Abstract: Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to the combustor by supplying fuel to the first fuel manifold via a first flow divider valve and supplying fuel to the second fuel manifold via a second flow divider valve. While supplying fuel to the combustor by supplying fuel to the first fuel manifold, the method includes stopping supplying fuel to the second fuel manifold and supplying pressurized gas to the second fuel manifold via the second flow divider valve to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated nozzles.

Abstract: Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to a combustor by supplying fuel to a first fuel manifold and a second fuel manifold of the gas turbine engine. The method also includes, while supplying fuel to the combustor by supplying fuel to the first fuel manifold: stopping supplying fuel to the second fuel manifold; and supplying pressurized air to the second fuel manifold to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated fuel nozzles.

Abstract: An aircraft motive flow line includes an outer tube made out of a first material and an inner tube extending longitudinally inside the outer tube. The inner tube is made out of a second material having a thermal conductivity coefficient lower than that of the first material. The first material has a strength coefficient greater than that of the second material. The inner tube is sized and held in position relative to the outer tube so as to define a gap between an exterior of the inner tube and an interior of the outer tube. A port fluidly connects an interior of the inner tube to the gap.

Abstract: A method of controlling a delivery pressure of an aircraft engine fuel system includes operating a rotodynamic fuel pump hydraulically connected to the fuel system to pump a fluid from an inlet of the rotodynamic pump and out of an outlet of the rotodynamic pump for delivery to the fuel system. The method further includes varying an angular relationship between the inlet and the outlet of the pump to control the delivery pressure. An aircraft engine fuel system and a rotodynamic pump are also described.

Abstract: A control circuit for changing the angle of propeller blades includes a propeller pitch change mechanism, and a fixed-displacement pump providing the supply of oil from an engine oil return system. A valve has an outlet port to direct oil from a cavity of the valve, and a pitch port in fluid communication with the pitch change mechanism. A spool of the valve is operable between a first position and a second position to respectively open and close the outlet port, and direct oil flow away from or to the pitch change mechanism.

Abstract: A rotodynamic pump for pumping a fluid includes an impeller, a housing surrounding the impeller, and a pressure regulating mechanism. The pressure regulating mechanism is configured to adjust the clearance between the impeller and the impeller housing to regulate pressure of the fluid downstream of the impeller. A method of regulating the delivery pressure is also disclosed.

Abstract: A liquid fuel system for an aircraft engine includes a first fuel supply conduit hydraulically connected to a fuel source, a second fuel supply conduit hydraulically connected to the engine, a fuel return conduit hydraulically connected to the second fuel supply conduit, and a fuel pump. The fuel pump has a main inlet hydraulically connected to the first fuel supply conduit, an outlet hydraulically connected to the second fuel supply conduit, and an intermediate inlet hydraulically connected to the fuel return conduit. The intermediate inlet is located between the main inlet and the outlet and in use has a pressure between the main inlet pressure and the outlet pressure. A method of supplying a liquid fuel to an aircraft engine is also described.

Abstract: A method of pumping fuel in a fuel system of a composite aircraft having a gas turbine engine includes feeding un-heated fuel from a fuel tank to the gas turbine engine, by using an ejector pump to draw the fuel from the fuel tank and feeding the fuel through an engine fuel pump within a main fuel line upstream of the gas turbine engine. Fuel from the main fuel line is bled and directed to the ejector pump via a motive flow pump assembly, the motive flow pump assembly including a motive flow pump generating a motive flow for the ejector pump. The bleed fuel flow is then passed through a hydrophobic fuel screen located upstream of the motive flow pump.

Abstract: A method of distributing oil to a component within a gas turbine engine includes directing a first oil flow from an oil source to an engine component and back to the oil source, directing a second oil flow from the oil source to a generator driven by the engine and back to the oil source, monitoring a parameter of the second oil flow downstream of the generator and upstream of the oil source, detecting a contaminant in the second oil flow based on the parameter, and reducing the second oil flow to the generator when the contaminant is detected without reducing the first oil flow to the engine component. A shared oil system for a component of a gas turbine engine and a generator driven by the gas turbine engine is also discussed.

Abstract: A method of distributing oil to a component within a gas turbine engine includes directing a first oil flow from an oil source to an engine component and back to the oil source, directing a second oil flow from the oil source to a generator driven by the engine and back to the oil source, monitoring a parameter of the second oil flow downstream of the generator and upstream of the oil source, detecting a contaminant in the second oil flow based on the parameter, and reducing the second oil flow to the generator when the contaminant is detected without reducing the first oil flow to the engine component. A shared oil system for a component of a gas turbine engine and a generator driven by the gas turbine engine is also discussed.

Abstract: A control circuit for changing the angle of propeller blades includes a propeller control unit controlling a supply of oil to modify an angle of propeller blades, and a fixed-displacement pump providing the supply of oil from an engine oil return system to the propeller control unit. An oil cooling line extends between an outlet of the pump and the engine oil return system. The oil cooling line defines an oil leakage path leading to the engine oil return system for cooling the oil. A flow regulator between the pump and the propeller control unit is operable between an open position where oil is directed through the oil cooling line to the engine oil return system for cooling the oil, and a closed position blocking the oil cooling line and directing oil toward the propeller control unit to modify the angle of the propeller blades.

Abstract: A fuel system for a composite aircraft is described which includes an ejector pump having a vacuum inlet in communication with a fuel storage tank, an engine feed pump having an inlet in fluid communication with an outlet of the ejector pump, a primary outlet in communication with an engine, and a motive flow outlet, upstream of an oil-fuel heat exchanger, that is in fluid communication with an inlet of the ejector pump. A motive flow pump assembly is disposed between the motive flow outlet of the engine feed pump and the inlet of the ejector pump. The motive flow pump assembly includes an inlet screen and a motive flow pump, the inlet screen having a plurality of openings therein and a hydrophobic upstream surface. The openings are dimensioned to prevent passage of particles greater than a selected threshold size while allowing liquids to flow therethrough.

Abstract: A control circuit for changing the angle of propeller blades includes a propeller pitch change mechanism, and a fixed-displacement pump providing the supply of oil from an engine oil return system. A valve has an outlet port to direct oil from a cavity of the valve, and a pitch port in fluid communication with the pitch change mechanism. A spool of the valve is operable between a first position and a second position to respectively open and close the outlet port, and direct oil flow away from or to the pitch change mechanism.

Abstract: A method of distributing oil to a component within a gas turbine engine includes directing a first oil flow from an oil source to an engine component and back to the oil source, directing a second oil flow from the oil source to a generator driven by the engine and back to the oil source, monitoring a parameter of the second oil flow downstream of the generator and upstream of the oil source, detecting a contaminant in the second oil flow based on the parameter, and reducing the second oil flow to the generator when the contaminant is detected without reducing the first oil flow to the engine component. A shared oil system for a component of a gas turbine engine and a generator driven by the gas turbine engine is also discussed.

Abstract: A control circuit for changing the angle of propeller blades includes a propeller control unit controlling a supply of oil to modify an angle of propeller blades, and a fixed-displacement pump providing the supply of oil from an engine oil return system to the propeller control unit. An oil cooling line extends between an outlet of the pump and the engine oil return system. The oil cooling line defines an oil leakage path leading to the engine oil return system for cooling the oil. A flow regulator between the pump and the propeller control unit is operable between an open position where oil is directed through the oil cooling line to the engine oil return system for cooling the oil, and a closed position blocking the oil cooling line and directing oil toward the propeller control unit to modify the angle of the propeller blades.

Abstract: A fuel system for a composite aircraft is described which includes an ejector pump having a vacuum inlet in communication with a fuel storage tank, an engine feed pump having an inlet in fluid communication with an outlet of the ejector pump, a primary outlet in communication with an engine, and a motive flow outlet, upstream of an oil-fuel heat exchanger, that is in fluid communication with an inlet of the ejector pump. A motive flow pump assembly is disposed between the motive flow outlet of the engine feed pump and the inlet of the ejector pump. The motive flow pump assembly includes an inlet screen and a motive flow pump, the inlet screen having a plurality of openings therein and a hydrophobic upstream surface. The openings are dimensioned to prevent passage of particles greater than a selected threshold size while allowing liquids to flow therethrough.

Abstract: An assembly of fuel tank and bubbler system comprises a fuel tank defining a storage volume adapted to receive fuel therein. The fuel tank comprises at least one fuel inlet, at least one fuel outlet, and at least one gas inlet adapted to be connected to an inert gas source to feed inert gas to fill an ullage in the storage volume. A bubbler system has at least one pipe extending into the fuel tank and adapted to be immersed into the fuel of the fuel tank. The pipe has a porous structure. The pipe is adapted to be connected to an inert gas source to inject inert gas via the porous structure into the fuel of the fuel tank. A method for treating fuel in a fuel tank is also provided.

Abstract: An assembly of fuel tank and bubbler system comprises a fuel tank defining a storage volume adapted to receive fuel therein. The fuel tank comprises at least one fuel inlet, at least one fuel outlet, and at least one gas inlet adapted to be connected to an inert gas source to feed inert gas to fill an ullage in the storage volume. A bubbler system has at least one pipe extending into the fuel tank and adapted to be immersed into the fuel of the fuel tank. The pipe has a porous structure. The pipe is adapted to be connected to an inert gas source to inject inert gas via the porous structure into the fuel of the fuel tank. A method for treating fuel in a fuel tank is also provided.

Abstract: A gas turbine engine pneumatic system for controlling an air bleed valve includes a variable orifice device for controllably discharging air from the pneumatic system in order to reduce a maximum air pressure applied to the air bleed valve, to a predetermined level. A filter device is provided to filter the air discharged from the variable orifice.

Abstract: A gas turbine engine pneumatic system for controlling an air bleed valve includes a variable orifice device for controllably discharging air from the pneumatic system in order to reduce a maximum air pressure applied to the air bleed valve, to a predetermined level. A filter device is provided to filter the air discharged from the variable orifice.