Patent Description:
Fuel storage tanks typically have a diffuser fitted to the inlet through which fuel is delivered into the tank. The function of the diffuser is to reduce the speed of the fuel entering the fuel tank during filling of the fuel tank, which in turn reduces static build up, reduces the creation of fuel vapour, and also reduces foaming effects. The flammability of the fuel tank is thereby lower than it would be if the diffuser was not present.

For aircraft applications it is desirable to pressure test fuel delivery pipework which connects a fuel source to the inlet, after it has been fully assembled and connected to the inlet. The presence of the diffuser over the inlet creates difficulties in accessing the inlet in order to block it off to enable such pressure testing. Conventionally, to test the pipework immediately upstream of the fuel tank inlet the diffuser must be removed and then refitted after the testing, which adds significant time to the assembly process. <CIT> describes an in-tank fuel pump assembly and mounting system. <CIT> describes a fuel system for an automobile which has electronic control. <CIT> describes an apparatus and method for testing an aircraft tank system. <CIT> discloses a cyclonic ice separator for low temperature jet fuels.

A first aspect of the present invention provides a fuel system for an aircraft according to claim <NUM>. The fuel system comprises a fuel tank for storing fuel during operation of the aircraft and a diffuser disposed inside the fuel tank. The diffuser is configured such that it forms part of a flow path configured to connect a fuel source to the inside of the fuel tank. The diffuser comprises a wall which at least partially defines an internal space of the diffuser; an opening in the wall, which provides access to the internal space; and a blocking component configured to block the opening.

Optionally, the blocking component is removably engaged with the wall.

Optionally, the fuel system further comprises a locking member configured to engage with the blocking component and the wall to prevent disengagement of the blocking component and the wall.

Optionally, the blocking component and the wall each comprise mutually interlocking features configured to be interlockable to retain the blocking component on the wall.

Optionally, the fuel system further comprises a seal element between the blocking component and the wall, the seal element being configured to prevent fuel flowing through the opening.

Optionally, the opening is configured to be engageable with at least two different types of blocking component.

Optionally, the fuel system further comprises a fuel delivery apparatus which forms a further part of the flow path. A first end of the fuel delivery apparatus is connectable to the fuel source and a second end of the fuel delivery apparatus is connected to the diffuser.

Optionally, the fuel tank is formed by structural components of an aircraft.

Optionally, the fuel tank is formed by a wing box of an aircraft.

The blocking component is a test blocking component, and is configured to block the flow path so as to prevent fuel flowing into the fuel tank.

The diffuser comprises an outlet through which fuel flows into the internal space of the diffuser during a process of delivering fuel into the fuel tank, and the test blocking component comprises a seal member configured to block the outlet.

Optionally, the seal member is configured to create a pressure-tight seal against the outlet.

Optionally, the test blocking component comprises a port configured to be engageable with a pressure test device such that the pressure test device is able to measure the pressure in the flow path upstream of the test blocking component when engaged with the port.

Optionally, the blocking component is an operational blocking component, and is configured to permit fuel from the fuel source to flow into the fuel tank through the diffuser when the operational blocking component is engaged with the opening.

A second aspect of the invention provides a kit of parts according to claim <NUM>. The kit of parts comprises a fuel tank, a diffuser, a test blocking component, and an operational blocking component. The fuel tank has an inlet through which fuel can flow into the fuel tank. The diffuser is disposed inside the fuel tank, is connected to the inlet, and comprises a wall which defines an opening and which is configured to be engageable with a blocking component. The test blocking component configured to engage with the wall to block the opening, and to prevent fuel from a fuel source connected to the inlet from flowing into the fuel tank when the test blocking component is engaged with the wall. The operational blocking component configured to engage with the wall to block the opening, and to permit fuel from a fuel source connected to the inlet to flow into the fuel tank when the operational blocking component is engaged with the opening.

Optionally, the kit of parts further comprises a locking component configured to engage with the operational blocking component and the wall when the operational blocking component is engaged with the wall, such that disengagement of the operational blocking component and the wall is prevented.

Optionally, the kit of parts is configured to form a fuel system according to the first aspect when assembled.

A third aspect of the invention provides an aircraft comprising a fuel system according to the first aspect when the blocking component is an operational blocking component.

A fourth aspect of the invention provides a method for use in manufacturing an aircraft according to claim <NUM>. The method comprises:.

Optionally, the method further comprises, after replacing the test blocking component with the operational blocking component; assembling the fuel tank component into a fuel tank.

Each example fuel system described herein is suitable for use on an aircraft, and comprises a fuel tank for storing fuel during operation of the aircraft and a diffuser. The diffuser is disposed inside the fuel tank and is configured such that the diffuser forms part of a flow path configured to connect a fuel source to the inside of the fuel tank. The diffuser comprises a wall which at least partially defines an internal space of the diffuser; an opening in the wall which provides access to the internal space; and a blocking component configured to block the opening.

The opening in the wall of the diffuser advantageously enables access to an inlet of the fuel tank whilst the diffuser is fitted. This allows the inlet to be blocked, so that pipework upstream of the inlet can be pressure tested, without needing to remove the diffuser. The blocking component is configured to be simple and quick to install over the opening, such that a process of installing the blocking component on the diffuser is significantly faster than removing and reinstalling the diffuser. Assembly time for an aircraft having a fuel system according to the invention is therefore reduced.

<FIG> shows an example fuel system <NUM> according to the invention. The fuel system <NUM> is for use on an aircraft. The fuel system <NUM> comprises a fuel tank <NUM> for storing fuel during operation of an aircraft on which the fuel system <NUM> is installed. The fuel tank <NUM> is configured to store a liquid fuel, and is shown partially filled with liquid fuel <NUM>. The ullage space <NUM> of the fuel tank <NUM> is filled with a gas (such as air or an inert gas). The fuel tank <NUM> may be formed by structural components of an aircraft. In such examples one or more walls of the fuel tank <NUM> may be formed by a wing rib, a wing skin panel, a spar, or any other structural component of a wing. In some examples the fuel tank <NUM> is formed by a wing box of an aircraft. The fuel tank comprises one or more outlets (not shown) through which fuel is delivered to engines of the aircraft.

The fuel system <NUM> further comprises a diffuser <NUM> disposed inside the fuel tank <NUM>. The diffuser <NUM> is configured and located such that the diffuser forms part of a flow path configured to connect a fuel source to the inside of the fuel tank <NUM>. The diffuser <NUM> is located near the bottom of the fuel tank <NUM>. The direction of flow of fuel into the fuel tank <NUM> through the diffuser <NUM> is indicated by the block arrows. In particular, the diffuser <NUM> is disposed on (or in) an inlet <NUM> of the fuel tank <NUM>. In some examples, the diffuser <NUM> is connected to (that is, it is in fluid communication with) a fuel delivery pipeline (not shown) which extends between the inlet <NUM> and a fuel source (or a port to which a fuel source is connectable). <FIG> and <FIG> show the diffuser <NUM> in more detail, in isolation from the fuel tank <NUM>.

<FIG> and <FIG> are cross-sections through the diffuser <NUM>. <FIG> shows the diffuser <NUM> in a test configuration suitable for pressure testing refuelling pipework connected to the fuel system <NUM>. <FIG> shows the diffuser <NUM> in an operational configuration, suitable for operation of an aircraft on which the fuel system <NUM> is installed. The illustrated diffuser <NUM> comprises a cuboidal body member formed by five walls, which together define an internal space <NUM> of the body member. The lower side (with respect to the orientation showing in Figuresla-c) of the body member is open. A pipe <NUM>, which is configured to sealingly connect to fuel delivery pipework, extends through one wall of the body member into the internal space <NUM> of the body member. The end of the pipe <NUM> which is disposed of within the internal space <NUM> is open, to allow fuel to enter the internal space <NUM> of the diffuser <NUM> through the pipe <NUM>. The open end of the pipe <NUM> is therefore an outlet through which fuel flows into the internal space <NUM> of the diffuser <NUM> during a process of delivering fuel into the fuel tank <NUM>.

An opening <NUM> is provided in a wall <NUM> of the body member. The wall <NUM> is opposite the wall through which the pipe <NUM> extends. The opening <NUM> provides access to the internal space <NUM>. The location of the opening <NUM> is such that the opening <NUM> provides access to the open end of the pipe <NUM>. In the illustrated example the opening <NUM> is substantially coaxial with the pipe <NUM>. The opening <NUM> is at least as large as an internal diameter of the pipe <NUM>, and may be significantly larger (as is the case in the illustrated example). The opening <NUM> may be (but need not be) circular. The opening <NUM> is configured to be engageable with at least two different types of blocking component, each of which is configured to block the opening <NUM>.

The diffuser <NUM> further comprises a blocking component 12a, 12b configured to block the opening <NUM>. The blocking component may be either a test blocking component 12a or an operational blocking component 12b, as will be explained below with reference to <FIG> and <FIG>. The blocking component 12a, 12b is removably engaged with the wall <NUM> of the diffuser <NUM>. In some examples the blocking component 12a, 12b is removably engaged with the pipe <NUM>. In some examples the blocking component 12a, 12b and the wall <NUM> each comprise mutually interlocking features configured to be interlockable to retain the blocking component 12a, 12b on the wall <NUM>. In some examples the engagement mechanism is configured such that the blocking component 12a, 12b can be engaged with the wall <NUM> and disengaged from the wall <NUM> manually by an operator without the use of any tools.

<FIG> show two alternative engagement mechanisms by which a blocking component can be removably engaged with a wall of a diffuser according to the invention. The illustrated diffuser walls 211a, 211b each have the same general features as the diffuser wall <NUM> described above. The illustrated blocking components 22a, 22b are test blocking components which each have substantially the same features as the example test blocking component 12a. However; the engagement mechanisms illustrated by <FIG> may equally be applied to an operational blocking component such as the example operational blocking component 12b.

The example engagement mechanism shown in <FIG> is based on a screw thread. In this example the diffuser wall 211a comprises a cylindrical rim 215a which extends perpendicularly from the outer face of the wall 211a. The rim 215a encircles the opening <NUM>, and in this example is coaxial with the opening <NUM>. The diameter of the rim 215a is greater than the diameter of the opening <NUM>. A screw thread <NUM> is provided on the inner surface of the rim 215a. A corresponding screw thread <NUM> is provided on an outer circumferential surface of a plate part 221a of the blocking component 22a. The plate part 221a is configured such that the outer circumferential surface on which the screw thread <NUM> is provided is disposed adjacent the inner surface of the rim 215a when the blocking component 22a is engaged with the wall 211a.

The blocking component 22a may therefore be engaged with the wall 211a by arranging the blocking component 22a to be coaxial with the rim 215a such that the screw threads <NUM>, <NUM> are in contact, and then rotating the blocking component 22a relative to the wall 211a in a direction such that the interaction of the screw threads <NUM>, <NUM> drives the blocking component 22a towards the wall 211a. The rotation may be continued until the blocking component 22a is in contact with the wall 211a. A "handle" feature 224a protrudes from the outer surface of the plate part 221a to facilitate rotation of the blocking component 22a by an operator. The handle feature 224a may be configured to be easily graspable by a hand, such that the use of a tool is not required to engage the blocking component 22a with the wall 211a.

The example engagement mechanism shown in <FIG> is a bayonet-style engagement mechanism. Part (i) is a cross-section through the blocking component 22b and the wall 211b in an engaged arrangement, part (ii) is a view of the rim 215b along an axial direction of the rim, and part (iii) is a view of the outer surface of a plate part 221b of the blocking component 22b, along an axial direction of the blocking component 22b. In this example the diffuser wall 211b comprises a cylindrical rim 215b which extends perpendicularly from the outer face of the wall 211a. The rim 215b has substantially the same features as the rim 215a of the <FIG> example, except that instead of a screw thread it comprises four radially-extending tabs <NUM> that protrude inwardly from a distal end of the rim 215b. In the illustrated example the tabs <NUM> are equally distributed around the rim 215b, with an angular separation of <NUM>° between adjacent tabs, although this may be different in other examples.

A plate part 221b of the blocking component 22b comprises four recesses <NUM>, the configurations and locations of which correspond to the configurations and locations of the tabs <NUM>. When the blocking component 22b and the rim 215b are coaxial and relatively oriented such that the tabs <NUM> and recesses <NUM> are aligned (as is the case in parts (ii) and (iii) of <FIG>), the plate part 221b of the blocking component 22b may be received within the recess defined by the rim <NUM> such that the plate part 221b is in contact with the outer surface of the wall 211b.

The blocking component 22b may therefore be engaged with the wall 211b by arranging the blocking component 22b to be coaxial with the rim 215b, at a rotational position relative to the rim 215b such that the recesses <NUM> are aligned with the tabs <NUM>. The blocking component 22b is then moved axially toward the wall 211b until the plate part 221b contacts the outer surface of the wall 211b. The blocking component 22b is then rotated by between <NUM>° and <NUM>° relative to the wall 211b, such that the recesses <NUM> are no longer aligned with the tabs <NUM>. This is the state shown in part (i) of <FIG>. It can be seen from part (i) of <FIG> that, in this non-aligned state, the tabs <NUM> act to prevent the blocking component 22b from moving axially away from the wall 211b. The blocking component 22b comprises a handle feature 224b having substantially the same features as the handle feature 224a, to facilitate rotation of the blocking component 22a by an operator.

Returning to <FIG>, in some examples the fuel system <NUM> comprises a locking member which is configured to engage with the blocking component 12a, 12b and with the wall <NUM> in order to prevent disengagement of the blocking component 12a, 12b from the wall <NUM>. In some examples the fuel system <NUM> comprises multiple such locking members. The locking member may take any suitable form known in the art.

<FIG> shows a particular example locking member <NUM> suitable for use with the fuel system <NUM>, retaining a blocking component <NUM> on a wall <NUM> of a diffuser. The illustrated diffuser wall <NUM> has the same general features as the diffuser wall <NUM> described above. The illustrated blocking component <NUM> is an operational blocking component which has substantially the same features as the example operational blocking component 12b. However; the locking member <NUM> may equally be applied to a test blocking component such as the example test blocking component 12a.

The illustrated example locking member <NUM> comprises a bolt <NUM> engaged with a nut <NUM>. The stem of the bolt <NUM> extends through the blocking component <NUM> and the wall <NUM>. The nut <NUM> is retained on the inner surface of the wall <NUM> by any suitable mechanism. In other examples the hole in the wall through which the stem of the bolt <NUM> extends is threaded, in which case the nut <NUM> is omitted. The locking member <NUM> may be installed such that the blocking component <NUM> is clamped against the wall <NUM>. The locking member <NUM> functions to prevent movement of the blocking component <NUM> relative to the wall <NUM>. In some examples more than one such locking member <NUM> may be engaged with the blocking component <NUM> and the wall <NUM>. This may facilitate preventing the blocking component <NUM> from rotating relative to the wall <NUM>.

Returning to <FIG>, in <FIG> a first type of blocking component 12a is disposed on the wall <NUM> of the diffuser <NUM> and is blocking the opening <NUM>. The first type of blocking component 12a is a test blocking component which is configured to block the flow path of fuel into the fuel tank <NUM>. The test blocking component 12a thereby prevents fuel from flowing into the fuel tank <NUM> when it is installed on the diffuser <NUM>. In the illustrated example the test blocking component 12a achieves blocking the flow path by having a seal member <NUM> which is configured to block an outlet of the diffuser <NUM> (which in the illustrated example is the open end of the pipe <NUM>).

As well as the seal member <NUM>, the test blocking component 12a also comprises a plate member <NUM> which is configured to block the opening <NUM>. The seal member <NUM> and the plate member <NUM> are integrally formed. The plate member <NUM> is configured to be disposed on an outer surface of the wall <NUM> and to completely cover the opening <NUM>. The outer surface of the plate member <NUM> may comprise one or more features (not shown) configured to enable the test blocking component 12a to be easily grasped and manipulated by an operator.

The plate member <NUM> is configured to removably engage with the wall <NUM> to retain the test blocking component in a desired position relative to the wall <NUM>. For example, the engagement between the plate member <NUM> and the wall <NUM> may be configured to resist axial movement of the test blocking component 12a relative to the wall <NUM> even in the face of a force acting to drive the test blocking component 12a away from the wall <NUM>. Such an engagement thereby ensures that the test blocking component 12a blocks the outlet of the pipe <NUM> even when the inside of the pipe is pressurised to a high pressure, as occurs during pressure testing of fuel delivery pipework connected to the diffuser <NUM>. The engagement mechanism may take any suitable form, such as mutually interlocking features and/or one or more locking components, as described above.

The seal member <NUM> extends from an inner surface of the plate member <NUM> (that is, a surface which faces towards the internal space <NUM> of the diffuser <NUM>). The seal member <NUM> is configured to create a pressure-tight seal with the open end of the pipe <NUM>. The seal member <NUM> is generally cylindrical, and has an outer diameter equal to the inner diameter of the outlet of the pipe <NUM>. The seal member <NUM> is coaxial with the pipe <NUM> when the test blocking component 12a is installed on the diffuser <NUM>. The axial length of the seal member <NUM> is greater than the distance (along the axial direction of the pipe <NUM>) between the outlet of the pipe <NUM> and the wall <NUM>. This means that the distal end of the seal member <NUM> extends into the pipe <NUM>. In some examples the seal member <NUM> is sized such that it is an interference fit in the pipe <NUM>.

In other examples the seal member <NUM> may have a different configuration to that shown in <FIG>. Indeed, any configuration which enables a pressure-tight seal between the seal member <NUM> and the open end of the pipe <NUM> to be achieved may be used. In one such alternative example the distal end of the seal member <NUM> comprises an axially extending cylindrical recess, the inner diameter of which is equal to the outer diameter of the open end of the pipe <NUM>. In that example the open end of the pipe <NUM> is received within the recess, and an outer surface of the pipe <NUM> is in close contact with an inner surface of the recess to create a seal.

In some examples an additional sealing component is provided between the seal member and the pipe to facilitate the achievement of a pressure-tight seal between the seal member <NUM> and the pipe when the test blocking component 12a is installed on the diffuser <NUM>. In examples where the seal member has the configuration shown in <FIG>, such an additional sealing component is provided between the outer surface of the seal member and the inner surface of the pipe <NUM>. The additional sealing component may be retained on the seal member, by any suitable mechanism. The additional sealing component may take any suitable form known in the art, such as a ring of impermeable resilient material.

An example test blocking component <NUM> comprising an additional sealing component <NUM> is shown in <FIG>. Apart from the additional sealing component <NUM> the test blocking component <NUM> is substantially identical to the test blocking component 12a of <FIG>. The test blocking component <NUM> is shown in an operational state in which it is blocking the open end of the pipe <NUM> of the diffuser <NUM>. The rest of the diffuser <NUM> is omitted from <FIG>. In this example the additional sealing component <NUM> is a resilient ring member which is bonded to the outer surface of a distal end of a seal member <NUM> of the test blocking component <NUM>. The resilient ring member <NUM> may be formed from any suitable material such as rubber or an elastomer. In some examples at least the outer surface of the resilient ring member <NUM> may be formed from a low-friction material to facilitate insertion of the seal member <NUM> into the open end of the pipe <NUM>.

Returning to <FIG>, in some examples the test blocking component 12a comprises a port configured to be engageable with a pressure test device such that the pressure test device is able to measure the pressure in the flow path upstream of the test blocking component 12a when engaged with the port.

<FIG> shows an example test blocking component <NUM> which comprises a pressure test port <NUM>. Part (i) is an axial view which shows an outer face of a plate member <NUM> of the test blocking component <NUM>, and part (ii) is a cross-section through the test blocking component <NUM> engaged with the diffuser pipe <NUM> (the rest of the diffuser is omitted for clarity). Apart from the pressure test port <NUM>, the example test blocking component <NUM> is substantially identical to the example test blocking component 12a of <FIG>. The pressure test port <NUM> comprises a bore which extends axially through the test blocking component <NUM> from the outer surface of the plate member <NUM> to the distal end of the blocking member <NUM>. The opening <NUM> of the bore where it meets the outer surface of the plate member <NUM> is configured to be engageable with a pressure test device (not shown) that is configured to measure a pressure within a sealed volume. In particular, the pressure test device is configured to measure the pressure within fuel delivery pipework upstream of and including the diffuser pipe <NUM>.

The pressure test port <NUM> is engageable with the pressure test device such that a pressure tight seal is formed between the port <NUM> and the pressure test device when the pressure test device is engaged with the port <NUM>. Such engagement may be achieved by means of cooperating features provided on the port opening <NUM> and the pressure test device, such as corresponding screw threads. In some examples the port opening <NUM> may comprise a seal element of any suitable type to facilitate the achievement of a pressure tight seal between the port <NUM> and the pressure test device.

Returning to <FIG>, in <FIG> a second type of blocking component 12b is disposed on the wall <NUM> of the diffuser <NUM> and is blocking the opening <NUM>. The second type of blocking component 12b is an operational blocking component which is configured to permit fuel from a fuel source connected to the inlet of the fuel tank <NUM> to flow into the fuel tank <NUM> when the operational blocking component 12b is installed on the diffuser <NUM>. The operational blocking component 12b achieves this by blocking the opening <NUM> without blocking the open end of the pipe <NUM>.

The operational blocking component 12b is in the form of a plate or cover, which is configured to block the opening <NUM>. The operational blocking component 12b is configured to be disposed on an outer surface of the wall <NUM> and to completely cover the opening <NUM>. The outer surface of the operational blocking component 12b may comprise one or more features (not shown) configured to enable the operational blocking component 12b to be grasped and manipulated by an operator. The operational blocking component 12b is removably engaged with the wall <NUM>. The engagement mechanism may take any suitable form, such as mutually interlocking features and/or one or more locking components, as described above.

The operational blocking component 12b may have substantially the same configuration as the plate member <NUM> of the test blocking component 12a. This enables the same engagement mechanism to be used to retain the operational blocking component 12b on the wall <NUM> as is used to retain the test blocking component 12a on the wall <NUM>. The operational blocking component 12b and the test blocking component 12a may thereby be readily interchangeable on the diffuser <NUM>.

In some examples a seal element is disposed between the operational blocking component 12b and the outer surface of the wall <NUM>. The seal element is configured to prevent fuel from flowing through the opening <NUM>. The seal element may be attached by any suitable mechanism to the outer surface of the wall <NUM> or to the inner surface of the operational blocking component 12b. The seal element may be a face seal. The seal element may take any suitable form known in the art, such as a ring of impermeable resilient material.

An example operational blocking component <NUM> comprising a seal element <NUM> is shown in <FIG>. Apart from the seal element, the operational blocking component <NUM> is substantially identical to the operational blocking component 12b of <FIG>. The operational blocking component <NUM> is shown in an operational state in which it is blocking the opening <NUM> in the wall <NUM> of the diffuser <NUM>. The rest of the diffuser <NUM> is omitted from <FIG>. In this example the seal element <NUM> is a resilient ring member which is bonded to the inner surface of the operational blocking component <NUM>. The resilient ring member <NUM> may be formed from any suitable material such as rubber or an elastomer.

In some examples the fuel system <NUM> of <FIG> comprises a fuel delivery apparatus which forms a further part of the flow path that is configured to connect a fuel source to the inside of the tank <NUM>. <FIG> shows such an example fuel system <NUM>. The fuel system <NUM> comprises the fuel tank <NUM> and diffuser <NUM>, as well as a fuel delivery pipe <NUM>. The fuel tank <NUM> is shown in an empty state in <FIG>. Although the fuel delivery pipe <NUM> is shown as a single straight pipe section for ease of depiction, it may more usually comprise multiple pipe sections. The fuel delivery pipe <NUM> may comprise one or more joints, bends, intersections, or the like. The fuel delivery pipe <NUM> may comprise or be connected to one or more fuel delivery-related devices such as pumps, valves, filters or the like.

A first end <NUM> of the fuel delivery pipe <NUM> is sealingly connected to the pipe <NUM> of the diffuser by a connector <NUM>. The connector <NUM> may be of any suitable design. Other examples are possible in which at least a part of the fuel delivery pipe <NUM> is formed integrally with the diffuser pipe <NUM>. A second end <NUM> of the fuel delivery pipe <NUM> is connected or connectable to a fuel source <NUM> (represented by a block arrow in <FIG>). For example, the second end <NUM> may be connectable to a refuelling port of the aircraft, or a further fuel tank of the aircraft. The second end <NUM> may comprise a connector suitable for forming the connection to the fuel source <NUM>. Fuel <NUM> which has flowed along the fuel delivery pipe <NUM> from the fuel source <NUM> to the diffuser <NUM> is shown entering the fuel tank <NUM> in the form of block arrows.

<FIG> shows a kit of parts <NUM> which is configured to form a fuel system according to the invention, such as the example fuel system <NUM> of <FIG>. The kit of parts <NUM> comprises a fuel tank <NUM>; a diffuser <NUM>; a test blocking component 82a; and an operational blocking component 82b. The test blocking component 82a and the operational blocking component 82b are interchangeably engageable with a wall <NUM> of the diffuser <NUM>. <FIG> shows the fuel tank <NUM> and diffuser <NUM> in cross-section, where the plane of the cross-section is parallel to an open side of the diffuser <NUM>. The fuel tank <NUM> has an inlet <NUM> through which fuel can flow into the fuel tank <NUM>, and the diffuser <NUM> is disposed inside the fuel tank and connected to the inlet <NUM>.

The diffuser <NUM> comprises a wall <NUM> which defines an opening <NUM> and which is configured to be engageable with the test blocking component 82a and also with the operational blocking component 82b. The test blocking component 82a is configured to engage with the wall <NUM> to block the opening <NUM> and is configured to prevent fuel from a fuel source connected to the inlet <NUM> from flowing into the fuel tank <NUM> when the test blocking component 82a is engaged with the wall <NUM>. The operational blocking component 82b is configured to permit fuel from a fuel source connected to the inlet <NUM> to flow into the fuel tank <NUM> when the operational blocking component 82b is engaged with the opening <NUM>. The components of the kit of parts <NUM> have the same features as the corresponding components of the fuel system <NUM> described above.

In some examples the kit of parts further comprises a locking component <NUM> configured to engage with the operational blocking component 82b and with the wall <NUM> when the operational blocking component 82b is engaged with the wall <NUM>, such that disengagement of the operational blocking component 82b and the wall <NUM> is prevented by the locking component <NUM>. The locking component may, in some examples, also be configured to engage with the test blocking component 82a and with the wall <NUM> when the test blocking component 82a is engaged with the wall <NUM>, such that disengagement of the test blocking component 82a and the wall <NUM> is prevented by the locking component <NUM>. The locking component <NUM> has the same features as the example locking component <NUM> of <FIG>. In some examples the kit of parts may comprise multiple locking components <NUM>.

<FIG> is a flow chart which illustrates a method <NUM> for use in manufacturing an aircraft. Performing the method results in the creation of a fuel system according to the invention, such as either of the example fuel systems <NUM>, <NUM> described above. In some examples the method may comprise assembling a kit of parts according to the invention, such as the example kit of parts <NUM> described above. The method may be performed as part of a process of testing a fuel system of the aircraft which is being manufactured.

A first block <NUM> of the method <NUM> comprises providing a fuel tank component configured to form at least part of an aircraft fuel tank. The fuel tank component may be suitable for forming at least part of a fuel tank having the features of the example fuel tank <NUM> or the example fuel tank <NUM> described above. The fuel tank component may comprise one or more structural components of the aircraft. In some examples, the fuel tank component comprises one or more structural wing components. In some examples the fuel tank component is provided already assembled into a fuel tank. In some such examples providing a fuel tank component may comprise providing an aircraft structure which forms a fuel tank, such as a wing box.

The fuel tank component is provided connected to a fuel delivery apparatus, which may have any of the features of the example fuel delivery apparatus of <FIG>. The fuel delivery apparatus is configured to define a flow path between a fuel source and the inside of the fuel tank of which the fuel tank component forms (or is intended to form) at least a part. The fuel delivery apparatus comprises a diffuser, which is intended to be disposed within the fuel tank. The diffuser may have the same features as the example diffuser <NUM> described above. The fuel delivery apparatus may further include one or more pipes; valves; connectors; or the like. The fuel delivery apparatus may comprise all components which define a flow path for fuel between a fuel source (such as a refuelling port of the aircraft) and the inside of the fuel tank.

In some examples performing block <NUM> may comprise connecting the fuel delivery apparatus to the fuel tank component. Connecting the fuel delivery apparatus to the fuel tank comprises forming a fluid-tight seal (in any suitable manner) between the fuel delivery apparatus and the fuel tank component. At the time of connecting the fuel delivery apparatus to the fuel tank component, the fuel tank component may not yet be connected to other fuel tank components, such that the fuel tank is in a non-assembled or a partially assembled state. In other examples performing block <NUM> comprises providing a pre-assembled fuel system, for example as part of a substantially complete aircraft wing structure which is in a condition to be joined to a fuselage structure.

In a second block <NUM>, a test blocking component is arranged on the diffuser such that the test blocking component blocks the flow path and prevents fluid flow between an internal space of the fuel delivery apparatus and the inside of the fuel tank of which the fuel tank component is to form a part. The test blocking component may have the same features as any of the example test blocking components 12a, 22a, 22b, <NUM>, <NUM>, 82b described above. The test blocking component is arranged on the diffuser in any manner suitable to the particular design of the test blocking component, such that the blocking function is achieved. For example arranging the test blocking component on the diffuser may comprise engaging the test blocking component with a wall of the diffuser, in any of the manners described above in relation to the example test blocking components 12a, 22a, 22b, <NUM>, <NUM>, 82a.

In a third block <NUM>, a pressure test of the fuel delivery apparatus is performed. In examples in which the fuel tank component is provided not assembled into a fuel tank, the pressure test is performed before the fuel tank component has been assembled into a fuel tank. This may be advantageous for enabling easy access to the fuel tank and fuel delivery apparatus for the purposes of performing the test and/or fixing any issues identified by the test. Alternatively, in examples in which the fuel tank component is provided already assembled into a fuel tank, the pressure test is performed when the fuel tank is in an assembled state. It may be desirable to perform the pressure test after the fuel tank has been assembled in case any damage has occurred to the fuel delivery system during the process of assembling the fuel tank.

The pressure test may be performed by a pressure test device. Performing the pressure test may comprise engaging such a pressure test device with a port comprised in the test blocking apparatus, as described above in relation to <FIG>. The pressure test may be performed in any suitable manner known in the art.

In block <NUM> the test blocking component is replaced with an operational blocking component which permits fluid flow between the internal space of the fuel delivery apparatus and the inside of the fuel tank. The operational blocking component may have the same features as any of the example operational blocking components 12b, <NUM>, <NUM>, 82b described above. Replacing the test blocking component with the operational blocking component comprises removing the test blocking component from the diffuser (for example by disengaging it from the wall of the diffuser in any suitable manner dependent on the nature of the engagement) and then arranging the operational blocking component on the diffuser.

The operational blocking component is arranged on the diffuser in any manner suitable to the particular design of the operational blocking component. For example arranging the operational blocking component on the diffuser may comprise engaging the operational blocking component with a wall of the diffuser, in any of the manners described above in relation to the example blocking components of <FIG>. The operational blocking component may be arranged on the diffuser sufficiently securely that it cannot become disengaged from the diffuser during normal operation of the aircraft.

Block <NUM> may be performed before the fuel tank component is assembled into a fuel tank. However; more typically it may be performed after the fuel tank component has been assembled into a fuel tank, since this enables pressure testing to be carried out at point during an aircraft assembly process when the risk of any damage being incurred by the fuel delivery apparatus is negligible. As mentioned above, the design of the diffuser and of the test and operational blocking components facilitates performing a pressure test in an assembled state of the fuel tank, since these items are configured such that the process of engaging and disengaging the test and operational blocking components with the diffuser is simple and easy to perform even with limited access.

In an optional fourth block <NUM> the fuel tank component is assembled into a fuel tank. Block <NUM> is only performed when the fuel tank component is provided in block <NUM> before it has been assembled into a fuel tank. Performing block <NUM> may comprise assembling an aircraft structure, such as a wing box, which forms all or part of the fuel tank. Upon completion of block <NUM> the fuel tank component may be comprised in a substantially fully assembled aircraft wing which is substantially ready to be joined to a fuselage of the aircraft.

<FIG> shows an example aircraft <NUM> comprising a fuel system according to the invention (such as the example fuel system <NUM> or the example fuel system <NUM> described above). The aircraft <NUM> comprises a fuselage <NUM>, a pair of wings 1002a and 1002b, a pair of engines 1003a and 1003b, and an empennage <NUM>.

The aircraft <NUM> comprises a plurality of fuel tanks (not visible) and a fuel distribution system for transporting fuel from the tanks to the engines 1003a, 1003b. For example, the fuel tanks may comprise sealed compartments at least partly formed by the structure of the wings 1002a, 1002b, the empennage <NUM>, and/or the fuselage <NUM>, and/or any other part of the aircraft <NUM>. The aircraft <NUM> further comprises a refuelling port (not visible) and fuel delivery apparatus (not visible) configured to provide a flow path for fuel between the refuelling port and one or more of the fuel tanks. An inlet of each fuel tank may be connected to the fuel delivery apparatus, and a diffuser within each fuel tank may be connected to the inlet of that fuel tank. At least some of the diffusers on the aircraft have the same general features as the example diffuser <NUM>, and these diffusers in combination with the fuel tanks in which they are located form fuel systems according to the invention.

In particular, each fuel tank which is formed by the structure of one of the wings 1002a, 1002b comprises a diffuser having the same general features as the diffuser <NUM>. Each wing 1002a, 1002b therefore comprises a fuel system according to the invention. Each wing tank fuel system according to the invention may have been manufactured according to the example method <NUM> described above.

Although the invention has been described above with reference to one or more preferred examples or embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claim 1:
A fuel system (<NUM>) for an aircraft, comprising:
a fuel tank (<NUM>) for storing fuel during operation of the aircraft; and
a diffuser (<NUM>) disposed inside the fuel tank (<NUM>) and configured such that the diffuser (<NUM>) forms part of a flow path configured to connect a fuel source to the inside of the fuel tank (<NUM>);
wherein the diffuser (<NUM>) comprises:
a wall (<NUM>) which at least partially defines an internal space (<NUM>) of the diffuser (<NUM>) ;
an opening (<NUM>) in the wall (<NUM>), which provides access to the internal space (<NUM>); and
a blocking component (12a) configured to block the opening (<NUM>),
the blocking component (12a) is a test blocking component, and is configured to block the flow path so as to prevent fuel flowing into the fuel tank (<NUM>);
and wherein the diffuser (<NUM>) comprises an outlet through which fuel flows into the internal space (<NUM>) of the diffuser (<NUM>) during a process of delivering fuel into the fuel tank (<NUM>), and wherein the test blocking component (12a) comprises a seal member (<NUM>) configured to block the outlet.