Compression fit EME protective seal cap

Abstract

To provide a protection seal cap for enclosing an end portion of a fastener which extends from a structure.SOLUTION: The protection seal cap includes a cap member, which includes a sidewall that defines an interior space within the cap member. The sidewall forms a continuous wall member positioned within the cap member. The continuous wall member defines an opening providing access to the interior space. The continuous wall member is configured to create an interference compression fit between the end portion of the fastener and the continuous wall member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to electromagnetic effect (“EME”) protective seal caps, and more particularly to EME protective seal caps employed to cover portions of fasteners extending from a surface within an aircraft to prevent sparks within the aircraft. [Background technology]

[0002] Current installation of EME protective seal caps, which cover the end portions of fasteners that extend from surfaces within an aircraft, requires significant time, labor, and expense, and suffers from a high rate of installation defects. Defective installation of EME protective seal caps, whether during aircraft manufacturing or during maintenance while the aircraft is in service, requires reinstallation of the imperfectly installed protective seal caps. Because some aircraft potentially utilize thousands of EME protective seal caps, reducing the number of installations and improving the quality of installations is highly valuable.

[0003] Whether during aircraft production or in-service maintenance of the aircraft, the EME protective seal caps are inspected and, if determined to not meet specifications, are removed and replaced. Replacement of protective seal caps for in-service maintenance that occurs in the field involves installation of the protective seal caps in a confined space, as opposed to the controlled environment of a factory during aircraft production. Installation of the EME protective seal cap requires the installer to hold the protective seal cap in place on the aircraft structure for approximately one minute while the sealant used in installing the protective seal cap reduces pressure under the protective seal cap.

[0004] If the protective seal cap is not held in place during sealant decompression, the decompression of the sealant will cause the protective seal cap to lift (peel off) against the surface of the structure to which it is secured, which is unacceptable and requires reinstallation of the protective seal cap, resulting in additional labor and expense.

[0005] There is a need to improve the time spent installing protective seal caps, including reducing the number of defects that require reinstallation of the protective seal cap. There is also a need to reduce the effort expended by installers in holding the protective seal cap during sealant application and sealant depressurization, especially in confined (tight) locations and in installation orientations that present gravity challenges in maintaining the protective seal cap in the desired position. Furthermore, there is a need to install protective seal caps during in-service maintenance without having to remove all of the old sealant from the fasteners. Summary of the Invention

[0006] One embodiment includes a protective seal cap for enclosing an end portion of a fastener extending from a structure. The protective seal cap includes a cap member including a sidewall defining an interior space within the cap member. The sidewall forms a continuous wall member disposed within the cap member. The continuous wall member defines an opening providing access to the interior space. The continuous wall member is configured to create an interference compression fit between the end portion of the fastener and the continuous wall member.

[0007] One embodiment includes a method for holding a protective seal cap in contact with a structure to enclose an end portion of a fastener extending from the structure. The method includes placing a cap member of the protective seal cap over the end portion of the fastener, the cap member including a sidewall defining an interior space within the cap member. The sidewall forms a continuous wall member defining an opening providing access to the interior space. The continuous wall member is configured to create an interference compression fit between the end portion of the fastener and the continuous wall member. The method further includes deforming the continuous wall member to create the interference compression fit between the continuous wall member and the end portion of the fastener.

[0008] The foregoing features, functions, and advantages may be realized individually in various embodiments or may be combined in yet other embodiments, further details of which may be understood by reference to the following description and drawings. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view of a protective seal cap for enclosing an end portion of a fastener extending from a structure. [Figure 2] FIG. 10 is an enlarged bottom perspective view of the protective sealing cap. [Figure 3] 3 is a cross-sectional view taken along line 3-3 of FIG. 1 with the end portion of the fastener enclosed within a protective sealing cap, deforming the continuous wall member. [Figure 3A] 4 is a view of FIG. 3 along with a phantom line view of the shape of the continuous wall member of FIG. 2 where the shape of the continuous wall member is not deformed by the end portion of the fastener. [Figure 4] 4 is a cross-sectional view of the protective seal cap and fastener taken along line 4-4 of FIG. 3A. [Figure 5] 5 is a cross-sectional view of the protective seal cap and fastener taken along line 5-5 of FIG. 3A. [Figure 6] 1 is a flowchart of a method for holding a protective seal cap in contact with a structure to encapsulate an end portion of a fastener extending through the structure. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1 and 2, a protective seal cap 10 for enclosing an end portion 12 of a fastener 14 extending from a structure 16 includes a cap member 18. The cap member 18 includes a sidewall 20 that defines an interior space 22 within the cap member 18. As seen in FIG. 2, the sidewall 20 forms a continuous wall member 24, which defines an opening 26 that provides access to the interior space 22. The continuous wall member 24 is configured to create an interference compression fit between the end portion 12 of the fastener 14 and the continuous wall member 24.

[0011] With respect to the description related to the continuous wall member 24, the continuous wall member may be designated as 24 in an undeformed state, as seen in FIG. 2, and may be referred to as 24' when the continuous wall member is deformed by an interference compression fit between the continuous wall member and the end portion 12 of the fastener 14, as seen in FIGS. 3-5. As seen in FIG. 4, for the continuous wall member 24', the side wall 20 has a width dimension D that is wider than the first width dimension D1 of the continuous wall member 24'. The continuous wall member 24' extends in a direction 25 away from the side wall 20 of the cap member 18. As seen in FIG. 2, the continuous wall member 24 has a first end surface 28. As seen in FIG. 2, the first end surface 28 of the continuous wall member 24 is disposed in a first plane P1. In this case, the first plane P1 is shown as a line designated as P1, aligned along the first end surface 28 and representing that the first end surface 28 lies within the first plane P1.

[0012] In this example, end portion 12 of fastener 14 includes a tool interface feature 30, as seen in FIG. 1 , for fastener 14 to engage a matching feature on a tool to facilitate the tool's gripping of fastener 14 to tighten or loosen fastener 14 relative to structure 16. Tool interface feature 30 can have a variety of shapes, so long as the shape is compatible for being gripped by the particular tool used to tighten or loosen fastener 14. In this example, end portion 12 of fastener 14 also includes a cylindrical portion 32. Cylindrical portion 32 is positioned adjacent tool interface feature 30 on one side of cylindrical portion 32 and abuts structure 16 on the other side of cylindrical portion 32. In this example, a twelve-point bolt head is the tool interface feature 30, which, together with cylindrical portion 32, is known as the head portion of fastener 14. The head portion of fastener 14 can have a wide variety of shapes and sizes. In this embodiment, when fastener 14 is tightened onto cylindrical portion 32, it applies a compressive force to structure 16 in conjunction with a nut or swaged collar (not shown) located on fastener 14 on the opposite side of structure 16.

[0013] As described above, the head portion of the end portion 12 of the fastener 14 can have a wide variety of shapes and sizes. Similarly, the end portion 12 of the fastener 14, located on the opposite side of the fastener 14, can have one of a wide variety of shapes and sizes, including, for example, a wide variety of nut(s) (not shown) or a wide variety of nut(s) and washer(s) (also not shown). In applying the cap member 18 to the end portion 12 of the fastener 14, the cap member 18 can be used to engage either end portion 12 of the fastener 14 as needed in aircraft manufacturing or maintenance. For example, as shown in FIGS. 1-5 , the cap member 18 can be used to enclose the end portion 12 of the fastener 14, including the head portion of the fastener 14, or to enclose the end portion 12 of the fastener 14, including the nut(s) or nut(s) and washer(s) portion of the fastener 14 on the opposite end of the fastener 14, not shown. In either application, the continuous wall member 24 creates an interference compression fit with the end portion 12 of the fastener 14, whereby the cap member 18, placed in contact with the structure 16, holds the fastener 14 in position, enclosing the end portion 12 of the fastener 14 within the cap member 18 and the structure 16. In achieving this interference compression fit, the opening 26 of the cap member 18 defined by the continuous wall member 24 can be shaped and sized by the continuous wall member 24 to create an interference compression fit with the end portion 12 of any of the fasteners 14, as described above, as needed. For example, as seen in the embodiment shown in FIGS. 4 and 5, the interference compression fit can be created with the head portion of the fastener 14, or with the nut(s), nut(s) and washer(s), or swage collar (not shown) of the fastener 14.

[0014] In this embodiment, as seen in Figure 2, the opening 26 formed by the continuous wall member 24 can have one of a wide variety of shapes and sizes. To the extent that the shape and size of the continuous wall member 24 allows the continuous wall member 24 to encounter the end portion 12 of the fastener 14, the end portion 12 of the fastener 14 will contact and deform the continuous wall member 24', creating an interference compression fit between the end portion 12 and the continuous wall member 24'.

[0015] 3, continuous wall member 24' is deformed by end portion 12 of fastener 14 in this embodiment at three spaced apart locations 34, 36, and 38 of continuous wall member 24'. In this embodiment, deformation of continuous wall member 24' includes compressing the portion of continuous wall member 24' that contacts cylindrical portion 32 of end portion 12 of fastener 14. In this embodiment, compressive deformation of the continuous wall member 24' occurs at each of three locations 34, 36, and 38. For example, at location 34, the continuous wall member 24 has a thickness "T." In that case, the cylindrical portion 32 contacts the continuous wall member 24', as opposed to the continuous wall member 24' having a thicker thickness "T1" between contact locations 34 and 36, where the end portion 12 of the fastener 14 does not contact the continuous wall member 24'. This deformation of the continuous wall member 24' occurs when the cap member 18 is constructed from a material, such as a thermoplastic or thermoset, which, in this embodiment, is softer than the end portion 12 of the fastener 14. Deformation of the continuous wall member 24' is seen at location 36 in FIG. 4 as deformation 37, at location 34 as deformation 35, and similarly shown at location 36 in FIG. 5 as deformation 37. In this embodiment, such deformation also occurs at location 38.

[0016] In this embodiment, further deformation of the continuous wall member 24' occurs with a deformation of the overall configuration or shape of the continuous wall member 24', which affects the shape of the opening 26 surrounded by the continuous wall member 24' when the end portion 12 of the fastener 14 is disposed within and in contact with the continuous wall member 24'. The shape of the continuous wall member 24' is distorted as can be seen in FIG. 3A. The undeformed and undistorted continuous wall member 24 of FIG. 2 is shown in phantom lines in FIG. 3A and is designated as continuous wall member 24. The continuous wall member 24' deformed and distorted by the end portion 12 of the fastener 14 is designated as continuous wall member 24' in FIG. 3A.

[0017] With deformation of the continuous wall member 24' at locations 34, 36, and 38 along with distortion of the shape of the continuous wall member 24', a compressive interference fit is created between the end portion 12 of the fastener 14 and the continuous wall member 24', creating friction between the end portion 12 of the fastener 14. With the cap member 18 placed in contact with the structure 16, the compressive friction keeps the cap member secured to the fastener 14 and the end portion 12 of the fastener 14 enclosed within the cap member 18. With the continuous wall member 24' gripping the end portion 12 of the fastener 14 through interference compression and creating friction, the cap member 18 can be placed and secured to the structure 16 within the aircraft in any orientation, despite the force of gravity acting on the cap member 18. This orientation can include extreme orientations of the cap member 18, such as being placed upside down on a surface, on a vertical plane, or on an inclined surface, without requiring an individual installer to hold the cap member 18 in place. By holding the cap member 18 in place with an interference compression fit and enclosing the end portion 12 of the fastener 14 within the cap member 18 and the structure 16, as will be described below, the cap member 18 is in the correct position to facilitate installation of the cap member 18 during injection of sealant into the cap member 18, and is in the correct position during decompression of the sealant without any need for the installer to hold the cap member 18 in place, improving the speed of quality installation. Furthermore, the compression fit capability of the continuous wall member 24' also eliminates the need for the installer to remove all of the sealant during in-service aircraft maintenance. The compression interference fit allows the cap member 18 to grip the end portion 12 of the fastener 14 without removing all of the sealant from the end portion 12, eliminating the need for the installer to remove all of the sealant when installing the cap member 18.

[0018] 2, 3, 4, and 5, the side wall 20 forms a wall member 40 spaced apart from the continuous wall members 24, 24′. The wall member 40 extends in a direction 25 away from the side wall 20 of the cap member 18, which defines the interior space 22, as seen in FIG. 4. The wall member 40 has a second end surface 42. As seen in FIG. 2, the second end surface 42 is configured such that the second end surface 42 extends within a second plane P2. In this case, the second plane P2 is shown as a line designated as P2, aligned along the second end surface 42 and indicating that the second end surface 42 lies within the second plane P2. In this embodiment, the first end surface 28 and the second end surface 42 are coplanar. In other embodiments of the cap member 18, the first and second planes P1 and P2 are not coplanar but are parallel to each other. Such a configuration ensures, for example, that when cap member 18 is placed on structure 16, first end 28 is spaced slightly away from the surface of structure 16 and second end 42 contacts the surface of structure 16. This configuration prevents sealant 62 from escaping out of channel 44 to exterior 56 of cap member 18, thereby preventing further washing of sealant 62 from the surface of structure 16, as described below. Conversely, sealant 62 is permitted to escape from channel 44 past first end 28 into interior space 22.

[0019] 2, 3, 4, and 5, a channel 44 defined by the sidewall 29 of the cap member 18 is disposed to extend around the continuous wall members 24, 24′ and is disposed between the continuous wall members 24, 24′ and the wall member 40. The wall member 40 defines two ports 46, 48 spaced apart from one another and extending therethrough. The two ports 46, 48 are disposed on opposite sides 50, 52 of the cap member 18, respectively. Each of the two ports 46, 48 is in fluid communication with the channel 44. A first flow path 54 extends from an exterior 56 of the cap member 18 into the channel 44, for example, through port 46 of the two ports 46, 48. A second flow path 58 extends from the inside 60 of the channel 44 to and through the port 48 of the two ports 46, 48 to the outside 56 of the cap member 18. As seen in FIG. 5 , this configuration allows an installer to inject sealant 62, for example, through the port 46 of the two ports 46, 48, with the sealant 62 exiting the port 48 of the two ports 46, 48. In this embodiment, with the sealant moving out of the port 48, the installer is provided with an indication that the sealant 62 is flowing through and present within the channel 44.

[0020] As previously mentioned, the fastener 14 is constructed from a harder material than the material from which the wall members 24, 24' are constructed. The force applied by the end portion 12 of the fastener 14 against the continuous wall member 24 causes the continuous wall member 24' to deform. The deformation of the continuous wall member 24, 24' provides an interference compression fit between the continuous wall member 24' and the end portion 12 of the fastener 14 that properly holds the cap member 18 in place so that injection of the sealant 62 can be accomplished and decompression of the sealant 62 can occur without the cap member 18 experiencing undesirable lifting from the structure 16.

[0021] Referring to FIG. 6 , a method 64 is shown for holding a protective seal cap 10 in contact with a structure 16 to enclose an end portion 12 of a fastener 14 extending from the structure 16. The method 64 includes positioning (66) a cap member 18 of the protective seal cap 10 over the end portion 12 of the fastener 14. The cap member 18 includes a sidewall 20 that defines an interior space 22 within the cap member 18. The sidewall 20 forms a continuous wall member 24 disposed within the cap member 18. The continuous wall member 24 defines an opening 26 that provides access to the interior space 22. The continuous wall member 24 is configured to create an interference compression fit between the end portion 12 of the fastener 14 and the continuous wall member 24. The method 64 further includes deforming (68) the continuous wall member 24′ to create an interference compression fit between the continuous wall member 24′ and the end portion 12 of the fastener 14.

[0022] Positioning (66) the cap member 18 further includes positioning the cap member 18 in contact with the structure 16. The sidewall 20 forms a wall member 40 that is spaced apart from the continuous wall member 24. The wall member 40 extends around the continuous wall member 24, with a channel 44 defined by the sidewall 20 being disposed between the wall member 40 and the continuous wall member 24. The wall member 40 defines two ports 46, 48 that extend through the wall member 40 and are in fluid communication with the channel 44. The method 64 further includes injecting a sealant 62 into the channel 44 through one of the two ports 46, 48.

[0023] Additionally, the present disclosure includes embodiments according to the following clauses: Article 1. A protective seal cap (10) for enclosing an end portion (12) of a fastener (14) extending from a structure (16), comprising: a cap member (18) having a sidewall (20) defining an interior space (22) within the cap member (18); The sidewall (20) forms a continuous wall member (24) disposed within the cap member (18); The continuous wall member (24) defines an opening (26) that provides access to the interior space (22); The continuous wall member (24) is configured to create an interference compression fit between the end portion (12) of the fastener (14) and the continuous wall member (24). Article 2. 2. The protective seal cap (10) of claim 1, wherein the side wall (20) has a width dimension (D) that is greater than the first width dimension (D1) of the continuous wall member (24'). Article 3. 3. The protective seal cap of claim 1 or 2, wherein the continuous wall member (24') extends in a direction (25) away from the side wall (20) of the cap member (18) that defines the interior space (22). Article 4. The continuous wall member (24) has a first end surface (28); 4. The protective seal cap (10) of any one of clauses 1 to 3, wherein the first end face (28) of the continuous wall member (24) is disposed in a first plane (P1). Article 5. 5. The protective seal cap (10) of any one of clauses 1 to 4, wherein the side wall (20) forms a wall member (40) spaced apart from the continuous wall member (24, 24'). Article 6. 6. The protective seal cap (10) of claim 5, wherein the wall member (40) extends in a direction (25) away from the side wall (20) of the cap member (18) that defines the interior space (22). Article 7. The wall member (40) has a second end surface (42), 7. The protective seal cap (10) of clause 5 or 6, wherein the second end surface (42) is configured such that the second end surface (42) extends in a second plane (P2). Article 8. 8. The protective seal cap (10) of any one of clauses 5 to 7, wherein the channel (44) is arranged to extend around the continuous wall member (24, 24') and is disposed between the continuous wall member (24, 24') and the wall member (40). Article 9. 9. The protective seal cap (10) of any one of clauses 5 to 8, wherein the wall member (40) defines two ports (46, 48) extending through the wall member (40). Article 10. 10. The protective seal cap (10) of clause 9, wherein the two ports (46, 48) are spaced apart from each other. Article 11. 11. The protective seal cap (10) of claim 10, wherein the two ports (46, 48) are disposed on opposite sides (50, 52) of the cap member (18), respectively. Article 12. 12. The protective seal cap (10) of any one of clauses 9 to 11, wherein the two ports (46, 48) are in fluid communication with the channel (44). Article 13. a first flow path (54) extending from an exterior (56) of the cap member (18) through one of the two ports (46, 48) into the channel (44); A protective seal cap (10) as described in clause 12, wherein a second flow path (58) extends from the inside (60) of the channel (44) to a second of the two ports (46, 48) and through the second port to the outside (56) of the cap member (18). Article 14. 14. The protective seal cap (10) of any one of clauses 1 to 13, wherein the fastener (14) is constructed from a material that is harder than the material from which the continuous wall members (24, 24') are constructed. Article 15. A method (64) for holding a protective seal cap (10) in contact with a structure (16) to enclose an end portion (12) of a fastener (14) extending from the structure (16), comprising: placing (66) a cap member (18) of a protective sealing cap (10) over the end portion (12) of the fastener (14); The cap member (18) includes a sidewall (20) that defines an interior space (22) within the cap member (18); The sidewall (20) forms a continuous wall member (24) disposed within the cap member (18); The continuous wall member (24) defines an opening (26) that provides access to the interior space (22); The continuous wall member (24) is configured to create an interference compression fit between the end portion (12) of the fastener (14) and the continuous wall member (24); The method further comprises: A method (64) including deforming the continuous wall member (24') to create an interference compression fit (68) between the continuous wall member (24') and the end portion (12) of the fastener (14). Article 16. 16. The method of claim 15, wherein disposing the cap member further comprises disposing the cap member in contact with the structure. Article 17. 17. The method (64) of clause 15 or 16, wherein the side wall (20) forms a wall member (40) spaced apart from the continuous wall member (24). Article 18. The wall member (40) extends around the continuous wall member (24); 18. The method (64) of clause 17, wherein the channel (44) defined by the sidewall (20) is disposed between the wall member (40) and the continuous wall member (24). Article 19. 19. The method (64) of clause 17 or 18, wherein the wall member (40) defines two ports (46, 48) extending through the wall member (40) and in fluid communication with the channel (44). Article 20. 20. The method (64) of clause 19, further comprising injecting a sealant (62) into the channel (44) through one of the two ports (46, 48).

[0024] While various embodiments have been described above, the present disclosure is not intended to be limited thereto. Modifications to the disclosed embodiments may be made and are within the scope of the appended claims.

Claims

1. A protective seal cap (10) for enclosing an end portion (12) of a fastener (14) extending from a structure (16), comprising: a cap member (18) constructed from a thermoplastic or thermosetting material, the cap member (18) having a sidewall (20) defining an interior space (22) within the cap member (18); The sidewall (20) forms a continuous wall member (24) disposed within the cap member (18); the continuous wall member (24) defines an opening (26) providing access to the interior space (22); the continuous wall member (24) is configured to create an interference compression fit between the end portion (12) of the fastener (14) and the continuous wall member (24); a thickness (T1) of the continuous wall member (24) between contact points (34, 36, 38) where the continuous wall member (24) contacts the end (12) of the fastener (14) is greater than a thickness (T) of the continuous wall member (24) at the contact points (34, 36, 38); Protective sealing cap (10).

2. 2. The protective seal cap (10) of claim 1, wherein said side wall (20) has a thickness (D) greater than a thickness (D1) of said continuous wall member (24').

3. The continuous wall member (24, 24') extends parallel to the central axis of the cap member (18) and in a direction (25) away from the side wall (20) that defines an interior space (22) within the cap member (18); 3. The protective sealing cap (10) of claim 1 or 2, wherein the continuous wall member (24) has a first end surface (28) disposed in a first plane (P1).

4. 4. The protective seal cap (10) of claim 3, wherein the side wall (20) extends in the direction and defines a wall member (40) spaced radially outward from the continuous wall member (24, 24').

5. The wall member (40) has a second end surface (42) configured to extend in a second plane (P2); 5. The protective seal cap (10) of claim 4, wherein the first plane (P1) and the second plane (P2) are parallel but not coplanar, and the first plane (P1) and the second plane (P2) are configured such that, when the cap member (18) is placed on the structure (16), the first end surface (28) is spaced apart from the surface of the structure (16) and the second end surface (42) contacts the surface of the structure (16).

6. 6. The protective seal cap (10) of claim 4 or 5, wherein a channel (44) is disposed to extend around the continuous wall member (24, 24') and is disposed between the continuous wall member (24, 24') and the wall member (40).

7. The protective seal cap (10) of claim 6, wherein the wall member (40) defines two ports (46, 48) extending through the wall member (40).

8. 8. The protective seal cap (10) of claim 7, wherein the two ports (46, 48) are spaced apart from one another.

9. The protective seal cap (10) of claim 8, wherein the two ports (46, 48) are in fluid communication with the channel (44).

10. a first flow path (54) extending from an exterior (56) of the cap member (18) through one of the two ports (46, 48) into the channel (44); 10. The protective seal cap (10) of claim 9, wherein a second flow path (58) extends from an inside (60) of the channel (44) to a second of the two ports (46, 48) and through the second port to an outside (56) of the cap member (18).

11. A set of a fastener (14) and a protective seal cap (10), comprising the fastener (14) extending from a structure (16) and the protective seal cap (10) described in any one of claims 1 to 10 for enclosing an end portion (12) of the fastener (14).

12. 12. The set of claim 11, wherein the fastener (14) is constructed of a material harder than the material of the continuous wall member (24) of the protective sealing cap (10).

13. 13. A method (64) for holding a protective seal cap (10) against a structure (16) and enclosing an end portion (12) of a fastener (14) extending from the structure (16) using the set of claims 11 or 12, comprising: placing (66) a cap member (18) of the protective sealing cap (10) over the end portion (12) of the fastener (14); and deforming a continuous wall member (24') formed by a sidewall (40) of the cap member (18) and disposed within the cap member (18) to create an interference compression fit (68) between the continuous wall member (24') and the end portion (12) of the fastener (14).

14. 14. The method of claim 13, further comprising injecting a sealant into a channel through one of two ports, the channel being disposed between a wall member formed by the sidewall and the continuous wall member, the wall member being spaced radially outward from the continuous wall member, and the two ports extending through the wall member.

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