Abstract: An aircraft fuel system, comprising: a fuel tank; a fuel line; and an engine; wherein the fuel line includes a first conduit configured to carry fuel from the tank towards the engine, and a second conduit configured to carry fuel from the engine towards the tank, wherein one of the first conduit or the second conduit is disposed annularly around the other of the first conduit or the second conduit. Also, a method of operating the system. The system may be used to suppress ice formation in the first conduit and/or provide leakage detection.

Abstract: A method of conditioning oxygen depleted air (ODA) exhausted from a fuel cell comprising the steps of; taking fuel from an aircraft fuel tank collector cell, delivering said fuel to a rear mounted engine via a primary heat exchanger, taking exhaust ODA from a fuel cell, passing the ODA through the primary heat exchanger in the opposite direction to the fuel, such that the fuel acts as a heat sink for the ODA, to cool the ODA, passing the ODA through a dryer, to dry the ODA and using the cooled, dried ODA to inert fuel in the aircraft fuel tank.

Abstract: A tank assembly with a tank for storing liquid hydrocarbon, the tank having a floor for supporting a weight of the liquid hydrocarbon. A filter is fitted to the floor of the tank. The filter is arranged to allow liquid water in the tank to drain out of the tank through the filter but substantially prevent the liquid hydrocarbon in the tank from doing so. The filter has a permeation member, such as a membrane, which is formed from a material such as graphene oxide which allows liquid water in the tank to drain out of the tank by permeating through the permeation member but substantially prevent the liquid hydrocarbon in the tank from doing so.

Abstract: A sensor for measuring a level of a liquid such as fuel and/or water in a tank such as a fuel tank. The sensor includes a stack of capacitors, each capacitor with one or more graphene measurement electrodes and one or more graphene reference electrodes. A measurement system is arranged to measure a capacitance of each capacitor between its measurement electrode(s) and its reference electrode(s) and thereby infer the liquid level. The graphene measurement and reference electrodes are formed in a single layer of graphene oxide by reductive etching.

Abstract: An aircraft aerial refueling system including at least one pressure controlled fuel pump having a control system adapted to regulate the pump outlet fuel pressure using an outlet fuel pressure signal as control feedback. Also, methods of operating an aircraft aerial refueling system.

Abstract: A dehumidifier comprises: a first channel for transporting air at a first pressure; a second channel for transporting air at a second pressure lower than the first pressure; and a graphene oxide barrier separating the first channel and the second channel. The relatively lower pressure of air in the second channel causes water vapor to be drawn out of the air in the first channel.

Abstract: A method of controlling a flow rate of inerting gas introduced into a vented aircraft fuel tank, the method comprising: monitoring changes in a quantity of a fuel in the aircraft fuel tank; monitoring changes in the ambient air pressure external to the aircraft fuel tank; and actively controlling a flow rate of inerting gas, {dot over (m)}(I), introduced into the aircraft fuel tank based upon changes in the quantity of fuel in the fuel tank and changes in the ambient air pressure, p. Also, an aircraft including a vented fuel tank, a supply of inerting gas for rendering inert the fuel tank ullage, and a controller for performing the method.

Abstract: An aircraft aerial refuelling system including at least one pressure controlled fuel pump having a control system adapted to regulate the pump outlet fuel pressure using an outlet fuel pressure signal as control feedback. Also, methods of operating an aircraft aerial refuelling system.

Abstract: A method for predicting a quantity of a contaminant in a fuel tank at the end of a time period, the method comprising the steps of: determining a quantity of the contaminant in the fuel tank at the start of the time period; determining at least one operating condition of the fuel tank during the time period; using information relating to the at least one operating condition of the fuel tank to generate a predicted quantity of the contaminant accumulated in the fuel tank during the time period; and calculating, based upon the quantity of the contaminant at the start of the time period and the predicted quantity of the contaminant accumulated during the time period, a predicted quantity of the contaminant at the end of a time period.

Abstract: An aircraft aerial refueling system including at least one pressure controlled fuel pump having a control system adapted to regulate the pump outlet fuel pressure using an outlet fuel pressure signal as control feedback. Also, methods of operating an aircraft aerial refueling system.

Abstract: A sumpless valve is disclosed, which has a closure member which is rotatable between a closed position and an open position. A substantially straight or convex bottom wall is provided in the valve, to provide a substantially flat-bottomed flow path through the valve, to avoid the build-up of unwanted fluids in a sump of the valve, located below a substantially straight flow path through the valve. A retraction mechanism for retracting the closure member before rotating it away from its closed position is also disclosed.

Abstract: An aircraft fuel system, comprising: a fuel tank; a fuel line; and an engine; wherein the fuel line includes a first conduit configured to carry fuel from the tank towards the engine, and a second conduit configured to carry fuel from the engine towards the tank, wherein one of the first conduit or the second conduit is disposed annularly around the other of the first conduit or the second conduit. Also, a method of operating the system. The system may be used to suppress ice formation in the first conduit and/or provide leakage detection.

Abstract: A fuel level probe has a series of stacked, annular capacitors, the capacitance of which changes with the dielectric constant of the fluid in which they are immersed. A multiplexer provides sequential measurement of each capacitor to determine a step change in capacitance and hence fluid levels based on the time at which the capacitance changes.

Abstract: A tank assembly with a tank for storing liquid hydrocarbon, the tank having a floor for supporting a weight of the liquid hydrocarbon. A filter is fitted to the floor of the tank. The filter is arranged to allow liquid water in the tank to drain out of the tank through the filter but substantially prevent the liquid hydrocarbon in the tank from doing so. The filter has a permeation member, such as a membrane, which is formed from a material such as graphene oxide which allows liquid water in the tank to drain out of the tank by permeating through the permeation member but substantially prevent the liquid hydrocarbon in the tank from doing so.

Abstract: A probe for determining a characteristic of the contents in a fuel tank. The probe includes at least one analysis element. The or each analysis element has an input for inputting light to a sampling region to be analysed and an output for outputting light that has passed through the sampling region from the input. A system including a probe and a spectrometer is also provided.

Abstract: An aircraft fuel tank ventilation system, comprising a refrigerative dehumidifying device having a refrigerating element in contact with air flowing between a vent open to the atmosphere and a fuel tank. Also, a method of dehumidifying air introduced into an aircraft fuel tank via the ventilation system, the method comprising directing atmospheric air from the vent into contact with the refrigerating element, and cooling the refrigerating element so as to remove water vapor from the air flowing from the vent towards the fuel tank by condensation.

Abstract: A fuel system includes a fuel tank, a vent tank fluidically connected to the fuel tank ullage, the vent tank having a duct open to the ambient atmosphere and the interior of the vent tank, and a catalyst disposed in the duct, wherein the catalyst is adapted to deplete one or more reactive components of gas flowing through the duct by catalytic reaction. Also, a method for depleting one or more reactive components of gas in the fuel system, includes depleting one or more reactive components of gas flowing through the duct using the catalyst.

Abstract: A method of measuring a height of a fuel surface of fuel in an aircraft fuel tank. One or more images of the fuel surface are captured, each image including a fuel surface line where the fuel surface meets a structure. Each image is analysed in order to determine a height of the fuel surface line at three or more points in the image. If the fuel surface line is not a straight line, then an average angle of the fuel surface line can be determined from the points in the image by spatial averaging. Preferably a series of images of the fuel surface are captured over a time period, and an average height of the fuel surface is determined from the series of images by time averaging. The height of the fuel surface line(s) at three or more points is used to determine a volume of the fuel, a mass of the fuel, and/or an attitude of the fuel surface.

Abstract: A dehumidifier comprises: a first channel for transporting air at a first pressure; a second channel for transporting air at a second pressure lower than the first pressure; and a graphene oxide barrier separating the first channel and the second channel. The relatively lower pressure of air in the second channel causes water vapour to be drawn out of the air in the first channel.

Abstract: A sensor for measuring a level of a liquid such as fuel and/or water in a tank such as a fuel tank. The sensor includes a stack of capacitors, each capacitor with one or more graphene measurement electrodes and one or more graphene reference electrodes. A measurement system is arranged to measure a capacitance of each capacitor between its measurement electrode(s) and its reference electrode(s) and thereby infer the liquid level. The graphene measurement and reference electrodes are formed in a single layer of graphene oxide by reductive etching.