Patent Description:
There is always a need in the art for improvements to fuel systems in the aerospace industry.

<CIT> discloses a prior art cooled fuel injector system for a gas turbine engine.

<CIT> discloses a prior art enclosed gas fuel delivery system.

<CIT> discloses a prior art method and system to detect and measure piping fuel leaks.

According to a first aspect of the present invention, there is provided a fuel system as set forth in claim <NUM>.

According to a further aspect of the present invention, there is provided an aircraft engine as set forth in claim <NUM>.

Further embodiments of the invention are provided as set forth in claims <NUM>, <NUM> and <NUM> to <NUM>.

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, an illustrative view of an embodiment of a fuel system in accordance with the disclosure is shown in <FIG> and is designated generally by reference character <NUM>. Other embodiments and/or aspects of this disclosure are shown in <FIG>.

In certain embodiments, referring to <FIG>, an aircraft <NUM> includes an engine <NUM>, where the engine can be a propulsive energy engine (e.g. creating thrust for the aircraft <NUM>), or a non-propulsive energy engine, and a fuel system <NUM>. A compressor <NUM> supplies pressurized air to a primary gas path <NUM> (e.g. as shown in <FIG>) of the aircraft engine <NUM>, the primary gas path <NUM> including fluidly in series a combustor and nozzle manifold for issued fluid to the combustor.

Referring now to <FIG>, the fuel system <NUM> comprises a fuel conduit interface <NUM> connecting a fuel conduit <NUM> to a component 101a,b, c, d, e, 103a, b, c, d, e, <NUM> of the fuel system <NUM>; and a sweep line structure <NUM>. As used herein, a conduit can include one or a combination of components forming a flow path <NUM> between at least two points, for example a fuel conduit <NUM> fluidly connecting component any of components 101a,b, c, d, e, 103a, b, c, d, e, <NUM> to another, may be any one of or a combination of: a fuel line, fuel filter, heat exchanger, or the like. In contrast, as used herein, a fuel line can be defined as a tube carrying fuel from one end of the tube to another.

The sweep line structure <NUM> includes an inner surface <NUM> facing toward, extending around, and defining a cavity <NUM> around the fuel conduit interface <NUM>, and an outer surface <NUM> opposite the inner surface <NUM>, the cavity <NUM> being fluidly sealed relative to the outer surface <NUM>.

In embodiments, the system includes a vent conduit <NUM> that includes the cavity <NUM> of the sweep line structure <NUM> and fluidly connects to atmosphere A. In embodiments, the fuel conduit interface <NUM> can include a plurality of fuel conduit interfaces 102a, b, c, d, e of the fuel system <NUM> of the aircraft engine <NUM>, for example. The vent conduit <NUM> includes a plurality of cavities 110a, b, c, d, e the cavity <NUM> a, b, c, d, e of each fuel conduit interface 102a, b, c, d, e of the plurality of fuel conduit interfaces <NUM> a, b, c, d, e being one of the plurality of cavities <NUM> a, b, c, d, e. In certain embodiments, the sweep line structure <NUM> is a plurality of sweep line structures <NUM> a, b, c, d, e, and wherein the inner surface <NUM> of each sweep line structure <NUM> of the plurality of sweep line structures <NUM> a, b, c, d, e defines the cavity <NUM> a, b, c, d, e around a fuel conduit interface <NUM> a, b, c, d, e of the plurality of fuel conduit interfaces <NUM> a, b, c, d, e that corresponds to that sweep line structure <NUM> a, b, c, d, e.

In certain embodiments, the sweep structure <NUM> surrounds at least a portion of the one or more fuel circuit components (e.g., fuel line segments 101a, b, c, d, e and connections to other components 103a, b, c, d, e) so as to allow a sweep fluid <NUM> to move a leaked fuel (e.g., leaked from a seal location or through a material) from the one or more fuel circuit components to the vent conduit <NUM> (e.g., in fluid communication with an outlet, e.g., atmosphere, exhaust nozzle, or an inner bypass fan duct). In certain embodiments, the sweep structure <NUM> surrounds each connection <NUM> (e.g., a mechanical fitting) between each flow component 103a, b, c, d, e, <NUM> and each fuel line 101a, b, c, d, e.

In certain embodiments, the plurality of fuel conduit interfaces 102a, b, c, d, e includes one of or a combination of two or more of any one of: a fuel conduit interface 102e defined by a fuel connection to a fuel nozzle manifold (e. g component <NUM>), a fuel conduit interface 102d defined by a fuel connection to a fuel manifold shutoff valve (e.g. component 103e), a fuel conduit interface 102c defined by a fuel connection to a gaseous hydrogen metering unit (e.g. component 103d), a fuel conduit interface 102b defined by a fuel connection to a pressure reducing valve (e.g. component 103c), a fuel conduit interface 102a defined by a fuel connection to a gaseous hydrogen accumulator (e.g. component 103b), and a fuel conduit interface <NUM> defined by a fuel connection to a liquid hydrogen pump (e.g. component 103a).

The sweep structure <NUM> can be in fluid communication with a sweep flow source. For example, the sweep flow source can be a pressurized air source (e.g., bled from a compressor or separately pumped) to create a constant flow in the sweep structure <NUM>. Any other suitable flow source and/or fluid is contemplated herein. In certain embodiments, the sweep structure <NUM> includes an inlet <NUM> configured to receive sweep fluid <NUM> from a source. For example, in certain embodiments, the inlet <NUM> of the sweep structure <NUM> can be configured to connect to the compressor <NUM> (e.g., a low pressure compressor stage of a turbomachine) to receive compressor air. The sweep structure <NUM> is sealingly engaged to each flow component 103a, b, c, d, e such that the sweep flow path <NUM> is substantially sealed between the inlet <NUM> and the vent portion <NUM>.

In certain embodiments, the sweep structure <NUM> includes a bypass line <NUM> passing around each flow component 103a, b, c, d, e to allow continuous flow from the inlet <NUM> to the vent portion <NUM>. As shown, in certain embodiments, the sweep structure <NUM> can fully encompass the entire fuel system or any suitable portion thereof (e.g., from a fuel tank to a combustor, e.g., a combustor outer casing).

In embodiments, the vent <NUM> conduit fluidly connects to a section of the compressor <NUM> that is at a higher pressure than pressure at an outlet of the vent conduit <NUM> that connects to the atmosphere. The section is a section of the compressor at which the pressurized air is below <NUM> degrees Fahrenheit in all normal operating conditions of the aircraft engine <NUM>. The compressor can include a P2. <NUM> compressor stage, a P2. <NUM> compressor stage, and a P2. <NUM> compressor stage; and the section of the compressor is one of the P2. <NUM> compressor stage, the P2. <NUM> compressor stage, and the P2. <NUM> compressor stage.

In certain embodiments, the fuel is hydrogen (e.g., which is more prone to leaking than traditional fuel). In certain such embodiments, a hydrogen sensor 115a is operatively connected to the vent conduit <NUM> at a location upstream of the outlet <NUM> of the vent conduit <NUM>, the hydrogen sensor <NUM> a being operable to sense at that location one or both of: presence of hydrogen and/or concentration of hydrogen. In certain embodiments, the outlet <NUM> of the vent conduit <NUM> can include a plurality of outlets fluidly venting the vent conduit <NUM> to the atmosphere at different locations in the vent conduit <NUM> (for example as described with respect to <FIG>. In embodiments, a temperature sensor 115b is operatively connected to the vent conduit <NUM> at a location upstream of the outlet <NUM> of the vent conduit <NUM>, the temperature sensor 115b being operable to sense temperature of a gas at that location.

In certain embodiments, referring to <FIG>, the sweep structure can be a first sweep structure 207a and the fuel system <NUM> can further include a second sweep structure 207b. In certain embodiments, the vent conduit 213b extends through a hot section (e.g. Zone <NUM>) of the aircraft engine <NUM>; and the vent conduit 213b fluidly connects to the section of the compressor at a location in the hot section. The vent conduit 213a can connect to the compressor at a location outside of the hot section (e.g. Zone <NUM>). At least one fuel conduit interface 202e of the plurality of fuel conduit interfaces is disposed in the hot section at a location in the vent conduit 213b that is fluidly between the location at which the vent conduit fluidly connects to the section of the compressor and the outlet of the vent conduit that connects to the atmosphere.

In this manner, the first sweep structure 207a is configured to sweep a cold zone portion 210a of the fuel system <NUM> to a first vent portion 213a (e.g., in fluid communication with an atmosphere or bypass duct), and the second sweep structure 210b is configured to sweep a hot zone portion 210b of the fuel system <NUM> to a second vent portion 213b (e.g., in fluid communication with an exhaust or bypass duct, for example). The first vent portion 213a and the second vent portion 213b can be connected to the same or different outlets.

In certain embodiments, each of the first and second sweep structures 207a, 207b can include a respective inlet 219a, 219b (e.g., mounted on or off the engine) and a respective vent portion 213a, 213b. In certain embodiments, each sweep structure 207a, 207b includes a leak detection location 215a, 215b positioned downstream of the one or more fuel circuit components associated with each sweep structure 207a, 207b. In certain embodiments, each sweep structure 207a, 207b includes one or more leak detection sensors 115a, 115b (e.g., as disclosed above).

In certain embodiments, such as the example shown in <FIG>, the sweep structure <NUM>, 207a includes a fitting structure <NUM> configured to engage a sweep line structure <NUM> at a first axial opening <NUM>. The first sweep fitting structure <NUM> can form a fitting flow cavity <NUM>. In certain embodiments, the first sweep fitting structure <NUM> is configured to surround one or more (e.g., all as shown) of a first end portion 122a of the fuel line <NUM>, a first end fitting <NUM> (e.g., all or a portion thereof) attached to the fuel line <NUM>, and/or a first opening 126a of a fuel system component (e.g. component 103a, b, c, d, e, <NUM>) attached to the first end fitting <NUM>.

In certain embodiments, the first end fitting <NUM> can be integral with the first end portion 122a. The first end fitting <NUM> can include any suitable number of parts (e.g., two as shown) configured to allow the fuel line <NUM> to fluidly connect to the first opening <NUM>. Any suitable type of fitting components (e.g. a threaded nipple) is contemplated herein.

In certain embodiments, the first sweep fitting structure <NUM> defines a first radial opening <NUM>. The first radial opening <NUM> can be configured to receive a bridge channel (e.g. bypass line <NUM>), e.g., as shown. The first radial opening <NUM> can be located closer to the fuel system component 103a, b, c, d, e than the axial opening <NUM>, for example.

In certain embodiments, the sweep line structure <NUM> defines a first connection end <NUM> configured to engage with a retainer <NUM> (e.g., an axial retention device) to retain the sweep line structure <NUM> to the first sweep fitting structure <NUM>. In certain embodiments, referring additionally to <FIG>, the first sweep fitting structure <NUM> is configured to be moveable (e.g., slidable as shown in <FIG>) relative to the sweep line structure <NUM> when the retainer <NUM> is not engaged to the sweep line structure <NUM>.

In certain embodiments, the first sweep fitting structure <NUM> includes a first seal groove <NUM> configured to receive a first seal 136a to seal against the sweep line structure <NUM>. In certain embodiments, the first sweep fitting structure <NUM> can include a second seal groove <NUM> configured to receive a second seal 138a to seal against the first opening 126a of the fuel system component <NUM> a, b, c, d, e. The first seal 136a and the second seal 138a can be an o-ring seal or any other suitable seal. Any other suitable seal arrangement configured to seal the components together to create a sealed sweep flow path (e.g., at least partially formed by the cavities <NUM>, <NUM>) is contemplated herein.

In certain embodiments, the first connection end <NUM> includes a snap ring groove <NUM> configured to receive a snap ring (e.g., retainer <NUM> being shown as a snap ring type retainer) to retain the first sweep fitting structure <NUM> (e.g., axially) between the snap ring (e.g., retainer <NUM>) and the fuel system component <NUM> a, b, c, d, e. Any other suitable type of retainer structure for any suitable type of retainer is contemplated herein.

In certain embodiments, the first connection end <NUM> defines an inner diameter mount <NUM> configured to mount the fuel line <NUM> concentrically therethrough. In certain embodiments, the inner diameter mount <NUM> includes an inner diameter tube shape axially extending from the first connection end <NUM>. For example, as shown, the inner diameter mount <NUM> can form a cylindrical shape (or other complimentary shape to the fuel line <NUM>) having an inner diameter that is the same or about the same size (e.g., to allow sliding) as an outer diameter of the fuel line <NUM>. As shown, the inner diameter mount <NUM> can extend away from the first connection end <NUM> (e.g., away from the sweep fitting structure <NUM>), however, any other suitable structure or direction of extension is contemplated herein. The sweep line structure <NUM> and/or the connection end <NUM> can be made using additive manufacturing, for example, to create the shown complex shape jacketed fluid line and connection.

In certain embodiments, the first connection end <NUM> defines one or more holes <NUM> defined at least partially axially therethrough (e.g., in a vertical wall of the first connection end) to allow sweep flow (e.g., air) to pass through the first connection end. Any suitable number of holes <NUM> is contemplated herein.

In certain embodiments, the bridge channel <NUM> is disposed in fluid commination with the first sweep fitting structure <NUM> (e.g., at the first radial opening <NUM> as shown) and configured to direct sweep flow around the fuel system component <NUM> a, b, c, d, e. In certain embodiments, the bridge channel <NUM> is connected to a second sweep fitting structure <NUM> to pass flow thereto to allow flow to a second sweep line structure <NUM>. However, in certain embodiments, the bridge channel <NUM> can be connected to a vent (e.g. vent <NUM>, <NUM>). It is contemplated that a last bridge channel <NUM> in a series can be connected to a vent, for example.

In certain embodiments, the bridge channel <NUM> is a flexible hose (e.g., braided steel) configured to allow the first sweep fitting structure <NUM> to move relative to the sweep line structure <NUM> without disconnecting the bridge channel <NUM> from the first sweep fitting structure <NUM> (and without having to disconnect any other mounted portion of the bridge channel <NUM>, e.g., at a second sweep fitting structure <NUM>. The bridge channel <NUM> can be a rigid channel in certain embodiments, but may require removal from one or more connections (e.g., from first fitting structure <NUM>) before being able to slide the first fitting structure away from the fuel system component <NUM> a, b, c, d, e (e.g., to gain line of sight access to the fuel line and/or fittings).

In certain embodiments, the bridge channel <NUM> can be connected to the first sweep fitting structure <NUM> (e.g., and any other sweep fitting structure at another end) in any suitable manner to provide a sealed sweep flow path. For example, a nipple-ferrule-nut connection can be used. Any other suitable connection type is contemplated herein.

In certain embodiments, the sweep line structure <NUM>, 207a defines a second connection end <NUM> at an opposite end relative to the first connection end <NUM>. The second connection end <NUM> can be the same as the first connection end <NUM>, for example (e.g., but facing an opposite direction). However, it is contemplated that the second connection end <NUM> can be different from the first connection end <NUM> in any suitable manner. In certain embodiments, the sweep structure <NUM>, 207a includes a second sweep fitting structure <NUM> configured to engage to the second connection end <NUM>, e.g., as shown in <FIG>, and the same as disclosed above with respect to connection end <NUM> and first sweep fitting structure <NUM>. In certain embodiments, the second sweep fitting structure <NUM> is the same as the first sweep fitting structure <NUM>, however, it is contemplated that the second sweep fitting structure <NUM> can be different from the first sweep fitting structure <NUM> in any suitable manner.

In certain embodiments, the sweep structure <NUM>, 207a includes a series of sweep line structures <NUM>, <NUM> connected in series via respective sweep fitting structures <NUM>, <NUM>. Any suitable number of sweep line structures <NUM>, <NUM> and sweep fitting structures <NUM>, <NUM>, <NUM> in any suitable series is contemplated herein (e.g., configured to cover the entire fuel system or any suitable portion thereof).

In certain embodiments, the fuel system <NUM>, <NUM> includes a control module <NUM> configured to determine whether a leak has occurred and to operate at least one of the one or more fuel components (e.g., pump 103a and/or valve 103e) based on the detected leak. In certain embodiments, the control module <NUM> is operatively connected to one or more components and can be configured to shut down or otherwise reduce fuel flow (e.g., to stop the pump 103a and/or to close valve 103e) if a leak is detected above a threshold (e.g., if an amount of hydrogen exceeds a high threshold or if a temperature exceeds a threshold indicating hydrogen burning in the sweep flow path). In certain embodiments, e.g., as shown in <FIG>, the control module <NUM> can be configured to determine a location of a leak based on which detection location is indicating a leak.

For example, if fuel from the fuel circuit is detected at the detection location 215a, the control module <NUM> can determine that a leak exists in the cold section, and may gauge the severity of the leak based on the amount of fuel detected (e.g., the control module <NUM> may allow continued operation below a certain threshold with sufficient sweeping due to low risk of ignition in the cold section). If fuel from the fuel circuit is detected at the detection location <NUM>, the control module <NUM> can determine that a hot section leak is present (e.g., from a fuel line, nozzle manifold, or other component) and can shut down the system, e.g., to prevent ignition in the hot section. Any suitable number of detection locations and sensors for detecting a leak in any suitable divisions of the fuel system is contemplated herein. The control module <NUM> can be operatively connected to any suitable component(s) to control any suitable components (e.g., a bleed valve to control sweep air flow, an inhibitor gas system for introducing inhibitor gas into the sweep flow path).

In accordance with at least one aspect of this disclosure, certain embodiments can be a hydrogen fuel system for an aircraft and can include a hydrogen fuel circuit and a leak detection system coupled to the hydrogen fuel circuit to and configured to detect a hydrogen leak from at least a portion of the hydrogen fuel circuit by sweeping at least a portion of the hydrogen fuel circuit with a sweep gas to a leak detection location having one or more leak detection sensors. In certain embodiments, e.g., as shown in <FIG>, the leak detection system includes a single sweep structure configured to sweep the entire hydrogen fuel circuit between a first location and one or more fuel nozzles. In certain embodiments, the one or more leak detection sensors are downstream of a fuel nozzle manifold in the sweep structure.

In certain embodiments, as shown in <FIG>, the leak detection system includes a first sweep structure configured to sweep a cold zone portion of the hydrogen fuel circuit and to a first vent portion, and wherein the leak detection system includes a second sweep structure configured to sweep a hot zone portion of the hydrogen fuel circuit to a second vent portion. In certain embodiments, the system includes a controller configured to control one or more components in the hydrogen fuel circuit as a function of signals received from the one or more leak detection sensors.

In accordance with at least one aspect of this disclosure, a method includes sweeping a sweep fluid over a fuel circuit to vent leaked fuel and/or to move leaked fuel to a leak detection location. The method can include any other suitable method(s) and/or portion(s) thereof.

Embodiments can include a single or multi vent embodiment, e.g., having a sweep structure made of a tube (e.g., a rigid metallic material such as high temp stainless steel). In embodiments, air can consistently sweep the fuel, e.g., hydrogen to a vent. Embodiments can include sweep that surrounds the entire hydrogen flow pathway and covers all leak areas to vent the leaked hydrogen. Embodiments can use an hydrogen sensor to detect a leak or a serious leak. A temperature sensor can be employed to sense if a leak starts a fire in the vent line, In certain embodiments, a controller can shut down flow in event of serious leakage detected,.

Certain multi zone embodiments can be divided into hot section and cold section. Some portion of exposed fuel line not in a sweeping circuit may exist in such embodiments, but a leakage can be more accurately located allowing a user or control module to react differently based on zone. Typical aircraft engine fuel supply system contains multiples fitting and coupling connections that may lead to a hydrogen leak. Hydrogen can leak at every connection and through the pipes carrying the hydrogen even (e.g., through a microcrack generated from hydrogen embrittlement phenomena). Hydrogen is far more volatile and prone to escape than conventional fuels. In certain cases, hydrogen gas can collect in parts of an airframe and can present a suffocation or explosion hazard. Some leaked hydrogen can simply auto-ignite in contact with hot surfaces of the engine (e.g., gas generator case, turbine support case, exhaust duct).

Embodiments can provide a fuel supply leakage detection and purging system for hydrogen aircraft engine, for example. Embodiments can include an air vent system integrated with the hydrogen (hydrogen) supply system such that all hydrogen supply lines and fitting connections are surrounded by a second layer skin that acts as a container (e.g., a tube in a tube) which is sealed and where a minimum constant air mass flow is passing between hydrogen supply line and second layer skin to catch and evacuate any hydrogen leakage that may occurs at any fitting connection or/and through hydrogen tube (cracks).

Air vent flow could be taken from engine compressor stage, or from OEM/engine accessory air compressor unit, for example (e.g., maximum air temperature of source being less than <NUM> degrees F (260deg C) and where total pressure is higher than pressure at outlet). Also the air vent system can be designed to maintain an adequate air pressure differential between air vent inlet and the air vent outlet to ensure minimal air flow velocity and adequate ventilation rate to reduce hydrogen/air ratio in case of hydrogen leakage from hydrogen supply system and therefore reduce risk of hydrogen ignition/fire.

Embodiments can evacuate any hydrogen leakage flow from hydrogen supply system from a vent outlet which could be located outside aircraft (atmosphere) or in exhaust jet nozzle or in a fan inner/outer bypass duct. A hydrogen sensor and temperature sensor can be installed in air vent outlet duct to detect abnormal hydrogen leakage level or/and abnormal air temperature raised that may indicate hydrogen fire situation. In certain embodiments, when abnormal hydrogen leakage or/and abnormal air temperature are detected, the control module can control a bleed air modulated valve could be used to increase air bleed flow through vent line system to dilute concentration of hydrogen in the air vent line. In certain embodiments, if abnormal temperature is detected by the temperature sensor in the air vent outlet duct, an inhibitor gas unit can be controlled by the control module to release inhibitor gas (e.g., nitrogen, CH3Br, CBrF3) to the air vent line to extinguish hydrogen diffusion flames.

In certain embodiments, instead of have a single air vent network, certain embodiments can include splitting the air venting network in two or more zones. The first zone can bring venting air to the fuel supply system located outside the engine (external-mounted or off mounted). The second zone can bring venting air to fuel supply system located inside the engine (e.g., core) located in the hot section. Such embodiments can allow the control module to identify which zone hydrogen leakage occurs where consequences/risks are not same between zone <NUM> and <NUM>. Such embodiments can also reduce size of vent/hydrogen tube passing thru bypass duct service fairing (e.g., to reduce aerodynamic blocking in bypass duct) for a turbofan type engine.

Embodiments can allow aircraft engines to safely use hydrogen as a fuel type. For example, embodiments provide a solution to mitigate the risk of hydrogen fluid leakages that may occur from aircraft engine fuel supply systems and where consequences may generate hazardous conditions (e.g., fire, explosion) in an aircraft power plant that may compromise aircraft/engine safety and airworthiness certification.

Certain embodiments disclosed herein include a system to detect, contain, and purge any hydrogen fluid leakages that may come out from an aircraft engine fuel supply system. A venting system can be comprised of a primary fluid supply system surrounded by a secondary fluid system acting as a container with the intent to capture leaks from the primary system and vent the leak out. The second layer can have a vent inlet and outlet for a secondary fluid to flow. The secondary fluid system can wrap around or bypass components that are using the primary fluid. The secondary inlet flow can be forced. The secondary outlet vent can have sensors for detecting temperature and fluid composition. The primary fluid can be hydrogen, for example.

In accordance with at least one aspect of this disclosure, a fuel system <NUM> includes a fuel line <NUM>, a fuel system component <NUM> a, b, c, d, e in fluid communication with the fuel line <NUM> and connected to the fuel line <NUM> at a first opening thereof 126a, and a sweep system. In certain embodiments, the sweep system is or includes any suitable sweep structure disclosed herein, e.g., structure <NUM>, 207a as described above. In certain embodiments, a fuel system <NUM> includes one or more fuel lines <NUM> connected to one or more fuel system components <NUM> a, b, c, d, e at one or more connections (e.g., fittings <NUM> connected to opening 126a), and a sweep system (e.g., being or including sweep structure <NUM>, 207a) defining a fluid path (e.g. flow path <NUM>) surrounding the one or more fuel lines <NUM> and each connection between each of the one or more fuel lines <NUM> and the one or more connections. The sweep system can be configured to allow sweeping of leaked fuel from the fuel lines <NUM> to a vent <NUM>, <NUM>. In certain embodiments, the sweep system includes a retainable, moveable component (e.g., fitting structure <NUM>) configured to provide access to the one or more connections and/or to allow removal of one or more components of the sweep system when moved to an access position (e.g., as shown in <FIG>). The fuel system can include any suitable embodiment of a sweep system and/or sweep structure in accordance with this disclosure.

Certain embodiments can include an outer secondary air vent tube fitted around a primary tube carrying a primary fluid to a component, the secondary air vent tube configured to capture and vent any leaks from the primary tube, or from the primary tube interface with the component. The outer tube can have an axially retractable connector with a vent line. The connector can have two sealing elements that interface with two surfaces, one sealing surface interface can be with the component and another can be with the outer (secondary) tube.

In certain embodiments, the vent lines may be connected between adjacent outer tubes via a bypass bridge tube. In certain embodiments, the secondary tube may have an axial retention feature snap ring to fix the retractable connector in place.

Embodiments can include a structures for providing air venting for a hydrogen supply line to contain and seal both air vent flow and any hydrogen fluid leakage flow coming from hydrogen unit-supply line connectors and while also permitting easy access to hydrogen unit and supply line connectors in order to perform maintenance, inspection, and/or hydrogen unit-line replacement in the field. Embodiments can provide a solution to contain both air vent flow and any hydrogen fluid leakage flow from a hydrogen fuel system. Typical aircraft engine fuel supply systems contain multiples fitting and coupling connections that may lead to hydrogen fluid leakages. While the systems and methods described herein are described with respect to aircraft fuel systems, it is contemplated that such systems and methods can be employed to other engines in fields outside of aerospace. For example, embodiments can be utilized with a fuel supply leakage detection and purging system for any gas fuel (e.g., hydrogen) engine. Moreover, the systems and methods can be used to detect and purge leaks from anywhere within the aircraft, for example outside the engine systems, including the aircraft hydrogen tank, or in a faulty hydrogen shut-off valve.

Embodiments provide a way to allow both sweeping and access to hydrogen line fittings/connectors, and to be able to disassemble/reassemble those hydrogen supply line connections.

Embodiments can include an air vent/purge tubing and fitting mechanical arrangement for a hydrogen supply line. Embodiments can include a mechanical arrangement that has an air vent connector, which can make a second "layer" between the hydrogen unit connector and the inter-tube seal housing tube, which, at both ends, the interface can be sealed by a sealing element which allows containing of air vent flow and also containing of any hydrogen fluid leakage flow coming from the hydrogen connectors or a defective hydrogen supply tube (e.g., cracks due to hydrogen embrittlement/HCF-LCF). Another function of the air vent connector can also be to redirect both air vent flow from air vent tube and any hydrogen fluid leakage flow into the air vent "bridge" tube. The air vent "bridge" tube can then be connected to the next hydrogen unit-air vent connection part of the air vent/purging network system.

In order to access to hydrogen unit and hydrogen supply line connection to perform maintenance, inspection, and/or hydrogen unit-supply line replacement, the axial retention element can be removed from the groove which allows the air vent connector to slide right to left (as shown in <FIG>) and disengage sealing elements from the sealing interfaces. In certain embodiments, the air vent "bridge" tube can be a flex hose which permits flexibility and movement during sliding of air vent connector which does not require any disconnection at the end fitting between. Alternatively, a rigid tube can be used.

Claim 1:
A fuel system (<NUM>) of an aircraft engine (<NUM>), comprising:
a hydrogen fuel source;
a hydrogen fuel circuit including a fuel conduit interface (<NUM>) connecting a fuel conduit (<NUM>) to a component (<NUM>) of the fuel system (<NUM>); and
a leak detection system operatively coupled to the hydrogen fuel circuit, the leak detection system including:
a sweep flow source;
a sweep line structure (<NUM>, <NUM>, <NUM>) having an inlet (<NUM>) fluidly connected to the sweep flow source, the sweep line structure (<NUM>, <NUM>, <NUM>) having:
an inner surface (<NUM>) facing toward, extending around, and defining a cavity (<NUM>) around the fuel conduit interface (<NUM>), and
an outer surface (<NUM>) opposite the inner surface (<NUM>), the cavity (<NUM>) being fluidly sealed relative to the outer surface (<NUM>),
a vent conduit (<NUM>, <NUM>) that includes the cavity (<NUM>) of the sweep line structure (<NUM>, <NUM>, <NUM>) and fluidly connects to atmosphere;
a bypass line (<NUM>) passing around the component (<NUM>) to allow continuous sweep flow from the inlet (<NUM>) to the vent portion (<NUM>, <NUM>);
a hydrogen sensor (115a) operatively connected to the vent conduit (<NUM>, <NUM>) at a location upstream of an outlet (<NUM>) of the vent conduit (<NUM>, <NUM>) and downstream of the component, the hydrogen sensor (115a) operable to sense at that location one or both of: presence of hydrogen and concentration of hydrogen; and
a controller (<NUM>, <NUM>) configured to control the component as a function of signals received from the hydrogen sensors.