Patent Description:
Aircraft wings extend spanwise from a root end nearest the fuselage to a tip end. The wing has an upper wing cover having an upper aerodynamic surface, a lower wing cover having a lower aerodynamic surface, a leading edge and a trailing edge. Internally the wing is typically configured to provide a fuel carrying volume. A plurality of ribs extend generally chordwise between a front spar and a rear spar, the front and rear spars extending generally spanwise. The ribs are coupled to the spars and the covers to create a 'wing box' structure which is the main load bearing structure of the wing. The ribs may also be used to segment the fuel carrying volume of the wing into different bays. Stringers, or longitudinal reinforcing members, extend generally spanwise along the length of the wing on the interior side of the upper and lower wing covers and pass through 'mouseholes' in the ribs or rib feet. Fuel may freely move through the mouseholes in the rib into the neighbouring bay, or the mousehole may be sealed to prevent the flow of fuel. In order to accommodate potential geometrical variations of the aircraft component shapes or dimensions the mouseholes are necessarily fairly large.

A 'dry bay' may be located within the wing directly above the engine/pylon for an aircraft with under-wing mounted engines. The dry bay does not contain any fuel and is a safety mechanism in case of engine failure, e.g. a rotor disk burst. However, the dry bay shares at least one rib with an adjacent fuel bay. Therefore, a number of mouseholes need to be sealed to prevent fuel leaking into the dry bay and keep the dry bay 'dry'.

Sealing the dry bay presents a number of challenges, as it has a large number of complex joints to the rest of the wing. Due to the difficulty of gaining access to the area within the assembled wing, reliable sealing of the dry bay mouseholes is particularly difficult. Furthermore, the gaps between the mouseholes and the stringers is very large, the shape of the stringer is not simple and dry bay rib mouseholes are obliquely angled with the dry bay rib, which provide further sealing challenges. Accordingly, providing a repeatable and effective solution to reliably seal each the dry bay rib mousehole can be difficult to achieve. Existing solutions for sealing rib mouseholes include attaching a metal cleat over the stringer and fastening to the adjacent wing cover and rib at the mousehole location, and filling the cleat with pieces of flexible open-cell polyurethane foam filled with curable sealant. The foam parts are custom trimmed for each location, and so are costly to procure and time consuming to assemble to achieve the required high level of fluid tightness. "BEAM SHOE" (retrieved from the Internet. URL: https://www. itwconstruction. ee/en/Connectors/Beam-Shoe_fBALTIC_219233. htm) shows beam shoes. <CIT> describes an apparatus comprising an elongated structure, a first plate, and a second plate. The elongated structure has a channel. The elongated structure is configured to be associated with a primary structure on a first side of the primary structure. <CIT> describes baffle fuel dams and tank boundary fuel dams having a single-piece or two-piece construction. <CIT> describes a sealing tool for sealing a stringer-receiving opening in an aircraft rib. The sealing tool includes a seal member arranged to seal a gap formed by the opening between the stringer and the rib. <CIT>, <CIT> disclose rib foot cleats and sealing methods.

According to an aspect of the invention, there is provided a rib foot cleat for sealing around a stringer passing through a rib mousehole in an aircraft assembly, according to claim <NUM>.

A cleat is a component fastened to support and hold something in position. A rib is a chordwise extending structural component of an aircraft wing. A rib mousehole is a hole in an edge of a rib. A stringer is a longitudinal reinforcing member. Here, the rib foot cleat is positioned over a stringer and is attached to the rib where the stringer passes through the rib mousehole, and is used to support and hold the sealant in place to seal around the stringer.

The channel lip may optimise the amount of sealant required to fully seal the joint. The channel lip may guide any excess sealant that may otherwise protrude from the first and/or second channel opening rim and be guided towards the stringer.

The channel lip may be made of sealant. The channel lip may be made of a curable material.

The channel lip may be of the same material as the injected sealant to create a seal. The injected sealant may be curable to the channel lip.

The channel lip may be made of silicone, polyurethane, polysulphide or silane-modified polymer.

The channel lip may be made of closed cell foam.

The rib foot cleat may comprise a first attachment flange for attaching the cleat body to the rib, and/or a second attachment flange for attaching the cleat body to a foot of the stringer.

A further aspect of the invention provides an aircraft assembly, comprising a stringer reinforced cover and a rib having a mousehole with the stringer passing through the mousehole in the rib, and a rib foot cleat according to the first aspect arranged over the stringer at the rib mousehole and with cured sealant material inside the rib foot cleat which seals around the stringer passing through the rib mousehole.

The rib may have a plurality of mouseholes each having a respective stringer passing through, and a respective rib foot cleat with cured sealant material which seals around the respective stringer passing through the respective rib mousehole.

The rib may form a fuel tank boundary and the rib foot cleat and sealant may form a fluid-tight seal.

The injected sealant may fully seal one side of the rib from the other.

The rib may form a boundary between a fuel tank and a dry bay, or between a fuel tank and another fuel tank.

In a further aspect of the invention there is provided a method a method of sealing around a stringer passing through a rib mousehole in an aircraft assembly, by providing a rib and a stringer extending through a mousehole of the rib, arranging a rib foot cleat according to the first aspect over the stringer, attaching the rib foot cleat to the rib; injecting sealant through the injection hole in the rib foot cleat to fill a gap between the cleat channel and the stringer with sealant so as to seal the gap.

Holes may be drilled through the rib foot cleat and the rib after arranging the rib foot cleat over the stringer and before attaching the rib foot cleat to the rib.

The lip(s) may be formed after drilling off the holes in the rib foot cleat and before the rib foot cleat is attached to the rib.

Drilling the holes in the rib foot cleat enables the rib foot cleat to be correctly positioned over the stringer before the sealant is injected. This provides a more effective seal as the rib foot cleat may be positioned centrally over the stringer, accommodating tolerances in the assembly.

The sealant may be injected in the injection hole by means of pneumatic assistance, preferably by a sealant gun.

This provides a fast and repeatable method of introducing the sealant into the rib foot cleat, reducing the time of manufacture and assembly.

The flow of injected sealant may be stopped when sealant escapes from the cleat channel.

Visually observing the sealant starting to escape provides an easy method of verifying when the sealant has completely filled the rib foot cleat, and therefore formed a reliable seal.

In a further aspect not of the invention, there is provided a tool for forming a lip on a rib foot cleat having a cleat body defining a cleat channel configured to be arranged over a stringer, and an attachment flange for attaching the cleat body to a rib, wherein the cleat channel is generally U-shaped and terminates at a first channel opening rim on one side of the cleat body and at a second channel opening rim on an opposite side of the cleat body, the tool comprising: a tool body configured to be placed against the cleat channel of the rib foot cleat, the tool body having at least one recess which extends at least partially around an interior of the cleat channel adjacent the first and/or second channel opening rim; and a locating feature for aligning the tool body against the cleat body of the rib foot cleat.

The tool body may comprise two respective recesses that extend around an interior of the cleat channel adjacent the respective first and second channel opening rim.

The tool may be collapsible. The tool body may be flexible to enable the collapsing of the tool. Alternatively the tool body may be more rigid and incorporate a hinge between tool body portions.

This enables the tool body to be removed easily from the rib foot cleat without damaging the formed channel lips.

The tool body may have at least one handle for manually collapsing the collapsible tool.

The tool may be made of nylon so that sealant does not adhere to the tool.

This allows the tool to be flexible while not promoting adhesion of the sealant to the tool itself. This encourages the channel lips to adhere to the rib foot cleat as opposed to the tool.

In a further aspect not of the invention, there is provided a method of forming a lip on a rib foot cleat having a cleat body defining a cleat channel configured to be arranged over a stringer, and an attachment flange for attaching the cleat body to a rib, wherein the cleat channel is generally U-shaped and terminates at a first channel opening rim on one side of the cleat body and at a second channel opening rim on an opposite side of the cleat body, the method comprising providing the tool, inserting the tool in the rib foot cleat such that the tool body is be placed against the cleat channel of the rib foot cleat; injecting sealant in the at least one recess of the tool body; curing the sealant and removing the tool.

<FIG> shows an aircraft <NUM> with starboard wing <NUM>, port wing <NUM>, fuselage <NUM>, a nose end <NUM> and a tail end <NUM>. The aircraft <NUM> is a typical jet passenger transonic transport aircraft but the invention is applicable to a wide variety of fixed wing aircraft types, including commercial, military, passenger, cargo, jet, propeller, general aviation etc. Each wing <NUM>,<NUM> has an upper and lower wing covers <NUM>, which are strengthened and stiffened by a plurality of stringers <NUM> which extend generally spanwise along the wing from the wing root near the fuselage to the wing tip. Internally the wing is configured to provide a fuel carrying volume.

A plurality of ribs <NUM> extend generally chordwise between a front spar and a rear spar (not shown), the front and rear spars extending generally spanwise. The ribs are coupled to the spars and the covers to create a 'wing box' structure which is the main load bearing structure of the wing. The ribs also segment the fuel carrying volume of the wing into different bays.

A 'dry bay' <NUM> is located adjacent and above an under-wing mounted main engine on the wing <NUM>. The dry bay does not contain fuel so that in the event of engine malfunction or failure, where components of the engine may directly impact the wing, no leak of fuel occurs. The dry bay is adjacent to at least one fuel tank bay in the wing. The port wing <NUM> is constructed similarly.

<FIG> shows a portion of an aircraft wing assembly <NUM> of the wing <NUM>, in particular the rib <NUM>, stringers <NUM>, lower wing cover <NUM> and rib mouseholes <NUM> through which the respective stringers <NUM> pass. The rib <NUM> forms a boundary between a fuel tank bay <NUM> and the dry bay <NUM>. Rib <NUM> extends generally perpendicular, vertically away from lower cover <NUM> and is connected to the lower cover at a lower end by rib feet and is connected to the upper cover at an upper end by rib feet (not shown). Rib <NUM> has a plurality of mouseholes <NUM> at the lower edge and a plurality of mouseholes at the upper edge (not shown). The rib mouseholes are formed in the rib to enable each of the stringers to pass though the rib without causing the requirement to fabricate any joints in the stringers.

Stringers <NUM> extend continuously through the respective rib mouseholes <NUM> of the rib <NUM>. The stringer profile in <FIG> is shown to be a 'Z' stringer, however, it will be understood that any number of stringer profiles may be used, such as omega, top-hat, C-shaped; or any other suitable design. The mouseholes are sized to closely match the profile of the stringer to minimise the gap between the stringer and the rib, whilst allowing a clearance.

Between at least some fuel bays, fuel may be allowed to move freely through the mouseholes in the rib. However between other fuel bays this may be undesirable, and between a fuel bay and the dry bay <NUM> the rib <NUM> must be sealed. This is achieved by sealing around the stringer <NUM> that passes through each mousehole <NUM>.

<FIG> shows the detail of an aircraft assembly <NUM> in which a rib foot cleat <NUM> is arranged over stringer 14a. In <FIG> the stringer 14a has a top hat profile different than the Z-shaped stringer <NUM> but any suitable stringer profile may be used. The rib foot cleat may be made of any suitable material, such as metal or a composite material. The rib foot cleat may be additively manufactured. <FIG> shows the rib foot cleat <NUM> alone for clarity.

The rib foot cleat <NUM> has a body <NUM> defining a cleat channel <NUM> configured to be arranged over the stringer 14a. The cleat body may have a bell-shaped, arched or roof portion extending over the cleat channel <NUM>. The rib foot cleat <NUM> is arranged on one side of the rib <NUM>, and is preferably on the inside of the dry bay <NUM>. However, two rib foot cleats <NUM> may be placed one on either side of one mousehole <NUM>.

The rib foot cleat body <NUM> has a first attachment flange <NUM> for attaching the cleat body to the rib <NUM>. A second attachment flange <NUM> extends perpendicular to the first attachment flange <NUM>. The second attachment flange is configured for attaching the cleat body to a foot of the stringer 14a and the wing cover <NUM>. The rib foot cleat body may be a unitary structure comprising the first and second attachment flanges <NUM>, <NUM> and the arched portion defining the cleat channel <NUM>. The second attachment flange <NUM> may be formed in two portions, one on either side of the cleat channel <NUM>. Each attachment flange <NUM>, <NUM> has a number of fastener holes <NUM>, used to secure the rib foot cleat <NUM> to the rib <NUM> and stringer 14a/cover <NUM> respectively.

The rib foot cleat channel <NUM> is U-shaped and terminates at a first channel opening rim 34a at one side of the cleat body <NUM> and a second channel opening rim 34b (shown in <FIG>) at the opposite side of the cleat body <NUM>. There is an injection hole <NUM> through the cleat body that is in fluid communication with the cleat channel <NUM> to allow sealant to be injected through the injection hole <NUM> in to the cleat channel <NUM> for sealing around the stringer 14a. The injection hole <NUM> may be formed in apex of the arched portion of the rib foot cleat body <NUM>. The injection hole may be formed by drilling or through any suitable method. It will be understood that the injection hole <NUM>, or a plurality of injection holes, may be positioned in any suitable area of the cleat body <NUM> so as to be placed in fluid communication with the cleat channel <NUM>. Preferably a single, apex located injection hole <NUM> is provided.

The rib foot cleat channel <NUM> is shown in <FIG> as being U-shaped and arranged over stringer 14a, which has a top-hat stringer profile. However, it will be understood that any suitable shape of stringer profile, such as C-shaped, Z-shaped; or any other suitable design may be used. The rib foot cleat channel <NUM> and rib foot body <NUM> may be sized and modified to closely match the profile of the stringer to minimise the gap between the stringer and rib foot cleat channel <NUM>, whilst permitting the rib foot cleat channel <NUM> to be placed over the stringer and for attachment of the rib foot cleat body <NUM> to the rib and to the foot of the stringer.

To prevent sealant escaping from the cleat body <NUM> through the channel opening rims 34a, 34b, the rib foot cleat <NUM> further includes a channel lip <NUM> (shown in <FIG>) that extends at least partially around the interior of the cleat channel <NUM> or adjacent to the first and/or second channel opening rim, 34a and 34b. The channel lip <NUM> is positioned in a way to act as a barrier between the channel body <NUM> and the external environment and preferably, to delimit the inserted sealant from exuding during the injection process. The channel lip <NUM> is preferably formed along the periphery of the channel rims 34a and 34b. However, it will be understood that a number of channel lip designs may be employed to seal a gap between the cleat body <NUM> and the stringer. For example, a single lip may be formed along the centre of the cleat body <NUM>, such that when sealant is injected, only one half of the cleat channel <NUM> is filled. Alternatively, the channel lips may be formed partially down the peripheral edges 34a and 34b, or from a set distance from the peripheral edge into the cleat channel.

Preferably, two channel lips <NUM> are formed adjacent to the respective first and second channel opening rim 34a and 34b. The channel lips are preferably formed before the rib foot cleat <NUM> is attached to rib <NUM> and stringer 14a. The channel lips may be formed from sealant. The lips may be made of any curable sealant, such as silicone, polyurethane, polysulphide, or silane-modified polymer. Preferably, the same material used for forming channel lips <NUM> is used to inject into the injection hole <NUM> and into the rib foot cleat channel <NUM>. The channel lips <NUM> are formed to guide the injected flow of sealant <NUM> in to the gap <NUM> so that it protrudes from the bottom of the rib foot cleat <NUM>, as shown in <FIG>, indicating that the injected sealant has completely filled the area between the stringer 14a and rib foot cleat body <NUM>.

The channel lips <NUM> shown in <FIG> are shown as being generally cuboid shaped with a rectangular cross-section. However, it will be understood that any suitable channel lip <NUM> shape may be formed within the rib foot cleat channel <NUM>. For example, the channel lips <NUM> may be formed with a triangular cross-section, with a base contacting and formed at least partially around the interior of the cleat channel <NUM> and an apex of the triangle extending into rib foot cleat channel <NUM>.

Alternatively, the channel lips <NUM> may be formed with a semi-circular cross section, with a base contacting and formed at least partially around the interior of the cleat channel <NUM> and a rounded peak extending into the rib foot cleat channel <NUM>.

When the channel lips <NUM> are formed with an apex or a rounded peak, the channel lips <NUM> are easier to detach from the tool <NUM> after curing (discussed further below) and compress more easily against the stringer. This enables the channel lips <NUM> to be manufactured easier and quicker. The channel lips <NUM> also conform to the profile of the stringer 14a better once the rib foot cleat body <NUM> is arranged over the stringer, improving the seal between the rib foot cleat and the stringer.

Alternatively, the channel lips <NUM> may be formed separately from the tool <NUM> and the rib foot cleat. The pre-formed channel lips <NUM> may then be adhered on to the rib foot cleat channel <NUM> using any suitable form of adhesion. The adhesive may be of the same material used to form the channel lips <NUM>.

Alternatively, the channel lips <NUM> may be formed by closed cell foam that is positioned within the rib cleat channel <NUM>. The closed cell foam may be positioned within the channel, or it may be adhered on to the walls of the channel <NUM>. The manufacturing and assembly time of the sealed mousehole may be reduced if closed foam is used for the channel lips, as less time may be required to adhere the closed cell foam than to form the channel lips of curable sealant.

<FIG> shows an exemplary tool <NUM> that is used to for forming the channel lips <NUM> from curable sealant material on the rib foot cleat <NUM>. As shown, the tool <NUM> has a profile that substantially corresponds to the profile of the rib foot cleat body <NUM>. As such, it will be understood that a number of profiles of tool <NUM> may be used, depending on the profile of the rib foot cleat body <NUM>. Tool <NUM> in <FIG> is shown as being substantially U-shaped in profile. The tool has two recesses 44a and 44b that correspond to the preferred positioning of the channel lips <NUM> along the first and second channel rim opening, 34a and 34b. These recesses extend at least partially along the interior of the cleat channel <NUM>, adjacent to the first and second channel opening rim, 34a and 34b. The tool <NUM> may alternatively only have one recess, or multiple recesses configured to correspond to the channel lips <NUM> that are to be formed on the rib foot cleat channel <NUM>.

The tool <NUM> shown in <FIG> has locating features <NUM> that are configured to support the rib foot cleat when positioned on the tool, as shown in <FIG>. Locating features <NUM> may be a protrusion used to support the first attachment flange <NUM> and/or the second attachment flange(s) <NUM>. Locating features <NUM> support the rib foot cleat <NUM> while channel lips <NUM> are being formed and (at least partially) cured, as described below. The features <NUM> may be temporarily clamped to the flange <NUM> by means of suitable spring c-clamps or similar to reduce the possibility of the tool from moving during the formation and the curing of the lips <NUM>.

Once the tool <NUM> is inserted into the rib foot cleat <NUM> (or vice versa), sealant is inserted, e.g. pasted or injected, into the recesses, 44a and 44b. Preferably, a nozzle with a narrow, preferably tapered tip is used to insert the sealant. The narrow tip ensures that once inserted, the nozzle can be used to insert the sealant into the bottom of recesses 44a and 44b (as shown in <FIG>). This ensures that the sealant is fully inserted in the recesses 44a and 44b and reduces the likelihood of air bubbles forming in the resulting channel lips <NUM>.

The shape of the recesses 44a and 44b can be modified depending on the desired final shape of the channel lips <NUM> to be formed. The resulting channel lips <NUM> are allowed to cure while the tool <NUM> remains supporting the rib foot cleat. This ensures the channel lips adhere to the rib foot cleat channel <NUM>. The channel lips <NUM> may be cured faster by heating channel lips <NUM> during the curing process. This is done by heating the tool <NUM> and the rib foot cleat after the sealant has been inserted into the recesses 44a and 44b. Any suitable form of heat treatment may be used. This reduces the time required to manufacture the channel lips <NUM>. Once the channel lips have cured, the tool <NUM> is removed.

As shown in <FIG>, tool <NUM> may have a flexible 'hinge' line <NUM> along the middle of the tool. Once the channel lips <NUM> have cured, the tool may be collapsed by rotating or flexing about line <NUM> to permit easy dismantling of the tool without disturbing the channel lips <NUM>. Tool <NUM> may further comprise handles <NUM> to help facilitate manually collapsing the tool within the rib foot cleat <NUM>. However, it well be understood that hinge line <NUM> may be at along any position of the tool to permit collapse. Any flexible, semi-rigid, or hinge jointed rigid construction of the tool body <NUM> that enables the tool the collapse about the rib foot cleat <NUM> to enables removal of the rib foot cleat after forming the channel lips <NUM> would be suitable.

The tool may be made of any material, such as metal or plastic, but preferably, the tool is manufactured by additive manufacturing. The tool may be made of ABS, PLA, PC but preferably, is made of nylon. Manufacturing the tool body <NUM> from nylon allows the sealant to be supported in position to cure, but does not encourage the sealant to adhere to the tool, thereby facilitating easy removal of the tool without requiring any undesirable release agent. The surface of the tool <NUM> may also be polished to further discourage the sealant from adhering to the tool. This may be done by any suitable method, such as heat treating or burnishing the tool to re-melt the surface of the tool after printing or rubbing the surface of the tool <NUM>.

A release agent may also be used on the tool <NUM> to further discourage the sealant adhering to the tool. The tool <NUM> may be coated with the release agent prior to forming the channel lips <NUM>. Preferably, once the channel lips <NUM> are formed, the tool <NUM> is cleaned to remove any residual release agent, before a new layer of release agent is coated on the tool. The release agent may be any suitable release agent, such as sodium alginate. <FIG> shows the rib foot cleat arrangement <NUM>, with rib foot cleat <NUM> removed with the tool, with channel lips <NUM> formed on the first opening rim 34a and second opening rim 34b of the cleat body <NUM>.

<FIG> shows the steps of assembling the rib foot cleat <NUM>, with steps for forming the channel lips <NUM>. The rib foot cleat is placed against the rib <NUM> and arranged over the stringer 14a to identify the final position of the rib foot cleat. The rib foot cleat should be centred on the stringer. Fastener holes <NUM> are drilled off through the rib foot cleat <NUM> (and the rib and the stringer foot) before removing the cleat from the rib <NUM> and stringer 14a. The injection (or inlet) hole <NUM> may be formed in the cleat body <NUM> at any time prior to offering up and drilling off the fastener holes <NUM>. Alternatively the inlet hole may be formed before forming the lips, or alternatively, the inlet hole may be made after the sealant lips have been made.

Once the rib foot cleat <NUM> has been removed from the rib <NUM>, the fastener holes <NUM> may be cleaned and deburred before the rib foot cleat is then offered up again to the rib for final fasteners installation.

Where the channel lips are to be formed on the rib foot cleat, after drilling off the fastener holes, the tool <NUM> is inserted in the rib foot cleat (or vice versa) and sealant is injected into recesses 44a and 44b and left to cure. Once the channel lips <NUM> have been cured, the tool <NUM> is removed.

The rib foot cleat <NUM> is then arranged on the stringer 14a and against rib <NUM>, before final fasteners are installed in the rib foot cleat <NUM> using the fastener holes <NUM> to fasten the rib foot cleat <NUM> to the rib <NUM> and the foot of the stringer 14a.

Once fastened, sealant <NUM> is injected through sealant injection hole <NUM>, as shown in <FIG>. Sealant <NUM> is injected through the injection hole <NUM> to fill gap <NUM> (shown in <FIG>) between the cleat body <NUM> and stringer 14a. The sealant is injected until sealant visibly protrudes from the rib foot cleat channel <NUM>. This allows an easy method of fully sealing rib foot cleat <NUM> after it has been secured to the rib <NUM> and over the stringer 14a. This also ensure reliability of the seal as visual inspection reduces the probability of forming an incomplete seal. The injectable sealant provides faster installation of the rib foot cleat <NUM>.

The sealant injected into the channel of the rib foot cleat fills the gap <NUM> between the stringer profile and the interior of the cleat channel <NUM> to fully seal the cavity and prevent fuel from moving through the mousehole <NUM>.

As mentioned above, the injectable sealant <NUM> is preferably made of the same type of material as the sealant used to form the channel lips <NUM>. This is advantageous as once the injected sealant is cured, it will fuse with the channel lips <NUM> and form one cohesive seal in gap <NUM>. This is advantageous as this promotes an effective seal.

The injectable sealant <NUM> may be introduced by any suitable means, but preferably the injectable sealant <NUM> is supplied from a pre-filled sealant cartridge <NUM> with a nozzle attached which is placed within a gun (not shown). The gun may use mechanics, air pressure or electromechanical drives to facilitate quick injection of the injectable sealant <NUM>. <FIG> shows a cross section <NUM> of the cleat body <NUM> with sealant in the cartridge <NUM> injecting sealant using flow of sealant <NUM>. As shown, the flow of sealant <NUM> will go through inlet hole <NUM> and around stringer 14a, filling gap <NUM>. The nozzle may be extended in length or bent appropriately in order to assist access into areas which are difficult to access within the wing assembly.

While the invention relates to providing a fuel tight boundary between a dry bay and fuel bay within an aircraft, it will be understood that similar designs may be implemented in any boundary within a wing, aircraft, or any other industry.

Where the word 'or' appears this is to be construed to mean 'and/or' such that items referred to are not necessarily mutually exclusive.

Claim 1:
A rib foot cleat (<NUM>) for sealing around a stringer (14a) passing through a rib mousehole (<NUM>) in an aircraft assembly, the rib foot cleat comprising:
a cleat body (<NUM>) for attaching to a rib (<NUM>) at a rib mousehole and defining a cleat channel (<NUM>) configured to be arranged over a stringer; and
an injection hole (<NUM>) through the cleat body in fluid communication with the cleat channel to allow a sealant material to be injected through the injection hole in to the cleat channel for sealing around the stringer, wherein the cleat channel is U-shaped and terminates at a first channel opening rim (34a) on one side of the cleat body and at a second channel opening rim (34b) on an opposite side of the cleat body, and characterised in that the cleat channel further comprises a channel lip (<NUM>) that extends at least partially around an interior of the cleat channel adjacent the first and/or second channel opening rim, wherein the channel lip is configured to delimit the sealant material injected through the injection hole.