Patent Publication Number: US-2021190124-A1

Title: Anchoring nut for an eme protection cap system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 15/960,835, entitled “Anchoring Washer for an EME Protection Cap System” and filed Apr. 24, 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, includes a first securement mechanism positioned about a periphery of a nut member of the metallic fastener assembly, wherein the first securement mechanism comprises a plurality of continuous grooves which extend about the periphery of the nut member. The cap system further includes a cap member which includes a sidewall having an inner surface which defines a cavity dimensioned to receive the nut member and defines a second securement mechanism complementary configured to engage the first securement mechanism positioned about the periphery of the nut member. The cap system further includes an end of the sidewall of the cap member defines an opening which provides the nut member 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 different example configurations of the metallic fastener assembly wherein the first example has a nut member of the metallic fastener assembly positioned on a surface of the structure; the second example has the nut member of the metallic fastener assembly positioned on one washer; and the third example has the nut member of the metallic fastener assembly positioned on two washers; 
         FIG. 4  is an enlarged bottom perspective view 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 different example configurations of the metallic fastener assembly wherein the first example has a nut member of the metallic fastener assembly positioned on a surface of the structure; the second example has the nut member of the metallic fastener assembly positioned on one washer; and the third example has the nut member of the metallic fastener assembly positioned on two washers; 
         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; 
         FIG. 9  is an exploded perspective view of a third embodiment of the cap system for enclosing an end portion of a metallic fastener assembly extending from a structure; 
         FIG. 10  is a cross section view along line  10 - 10  of  FIG. 9  of the third embodiment of the cap system assembled; 
         FIG. 11  is a perspective cross section view schematic employment of the third embodiment of the cap system of  FIG. 9  utilizing different example configurations of the metallic faster assembly wherein the first example has a nut member of the metallic fastener assembly positioned on a surface of the structure; the second example has the nut member of the metallic fastener assembly positioned on one washer of the metallic fastener assembly; and the third example has the nut member of the metallic fastener assembly positioned on two washers; 
         FIG. 12  is an enlarged bottom perspective view of the cap member of FIG;  9  showing a third example of the end of the cap member; 
         FIG. 13  is an exploded perspective view of a fourth embodiment of the cap system for covering a metallic fastener assembly extending from a structure; 
         FIG. 14  is a cross section view along line  14 - 14  of  FIG. 13  of the fourth embodiment of the cap system assembled; 
         FIG. 15  is a perspective cross section view of employment of the cap system of the fourth embodiment of  FIG. 13  utilizing different example configurations of the metallic fastener assembly wherein the first example has a nut member of the metallic fastener assembly positioned on a surface of the structure; the second example has the nut member of the metallic fastener assembly positioned on one washer; and the third example has the nut member of the metallic fastener assembly positioned on two washers; and 
         FIG. 16  is an enlarged perspective view of the cap member of the cap system of  FIG. 13  showing the second 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 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 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 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, 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 threaded stud, the 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 and 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), the side in which the cap system to be described herein will be positioned. Washer(s) may be positioned between the nut member and the structure(s). With respect to employing a threaded bolt, the 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 and 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), the side in which the cap system to be described herein will be positioned. Washer(s) may be positioned between the nut member and the structure(s). 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 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. With the metallic fastener assembly in a secured position with respect to the structure and with a cap member of the cap system enclosing the threaded stud or the threaded bolt which extends from the structure along with the nut member and in addition any washer(s) which may be used in association with the nut member, the cap member at the same time will secure to the metallic fastener assembly and the cap member will be 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 , and in this example, metallic fastener assembly  11  includes 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 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  obtaining a secured position with respect to structure  14 . In this example, washer  20  is positioned between nut member  22  and structure  14 . 
     In  FIG. 1 , first embodiment of cap system  26 A is shown having 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 , which defines cavity  32 A which is dimensioned to receive nut member  22 . First securement mechanism  34 A, as seen in  FIG. 1 , is positioned about periphery  36 A of nut member  22 . Inner surface  30 A of cap member  28 A 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 nut member  22 . End  40 A of sidewall  29 A of cap member  28 A defines opening  42 A which provides nut member  22  to have access into cavity  32 A. 
     As seen in  FIG. 1 , first securement mechanism  34 A includes threads  44 A which are interrupted or non-continuous as threads  44 A extend about periphery  36 A of nut member  22 . Threads  44 A which are interrupted are defined by a plurality of ridge members  46 A positioned on nut member  22 . Ridge members  46 A extend in radial direction  48 A away from nut member  22 . Adjacent ridge members  46 A of the plurality of ridge members  46 A are spaced apart about nut member  22  wherein each ridge member  46 A is equally spaced apart from adjacent ridge members  46 A. This configuration of equally spaced apart ridge members  46 A permit the installer to use a conventional socket wrench tool to engage nut member  22  and tighten nut member  22  onto threaded stud or threaded bolt  16  relative to structure  14  without imparting damage to threads  44 A positioned on ridge members  46 A. 
     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 at least a portion of the interrupted threads  44 A of nut member  22 , end  40 A of cap member  28 A is positioned against structure  14  enclosing and securing to end portion  10  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 nut member  22  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  28 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 in this example above surface  12  of structure  14  is seen wherein first embodiment of cap system  26 A is shown enclosing 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 directly abuts surface  12  (without a washer) and threads  44 A of nut member  22  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  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 is positioned on washer  20  which positions threads  44 A, which are engaged to threads  50 A of cap member  28 A, above surface  12  at a higher elevation profile than that of threads  44 A 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 nut member  22  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  regardless of the difference in elevation profile of threads  44 A with respect to surface  12 . 
     This similarly is the case with respect to third example  52 A 2 , in  FIG. 3 , wherein nut member  22  is secured to threads  18  of threaded stud or threaded bolt  16  and is positioned on washer  20 ′ and washer  20 ″ raising the elevation profile of threads  44 A in this third example  52 A 2  to even a higher elevation profile above surface  12  of structure  14  than second example  52 A 1 . Again, threads  50 A extending in direction D permit threads  44 A of nut member  22  to be engaged to threads  50 A in third example  52 A 2  with end  40 A abutting surface  12  providing a secured enclosure of end portion  10  of metallic fastener assembly  11  with cap member  28 A. 
     Thus, with the installer having tightened nut member  22  onto 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 member  28 A to have threads  44 A of nut member  22  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 nut member  22  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 referring to  FIG. 5 , second embodiment of cap system  26 B is shown having 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. Cap member  28 B has sidewall  29 B having an inner surface  30 B, as seen in  FIGS. 6-8 , which defines cavity  32 B which is dimensioned to receive nut member  22 . First securement mechanism  34 B as seen in  FIG. 5  includes continuous threads  35 B positioned to extend uninterrupted about nut member  22 . Inner surface  30 B, as seen in  FIG. 8 , defines second securement mechanism  38 B which is complementary configured to engage first securement mechanism  34 B positioned about periphery  36 B of nut member  22 . End  40 B of sidewall  29 B of cap member  28 B defines opening  42 B which provides nut member  22  to have access into cavity  32 B. 
     As seen in  FIG. 5 , first securement mechanism  34 B includes continuous threads  35 B which extend uninterrupted about periphery  36 B of nut member  22 . Continuous threads  35 B are positioned in a lower portion of nut member  22  so as not to interfere with spaced apart plurality of ridges configuration  47  positioned in an upper portion of nut member  22 . Plurality of ridges configuration  47  is compatible with a standard socket wrench, in this example, for securing nut member  22  on threaded stud or threaded bolt  16  in a secured position with respect to structure  14  without imparting damage to continuous threads  35 B. 
     Second securement mechanism  38 B includes threads  50 B defined by inner surface  30 B of sidewall  29 B of cap member  28 B, as seen in  FIG. 8 . Threads  50 B extend about inner surface  30 B of sidewall  29 B of cap member  28 B and 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 threads  50 B engaging at least a portion of continuous threads  35 B of nut member  22 , end  40 B is positioned against structure  14  enclosing end portion  10  of metallic fastener assembly  11 . With threads  50 B extending in direction D, threads  50 B extend toward higher elevations above surface  12  of structure  14  with end  40 B in abutting relationship with surface  12  of structure  14 , as shown in  FIG. 7 . Threads  50 B can accommodate and engage continuous threads  35 B of nut member  22  with continuous threads  35 B positioned at different elevation profiles above surface  12  as seen in  FIG. 7 . 
     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 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 surface  12  (without a washer) and continuous threads  35 B of nut member  22  are engaged to threads  50 B wherein continuous threads  35 B are positioned above surface  12  at an elevation profile lesser than continuous threads  35 B of second example  52 B 1 . 
     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  positioned extending above surface  12 . 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  20  which positions continuous threads  35 B above surface  12  at a higher elevation profile than that of continuous threads  35 B of first example  52 B. Threads  50 B of cap member  28 B extend in direction D, as seen in  FIG. 8 , permitting continuous threads  35 B of nut member  22  to be engaged to threads  50 B in both the first example  52 B and second example  52 B 1  with end  40 B of sidewall  29 B of cap member  28 B abutting surface  12  of structure  14 . As a result, cap member  28 B encloses end portion  10  of metallic fastener assembly  11  regardless of the difference in elevation profile of continuous threads  35 B with respect to surface  12 . 
     This similarly is the case with respect to third example  52 B 2 , in  FIG. 7 , wherein nut member  22  is secured to threads  18  of threaded stud or threaded bolt  16  and is positioned on washer  20 ′ and washer  20 ″ raising the elevation profile of continuous threads  35 B in this third example  52 B 2  to even a higher elevation profile above surface  12  of structure  14  than second example  52 B 1 . Again, threads  50 B extending in direction D permit continuous threads  35 B of nut member  22  to be engaged in third example  52 B 2  with end  40 B abutting surface  12  providing a secured enclosure of end portion  10  of metallic fastener assembly  11  with cap member  28 B. 
     Thus, with the installer having tightened nut member  22  on threads  18  of threaded stud or threaded bolt  16  into a secured position relative to structure  14 , the installer can then position second embodiment of cap member  28 B to have continuous threads  35 B of nut member  22  engage threads  50 B of cap member  28 B. The installer can then turn and tighten cap member  28 B, with continuous threads  35 B and threads  50 B engaged, until end  40 B abuts surface  12 . Cap member  28 B is then secured to surface  12  of structure  14  enclosing end portion  10  of metallic fastener assembly  11 . As explained above, with threads  50 B extending in direction D, continuous threads  35 B of nut member  22  positioned at different elevation profiles above surface  12  can engage and reliably secure to threads  50 B thereby securing cap member  28 B to end portion  10  of metallic fastener assembly  11  and with end  40 B abutting surface  12  cap member  28 B securely encloses end portion  10  of metallic fastener assembly  11 . 
     In referring to  FIG. 9 , third embodiment of cap system  26 C is shown having cap member  28 C. As mentioned earlier cap member  28 C will be constructed of a nonconductive material such as one of a polymer, thermoset or other nonconductive material. Cap member  28 C has sidewall  29 C having an inner surface  30 C, as seen in  FIGS. 10-12 , which defines cavity  32 C which is dimensioned to receive nut member  22 . First securement  34 C as seen in  FIG. 9  is positioned about periphery  36 C of nut member  22 . Inner surface  30 C of cap member  28 C defines second securement mechanism  38 C, as seen in  FIG. 8 , which is complementary configured to engage first securement mechanism  34 C positioned about periphery  36 C of nut member  22 . End  40 C of sidewall  29 C of cap member  28 C defines opening  42 C which provides nut member  22  to have access into cavity  32 C. 
     As seen in  FIG. 9 , first securement mechanism  34 C includes a plurality of grooves  37 C positioned spaced apart about periphery  36 C of nut member  22 . Plurality of ridge members  46 C which extend in a radial direction  48 C away from nut member  22  define a plurality of grooves  37 C. Adjacent ridge members  46 C are spaced apart about nut member  22 . Each of the plurality of ridge members  46 C is equally spaced apart from adjacent ridge members  46 C. A portion of plurality of grooves  37 C are positioned spaced apart on each ridge member  46 C aligned in a row  47 C, as seen in  FIG. 9 . Rows  47 C of a portion of the plurality of grooves  37 C are positioned in this example on each of ridge members  46 C positioned about nut member  22 . Rows  47 C extend in direction D′ which extends in the direction of thickness T of nut member  22 . This configuration of spaced apart ridge members  46 C permit the installer to use a conventional socket wrench tool to engage nut member  22  and tighten nut member  22  onto threaded stud or threaded bolt  16  relative to structure  14  without imparting damage to portions of plurality of grooves  37 C positioned on ridge members  46 C. 
     Second securement mechanism  38 C, as seen in  FIGS. 10 and 12 , which includes at least one annular ledge  39 C defined by inner surface  30 C of sidewall  29 C of cap member  28 C. At least one annular ledge  39 C is positioned about inner surface  30 C of cap member  28 C. At least one annular ledge  39 C is positioned spaced away in a direction D″ from end  40 C of cap member  28 C such that with nut member  22  and threaded stud or threaded bolt  16  of metallic fastener assembly  11  in a secured position with respect to structure  14  and with at least one annular ledge  39 C engaging at least a portion of the plurality of grooves  37 C, end  40 C of cap member  28 C is positioned against structure  14 . Nut member  22  is constructed, in this example, with metallic material and is less flexible than at least one annular ledge  39 C constructed of a more flexible material such as a polymer or thermoset material wherein as the installer pushes down on cap member  28 C over end portion  10  of metallic fastener assembly  11  at least one annular ledge  39 C will flex against nut member  22 . In this example, at least one annular ledge  39 C will flex back into plurality of grooves  37 C as grooves  37 C come into alignment with at least one annular ledge  39 C. Once end  40 C of cap member  28 C abuts against surface  12  of structure  14  and at least one annular ledge  39 C is in alignment with plurality of grooves  37 C, cap member  28 C is secured to end portion  10  of metallic fastener assembly  11  and against surface  12 . 
     In  FIG. 11 , a schematic first example  52 C of end portion  10  of metallic fastener assembly  11  extending above surface  12  of structure  14  is seen wherein third embodiment of cap system  26 C is shown enclosing and securing to end portion  10  of metallic fastener assembly  11 . In referring to first example  52 C, nut member  22  is secured to one of threaded stud or threaded bolt  16  directly abuts surface  12  (without a washer) placing grooves  37 C, as seen in  FIG. 9 , on each row  47 C at predetermined elevations above surface  12  of structure  14 . For example, as seen in  FIG. 9  grooves  37   a,    37   b  and  37   c  will be positioned at predetermined elevations above surface  12  with nut member  22 , in this first example  52 C, abutting surface  12  of structure  14 . At least one annular ledge  39 C of cap member  28 C, as seen in  FIG. 12 , can be positioned spaced away in direction D″ from end  40 C, such that with end  40 C abutting surface  12 , at least one annular ledge  39 C engages grooves  37 C at an elevation above surface  12  which are positioned for example as groove  37   a.    
     In referring to second schematic example  52 C 1 , nut member  22  is secured to one of threaded stud or threaded bolt  16  and is positioned on washer  20  positioning plurality of grooves  37 C at a higher elevation profile above surface  12  than positioned in first example  52 C. In this second schematic example  52 C 1 , at least one annular ledge  39 C of cap member  28 C, as used in first example  52 C, engages grooves  37 C at an elevation above surface  12  which are positioned as groove  37   b,  for example as seen in  FIGS. 9 and 10 , with end  40 C abutting surface  12  of structure  14 . 
     In referring to third schematic example  52 C 2 , nut member  22  is secured to one of threaded stud or threaded bolt  16  and is positioned on washer  20 ′ and washer  20 ″ positioning plurality of grooves  37 C at a higher elevation profile above surface  12  than positioned in second example  52 C 1 . In third schematic example  52 C 2 , at least one annular ledge  39 C of cap member  28 C, as used in first example  52 C and second example  52 C 1 , engages grooves  37 C at an elevation above surface  12  which are positioned as groove  37   c,  for example as seen in  FIGS. 9 and 10 , with end  40 C abutting surface  12  of structure  14 . In these examples, at least one annular ledge  39 C can be positioned within cap member  28 C spaced away from end  40 C such that with nut member  22  positioned on surface  12  or on washer  20  or on washer  20 ′ and washer  20 ″, at least one annular ledge  39 C is positioned within cap member  28 C to engage grooves  37 C such as  37   a,    37   b  or  37   c,  as described above, with end  40 C abutting surface  12  of structure  14 . 
     Thus, in this third embodiment of cap system  26 C, the installer having tightened nut member  22  on threaded stud or threaded bolt  16  into a secured position relative to structure  14 , the installer can then position third embodiment of cap member  28 C over nut member  22  and push cap member  28 C over nut member  22  flexing at least one annular ledge  39 C of inner surface  30 C of cap member  28 C until cap member  28 C abuts surface  12  of structure  14  and plurality of grooves  37 C of nut member  22  engage at least one annular ledge  39 C. Cap member  28 C is then secured to end portion  10  and abuts surface  12  of structure  14  enclosing end portion  10  of metallic fastener assembly  11 . As explained above, with at least one annular ledge  39 C spaced away extending in direction D″ from end  40 C of cap member  28 C, plurality of grooves  37 C of nut member  22  positioned at different predetermined elevation profiles above surface  12 , such as in this example  37   a,    37   b  and  37   c,  can engage and reliably secure at least one annular ledge  39 C securing cap member  28 C to end portion  10  of metallic fastener assembly  11  with end  40 C abutting surface  12  thereby securing to and enclosing end portion  10  of metallic fastener assembly  11 . 
     In referring to  FIG. 13 , fourth embodiment of cap system  26 D is shown having cap member  28 D. As mentioned earlier cap member  28 D will be constructed of a nonconductive material such as one of a polymer, thermoset or other nonconductive material. Cap member  28 D has sidewall  29 D having an inner surface  30 D, as seen in  FIGS. 14-16  which defines cavity  32 D which is dimensioned to receive nut member  22 . First securement  34 D as seen in  FIG. 13  is positioned about periphery  36 D of nut member  22 . Inner surface  30 D of cap member  28 D defines second securement mechanism  38 D, as seen in  FIG. 16 , which is complementary configured to engage first securement mechanism  34 D positioned about periphery  36 D of nut member  22 . End  40 D of sidewall  29 D of cap member  28 D defines opening  42 D which provides nut member  22  to have access into cavity  32 D. 
     As seen in  FIG. 13 , first securement mechanism  34 D includes a plurality of continuous grooves  41 D which extend about periphery  36 D of nut member  22 . Continuous grooves  41 D are positioned in a lower portion of nut member  22  so as not to interfere with plurality of ridges configuration  51  positioned in an upper portion of nut member  22 . Plurality of ridges configuration  51  is compatible with a standard socket wrench, in this example, for securing nut member  22  on threaded stud or threaded bolt  16  in a secured position with respect to structure  14  without imparting damage to continuous grooves  41 D. Plurality of ridges configuration  51  extend in a radial direction away from nut member  22  as seen in  FIG. 13 , wherein adjacent ridge members  55  of the plurality of ridges configuration  51  are spaced about nut member  22  such that each ridge member  55  is equally spaced apart from an adjacent ridge member  55 . 
     Second securement mechanism  38 D, as seen in  FIG. 16 , which includes a plurality of teeth  53 D positioned along inner surface  30 D of sidewall  29 D of cap member  28 D. Plurality of teeth  53 D are positioned about at least a portion of inner surface  30 D of cap member  28 D. Plurality of teeth  53 D are positioned extending in a direction D′″ along inner surface  30 D of cap member  28 D away from end  40 D of cap member  28 D such that with nut member  22  and threaded stud or threaded bolt  16  of metallic fastener assembly  11  in a secured position with respect to structure  14  and with at least a portion of plurality of teeth  53 D engaging at least a portion of the plurality of continuous grooves  41 D, end  40 D of cap member  28 D is positioned against structure  14 . Nut member  22  is constructed, in this example, with metallic material and is less flexible than plurality of teeth  53 D constructed of a more flexible material such as a polymer or thermoset material wherein as the installer pushes down on cap member  28 D over end portion  10  of metallic fastener assembly  11  plurality of teeth  53 D will flex against nut member  22 . In this example, plurality of teeth  53 D will flex back into plurality of continuous grooves  41 D as continuous grooves  41 D come into alignment with plurality of teeth  53 D. Once end  40 D of cap member  28 D abuts against surface  12  of structure  14  and plurality of teeth  53 D are in alignment with plurality of continuous grooves  41 D, cap member  28 D is secured to nut member  22  of end portion of metallic fastener assembly  11  and is positioned against surface  12 . 
     In  FIG. 11 , first example  52 D of end portion  10  of metallic fastener assembly  11  extending above surface  12  of structure  14  is seen wherein fourth embodiment of cap system  26 D is shown enclosing and securing to end portion  10  of metallic fastener assembly  11 . In first example  52 D, nut member  22  is secured to one of threaded stud or threaded bolt  16  and directly abuts surface  12  (without a washer) and continuous grooves  41 D of nut member  22  are engaged by plurality of teeth  53 D and are positioned above surface  12  at an elevation profile lesser than that of second example  52 D 1 . 
     In second example  52 D 1  fourth embodiment of cap system  26 D encloses and secures to end portion  10  of metallic fastener assembly  11  positioned extending above surface  12 . In second example  52 D 1 , nut member  22  is secured to one of threaded stud or threaded bolt  16  and is positioned on washer  20  which positions plurality of continuous grooves  41 D above surface  12  at a higher elevation profile than that of plurality of continuous grooves  41 D of first example  52 D. Plurality of teeth  53 D within cap member  28 D extending in direction D″&#39; as seen in  FIGS. 15 and 16  permit plurality of continuous grooves  41 D of nut member  22  to be engaged in both the first example  52 D and second example  52 D 1  with end  40 D of sidewall  29 D of cap member  28 D abutting surface  12  of structure  14  thereby providing a secured enclosure of end portion  10  of metallic fastener assembly  11  regardless of the difference in elevation profile of plurality of continuous grooves  41 D with respect to surface  12 . 
     This similarly is the case with respect to third example  52 D 2  wherein nut member  22  is secured to one of threaded stud or threaded bolt  16  and is positioned on washer  20 ′ and washer  20 ″ raising the elevation profile of plurality of continuous grooves  41 D in this third example  52 D 2  to even a higher elevation profile above surface  12  of structure  14  than second example  52 C 1 . Again, plurality of teeth  53 D extending in direction D″′ permit plurality of continuous grooves  41 D of nut member  22  to be engaged by plurality of teeth  53 D in third example  52 D 2  with end  40 D abutting surface  12  providing a secured enclosure of end portion  10  of metallic fastener assembly  11 . 
     Thus, in this fourth embodiment of cap system  26 D, the installer having tightened nut member  22  on threaded stud or threaded bolt  16  into a secured position relative to structure  14 , the installer can then position fourth embodiment of cap member  28 D over nut member  22  and push cap member  28 D over nut member  22  flexing plurality of teeth  53 D positioned on inner surface  30 D of cap member  28 C until cap member  28 C abuts surface  12  of structure  14  and plurality of continuous grooves  41 D of nut member  22  engage plurality of teeth  53 D. Cap member  28 D is then secured to nut member  22  of end portion  10  and abuts surface  12  of structure  14  enclosing end portion  10  of metallic fastener assembly  11 . As explained above, with plurality of teeth  53 D extending in direction D″′, plurality of continuous grooves  41 D of nut member  22  positioned at different elevation profiles above surface  12  can engage and reliably secure to plurality of teeth  53 D securing cap member  28 D to end portion  10  of metallic fastener assembly  11  with end  40 D abutting surface  12  thereby securing cap member  28 D to end portion  10  and enclosing end portion  10  of metallic fastener assembly  11 . 
     In installing cap members of the cap system described above, selective configurations for ends  40 A-D of cap members  28 A-D respectively can be employed. Three examples of configurations of the configurations include examples  60 ,  70  and  90  to be discussed in greater detail below. For example, with respect to ends  40 A and  40 C, any of the three examples  60 ,  70  or  90  can be employed and for example, with respect to ends  40 B and  40 D, first or second examples  60  or  70  can be employed. 
     First example  60 , shown in  FIG. 4 , end  40 A, of cap member  28 A forms a continuous annular flat surface  62  which will abut surface  12  of a planar configuration of structure  14  as seen in  FIGS. 2-4 . 
     Second example  70 , of configuration of an end, is shown in  FIGS. 8 and 16  as end  40 B and  40 D respectively. Since the second example  70  is the same configuration for  FIG. 8  as is in  FIG. 16 , second example  70  will be described for end  40 B, of  FIG. 8 , wherein sidewall  29 B of cap member  28 B defines groove  72  which extends about cap member  28 B. First opening  74  defined by and extends through first portion  76  of sidewall  29 B of cap member  28 B communicates with groove  72  such that a path  78  extends through first opening  74  and into groove  72  for conveyance of sealant through first opening  74  into groove  72 . Second opening  80 , defined by and extends through first portion  76  of sidewall  29 B of cap member  28 B, is spaced apart about cap member  28 B from first opening  74  wherein second opening  80  communicates with groove  72  such that second flow path  82  extends from groove  72  through second opening  80  of cap member  28 B for conveyance of sealant. 
     With respect to second example  70 , once installer has secured cap member  28 B to surface  12  of structure  14 , the installer will inject a sealant material into first opening  74  having sealant flow in groove  72  about cap member  28 B until sealant begins to leak from second opening  80 . At that point the installer has a confirmation that sealant has been positioned within groove  72  providing additional assurance to the installer that end portion  10  of metallic fastener assembly  11  has been further electrically isolated within cap member  28 B. Second example  70  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. 
     Third example  90  of configuration of an end is shown in  FIG. 12  as end  40 C. Sidewall  29 C of cap member  28 C defines groove  92  which extends about cap member  28 C. Third opening  94  defined by and extends through first portion  96  of sidewall  29 C of cap member  28 C such that third opening  94  communicates with groove  92 . First flow path  98  extends through first portion  96  of sidewall  29 C of cap member  28 C and into groove  92  for conveyance of sealant. Fourth opening  100  defined by and extends through second portion  102  of sidewall  29 C of cap member  28 C such that fourth opening  100  communicates with groove  92  and fourth opening  100  communicates with cavity  32 C of cap member  28 C such that second flow path  104  extends from groove  92  through fourth opening  100  of sidewall  29 C of cap member  28 C and into cavity  32 C. Once installer has injected sealant into groove  92  and sealant flows through groove  92  and expels into cavity  32 C from fourth opening  100 , the sealant continues to flow past nut member  22  between  46 C, in this example, upwardly into cap member  28 C. Fifth opening  106 , as seen in  FIGS. 9-11 , defined by and extends through the sidewall  29 C of cap member  28 C such that fifth opening  106  provides a third flow path  108 , as seen in  FIG. 10 . 
     With respect to third example  90 , once the installer has secured cap member  28 B to surface  12  of structure  14 , the installer will inject a sealant material into third opening  94  having sealant flow in groove  92  about cap member  28 C. With groove  92  is nearly full or full of sealant, sealant begins to leak from fourth opening  100 . At that point, the installer is still injecting sealant into third opening  94  and cavity  32 C becomes full of sealant at which point sealant begins to expel from fifth opening  106 . At that point installer understands cap member  28 C is full of sealant and stops injecting further sealant. With sealant expelling from fifth opening  106 , installer has a confirmation that sealant has been positioned within groove  72  and cavity  32 C providing additional assurance to the installer that end portion  10  of metallic fastener assembly  11  has been further electrically isolated within cap member  28 B. This third 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. 
     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.