AIRCRAFT JOINT

Abstract

An aircraft joint between overlapping first and second components includes a fastener having a head and a shank, and a fastener retainer fixedly attached to the second component at the overlap region. The fastener retainer has a recess and a through hole. The fastener head is situated in the recess and between the fastener retainer and the second component. The fastener shank extends through the hole in the fastener retainer and into the first component to fasten the first component to the second component. The joint may be between an aircraft wing cover and a wing panel.

Claims

1. An aircraft joint comprising a first component, a second component overlapping the first component at an overlap region, a fastener having a head and a shank, and a fastener retainer fixedly attached to the second component at the overlap region, wherein the fastener retainer has a recess and a through hole, the fastener head is situated in the recess and between the fastener retainer and the second component, and the fastener shank extends through the hole in the fastener retainer and into the first component to fasten the first component to the second component.

2. An aircraft joint according to claim 1, wherein the fastener retainer is attached to the second component such that the fastener head is situated in the recess of the fastener retainer and between the fastener retainer and the second component for retaining the fastener with the second component prior to joining the first and second components together.

3. An aircraft joint according to claim 1, wherein the fastener shank is threaded.

4. An aircraft joint according to claim 1, further comprising a fastener receptacle which receives the fastener shank, preferably wherein the fastener receptacle is removable from the fastener shank.

5. An aircraft joint according to claim 1, wherein the fastener retainer is attached to the second component by one or more of bonding, fastening or welding.

6. An aircraft joint according to claim 1, wherein the fastener retainer is a plate or strip.

7. An aircraft joint according to claim 1, wherein the fastener head is held captive in the fastener retainer recess between the fastener retainer and the second component.

8. An aircraft joint according to claim 7, wherein the through hole in the fastener retainer has a diameter smaller than a diameter of the fastener head.

9. An aircraft joint according to claim 1, wherein the through hole in the fastener retainer has a first aperture having a diameter smaller than a diameter of the fastener head, and a second aperture adjacent the first aperture and having a diameter larger than the diameter of the fastener head, and a slot between the first aperture and the second aperture.

10. An aircraft joint according to claim 9, wherein the fastener is slidable in the slot between the first aperture and the second aperture of the fastener retainer and is removable from the fastener retainer through the second aperture only when the first and second components are disassembled.

11. An aircraft joint according to claim 1, further comprising a plurality of the fasteners, wherein the fastener retainer has a plurality of through holes, each fastener head is situated in a recess of the fastener retainer and between the fastener retainer and the second component, and each fastener shank extends through a respective one of the through holes and into the first component.

12. An aircraft joint according to claim 1, wherein the first component has an outer aerodynamic surface, and the second component has an outer aerodynamic surface, and the fastener constrains movement of the first component relative to the second component in a direction normal to the outer aerodynamic surfaces of first and second components in the vicinity of the fastener.

13. An aircraft joint according to claim 12, wherein the outer aerodynamic surfaces of the first and second components are substantially flush across the joint.

14. An aircraft joint according to claim 1, wherein the first and second components are an aircraft wing cover and an aircraft wing leading edge panel.

15. A method of assembling an aircraft joint according to claim 1, the method comprising: inserting the fastener shank through the hole in the fastener retainer until the fastener head is situated in the recess in the fastener retainer; attaching the fastener retainer to the second component; positioning the second component having the fastener retainer attached thereto and with the fastener therein with respect to the first component; and fastening the first component to the second component using the fastener.

16. A method according to claim 15, wherein the fastener retainer is attached to the second component prior to or after inserting the fastener shank through the hole in the fastener retainer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0029] FIG. 1 illustrates a fixed wing aircraft;

[0030] FIG. 2 illustrates schematically a known joint between an upper wing cover and a wing leading edge panel comprising a row of fasteners;

[0031] FIG. 3 illustrates a side view of a leading edge region of a laminar flow aerofoil for a fixed wing aircraft;

[0032] FIG. 4 illustrates a three dimensional view of a joint between a wing cover and a leading edge panel according to a first embodiment of the invention;

[0033] FIG. 5 illustrates plan and section views of the joint of FIG. 4;

[0034] FIG. 6 illustrates a three dimensional view of a joint between a wing cover and a leading edge panel according to a second embodiment of the invention;

[0035] FIG. 7 illustrates plan and section views of the joint of the second embodiment;

[0036] FIG. 8 illustrates detailed section views of the installed fastener in the joint of the second embodiment;

[0037] FIG. 9 illustrates a three dimensional view of a joint between a wing cover and a leading edge panel according to a third embodiment of the invention; and

[0038] FIG. 10 illustrates plan and section views of the joint of the third embodiment.

DETAILED DESCRIPTION OF EMBODIMENT(S)

[0039] FIG. 1 illustrates a typical configuration for a fixed wing passenger transonic jet transport aircraft 1. The aircraft 1 comprises a fuselage 2, wings 3, main engines 4 and horizontal and vertical tailplanes 5. It will be appreciated that this invention is applicable to a wide variety of aircraft types not just that illustrated in FIG. 1. For example, the aircraft, may be for commercial or military purposes, may be for transporting passengers or cargo, may have jet, propeller or other engine propulsion systems, may have a variety of fuselage/wing configurations, e.g. a high wing, low wing or blended wing body, and may be designed to fly at subsonic, transonic or supersonic speeds.

[0040] FIG. 2 illustrates a known joint between an upper wing cover 20 and a wing leading edge panel 21. The upper wing cover 20 is attached to a front spar 22. A forward edge of the upper wing cover 20 includes a joggle 23 and the wing leading edge panel 21 is fastened to the upper wing cover 20 by a plurality of fasteners 24. The outer surface 25 of the upper wing cover 20 and the outer surface 26 of the wing leading edge panel 21 are arranged substantially flush across the joint. The fasteners are countersunk but nevertheless the line of fasteners 24 provide exposed fastener heads which create a small but appreciable step in the upper surface of the wing adjacent the leading edge, which may have a detrimental effect on laminar flow.

[0041] FIG. 3 illustrates a cutaway side view of the leading edge region of a laminar flow aerofoil for a fixed wing aircraft such as that shown in FIG. 1. The laminar flow wing 30 includes an upper wing cover 31, a lower wing cover 32, a front spar 33, a leading edge rib 34, an upper leading edge panel 35 and a lower leading edge panel 36.

[0042] The upper and lower wing covers 31, 32 are attached to the front spar 33. A plurality of the leading edge ribs 34 are provided spaced spanwise in front of the front spar 33 and are fixed thereto. The lower leading edge panel 36 extends spanwise across multiple leading edge ribs 34 and is attached to the ribs 34 and to the forward edge of the lower wing cover 32. The upper leading edge panel 35 also extends spanwise across a plurality of the leading edge ribs 34. The upper leading edge panel 35 extends forward of the upper wing cover 31 to the leading edge 37 of the wing 30 and curls under to attach to the underside of the rib 34 just aft of the wing leading edge 37. A cavity 38 is formed between the wing leading edge panels 37 and 36 which receives a Krueger flap high lift device (not shown). A joint 40 is used to attach upper leading edge panel 35 to the upper wing cover 31.

[0043] FIG. 4 shows an isometric view of the joint 40 between the upper wing cover 31 and the upper wing leading edge panel 35 according to a first embodiment of the invention. The upper wing cover 31 has an outer aerodynamic surface 31a and an inner surface 31b opposite the outer surface 31a. The upper wing leading edge panel 35 has an outer aerodynamic surface 35a and an inner surface 35b opposite the outer surface 35a. The forward edge of the upper wing cover 31 includes a joggle 39. The upper wing leading edge panel 35 overlaps the joggle 39 of the wing cover 31 to provide an overlap region 41 where the upper wing leading edge panel 35 overlaps the wing cover 31. A row of fasteners 42 in the overlap region 41 joins the upper wing leading edge panel 35 to the upper wing cover 31. A fastener retainer 43 is fixedly attached to the inner surface 35b of the upper wing leading edge panel 35.

[0044] As best shown in FIG. 5, each of the fasteners 42 has a fastener head 42a and a fastener shank 42b. The fastener retainer 43 has a recess 43a which receives the fastener head 42a between the fastener retainer 43 and the upper wing leading edge panel 35. The fastener retainer 43 also has a through hole 43b and the fastener shank 42b extends through the hole 43b in the fastener retainer 43 and through a hole 44 in the upper wing cover 31. The hole 44 has a diameter larger than the diameter of the fastener shank to allow easy installation and removal of the fastener 42.

[0045] A fastener receptacle 45, which in the illustrated embodiment is a nut, receives a threaded end of the fastener shank 42b opposite the fastener head end. The fastener receptacle 45 has an internally threaded bore which is screw threaded onto the threaded end of fastener shank 42b. Tightening the fastener receptacle on the fastener shank causes the fastener receptacle 45 to bear (either directly or indirectly) against the inner surface 31b of the upper wing cover 31 so as to clamp the upper wing cover 31 to the fastener retainer 43. The fastener retainer 43 is attached by bonding to the inner surface 35b of the upper wing leading edge panel 35.

[0046] In the illustrated embodiment the fastener retainer 43 is a strip or plate having a recessed channel groove 43a along its length. The fastener receiving through holes 43b in the fastener retainer 43 are provided at discrete locations along the length of the recessed groove 43a. In an alternative arrangement (not shown) the recess maybe a discrete cut outs of required dimension around the respective fastener receiving through holes 43b in the fastener retainer 43 but, as in the illustrated embodiment, the recess 43a must be of sufficient dimension (depth and diameter) to receive the fastener head 42a.

[0047] With the fasteners 42 installed, movement of the upper leading edge panel 35 relative to the upper wing cover 31 in a vertical direction (i.e. normal to the outer surfaces 31a, 35a of the upper wing cover 31 and the upper wing leading edge panel 35) is constrained at the overlap region 41. The fasteners 42 therefore hold the wing leading edge panel 35 in contact with the joggled wing upper cover 31 and stops relative vertical movement between these components.

[0048] The outer aerodynamic surfaces of the upper wing cover 31 and the upper wing leading edge panel 35 are substantially flush across the joint 40, A small gap between the cover and the panel is filled with sealant (not shown) prior to use to create a contiguous aerodynamic surface across the joint. The fasteners 42 sit fully inside the wing 30 within the wing leading edge region and therefore avoiding any disturbance to the laminar flow around the outer surface of the wing 30.

[0049] As discussed above the fastener retainer 43 is attached to the inner surface 35b of the upper wing leading edge panel 35 by bonding. Any suitable aerospace adhesive similar may be used for this purpose. Since the leading edge panel 35 is a “panel” i.e. it does not carry the main wing loads and is provided simply to maintain the aerodynamic shape of the wing, bonding of the fastener retainer 43 to the upper wing leading edge panel 35 is sufficient. It will be appreciated that in other embodiments the fastener retainer 43 may be attached to the upper wing leading edge panel 35 by other attachment means including, for example, by fasteners. It is preferable that where fasteners are used, these do not have exposed fastener head in the outer aerodynamic surface of the wing.

[0050] The fastener retainer 43 may be made of a variety of materials. For example, the fastener retainer 43 may be of metal, composite (such as carbon fibre reinforced polymer), glass, etc. The upper wing leading edge panel 35 may comprise metal, such as aluminium, composite (such as carbon fibre reinforced polymer, for example) or may comprise a laminate construction including one or more metal plies and one or more composite plies. In the event that the inner surface 35b of the upper wing leading edge panel 35 is metallic and the fastener retainer 43 is also made of metal then welding of the fastener retainer 43 to the inner surface 35b of the upper leading panel 35 becomes possible as an alternative to bonding and/or fastening to attach these components together.

[0051] The upper wing leading edge panel 35 is installed to the upper wing cover 31 as follows. The plurality of fasteners 42 are inserted in the respective through holes 43b in the fastener retainer 43 such that the fastener heads 42a are situated in the recess 43a in the fastener retainer 43. The faster retainer 43 is then attached to the inner surface 35b of the upper wing leading edge panel 35 as discussed above. At this point, the plurality of fasteners 42 become “captive” fasteners since they can no longer be removed from the fastener retainer 43 due to the larger diameter of the fastener heads 42a than the diameter of the through holes 43b in the fastener retainer 43. The upper wing leading edge panel 35 is then positioned with respect to the upper wing cover 31 to align the plurality of fasteners 43 with the through holes 44 in the joggle 39 of the upper wing cover 31. Once the upper wing leading edge panel 35 is appropriately aligned with the upper wing cover 31 such that the plurality of the fastener shanks 42b each project through their respective through holes 44 in the upper wing cover 31 and project from the inner surface 31b thereof, the respective fastener receptacles 45 are then threadably secured onto the projecting threaded ends of the fasteners 42.

[0052] To replace the leading edge panel 35, the fastener receptacles 45 are removed from the fasteners 42 by access through the aperture 38 in the wing 30, which may require deployment of the Krueger high lift device. Once all fasteners 42 are released the panel 35 can be removed from the wing 30. A replacement panel 35 having a plurality of replacement fasteners 42 and a replacement fastener retainer 43 installed thereon may then be offered up to the wing 30. Once all of the fastener receptacles 45 are installed on the fasteners 42 the Krueger may then be moved back to its retracted position.

[0053] The captive fasteners allow for a reduction in the number of exposed fastener heads in the outer aerodynamic surface of the wing. This is particularly beneficial in areas where the local flow is expected to be laminar as it enables laminar flow to be maintained as far as possible in the downstream flow direction. Secondly, the captive fasteners enable faster installation and removal of the panel 35 from the wing 30 as compared with traditional countersunk fasteners such as illustrated in FIG. 2. This improves manufacturing times for new aircraft and reduced maintenance downtime.

[0054] Inspection of the fasteners 42 may require deployment of the Krueger high lift device to open aperture 38 to allow access to the fastener receptacles 43 visually or physically.

[0055] FIG. 6 illustrates an isometric view of a joint 140 between the wing cover 31 and the leading edge panel 35 according to a second embodiment of the invention. Like reference numerals have been used to denote like parts and only those differences between the second embodiment and the first embodiment will be described in the following. As can be seen from FIG. 6 the upper wing cover 31, the upper wing leading edge panel 35, the overlap region 41, the fasteners 42 and the joggle 39 are identical to the first embodiment shown in FIGS. 4 and 5. The only difference between the joint 140 of the second embodiment and the joint 40 of the first embodiment arises in the fastener retainer 143.

[0056] Like the fastener retainer 43 of the first embodiment, the fastener retainer 143 of the second embodiment is arranged as a strip or plate having a grooved recess 143a. The dimensions, location, material, attachment to the upper wing leading edge panel 35 are identical to that of the fastener retainer 43 of the first embodiment. However, a hole 143b in the fastener retainer 143 for receiving the fastener 42 has a different shape that of the hole 43b.

[0057] The hole 143b is best shown in section view C-C of FIG. 8. The fastener retainer 143 has a through hole 143b having a generally figure of eight shape with a first aperture 143c having a diameter smaller than the diameter of the fastener head 42a, and a second aperture 143d adjacent to the first aperture 143c and having a diameter larger than the diameter of the fastener head 42a. A slot 143e joins the first aperture 143c to the second aperture 143d.

[0058] The through hole 44 in the upper wing cover 31 is co-axial with the first aperture 143c in the fastener retainer 143. The upper wing cover 31 has no through hole co-axial with the second aperture 143d of the fastener retainer 143. The fastener 42 is slidable in the slot 143e between the first aperture 143c and the second aperture 143d of the fastener retainer 143 only when the upper wing cover 31 and the upper wing leading edge panel 35 are disassembled (i.e. prior to assembly for the first time or after subsequent disassembly). The fastener 42 is removable from the fastener retainer 143 through the second aperture 143d only when the upper wing cover 31 and the upper wing leading edge panel 35 are disassembled. Therefore, unlike in the first embodiment, in the second embodiment the fasteners 42 are not “captive” fasteners once the fastener retainer 143 is attached to the inner surface 35b of the upper wing leading edge panel 35.

[0059] Assembly of the joint 140 is similar to that described above with reference to the first embodiment with the exception that the fastener 42 may be installed in the fastener retainer 143 after attaching the fastener retainer 143 to the upper wing leading edge panel 35. Once the fastener retainer 143 is attached to the upper wing leading edge panel 35 the fastener 42 is installed by passing the fastener head 42a through the second aperture 143d and sliding the fastener 42 laterally in the slot 143e until it rests in position in the first aperture 143c. Thereafter, assembly of the joint 140 is identical to that for the joint 40 of the first embodiment. Likewise, disassembly of the joint 140 is substantially identical to disassembly of the joint 40 of the first embodiment with the exception that once the fastener receptacles 45 are removed from the fasteners 42 and the panel 35 is removed from the aircraft wing 30, the fasteners 42 may be removed from the fastener retainer 143 by sliding the fasteners 42 laterally from the first aperture 143c to the second aperture 143d where upon the fasteners 42 may be removed through the second aperture 143d.

[0060] As shown in FIG. 6 the generally figure of eight shaped through holes 143b are oppositely handed consecutively along the row of fasteners 42 such that the first apertures 143c of adjacent through holes 143b are nearest each other. This provides a self-locking arrangement when the joint 140 is assembled.

[0061] All alternatives and variants described above with respect to the first embodiment are equally applicable to the second embodiment.

[0062] FIG. 9 illustrates an isometric view of a joint 240 between the upper wing cover 31 and the upper wing leading edge panel 35 in accordance with a third embodiment of the invention. In the third embodiment like reference numerals are used to denote like parts with the second embodiment and only the differences between the third embodiment and the second embodiment will now be described. The only difference between the joint 240 of the third embodiment and the joint 140 of the second embodiment arises in the fastener retainer 243.

[0063] Like the fastener retainer 143 of the second embodiment, the fastener retainer 243 of the second embodiment is arranged as a strip or plate. The dimensions, location, material, attachment to the upper wing leading edge panel 35 are identical to that of the fastener retainer 143 of the second embodiment. However, whereas in the fastener retainer 143 the recess 143a is a channel groove extending along the length of the fastener retainer, the fastener retainer 243 has a plurality of discrete recesses 243a each for receiving respective fastener head 42a.

[0064] Situated in the base of each recess 243a is a through hole 243b having a generally figure of eight shape substantially identical to that of the through holes 143b of the second embodiment. Each through hole 243b has a first aperture 243c having a diameter smaller than the diameter of the fastener head 42a, and a second aperture 243d adjacent to the first aperture 243c and having a diameter larger than the diameter of the fastener head 42a. A slot 243e extends between the first aperture 243c and the second aperture 243d.

[0065] Whereas in the second embodiment the movement of the fastener 42 between the first and second apertures 143c and 143d is in a lateral direction along the row of fasteners 42. in the third embodiment the movement of the fasteners 42 from the first aperture 243c to the second aperture 243d is in a generally transverse direction perpendicular to the row of fasteners 42. Similar to the second embodiment, in the third embodiment the generally figure of eight shaped through hole 243b is oppositely handed for each consecutive recess 243a along the row of fasteners 42 such that the first apertures 243c are nearest the upper wing cover 31 for every other one of the fasteners 42 along the row of fasteners. This provides a self-locking arrangement when the joint 240 is assembled. The manner of attaching the fastener retainer 243 and the installation of the fasteners 42 is substantially identical to that of the second embodiment and so will not be repeated here.

[0066] All alternatives and variants described above with respect to the second embodiment are equally applicable to the third embodiment.

[0067] Although the invention has been described above with reference to one or more preferred 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.