Patent Publication Number: US-2021164513-A1

Title: Anchoring washer for an eme protection cap system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 15/964,340, entitled “Anchoring Washer for an EME Protection Cap System” and filed Apr. 27, 2018, the entire disclosure of which is incorporated by reference herein. 
    
    
     FIELD 
     This disclosure relates to an electrical insulation cap assembly for insulating metallic fasteners from transmitting current or sparks into the vicinity of the location of the metallic fastener assembly with the occurrence of electromagnetic effect (“EME”) or lightning strike event and more particularly for electrical insulating containment caps which enclose a metallic threaded fastener. 
     BACKGROUND 
     Electrically insulated sealant and containment caps have been used to cover an end portion of a metallic fastener assembly which includes a nut and a threaded end portion of a stud which extends beyond the nut and which may include one or more washers. The sealant caps electrically insulate the end portion of the metallic fastener assembly so as to electrically isolate and contain the end portion of the metallic fastener assembly from critical surroundings of the metallic fastener assembly such as within a vicinity of a fuel tank or sensitive electronic equipment within an aircraft. Electrically isolating and containing the end portion of the metallic fastener assembly prevents unwanted sparks or electrical current transmissions entering into such important surroundings upon an EME or lightning strike event. 
     The insulation and containment caps are made from sealant material such as for example a thermoset plastic. The caps are also filled with a liquid form of sealant material. Once the cap is filled with liquid sealant, the cap is positioned over the end portion of the metallic fastener assembly enclosing the end portion of the metallic fastener assembly within the cap and a surface of a structure from which the end portion of the metallic fastener assembly extends. At times sealant is expelled from the cap being over filled with sealant. This expelling of sealant can also occur by way of a sufficient amount of sealant being present such that expelling of some sealant from the cap can occur which indicates an adequate amount of sealant has been used. The expelled sealant in either occurrence must then be smoothed out about the cap to ensure proper sealing of the cap and for aesthetics. This smoothing out process is tedious and time consuming. 
     The cap also requires being held in place for a time period so as to maintain the cap&#39;s position to prevent an occurrence of the cap experiencing slumping or lifting off of the surface of a structure from which the end portion of the metallic fastener assembly extends during the curing of the sealant. The cap-to-structure joints are subject to high quality standards and often require rework. 
     There is a need to reduce the time to install EME or lightning strike event protective caps enclosing end portions of metallic fastener assemblies in high criticality areas such as in the proximity of fuel tanks or sensitive electronic equipment of an aircraft. In addition there is a need to have a reliable securement mechanism for securing the caps to the end portions of the metallic fasteners. 
     SUMMARY 
     A cap system for enclosing a metallic fastener assembly extending through a structure including a first securement mechanism positioned about a periphery of a washer of the metallic fastener assembly wherein the first securement mechanism includes threads. A cap member includes a sidewall having an inner surface which defines a cavity dimensioned to receive the washer and defines a second securement mechanism complementary configured to engage the first securement mechanism positioned about the periphery of the washer. The cap system further includes an end of the sidewall of the cap member defines an opening which provides the washer to have access into the cavity. 
     A cap system for enclosing a metallic fastener assembly extending through a structure including a first securement mechanism positioned about a periphery of a washer of the metallic fastener assembly wherein the first securement mechanism includes a first tab member extending in a direction transverse to a plane of a surface of the washer and a second tab member extending in a direction transverse to the plane of the surface of the washer spaced apart from the first tab member about the periphery of the washer. The cap system further includes a cap member including a sidewall having an inner surface which defines a cavity dimensioned to receive the washer and defines a second securement mechanism complementary configured to engage the first securement mechanism positioned about the periphery of the washer. The cap system further includes an end of the sidewall of the cap member defines an opening which provides the washer to have access into the cavity. 
     The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF SUMMARY OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a first embodiment of a cap system for enclosing an end portion of a metallic fastener assembly extending from a structure; 
         FIG. 2  is a cross section view along line  2 - 2  of  FIG. 1  of the first embodiment of the cap system assembled; 
         FIG. 3  is a perspective cross section view of employment of the first embodiment of the cap system of  FIG. 1  utilizing three different example configurations of the metallic fastener assembly; 
         FIG. 4  is an enlarged bottom perspective view of the first embodiment of the cap member of  FIG. 1  showing a first example of the end of the cap member; 
         FIG. 5  is an exploded perspective view of a second embodiment of the cap system for enclosing an end portion of the metallic fastener assembly extending from the structure; 
         FIG. 6  is a cross section view along line  6 - 6  of  FIG. 5  of the second embodiment of the cap system assembled; 
         FIG. 7  is a perspective cross section view of employment of the second embodiment of the cap system of  FIG. 5  utilizing three different example configurations of the metallic fastener assembly; 
         FIG. 8  is an enlarged bottom perspective view of the cap member of  FIG. 5  showing a second example of the end of the cap member; and 
         FIG. 9  is an enlarged bottom perspective schematic view of a cap member showing a third example of the end of the cap member. 
     
    
    
     DESCRIPTION 
     A cap system described herein will be employed to enclose an end portion of a metallic fastener assembly which is secured to and projects from a structure, in this example, a structure positioned within an aircraft. The cap system has a cap member. The cap member is to be positioned over and enclose the end portion of the metallic fastener assembly which extends from the structure and the cap member secures to the metallic fastener assembly. With an end of the cap member positioned abutting a surface of the structure, the end portion of the metallic fastener assembly is enclosed within the confines of the cap member and a surface of the structure. With positioning the cap member to enclose the end portion of the metallic fastener assembly the cap member also secures to the metallic fastener assembly. 
     The cap is constructed of a nonconductive material such as a polymer, thermoset or of other nonconductive material and a nonconductive sealant material may be additionally used in association with the cap member to further electrically isolate the end portion of the metallic fastener assembly from the surrounding vicinity of the metallic fastener assembly positioned outside of the cap member. Surrounding vicinities within an aircraft which would need electrical transmission isolation from a metallic fastener assembly include areas such as a fuel tank, areas which contain sensitive electronic equipment or areas which could otherwise be adversely affected by a transmission from an EME or lightning strike event such as experienced by an aircraft. 
     A metallic fastener assembly, in this example, two configurations could include a threaded stud which includes at one end a nut or could include a threaded bolt which at one end includes a head. In employing a first configuration of the metallic fastener assembly a threaded stud is extended through the structure(s) and a nut is positioned onto the threaded stud on one side of the structure(s) to which the metallic fastener assembly is to be secured. A nut member with threads compatible to the threads of the threaded stud is engaged to the threaded stud on an opposing second side of the structure(s), a side to which the cap system to be described herein will be positioned. At least one washer is positioned between the nut member and the structure(s) wherein the cap system includes a portion of the at least one washer which engages a cap member of the cap system and the cap member encloses the nut member, the at least one washer and the threaded stud projecting from the structure(s). 
     In a second configuration of the metallic fastener assembly a threaded bolt is extended through the structure(s) with the head of the threaded bolt positioned on one side of a structure(s) to which the metallic fastener assembly is to be secured. A nut member with threads compatible to the threads of the threaded bolt is engaged onto the bolt on an opposing second side of the structure(s), a side to which the cap system to be described herein will be positioned. At least one washer is positioned between the nut member and the structure(s) wherein the cap system includes a portion of the at least one washer which engages a cap member of the cap system and the cap member encloses the nut member, the at least one washer and the threaded bolt projecting from the structure(s). 
     In a third configuration of the metallic fastener assembly a threaded bolt is extended through the structure(s) with the head of the threaded bolt positioned on the side of the structure(s) in which the cap system to be described herein will be positioned. A nut with compatible threads is secured to the threaded bolt on an opposite side of the structure(s). At least one washer is positioned between the head and the structure(s) wherein the cap system includes a portion of the at least one washer which engages a cap member of the cap system and the cap member encloses the head and the at least one washer. 
     In the first and second configuration of the metallic fastener assembly, with the tightening of the nut member on the threaded stud or on the threaded bolt in a direction toward the structure(s) a compressive force is applied to the structure(s) positioned between the nut (not shown) and the nut member with respect to the threaded stud or the compressive force is applied to the structure(s) positioned between the head (not shown) and the nut member with respect to the threaded bolt. With the compressive force applied with the nut member on one of a threaded stud or threaded bolt of the metallic fastener assembly, the metallic fastener assembly is in a secured position with respect to the structure(s). In the third configuration of the metallic fastener assembly, with tightening of the head of the threaded bolt in a direction toward the structure(s) a compressive force is applied to the structure(s) positioned between the head and the nut secured to the threaded bolt positioned on the other side of the structure(s). With the compressive force applied the threaded fastener assembly in this third configuration, the metallic fastener assembly is in a secured position with respect to the structure(s). 
     With the metallic fastener assembly in a secured position with respect to the structure(s) and with a cap member of the cap system enclosing an end portion of the metallic fastener assembly positioned projecting from a side of the structure(s) the cap member of the cap system at the same time secures to a portion of at least one washer of the cap system, and the cap member will be secured to the metallic fastener assembly and positioned against the structure. 
     In referring to  FIG. 1 , in this example, an end portion  10  of metallic fastener assembly  11  is shown projecting from surface  12  of structure  14 . Structure  14  is shown schematically wherein structure  14  may include one or more components to which metallic fastener assembly  11  is secured. Metallic fastener assembly  11  in this example includes threaded stud or bolt  16  which has a nut (not shown) or head (not shown) positioned beneath structure  14 . Threaded stud or threaded bolt  16  has threads  18 , metallic fastener assembly  11  includes, in this example, washer  20  which is positioned surrounding threaded stud or threaded bolt  16  and abuts surface  12  of structure  14 . Metallic fastener assembly  11  further includes washer  21  positioned on washer  20 . Metallic fastener assembly  11  also includes nut member  22  which has threads  24  positioned within nut member  22  which are compatible to engage with threads  18  of threaded stud or threaded bolt  16  wherein threaded stud or threaded bolt  16  extends through structure  14 . Threads  24  of nut member  22  can engage threads  18  of threaded stud or threaded bolt  16  and be tightened down resulting in exerting a compressive force with respect to structure  14 . With structure  14  positioned between nut member  22  and nut (not shown) or head (not shown) of threaded stud or threaded bolt  16 , respectively, of metallic fastener assembly  11 , metallic fastener assembly  11  obtains a secured position with respect to structure  14 . In this example, washer  21  is positioned between nut member  22  and washer  20 . 
     In  FIG. 1 , first embodiment of cap system  26 A is shown enclosing metallic fastener assembly  11  extending through structure  14 . Cap system  26 A has cap member  28 A. As mentioned earlier cap member  28 A will be constructed of a nonconductive material such as one of a polymer, thermoset or other nonconductive materials. Cap member  28 A has sidewall  29 A having inner surface  30 A, as seen in  FIGS. 2-4 . First securement mechanism  34 A of cap system  26 A, as seen in  FIG. 1 , is positioned about periphery  36 A of washer  21  of metallic fastener assembly  11 . Cap member  28 A includes sidewall  29 A having inner surface  30 A which defines cavity  32 A dimensioned to receive washer  21  and defines second securement mechanism  38 A, as seen in  FIG. 4 , which is complementary configured to engage first securement mechanism  34 A positioned about periphery  36 A of washer  21 . End  40 A of sidewall  29 A of cap member  28 A defines opening  42 A which provides in this example washers  20 ,  21 , nut member  22  including threaded portion of one of threaded stud or threaded bolt  16  which projects from structure  14  to have access into cavity  32 A. 
     As seen in  FIG. 1 , first securement mechanism  34 A includes threads  44 A positioned on washer  21 . Nut member  22  includes ridge members  46 A, in this example, which are configured to receive and engage a standard socket wrench for tightening nut member onto washers  20  and  21  and securing washers  20  and  21  against structure  14 . 
     Second securement mechanism  38 A includes threads  50 A defined by inner surface  30 A of sidewall  29 A of cap member  28 A, as seen in  FIG. 4 . Threads  50 A extend about inner surface  30 A of cap member  28 A and extend in a direction D away from end  40 A of sidewall  29 A of cap member  28 A. As will be discussed further below, with nut member  22  and threaded stud or threaded bolt  16  in a secured position with respect to structure  14  and with threads  50 A engaging threads  44 A of washer  21 , end  40 A of sidewall  29 A of cap member  28 A is positioned against structure  14  enclosing end portion  10  of metallic fastener assembly  11  and cap member  28 A is secured to washer  21  of metallic fastener assembly  11 . With threads  50 A extending in direction D, threads  50 A extend toward higher elevations with respect to surface  12  with end  40 A abutting surface  12  as shown in  FIG. 3 . Threads  50 A can accommodate and engage threads  44 A of washer  21  as threads  44 A may differ in elevation position relative to surface  12  as will be shown and discussed with respect to  FIG. 3 , thereby ensuring securement of cap member  26 A to end portion  10  of metallic fastener assembly  11  and end  40 A abutting surface  12  enclosing end portion  10 . 
     In  FIG. 3 , first example  52 A of end portion  10  of metallic fastener assembly  11  extending above surface  12  of structure  14  is seen wherein first embodiment of cap system  26 A is shown enclosing of end portion  10  and securing to end portion  10  of metallic fastener assembly  11 . In first example  52 A, nut member  22  is secured to threads  18  of threaded stud or threaded bolt  16  and nut member  22  directly abuts washer  21  which in turn abuts surface  12 . Threads  44 A of washer  21  are engaged to threads  50 A wherein threads  44 A are positioned above surface  12  at an elevation profile lesser than that of threads  44 A in second example  52 A 1 . 
     In second example  52 A 1 , in  FIG. 3 , first embodiment of cap system  26 A encloses and secures to end portion  10  of metallic fastener assembly  11  which is positioned extending in this example above surface  12 . In second example  52 A 1 , nut member  22  is secured to threads  18  of threaded stud or threaded bolt  16  and nut member  22  is positioned on washer  21  which positions threads  44 A of washer  21  which engage to threads  50 A of cap member  28 A. Threads  44 A are positioned above surface  12  at a higher elevation profile than that of threads  44 A of washer  21  of first example  52 A. Threads  50 A of cap member  28 A extend in direction D as seen in  FIG. 4  permitting threads  44 A of washer  21  to be engaged to threads  50 A in both the first example  52 A and second example  52 A 1  with end  40 A of sidewall  29 A of cap member  28 A abutting surface  12  of structure  14 . As a result, cap member  28 A encloses end portion  10  of metallic fastener assembly  11  and secures to end portion  10  of metallic fastener assembly  11  with the engagement of threads  44 A of washer  21  with threads  50 A of cap member  28 A regardless of the difference in elevation profile of threads  44 A with respect to surface  12 , as seen in first example  52 A and  52 A 1 . 
     Thus, with an installer having tightened nut member  22 , of the first and second examples  52 A and  52 A 1  in  FIG. 3  with threads  24  compatible with threads  18  of threaded stud or threaded bolt  16 , into a secured position relative to structure  14 , the installer can then position first embodiment of cap  28 A to have threads  44 A of washer  21  engage threads  50 A of cap member  28 A. The installer can then turn and tighten cap member  28 A, with threads  44 A and  50 A engaged, until end  40 A is positioned against or abuts surface  12 . Cap member  28 A is then secured to surface  12  and secured to metallic fastener assembly  11  enclosing end portion  10  of metallic fastener assembly  11 . As explained above, with threads  50 A extending in direction D, threads  44 A of washer  21  positioned at different elevation profiles above surface  12  can engage and reliably secure to threads  50 A thereby securing cap member  28 A to end portion  10  of metallic fastener assembly  11  and with end  40 A abutting surface  12  cap member  28 A securely encloses end portion  10  of metallic fastener assembly  11 . 
     In the third example  52 A 2 , as seen in  FIG. 3 , metallic fastener assembly  11  includes head  53  of a threaded bolt member  16  wherein head  53  is positioned in overlying relationship to washer  21 . Head  53  is positioned in a secure relationship with respect to structure  14  with a nut (not shown) positioned below structure  14  secured to threads  18  of threaded bolt  16 . Washer  21  is positioned between head  53  and structure  14  and with threads  44 A positioned about periphery  36 A of washer  21  engaging threads  50 A defined by inner surface  30 A of cap member  28 A, end  40 A, as seen in  FIG. 4 , of cap member  28 A is positioned against structure  14 . 
     In this third example  52 A 2 , the installer having tightened head  53  onto threads  18  of threaded bolt  16  into a secured position relative to structure  14  with nut (not shown) positioned on threaded bolt  16  positioned on opposite side of structure  14  than head  53 , the installer can then position first embodiment of cap  28 A to have threads  44 A of washer  21  engage threads  50 A of cap member  28 A. The installer can then turn and tighten cap member  28 A, with threads  44 A and  50 A engaged, until end  40 A abuts surface  12 . Cap member  28 A is then secured to surface  12  and secured to metallic fastener assembly  11  enclosing end portion  10  of metallic fastener assembly  11 . As explained above, with threads  50 A extending in direction D, threads  44 A of washer  21  positioned at different elevation profiles, based on for example an addition of a washer, above surface  12  threads  44 A can engage and reliably secure to threads  50 A thereby securing cap member  28 A to end portion  10  of metallic fastener assembly  11  and with end  40 A abutting surface  12 , cap member  28 A securely encloses end portion  10  of metallic fastener assembly  11 . 
     In referring to  FIG. 5 , second embodiment of cap system  26 B is shown enclosing metallic fastener assembly  11  extending through structure  14 . Cap system  26 B has cap member  28 B. As mentioned earlier cap member  28 B will be constructed of a nonconductive material such as one of a polymer, thermoset or other nonconductive material and will be more flexible of a material than a metal construction of the metallic fastener assembly  11  including the portion of the washer  21 ′ or first securement mechanism  34 B. Cap member  28 B has sidewall  29 B having an inner surface  30 B, as seen in  FIGS. 6-8 . First securement mechanism  34 B of cap system  26 B, as seen in  FIG. 5 , is positioned about periphery  36 B of washer  21  of metallic fastener assembly  11 . Cap member  28 B includes sidewall  29 B having an inner surface  30 A which defines cavity  32 B dimensioned to receive washer  21 ′ and defines second securement mechanism  38 B, which is seen in  FIG. 8 , which is complementary configured to engage first securement mechanism  34 B positioned about periphery  36 B of washer  21 . End  40 B of sidewall  29 B of cap member  28 B defines opening  42 B which provides in this example washers  20 ,  21 ′, nut member  22  and threaded portion of one of threaded stud or threaded bolt  16  which projects from structure  14  to have access into cavity  21 BAs seen in  FIG. 5 . 
     First securement mechanism  34 B includes first tab member  45 B extending in a direction D′ transverse to a plane P of surface  49 B of washer  21 ′ and second tab member  47 B extending in the direction D′ transverse to the plane P of the surface  49 B of washer  21 ′ spaced apart from first tab member  45 B about periphery  36 B of washer  21 ′. Each of first and second tab members  45 B and  47 B include plurality of grooves  51 B. Nut member  22  includes plurality of ridges  46 B which are compatible with a standard socket wrench so as to receive and engage a standard socket wrench for tightening nut member  22  onto washers  20  and  21 ′ against structure  14 . Second securement mechanism  38 B includes plurality of teeth  50 B defined by inner surface  30 B of sidewall  29 B of cap member  28 B, as seen in  FIG. 8 . Plurality of teeth  50 B extend about at least a portion of inner surface  30 B of sidewall  29 B of cap member  28 B. Plurality of teeth  50 B extend in a direction D away from end  40 B of sidewall  29 B of cap member  28 B. As will be discussed further below, with nut member  22  and threaded stud or threaded bolt  16  in a secured position in relationship to structure  14  and with plurality of teeth  50 B engaging at least a portion of continuous threads  44 B of washer  21 , end  40 B is positioned against structure  14  enclosing end portion  10  of metallic fastener assembly  11 . Plurality of teeth  50 B can be extended in direction D away from end  40 B of cap member  28 B if needed. Plurality of teeth  50 B can extend (not shown) toward higher elevations above surface  12  of structure  14  which can accommodate different positions of elevation profile of plurality of grooves  51 B with end  40 B in abutting relationship with surface  12  of structure  14 . As a result, plurality of teeth  50 B can accommodate and engage plurality of grooves  51 B of washer  21 ′ at different elevations of position of grooves  51 B with respect to structure  14  if needed. Plurality of teeth  50 B as mentioned earlier are constructed of a material more flexible than the material which constructs the plurality of grooves  51 B. In this instance, as the installer pushes downwardly or toward structure  14  plurality of teeth  50 B flex as they contact grooves  51 B. With end  40 B positioned against structure  14  plurality of teeth  50 B in alignment with plurality of grooves  51 B, plurality of teeth  50 B flex back and engage plurality of grooves  51 B. 
     With installer inserting first and second tab members  45 B and  47 B into cap member  28 B, first and second tab members  45 B and  47 B respectively are aligned with first slot  55 B and second slot  57 B, respectively as seen in  FIG. 8  defined by cap member  28 B. This alignment of first and second tab members  45 B and  47 B with first and second slots  55 B and  57 B respectively, provides the installer easy alignment of plurality of grooves  51 B with plurality of teeth  50 B and provides resistance of rotational movement of cap member  28 B relative to washer  21 ′. 
     In  FIG. 7 , first example  52 B of end portion  10  of metallic fastener assembly  11  extending in this example above surface  12  of structure  14  is seen wherein second embodiment of cap system  26 B is shown enclosing of and securing to end portion  10  of metallic fastener assembly  11 . In first example  52 B, nut member  22  is secured to threads  18  of threaded stud or threaded bolt  16  and directly abuts washer  21 ′ and with plurality of grooves  51 B engaged with plurality of teeth  50 B, end  40 B is positioned against structure  14 . 
     In second example  52 B 1 , in  FIG. 7  second embodiment of cap system  26 B encloses and secures to end portion  10  of metallic fastener assembly  11  wherein washer  21 ′ is positioned in the same position as shown in first example  52 B however washer  23  is positioned between washer  21 ′ and nut member  22 . In this example plurality of teeth  51 B extend in direction D. However, plurality of teeth  51 B can be limited in this example in how far plurality of teeth  51 B extend from end  40 B since elevation of plurality of grooves  51 B of first and second tab members  45 B and  47 B with respect to first and second examples  52 B and  52 B 1  are without change. In second example  52 B 1 , nut member  22  is secured to threads  18  of threaded stud or threaded bolt  16  and is positioned on washer  23  which elevates nut member  22  however, washer  21 ′ remains on structure  14  at the same elevation as seen in first example  52 B. Metallic fastener assembly  11  further includes nut member  22 . Nut member  22  has threads  24  compatible with threads of one of threads of a threaded stud of the metallic fastener assembly or threads of a threaded bolt  16  of metallic fastener assembly  11 , is positioned on one of the threaded stud or the threaded bolt  16  of metallic fastener assembly  11  in a secured position with respect to the structure  14 . With washer  21 ′ positioned between nut member  22  and structure  14 , in this example with washer  23  positioned between nut member  22  and washer  21 ′, with plurality of grooves  51 B aligned with plurality of teeth  50 B, end  40 B of cap member  28 B is positioned against structure  14 . 
     In the third example  52 B 2 , in  FIG. 7 , head  53  of threaded bolt  16  is positioned on washer  21 ′. In this third example of the metallic fastener assembly  11  head  53  of threaded bolt member  16  is positioned in overlying relationship to washer  21 ′ such that with head  53  in a secure relationship with respect to structure  14 , with washer  21 ′ positioned between head  53  and structure  14  and with plurality of grooves  51 B aligned with plurality of teeth  50 B, end  40 B of cap member  28 B is positioned against structure  14 . 
     In installing cap member  28 B metallic fastener assembly  11  is in this example in a secured relationship with respect to structure  14 . The installer positions cap member  28 B over end portion  10  of metallic fastener assembly  11  and pushes cap member  28 B toward structure  14  until end  40 B is positioned against structure  14  and plurality of grooves  51 B are aligned and engaged with plurality of teeth  50 B. As a result cap member  28 B is secured to metallic fastener assembly  11  and end portion  10  of metallic fastener assembly  11  is enclosed and electrically isolated from electrically sensitive areas of the aircraft. 
     In installing cap members of the cap system described above, configurations of ends  40 A,  40 B and  40  as seen in  FIGS. 4, 8 and 9 , can be selectively employed to the different embodiments of the cap members described herein. Three examples of configurations include examples  60 ,  70  and  90  to be discussed in greater detail below. For example, with respect to ends  40 A and  40 B, any of the three examples of end configurations  60 ,  70  or  90  can be employed. 
     In a first example  60  of configuration of an end is shown in  FIG. 4  as end  40 A. Sidewall  29 A of cap member  28 A defines groove  92  which extends about cap member  28 A. First opening  94  defined by and extends through first portion  96  of sidewall  29 A of cap member  28 A such that first opening  94  communicates with groove  92 . First flow path  98  extends through first portion  96  of sidewall  29 A of cap member  28 A and into groove  92  for conveyance of sealant. Second opening  100  defined by and extends through second portion  102  of sidewall  29 A of cap member  28 A such that second opening  100  communicates with groove  92  and second opening  100  communicates with cavity  32 A of cap member  28 A such that second flow path  104  extends from groove  92  through second opening  100  of sidewall  29 A of cap member  28 A and into cavity  32 A. Once installer has injected sealant into groove  92  and sealant flows through groove  92  and expels into cavity  32 A from second opening  100 , the sealant continues to flow past nut member  22  between ridge members  46 A, in this example, upwardly into cap member  28 A. Third opening  106 , as seen in  FIGS. 1, 2 and 4 , defined by and extends through sidewall  29 A of cap member  28 A such that third opening  106  provides third flow path  108 , as seen in  FIG. 4 . 
     In this first example  60 , once the installer has secured cap member  28 A to surface  12  of structure  14 , the installer will inject a sealant material into first opening  94  having sealant flow in groove  92  about cap member  28 A. With groove  92  nearly full or full of sealant, sealant begins to leak from second opening  100 . At that point, the installer is still injecting sealant into first opening  94  and cavity  32 A becomes full of sealant at which point sealant begins to expel from third opening  106 . At that point installer understands cap member  28 A is full of sealant and stops injecting further sealant. With sealant expelling from third opening  106 , installer has a confirmation that sealant has been positioned within groove  72  and cavity  32 A providing additional assurance to the installer that end portion  10  of metallic fastener assembly  11  has been further electrically isolated within cap member  28 A. This first example configuration provides the installer the ability to not expel excessive sealant onto surface  12  and reduces the need for tedious and time consuming smoothing out of excess sealant. 
     In the second example  70 , shown in  FIG. 8 , end  40 B of cap member  28 B forms a continuous annular flat surface  62  which will abut surface  12  of a planar configuration of structure  14  as seen in  FIGS. 6 and 7 . 
     Third example  90  of configuration of an end, is shown in  FIG. 9  as end  40 . Sidewall  29  of cap member  28  defines groove  110  which extends about cap member  28 . First opening  112  defined by and extends through first portion  114  of sidewall  29  of cap member  28  communicates with groove  110  such that a first flow path  116  extends through first opening  112  and into groove  110  for conveyance of sealant through first opening  112  into groove  110 . Second opening  118 , defined by and extends through first portion  114  of sidewall  29  of cap member  28 , is spaced apart about cap member  28  from first opening  112  wherein second opening  118  communicates with groove  110  such that second flow path  120  extends from groove  110  through second opening  118  of cap member  28  for conveyance of sealant. 
     In this third example  90 , once installer has secured cap member  28  to surface  12  of structure  14 , the installer will inject a sealant material into first opening  112  having sealant flow in groove  110  about cap member  28  until sealant begins to leak from second opening  118 . At that point the installer has a confirmation that sealant has been positioned within groove  110  providing additional assurance to the installer that end portion  40  of metallic fastener assembly  11  has been further electrically isolated within cap member  28 . This third example  90  configuration provides the installer ability to not expel excessive sealant onto surface  12  and reduces the need for tedious and time consuming smoothing out of excess sealant. 
     While various embodiments have been described above, this disclosure is not intended to be limited thereto. Variations can be made to the disclosed embodiments that are still within the scope of the appended claims.