the first heat exchanger, puts the oil in heat exchange with fuel in the engine's fuel supply system and discharges the oil back to the lubricating oil system. A valve or valves (20, 24) are used to control flow from high and low temperature sources of the heat exchange medium through the first heat exchanger (12) such that the direction of heat flow between the oil and the cooling or heating medium can be changed as necessary to prevent the fuel temperature from straying beyond predetermined limits.

Abstract: A valve assembly for controlling the fluid flow to the fuel spray nozzles in the combustion chamber of a gas turbine aeroengine. The valve assembly comprises a main flow valve whereby translation of the main valve beyond a predetermined limit initiates movement of a control valve by a mechanical interconnection means. Movement of the control valve serves to activate means for fluid communication between the main valve and the control valve, venting some of the pressurized fluid flow acting on main valve to the control valve and subsequently to the fluid outlet. The more sensitive operation and hence quicker response time for any given change in fluid pressure at the inlet to the valve assembly results in rapid closure of the valve assembly when the fluid flow is decreasing which discourages dribble occurring.

Abstract: The present invention is particularly concerned with the supply of fuel to fuel servos of gas turbine engines. A check valve (62) is positioned in a return pipe (40, 24, 22, 26) from a fuel spill valve (12) to the upstream low pressure side of a high pressure pump (10). An aperture (32) in a piston (30) of the check valve (62) produces a predetermined pressure drop across the check valve (62) when the flow of excess fuel reaches a predetermined value. A fuel servo shut off valve (64) is positioned in a pipe (42, 58) connecting a fuel flow regulator (14) to a fuel servo (80). A piston (46) of the fuel servo shut off valve (64) initially closes a chamber (56) to prevent fuel being supplied to the fuel servo (80), from the fuel flow regulator (14). The piston (46) of the fuel servo shut off valve (64) is moved against a spring (48) when the predetermined pressure drop is formed across the check valve (62) to allow fuel to be supplied from the fuel flow regulator (14) to the fuel servo (80) via chamber (56).