Spark protection cap plate

Abstract

A spark protection cap plate (20) is disclosed, the spark protection cap plate (20) comprising: a base (22); and two or more spark protection caps (21a, 21b, 21c); each spark protection cap (21a, 21b, 21c) includes a cover portion (24) extending from the base (22), the cover portion (24) defining a cavity (26) inside the spark protection cap (21a, 21b, 21c) within which an end (203) of the fastener (202) may be enclosed. Also disclosed is a fastener joint (200), the fastener joint (200) comprising: a structural member (28); two or more fasteners (202), each fastener (202) having a fastener end (203) protruding from a surface of the structural member (28); and a spark shield cap plate (20), the spark shield cap plate (20) comprising a base (22) and two or more spark shield caps (21a, 21b, 21c), each of the spark shield caps (21a, 21b, 21c) comprising a cover portion (24) extending from the base (22), the cover portion (24) defining a cavity (26) inside the spark shield cap (21a, 21b, 21c), an end (203) of the fastener (202) may be enclosed inside the cavity; and a cured sealing material (27) disposed between the spark shield cap plate (20) and the structure (28), the cured sealing material fixing the spark shield cap plate (20) to the structure (28) in a position such that each end (203) of each fastener (202) is enclosed within the spark shield cap (21a, 21b, 21c).

Description

Technical Field

[0001] The present invention relates to a spark protection cap plate, a fastener joint, an aircraft including at least one of the spark protection cap plate and the fastener joint, and a method of securing a fastener and a spark protection cap plate to a structure. Background Art

[0002] Large passenger aircraft are typically struck by lightning once or twice a year, with each strike delivering up to 200,000 amperes of current seeking the path of least resistance. Many modern passenger aircraft have exterior surfaces made of composite materials with very high electrical resistance. Therefore, there is a high probability of lightning attaching to any of the many metal fasteners on the exterior surface, which have much lower electrical resistance. In wings, some of these fasteners penetrate the outer wing skin and into the fuel tanks.

[0003] In the event that the lightning strike is attached to a fastener, sparks or plasma or exhaust may occur. In fact, a lightning strike at a fastener located at the fuel tank boundary and therefore immersed in fuel or steam rich gas may provide a spark and hot gas ignition source, which may cause ignition of the fuel.

[0004] It is known to suppress such sparks by enclosing the fastener in a spark protection cap. FIG1 shows a prior art example of a fastener joint including a spark protection cap as described in EP 4 112 479 A1. FIG1 shows a fastener joint 10 including a single-sided fastener 12 fastened to a structural member 11. The spark protection cap 13 is secured to the structural member 11 by a curing sealing material in the form of an adhesive 14 disposed between a base 15 and a surface of the structural member 11. The cap 13 includes a closed body 18. The body 18 has a base 15 and a cover portion 19 extending from the base 15. The base 33 and the cover portion 34 together define a cavity 35 within the closed body 32. The single-sided fastener 12 protrudes through a hole 16 formed in the structural member 11 and the base 15 of the cap 13 so that the end of the fastener is enclosed in a cavity 17 of the closed body 18 defined by the base 15 and the cover portion 19.

[0005] Spark arresters, such as those described in EP 4 112 479 A1, provide good lightning strike protection at fasteners. However, large passenger aircraft may contain thousands of fasteners, and it may take a long time to install all the spark arresters required to cover each of the fasteners. Summary of the Invention

[0006] A first aspect of the present invention provides a spark shield cap plate comprising: a base; and two or more spark shield caps, each spark shield cap comprising a cover portion extending from the base, the cover portion defining a cavity inside the spark shield cap, wherein an end of a fastener can be enclosed inside the cavity.

[0007] This arrangement allows multiple spark arresters to be secured in place at once. The spark arrester plate allows the spark arrester to be easily and accurately positioned on a structure that will house multiple fasteners requiring lightning protection. This can significantly reduce the time required for assembly at locations where the spark arrester plate is used.

[0008] The base may comprise an attachment surface for attaching the spark protection cap plate to a structural member.In this way, a strong adhesive bond between the spark protection cap and the structural member to which the spark protection cap is to be fixed may be easily achieved.

[0009] The base may include one or more alignment features. This may help accurately position the spark protection cap plate on the structure. This is particularly relevant if the spark protection cap plate is positioned and attached to the structure before any holes for fasteners are drilled in the structure.

[0010] One or more alignment features can engage with corresponding features on the structural element to which the spark protection cap plate is to be secured. This can provide for faster and more accurate positioning of the spark protection cap plate on the structural element.

[0011] The base may be substantially planar. This will enable the spark shield plate to be secured to a planar surface of a structure.

[0012] The base may have a non-planar contour shape. Thus, the base may be shaped to fit a non-planar structural element to which the base is to be secured, or may be a complex shape to fit a complex structural contour.

[0013] The base may include two or more apertures, and a spark arrester may be positioned over each aperture. Thus, the base is already provided with apertures or holes in the correct locations through which fasteners may be received. This may make positioning the spark arrester on the base easier.

[0014] The base may comprise a sacrificial material having openings formed therein so that the fastener ends may be received into cavities within the two or more spark arrester caps. This allows the holes to be formed at a later stage during manufacture or assembly and reduces the likelihood of any misalignment of the apertures.

[0015] Two or more spark protection caps can be attached to the base to form a spark protection cap plate.Attaching the caps to the base allows for a quick and secure bond between the caps and the base.

[0016] Each spark protection cap may include a cap base, and the cap base may be attached to the base.

[0017] The cover portion of each spark arrester cap may include an annular opening, and each spark arrester cap may be attached to the base portion at the annular opening.

[0018] The base and the two or more spark protection caps can be formed from a single piece, and the spark protection caps can be molded from the material forming the base. This allows the entire spark protection cap plate to be formed from a single piece of material and can reduce the cost and weight of the spark protection cap plate.

[0019] The base can be formed of an electrically insulating material. Thus, the spark arrester cap plate can provide two independent lightning strike protection features in one product: the base provides robust electrical isolation for the structure to which it is attached and the fasteners to which it is securely attached, and the spark arrester cap also provides protection from any voltage sparks and exhaust.

[0020] According to a second aspect of the present invention, there is provided a fastener joint, comprising: a structural member; two or more fasteners, each fastener having a fastener end protruding from a surface of the structural member; and a spark shield cap plate, the spark shield cap plate comprising a base and two or more spark shield caps, each of the spark shield caps comprising a cover portion extending from the base, the cover portion defining a cavity inside the spark shield cap, wherein the ends of the fasteners can be enclosed inside the cavity; and a curable sealing material disposed between the spark shield cap plate and the structural member, the curable sealing material securing the spark shield cap plate to the structural member in a position such that each end of each fastener is enclosed within the spark shield cap.

[0021] According to a third aspect of the present invention, there is provided a method of securing a fastener and a spark protection cap plate to a structural member, the method comprising: securing the spark protection cap plate according to any one of claims 1 to 12 to a surface of the structural member; forming a hole through at least one of the structural member and the spark protection cap plate at a position where the hole is aligned with the spark protection cap; and inserting a fastener through the hole and tightening the fastener to secure the fastener to the structural member.

[0022] By this method, the time required to position the plurality of spark protection caps on the structural member can be greatly reduced. The step of fixing the spark protection cap plate to the surface of the structural member places the plurality of spark protection caps on the structural member. This can also greatly simplify the assembly process.

[0023] The step of securing the spark protection cap plate to the surface of the structure may include applying an adhesive between a base of the spark protection cap plate and the structure and curing the adhesive.

[0024] The step of forming a hole through at least one of the structure and the spark protection cap plate may include drilling a common hole through the structure and a base of the secured spark protection cap plate.

[0025] According to a fourth aspect of the present invention, there is provided an aircraft comprising at least one of a spark protection cap plate or a fastener joint as described in any of the statements above.

[0026] Of course, it will be understood that features described with respect to one aspect of the invention may be incorporated into other aspects of the invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention, and the apparatus of the invention may incorporate any of the features described with reference to the method of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0028] FIG1 shows a prior art example of a fastener joint including a spark protection cap;

[0029] Figure 2A shows a cross-sectional view of a spark protection cap plate according to a first embodiment;

[0030] Figure 2B Shown is the formation including Figure 2A Cross-sectional views of various steps of a method for fastening a spark protection cap plate to a fastener joint;

[0031] Figure 2C Shown Figure 2B The enlarged part;

[0032] Figure 3A shows a cross-sectional view of a spark protection cap plate according to a second embodiment;

[0033] Figure 3B Shown is the formation including Figure 3A Cross-sectional views of various steps of a method for fastening a spark protection cap plate to a fastener joint;

[0034] Figure 3C Shown Figure 3B The enlarged part;

[0035] Figure 4A shows a cross-sectional view of a spark protection cap plate according to a third embodiment;

[0036] Figure 4BShown is the formation including Figure 4A Cross-sectional views of various steps of a method for fastening a spark protection cap plate to a fastener joint;

[0037] Figure 4C Shown Figure 4B The enlarged part;

[0038] Figure 5A and Figure 5B The installation of a spark shield plate onto a structure having a complex shape is shown; and

[0039] Figure 6 Another embodiment of a spark shield plate is shown for mounting to a structure having a complex shape; and

[0040] Figure 7 It is a three-dimensional image of the aircraft. DETAILED DESCRIPTION

[0041] Figure 2A A cross-sectional view through a first embodiment of a spark arrester plate 20 is shown. The spark arrester plate 20 includes a base 22 and a plurality of spark arrester caps 21 secured to the base 22. In the illustrated embodiment, there are three spark arrester caps 21a, 21b, and 21c. For clarity, reference numerals for features of the spark arrester caps will primarily be shown with respect to only the spark arrester cap 21a. However, it will be understood that each of the spark arrester caps 21a, 21b, and 21c are identical, and therefore reference numerals will also apply to 21b and 21c.

[0042] Each spark protection cap 21, which may be more simply referred to herein as a cap 21, includes an enclosed body 23. The body 23 has a cap base 25 and a cover portion 24 extending from the cap base 25. The cap base 25 and the cover portion 24 together define a cavity 26 within the enclosed body 23. The end of a fastener can be received in the cavity 26, which will be described in more detail below. The cap base 25 provides an attachment surface for attaching the cap 21 to the base 22. In this way, it can be said that the cover portion 24 also extends away from the base 22. An adhesive 27 is shown between the caps 21a, 21b, 21c and the base 22, and the adhesive 27 may be an epoxy adhesive, a gasket material, or a polysulfide sealant. For example, the epoxy adhesive may be a two-part epoxy adhesive, such as 3M TM Scotch-Weld TM Structural Epoxy Adhesive 9323 or 3M TM Scotch-Weld TM Structural Epoxy Adhesive EC-7256B / A. During assembly of the spark shield plate 20, the adhesive 27 is applied to the base 22, the spark shield 21 is positioned on the base 22, and the adhesive 27 is allowed to cure. Figure 2A As shown in FIG, excess adhesive can form a lip around the perimeter of cap 21. This lip helps strengthen the bond between cap 21 and base 22 and, once the fastener is in place, subsequently serves to seal cavity 26 within body 23 to prevent exhaust products from escaping. The seal between cap 21 and base 22 also prevents fuel, water, or other contaminants from entering cavity 26 and also prevents plasma or other exhaust products from leaving the cavity in the event of a lightning strike.

[0043] The base 22 is formed of a polymer or glass reinforced plastic and is sized to fit the specific structural element of the wing / fuel tank. By providing the spark shield cap plate 20 with a large base 22, this allows the cap 21 to be easily and accurately positioned in the correct position on the structure and also allows multiple caps 21 ( Figure 2A The embodiment of the present invention is a schematic diagram of a plurality of caps 21 mounted on a base 22, wherein three caps are shown, to allow multiple caps 21 to be installed in one operation, thereby saving a lot of time and cost. Although not shown in this embodiment, this also allows caps 21 of different sizes to be installed together depending on the specific fasteners that the caps will protect.

[0044] In this embodiment, the cap 21 is manufactured as a single piece by blow molding. Blow molding has lower tooling and production costs than injection molding and can provide a faster, easier, and cheaper manufacturing alternative to typical spark protection caps. The cap 21 needs to be formed of a material that can be blow molded but also resists long-term exposure to fuel. Examples of such materials can be nylon PA6, PA66, and PA12. Another example can be ULTEM®. TM 2300, although this material requires injection molding rather than blow molding. Depending on the needs of the cap 21, these materials may require additional treatment or primer coating to enhance adhesion.

[0045] Figure 2B A cross-sectional view of the spark protection cap plate 20 secured to the structure 28 is shown with each of the caps 21 a , 21 b , and 21 c at a different step in the method of forming the fastener joint 200 . Figure 2C Shown Figure 2B An enlarged closed segment as indicated by the dashed box labeled A.

[0046] Spark protection cap plate 20 is secured to structure 28 via adhesive layer 29. Cap 21c illustrates how cap 21c will look once spark protection cap plate 20 is secured to structure 28 and before any further steps are taken. The cap base 25 of each cap 21 is made of a sacrificial material, allowing holes 201 to be drilled through structure 28 and also through the sacrificial portion of base 25, through which fasteners can be inserted. A common hole 201 has been drilled through structure 28, base 22 of plate 20, and cap base 25 of cap 21b. A similar hole 201 has also been formed through cap 21a, and furthermore, a blind fastener 202 has been inserted through hole 201 and secured in place.

[0047] Here, cap 21a shows a portion of a completed fastener joint, which is the end result when a blind fastener 202 is fastened to a structural member 28 as described above. In the completed fastener joint, the spark protection cap plate 20 is secured to the structural member 28 by a cured sealing material in the form of an adhesive 29 disposed between the base 22 and the surface of the structural member 28. The protruding end 203 of the blind fastener 202 protrudes through the hole 201 formed in the structural member 28 and the spark protection cap plate 20, such that the end of the fastener 203 is enclosed within a cavity 26 in the enclosed body 23 defined by the cap base 25 and the cover portion 24.

[0048] Figure 3A A cross-sectional view through an alternative embodiment of a spark arrester plate 30 is shown. Similar to the first embodiment described above, the spark arrester plate 30 includes a base 32 and a plurality of spark arrester caps 31 secured to the base 32. In the illustrated embodiment, there are three spark arrester caps 31a, 31b, and 31c. For clarity, reference numerals for features of each spark arrester cap 31 will primarily be shown with respect to spark arrester cap 31a only; however, it should be understood that each of spark arrester caps 31a, 31b, and 31c are identical, and therefore reference numerals will also apply to caps 31b and 31c.

[0049] Each spark protection cap 31 , also referred to herein more simply as a cap 31 , includes a closed body 33 . Unlike the cap 21 of the first embodiment described above, this cap 31 does not have a cap base, but rather simply a cover portion 34 . Instead of a cap base enclosing cap 31 , cap 31 has an opening 35 defined by the annular end of cover portion 34 . However, cap 31 is still considered closed because cap 31 is attached to base 32 such that base 35 encloses opening 35 . Base 32 and cover portion 34 together define a cavity 36 within closed body 33 . The end of a fastener can be received in this cavity 36 , as will be described in more detail below. Cover portion 34 includes an outer flange 34 a located at the annular opening, which provides an attachment surface for attaching cap 31 to base 32 . Adhesive 37 is disposed in an annular ring between caps 31 a, 31 b, 31 c and base 32 . Adhesive 37 may be an epoxy adhesive, a gasket material, or a polysulfide sealant. For example, the epoxy adhesive may be a two-component epoxy adhesive such as 3M TM Scotch-Weld TM Structural Epoxy Adhesive 9323 or 3M TM Scotch-Weld TM Structural Epoxy Adhesive EC-7256B / A. During assembly of the spark protection cap plate 30, adhesive 37 is applied to the outer flange 34a or base 32, and the spark protection cap 31 is positioned on the base 32 and the adhesive 37 is allowed to cure. Excess adhesive may form a small ridge around the perimeter of the cap 31, such as Figure 3A As shown in (and Figure 3C ). This lip helps strengthen the bond between cap 31 and base 32 and will also serve to seal cavity 36 to prevent fuel, water, or other contaminants from entering cavity 36, and also to prevent plasma or other exhaust products from leaving the cavity in the event of a lightning strike.

[0050] Similar to the first embodiment, the base 32 in this second embodiment is formed from a polymer or glass reinforced plastic and is sized to fit the specific structural element of the wing / fuel tank. By providing the spark protection cap plate 30 with a large base 32, this allows the cap 31 to be easily and accurately placed in the correct position on the structure and also allows multiple caps 31 ( Figure 3A and Figure 3B The embodiment of the present invention is a schematic diagram of a plurality of caps 31 mounted on a base 32, wherein three caps are shown (three caps are shown) to allow multiple caps 31 to be installed in one operation, thereby saving a lot of time and cost. Although not shown in this embodiment, this also allows caps 31 of different sizes to be installed together depending on the specific fasteners that the caps will protect.

[0051] In this embodiment, the cap 21 can be manufactured by injection molding. The cap 31 can be made of a material such as ULTEMTM 2300. Depending on the requirements of the cap 31 and the spark protection cap plate 30, the cap 31 may require additional treatment or primer coating to enhance adhesion.

[0052] Figure 3B A cross-sectional view of the spark protection cap plate 30 secured to the structure 38 is shown, and wherein each of the caps 31 a , 31 b , and 31 c is at a different step in the method of forming the fastener joint 300 . Figure 3C Shown Figure 3B An enlarged section as indicated by the dashed box labeled B.

[0053] The spark protection cap plate 30 is secured to the structure 38 by an adhesive layer 39. Cap 31c shows what the cap 31c will look like once the spark protection cap plate 30 is secured to the structure 38 and before any further steps are taken. In this embodiment, none of the caps 31 include a cap base (as described above with respect to Figure 2A 、 Figure 2B and Figure 2C (as is the case with the first embodiment described), and therefore, the hole 301 drilled through the structural member 38 does not need to be drilled through the cap base. Instead, a common hole 301 has been drilled through the structural member 38 and the base 32 of the plate 30 into the cavity 36 of the cap 31b. A similar hole 301 has also been formed through the cap 31a, and in addition, the blind fastener 302 has been inserted through the hole 301 and fastened in place.

[0054] Cap 31a shows a portion of a completed fastener joint 300, which is the end result when a blind fastener 302 is fastened to a structural member 38 as described above. In the completed fastener joint, the spark protection cap plate 30 is secured to the structural member 38 by a cured sealing material in the form of an adhesive 39 disposed between the base 32 and the surface of the structural member 38. The protruding end 303 of the blind fastener 302 protrudes through a hole 301 formed in the structural member 38 and the spark protection cap plate 30, such that the end of the fastener 303 is enclosed within a cavity 36 in the enclosed body 33 defined by the base 32 and the cap portion 34.

[0055] Figure 4AA cross-sectional view through another alternative embodiment of a spark arrester cap plate 40 is shown. The spark arrester cap plate 40 includes a base 42 and a plurality of spark arrester caps 41. In this embodiment, the spark arrester caps 41 are molded into the base 42 such that the base 42 and the caps 41 are formed from a single piece of material. In the illustrated embodiment, there are three spark arrester caps 41a, 41b, and 41c. For clarity, reference numerals for features of each spark arrester cap 41 will primarily be shown with respect to spark arrester cap 41a only. However, it should be understood that each of the spark arrester caps 41a, 41b, and 41c are identical, and therefore reference numerals will also apply to caps 41b and 41c.

[0056] Each spark protection cap 41 includes a body 43. Unlike the caps 21 and 31 of the first and second embodiments described above, this cap 41 is not closed. Instead of a cap base or base that closes the spark protection cap plate of the cap, the cap 41 has a cover portion 44 and an opening 45. During use, as shown in FIG. Figure 4B As shown in FIG, when the spark protection cap 40 is attached to the surface of the structural member 48, the cap 41 will be closed. The surface of the structural member 48 and the cover portion 44 together define a cavity 46 within the now closed body 43. The end of the fastener can be received in this cavity 46. Since the cap 41 is molded from the same material as the base 42, it is not necessary to attach the cap 41 to the base 42.

[0057] The base 42 may be formed of a suitable moldable material such as a polymer or glass reinforced plastic and sized to fit the specific structural element of the wing / fuel tank. By providing the spark shield cap plate 40 with a large base 42, this allows the cap 41 to be easily and accurately positioned in the correct position on the structure and also allows multiple caps 41 ( Figure 4A and Figure 4B Three caps are shown in the figure) are molded into one base 42 to allow multiple caps 41 to be installed in one operation, thereby saving a lot of time and cost. Although not shown in this embodiment, different sized caps 41 can also be installed together depending on the specific fasteners that the caps will protect.

[0058] Figure 4B A cross-sectional view of the spark protection cap plate 40 secured to the structure 48 is shown, and wherein each of the caps 41 a , 41 b , and 41 c is at a different step in the method of forming the fastener joint 400 . Figure 4C Shown Figure 4B An enlarged section as indicated by the dashed box labeled C.

[0059] On the spark protection cap plate 40 between the caps 41, the base 42 has a flat base portion 42a that provides an attachment surface for attaching the spark protection cap plate 40 to the structure 48. The adhesive may be in the form of a two-part epoxy adhesive, such as 3M TM Scotch-Weld TM Structural Epoxy Adhesive 9323 or 3M TM Scotch-Weld TM Structural epoxy adhesive EC-7256B / A.

[0060] As previously described, cap 41 is now closed because spark protection cap 40 is attached to the surface of structural member 48. The surface of structural member 48 and cover portion 44 together define cavity 46 within the now closed body 43. Holes 401 have been drilled through structural member 48 into cavity 46 of caps 41a and 41b. Blind fasteners 402 have been inserted through holes 401 in cap 41a and fastened in place.

[0061] Thus, cap 41a illustrates a portion of a completed fastener joint 400, which is the end result when a blind fastener 402 is fastened to a structural member 48 as described above. In the completed fastener joint, the spark protection cap plate 40 is secured to the structural member 48 by a cured sealing material in the form of an adhesive 49 disposed between the base 42 and the surface of the structural member 48. The protruding end 403 of the blind fastener 402 protrudes through the hole 401 formed in the structural member 48, such that the end of the fastener 403 is enclosed within a cavity 46 in the enclosed body 43 defined by the surface of the structural member 48 and the cap portion 44.

[0062] Figure 5A and Figure 5B The spark shield plate 50 is shown mounted on a complex-shaped structural member 51. The structural member 51 is given by way of example of a structural member having a complex shape and includes a first face 52 and a second face 53 that is substantially orthogonal to the first face 52. The first face 52 and the second face 53 are connected by a curved section 54. The structural member 51 has an outer edge 55 that follows a curved and non-uniform path, as may be required of some structural members, particularly in aerospace applications, for example due to space constraints.

[0063] When used on an aircraft, the structural member 51 will have holes drilled through it and fasteners attached, and therefore will require lightning strike protection for the exposed ends of the fasteners. However, in this state, the holes have not yet been drilled through the structural member, and it is therefore difficult to determine where the holes will be located. If separate spark arrester caps were to be attached to the structural member, each cap would need to be carefully positioned, possibly requiring measurement from a specific predetermined point on the non-uniform outer edge 55. This can be complex and time-consuming.

[0064] However, if Figure 5A As shown in FIG, the spark protection cap plate 50 includes a base 56 and three spark protection caps 58a, 58b, and 58c. Thus, the plate 50 is provided with the caps 58a, 58b, 58c already precisely positioned in the correct position. The base 56 also has an outer edge 57 that is shaped to align with the outer edge 55 of the structural member 51. This makes installing the spark protection cap plate 50 very quick and easy, as the outer edge 57 serves as an alignment feature with the outer edge 55 of the structural member 51. To secure the plate 50 in place, an adhesive (not shown) is applied to the surface of the first face 53 or the underside of the base 56, and then, using the alignment of the outer edges 55 and 57 as a positioning guide, the plate 50 is brought into position as indicated by arrow D. The adhesive is then allowed to cure.

[0065] Figure 5B The resulting structure 51 is shown with the plate 50 secured in the correct position. A second plate (not shown) can be secured to the second face 53 before the structure is subsequently assembled in place and holes drilled for the fasteners. The ability to secure the spark protection cap plate in place on the structure before using the structure and drilling any holes, and to apply multiple spark protection caps to each plate, can significantly reduce the complexity and time required for an assembly or aircraft.

[0066] Figure 6 Another embodiment of mounting a spark shield plate 60 to a complex-shaped structure 61 is shown. The structure 61 is a corner joint and has a surface 62 to which fasteners are fastened, as indicated by fastener position markings 63. A sidewall 64 has a rib feature 65 extending along the sidewall 64 and into abutment with the surface 62.

[0067] The spark protection cap plate 60 includes a base 66 and three spark protection caps 67. In this embodiment, the base 66 includes a notch 68 that will engage with the rib feature 65 to help align and position the spark protection cap plate 60 with the surface 62 of the structure 61.

[0068] The spark shield plates, fastener joints, and corresponding assembly methods described herein may be used in any application, but most preferably, they are used in aircraft, such as Figure 7 FIG. 7 shows an aircraft 70. The aircraft 70 includes a fuselage 72. Two wings 73 extend from the fuselage 72. It will be appreciated that the fuselage 72 and the wings 73 may be shaped and contoured in a variety of different designs depending on the specific application. Fuel tanks 74 are formed in the fuselage 72 and the wings 73. Figure 7Schematically illustrating one such fuel tank 74 is shown in FIG. The upper and lower boundaries of tank 74 are provided by the upper and lower skins of wing 73, and the front and rear boundaries are provided by the front and rear spars of the wing. In the above embodiment, both the spark shield cap plate and the end of the blind fastener can be located within the interior of fuel tank 74.

[0069] Although the present invention has been described and illustrated with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention lends itself to many different variations not specifically described herein. Some possible variations will now be described by way of example only.

[0070] For example, in each of the embodiments described herein, the spark protection cap plate is provided with a spark protection cap. However, alternative embodiments may include two caps, and other embodiments may include more than three caps per plate. The number of caps provided on the plate will depend on the specific requirements of the application.

[0071] Furthermore, in the above-described embodiment, the caps provided on the spark protection cap plate are all identical. However, the caps may be different. For example, a structural member may have two or more fasteners of different sizes to be used thereon, and thus, two or more spark protection caps of different sizes or shapes may be provided on the plate.

[0072] Furthermore, the adhesives described above, which can be used to secure the spark protection cap to the spark protection cap plate, or alternatively, the spark protection cap plate to the structural member, are all two-part epoxy adhesives. However, in alternative embodiments, adhesives that cure using UV light can be used. In such embodiments, it may be beneficial to form the spark protection cap and / or the spark protection cap plate from a transparent material that allows UV curing of the adhesive through the cap.

[0073] The above embodiments are to be understood as illustrative examples of the present invention. Equivalents and modifications not described above may also be employed without departing from the scope of the present invention, which is defined in the accompanying claims.

[0074] It should be understood that any feature described with respect to any one embodiment may be used alone or in combination with other features described, and may also be used in combination with one or more features of any other embodiment or any combination of any other embodiments.

[0075] The reader will also understand that integers or features of the invention that are described as preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims. Furthermore, it should be understood that such optional integers or features, while potentially beneficial in some embodiments of the invention, may not be desirable in other embodiments and, therefore, may not be present.

[0076] It should be noted that throughout this specification, “or” should be interpreted as “and / or”.

[0077] Although the present invention has been described above primarily in the context of fixed-wing aircraft applications, the present invention may also be advantageously applied to a variety of other applications, including but not limited to applications on vehicles such as helicopters, drones, trains, motor vehicles, and spacecraft.

Claims

1. A spark protection cap plate, comprising: base; as well as Two or more spark protection caps; each spark protection cap includes a cover portion extending from the base, the cover portion defining a cavity inside the spark protection cap, and the end of a fastener can be enclosed inside the cavity.

2. The spark protection cap plate according to claim 1, wherein: The base includes an attachment surface for attaching the spark shield plate to a structure.

3. A spark protection cap plate according to any preceding claim, wherein: The base includes one or more alignment features.

4. The spark protection cap plate according to claim 3, wherein: The one or more alignment features are engageable with corresponding features on a structural element to which the spark protection cap plate is to be secured.

5. The spark protection cap plate according to any one of the preceding claims, wherein: The base is substantially planar.

6. The spark protection cap plate according to any one of claims 1 to 4, wherein: The base has a non-planar contour shape.

7. The spark protection cap plate according to any one of the preceding claims, wherein: The base includes two or more apertures, and a spark arrester is positioned over each aperture.

8. The spark protection cap plate according to any one of claims 1 to 6, wherein: The base includes a sacrificial material having openings formed therein to enable fastener ends to be received within the cavities within two or more of the spark arrestor caps.

9. The spark protection cap plate according to any one of the preceding claims, wherein: Two or more of the spark protection caps are attached to the base to form the spark protection cap plate.

10. The spark protection cap plate according to claim 9, wherein: Each spark protection cap includes a cap base, and the cap base is attached to the base.

11. The spark protection cap plate according to claim 9, wherein: The cover portion of each spark protection cap includes an annular opening, and each spark protection cap is attached to the base at the annular opening.

12. The spark protection cap plate according to any one of claims 1 to 9, wherein: The base and the two or more spark protection caps are formed from a single piece, and the spark protection caps are molded from the material forming the base.

13. The spark protection cap plate according to any one of the preceding claims, wherein: The base is formed of an electrically insulating material.

14. A fastener joint comprising: Structural parts; two or more fasteners, each fastener having a fastener end projecting from a surface of the structural member; as well as A spark protection cap plate, comprising: base; and Two or more spark arresters; Each of the spark protection caps includes a cover portion extending from the base portion, the cover portion defining a cavity within the interior of the spark protection cap, an end portion of the fastener being enclosed within the cavity; and A cured sealing material is disposed between the spark protection cap plate and the structural member, the cured sealing material securing the spark protection cap plate to the structural member in a position such that each end of each fastener is enclosed within the spark protection cap.

15. A method of securing a fastener and a spark shield plate to a structural member, the method comprising: fixing the spark protection cap plate according to any one of claims 1 to 13 to the surface of the structural member; forming a hole through at least one of the structural member and the spark protection cap plate at a location where the hole is aligned with the spark protection cap; as well as A fastener is inserted through the hole and tightened to secure the fastener to the structure.

16. The method of securing a fastener and a spark shield plate to a structure according to claim 15, wherein: The step of securing the spark protection cap plate to the surface of the structural member includes applying an adhesive between the base of the spark protection cap plate and the structural member and curing the adhesive.

17. A method of securing a fastener and a spark protection cap plate to a structure according to claim 15 or 16, wherein: The step of forming a hole through at least one of the structural member and the spark protection cap plate includes drilling a common hole through the structural member and the base of the secured spark protection cap plate.

18. An aircraft comprising at least one of the spark protection cap plate according to any one of claims 1 to 13 or the fastener joint according to claim 14.

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