Patent Publication Number: US-2023150692-A1

Title: System and method for assembling an aft fuselage section of an aircraft

Description:
FIELD OF THE DISCLOSURE 
     Examples of the present disclosure generally relate to a system and a method for assembling an aft or otherwise unpressurized fuselage section of an aircraft. 
     BACKGROUND OF THE DISCLOSURE 
     Certain known aircraft, such as certain commercial jets, include a horizontal stabilizer secured to an aft or unpressurized fuselage section.  FIG.  1    illustrates an isometric exploded view of a known aft fuselage section  10 . The aft or unpressurized fuselage section  10  includes a forward section  12 , a bulkhead  14 , and an aft section  16 . 
     Typically, pivot fittings  18  are secured to the bulkhead  14 .  FIG.  2    illustrates an isometric front view of the bulkhead  14 . As shown, the pivot fittings  18  are secured to a front surface  20  of the bulkhead  14 . Separate and distinct beams  19  are coupled to one or both of the pivot fittings  18 . The beams  19  are separately positioned and secured to the bulkhead  14  and the pivot fitting(s)  18 . The beams  19  are typically necessary to react to lateral loads. 
     Referring to  FIGS.  1  and  2   , the bulkhead  14  is joined to the aft section  16 . The horizontal stabilizer  22  is then pivotally coupled to the pivot fittings  18 , such as through spherical bearings. After the horizontal stabilizer  22  is coupled to the bulkhead  14  through the pivot fittings  18 , and the bulkhead  14  is joined to the aft section  16 , the resulting sub-assembly  24  is then joined to the forward section  12 . 
       FIG.  3    illustrates an isometric internal view of the known aft fuselage  10  section during a manufacturing process. Referring to  FIGS.  1 - 3   , individuals  30  enter confined spaces of the aft fuselage section  10  to complete installation through various operations, including drilling through-holes, inserting shims, inserting and torquing fasteners, and the like. The individuals  30  drill various holes, connect shims, and couple various joints together through numerous fasteners. Typically, the individuals  30  perform such operations within confined spaces within the aft fuselage section  10 . As can be appreciated, performing such operations inside the confined spaces can be ergonomically challenging (as shown in  FIG.  3   ), as well as time and labor intensive. 
     Further, existing architecture for the aft fuselage section  10  includes a convoluted load path for the fuselage to support the horizontal stabilizer  22 . In general, the load of the horizontal stabilizer  22  is supported by intercostals and/or other such backup structure  23  in the aft fuselage section  10 , and these loads are transferred to the forward section  12  by another set of intercostals via tension bolts that connect to forward longerons. The intercostals and longeron fittings are metallic and tightly-fit (for example, with numerous shims) due to high load transfer requirements. Final installation operations of the intercostals and longerons within the confined spaces of the aft fuselage section  10  is time consuming due to tension bolt installation (torquing requirements), fay surface seal (dissimilar material), and debur (fatigue) requirements. 
     SUMMARY OF THE DISCLOSURE 
     A need exists for a system and a method for efficiently and effectively joining a horizontal stabilizer to an aft fuselage section of an aircraft. Further, a need exists for a simpler and easier method for joining the horizontal stabilizer to the aft fuselage section. Additionally, a need exists for a more ergonomic method for securing the horizontal stabilizer to the aft fuselage section. 
     With those needs in mind, certain examples of the present disclosure provide a system for forming an aft fuselage section of an aircraft. The system includes a forward section having a stabilizer channel. The forward section includes an upper sill beam and a lower sill beam. One or more pivot fittings are securely fastened between the upper sill beam and the lower sill beam. The one or more pivot fittings are configured to pivotally couple to a horizontal stabilizer within the stabilizer channel. 
     In at least one example, the one or more pivot fittings include a first pivot fitting at a first side of the forward section, and a second pivot fitting at a second side of the forward section, wherein the second side is opposite from the first side. 
     In at least one example, each of the upper sill beam and the lower sill beam includes a joint panel that mounts to a rear face of the forward section, and a fitting panel that mounts to the one or more pivot fittings. As a further example, the joint panel is perpendicular to the fitting panel. 
     In at least one example, the one more pivot fittings are securely fastened to the forward section, and the horizontal stabilizer is pivotally coupled to the one or more pivot fittings before the forward section is secured to an aft section. 
     In at least one example, each of the one or more pivot fittings includes a central column, an outboard flange, and an inboard flange. 
     In at least one example, the central column includes a base. Lateral support walls extend upwardly from the base. A front wall extends upwardly from the base. A bearing slot is formed in the front wall. The bearing slot is configured to retain a spherical bearing of the horizontal stabilizer. A top ledge is connected to upper portions of the lateral support walls and the front wall. The base secures to the lower sill beam through a first plurality of fasteners, and the top ledge secures to the upper sill beam through a second plurality of fasteners. In at least one example, the outboard flange includes a lower ledge connected to an upper ledge by an outer extension beam. The lower ledge secures to the lower sill beam through a third plurality of fasteners, and the upper ledge secures to the upper sill beam through a fourth plurality of fasteners. In at least one example, the extension beam includes an inboard surface and an outboard surface opposite from the inboard surface. The inboard surface abuts against one of the lateral support walls of the central column. 
     In at least one example, the inboard flange includes a lower panel inwardly extending from a lower portion of an inboard surface of an inner extension beam. The lower panel connects to a front support brace that angles upwardly and inwardly to connect to a central portion of the inner extension beam. An upper panel inwardly extends from an upper portion of the inboard surface of the inner extension beam. The upper panel connects to a front support brace that angles downwardly and inwardly to connect to the central portion. In at least one example, the inner extension beam includes the inboard surface and an outboard surface opposite from the inboard surface. The outboard surface abuts against one of the lateral support walls of the central column. 
     In at least one example, the one or more fittings are temporarily attached to the upper sill beam and the lower sill beam before the horizontal stabilizer is coupled to the one or more pivot fittings. In at least one example, the one or more fittings are configured to be removed from the upper sill beam and the lower sill beam. The horizontal stabilizer is configured to be coupled to the one or more fittings. The horizontal stabilizer is configured to be moved into the stabilizer channel of the forward section. The one or more fittings are configured to be re-secured to the upper sill beam and the lower sill beam to secure the horizontal stabilizer within the stabilizer channel of the forward section. 
     In at least one example, a sub-assembly includes the one or more fittings secured to the upper sill beam and the lower sill beam, and the horizontal stabilizer coupled to the one or more fittings within the stabilizer channel. A bulkhead is secured to an aft section or the sub-assembly. The sub-assembly is secured to the aft section. 
     Certain examples of the present disclosure provide a method for forming an aft fuselage section of an aircraft. The method includes fastening one or more pivot fittings securely between an upper sill beam and a lower sill beam of a forward section; and coupling a horizontal stabilizer within a stabilizer channel of the forward section to the one or more pivot fittings. 
     In at least one example, said fastening and said coupling occur before securing the forward section to an aft section. 
     In at least one example, the method also includes temporarily attaching the one or more fittings to the upper sill beam and the lower sill beam before said coupling; removing one or more fittings from the upper sill beam and the lower sill beam; coupling the horizontal stabilizer to the one or more fittings outside of the stabilizer channel; moving the horizontal stabilizer into the stabilizer channel of the forward section; and re-securing the one or more fittings to the upper sill beam and the lower sill beam to secure the horizontal stabilizer within the stabilizer channel of the forward section. 
     In at least one example, the method also includes forming a sub-assembly including the one or more fittings secured to the upper sill beam and the lower sill beam, and the horizontal stabilizer coupled to the one or more fittings within the stabilizer channel; securing a bulkhead to an aft section or the sub-assembly; and securing the sub-assembly is secured to the aft section. 
     Certain examples of the present disclosure provide a pivot fitting for coupling a horizontal stabilizer to a forward section of an aft fuselage section of an aircraft. The pivot fitting includes a central column, an outboard flange, and an inboard flange, as described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an isometric exploded view of a known aft fuselage section. 
         FIG.  2    illustrates an isometric front view of a bulkhead. 
         FIG.  3    illustrates an isometric internal view of the known aft fuselage section during a manufacturing process. 
         FIG.  4    illustrates an isometric rear view of a horizontal stabilizer coupled to a forward section of an aft fuselage section, according to an example of the present disclosure. 
         FIG.  5    illustrates an isometric rear view of a pivot fitting secured to an upper sill beam and a lower sill beam of the forward section, according to an example of the present disclosure. 
         FIG.  6    illustrates an isometric rear view of a pivot fitting, according to an example of the present disclosure. 
         FIG.  7    illustrates an isometric front view of the pivot fitting of  FIG.  6   . 
         FIG.  8    illustrates a first lateral view of the pivot fitting of  FIG.  6   . 
         FIG.  9    illustrates a second lateral view of the pivot fitting of  FIG.  6   . 
         FIG.  10    illustrates an isometric exploded rear view of the pivot fitting of  FIG.  6   . 
         FIG.  11    illustrates an isometric rear view of an aft fuselage section having pivot fittings, according to an example of the present disclosure. 
         FIG.  12    illustrates an isometric rear view of the aft fuselage section with the pivot fittings removed, according to an example of the present disclosure. 
         FIG.  13    illustrates an isometric rear view of a horizontal stabilizer separated from a forward section of the aft fuselage section, according to an example of the present disclosure. 
         FIG.  14    illustrates an isometric rear view of a sub-assembly of the aft fuselage section, according to an example of the present disclosure. 
         FIG.  15    illustrates an isometric rear view of a completed aft fuselage section, according to an example of the present disclosure. 
         FIG.  16    illustrates a flow chart of a method of forming an aft fuselage section, according to an example of the present disclosure. 
         FIG.  17    illustrates an isometric front view of an aircraft, according to an example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The foregoing summary, as well as the following detailed description of certain examples will be better understood when read in conjunction with the appended drawings. As used herein, an element or step recited in the singular and preceded by the word “a” or “an” should be understood as not necessarily excluding the plural of the elements or steps. Further, references to “one example” are not intended to be interpreted as excluding the existence of additional examples that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, examples “comprising” or “having” an element or a plurality of elements having a particular condition can include additional elements not having that condition. 
     Examples of the present disclosure provide a pivot fitting that enables streamlined assembly of an aft fuselage section of an aircraft. The pivot fitting allows individuals to work outside of the aircraft (in contrast to within the confined spaces of an aft fuselage section) to complete integration of the horizontal stabilizer to the aft fuselage section. Examples of the present disclosure provide a structural arrangement that improves installation ergonomics for the horizontal stabilizer to the aft fuselage section. The pivot fitting also creates improved load paths for pivot fitting integration to the pivot bulkhead. 
       FIG.  4    illustrates an isometric rear view of a horizontal stabilizer  100  coupled to a forward section  102  of an aft fuselage section  104 , according to an example of the present disclosure.  FIG.  4    illustrates a system  101  for securing the horizontal stabilizer to the forward section  102  of the aft fuselage section  104 . The system  101  is configured to form the aft fuselage section  104 , which includes an aft section (not shown) that is secured to the forward section  102 . 
     The forward section  102  includes a stabilizer channel  106  extending into the forward section  102  between an upper canopy  108 , a lower base  110 , and a main body  112 . An upper sill beam  114  is secured to a rear surface of the upper canopy  108  above an open end  116  of the stabilizer channel  106 . A lower sill beam  118  is secured to the rear surface of the lower base  110  above the open end  116  of the stabilizer channel  106 . 
     A first pivot fitting  120   a  is secured between the upper sill beam  114  and the lower sill beam  118 . A second pivot fitting  120   b  is secured between the upper sill beam  114  and the lower sill beam  118 . The first pivot fitting  120   a  is at one side (a first side)  122  of the forward section  102  (between respective first ends  126 ,  128  of the upper sill beam  114  and the lower sill beam  118 ), and the second pivot fitting  120   b  is at an opposite side (a second side)  124  of the forward section  102  (between respective second ends  130 ,  132  of the upper sill beam  114  and the lower sill beam  118 ). 
     As described herein, the system  101  for forming the aft fuselage section  104  of an aircraft includes the forward section  102  having the stabilizer channel  106 . The forward section  102  includes the upper sill beam  114  and the lower sill beam  118 . One or more pivot fittings  120   a  and/or  120   b  are securely fastened between the upper sill beam  114  and the lower sill beam  118 . The pivot fitting(s)  120   a  and/or  120   b  are configured to pivotally couple to the horizontal stabilizer  100  within the stabilizer channel  106 . 
       FIG.  5    illustrates an isometric rear view of the pivot fitting  120   a  secured to the upper sill beam  114  and the lower sill beam  118  of the forward section  102 , according to an example of the present disclosure. While the pivot fitting  120   a  is shown, the pivot fitting  120   b  shown in  FIG.  4    is secured to the upper sill beam  114  and the lower sill beam  118  as shown in  FIG.  5   . 
     The upper sill beam  114  includes a joint panel  140  and a fitting panel  142 . In at least one example, the joint panel  140  is orthogonal to the fitting panel  142 . That is, the joint panel  140  can be perpendicular to the fitting panel  142 . The joint panel  140  mounts onto and secures to a rear face  144  of the forward section  102  above the stabilizer channel  106  through a plurality of fasteners  146 . The fitting panel  142  mounts over an upper surface  148  of the pivot fitting  120   a , and secures thereto through a plurality of fasteners  146 . 
     Similarly, the lower sill beam  118  includes a joint panel  150  and a fitting panel  152 . In at least one example, the joint panel  150  is orthogonal to the fitting panel  152 . That is, the joint panel  150  can be perpendicular to the fitting panel  152 . The joint panel  150  mounts onto and secures to a rear face  154  of the forward section  102  below the stabilizer channel  106  through a plurality of fasteners  146 . The fitting panel  152  mounts below a lower surface  158  of the pivot fitting  120   a , and secures thereto through a plurality of fasteners  146 . 
     Notably, operations to form the through-holes for the various fasteners  146  (such as drilling), as well as inserting the fasteners  146  and torquing the fasteners to secure fastening positions occurs before the forward section  102  is secured to an aft section. As such, individuals are able to perform the various operations (such as drilling, inserting fasteners, torquing the fasteners, and the like) outside of the fuselage section  104 . In this manner, the individuals can ergonomically comfortably perform such operations (in contrast to being at cramped, awkward, and/or contorted positions within a confined space of the of the aft fuselage section  104 ). 
     As shown in  FIG.  5   , the upper sill beam  114  and the lower sill beam  118  are securely fastened to the forward section  102 , via the fasteners  146 . The upper sill beam  114  and the lower sill beam  118  are secured to the pivot fittings  120   a  and  120   b  through vertical fasteners  146  (that is, an individual vertically inserts the fasteners  146 ), which is an operation that can be performed while comfortably standing outside of the forward section  102 . 
       FIG.  6    illustrates an isometric rear view of a pivot fitting  120 , according to an example of the present disclosure.  FIG.  7    illustrates an isometric front view of the pivot fitting  120  of  FIG.  6   .  FIG.  8    illustrates a first lateral view of the pivot fitting  120  of  FIG.  6   .  FIG.  9    illustrates a second lateral view of the pivot fitting  120  of  FIG.  6   .  FIG.  10    illustrates an isometric exploded rear view of the pivot fitting  120  of  FIG.  6   . The pivot fittings  120   a  and  120   b  shown in  FIG.  4    are configured as shown in  FIGS.  6 - 10   . For example, the pivot fitting  120   a  is configured as shown in  FIGS.  6 - 10   , and the pivot fitting  120   b  can be configured as a mirror image thereof. 
     Referring to  FIGS.  6 - 10   , the pivot fitting  120  includes a central column  160 , an outboard flange  162 , and an inboard flange  164 . The central column  160  includes a base  166 , lateral support walls  168 ,  169  extending upwardly from the base  166 , a front wall  170  extending upwardly from the base  166 , and a top ledge  172  connected to upper portions of the lateral support walls  168  and the front wall  170 . A rear portion  174  of the central column  160  can be open. As shown and described herein, the base  166  secures to the lower sill beam  118  through a plurality (such as a first or second plurality) of fasteners  146 , and the top ledge  172  secures to the upper sill beam  114  through a plurality (such as the other of the first or second plurality) of fasteners  146 . 
     A bearing slot  176  is formed in the front wall  170 . The bearing slot  176  extends between opposed lateral fins  178  having bearing openings  180 . A bearing axis  182  is defined between the opposed bearing openings  180 . A spherical bearing of the horizontal stabilizer  100  (shown in  FIG.  4   ) is configured to be rotatably coupled to the bearing slot  176  between the opposed bearing openings  180 . 
     The outboard flange  162  includes a lower ledge  184  connected to an upper ledge  186  by an outer extension beam  188 . As shown and described herein, the lower ledge  184  secures to the lower sill beam  118  through a plurality of fasteners, and the upper ledge  186  secures to the upper sill beam  114  through a plurality of fasteners. The outer extension beam  188  includes an inboard surface  190  and an outboard surface  192  opposite from the inboard surface  190 . The inboard surface  190  abuts against the lateral support wall  168  of the central column  160 . A bearing opening  194  is formed through a spur  195  of the outer extension beam  188 . The bearing opening  194  is coaxially aligned with the bearing openings  180  of the central column  160 . The outboard flange  162  may or may not secure to the central column  160  through fasteners. Referring to  FIGS.  4 - 10   , in at least one example, the outboard flange  162  is not separately secured to the central column  160  through separate fasteners. Instead, the outboard flange  162  is fixed in relation to the central column  160  by way of the fasteners  146  that secure the pivot fitting  120  to the upper sill beam  114  and the lower sill beam  118 . 
     The inboard flange  164  includes a lower panel or ledge  196  inwardly extending from a lower portion of an inboard surface  197  of an inner extension beam  198 . The lower ledge  196  connects to a front support brace  200  that angles upwardly and inwardly to connect to a central portion  202  of the inner extension beam  198  below a bearing opening  204 , which is coaxially aligned with the bearing openings  180  of the central column  160 . 
     The inboard flange  164  also includes an upper panel or ledge  210  inwardly extending from an upper portion of the inboard surface  197  of the inner extension beam  198 . The upper ledge  210  connects to a front support brace  212  that angles downwardly and inwardly to connect to the central portion  202  of the inner extension beam  198  above the bearing opening  204 . 
     The inner extension beam  198  includes the inboard surface  197  and an outboard surface  199  opposite from the inboard surface  197 . The outboard surface  199  abuts against the lateral support wall  169  of the central column  160 . The inboard flange  164  may or may not secure to the central column  160  through fasteners. Referring to  FIGS.  4 - 10   , in at least one example, the inboard flange  164  is not separately secured to the central column  160  through separate fasteners. Instead, the inboard flange  164  is fixed in relation to the central column  160  by way of the fasteners  146  that secure the pivot fitting  120  to the upper sill beam  114  and the lower sill beam  118 . 
     The upper ledge  186  of the outboard flange  162 , the top ledge  172  of the central column  160 , and the upper ledge  210  of the inboard flange  164  provide flat surfaces that abut against a lower surface of the fitting panel  142  of the upper sill beam  114 , which allow for through-holes to be vertically drilled therethrough, and the fasteners  146  to be easily inserted (such as vertically inserted) and engaged from positions outside of the aft or unpressurized fuselage section  104 . Similarly, the lower ledge  184  of the outboard flange  162 , the base  166  of the central column  160 , and the lower ledge  196  of the inboard flange  164  also provide flat surfaces that abut against an upper surface of the fitting panel  152  of the lower sill beam  118 , which allow for through-holes to be vertically drilled therethrough, and the fasteners  146  to be easily inserted (such as vertically inserted) and engaged from positions outside of the aft fuselage section  104 . 
     The lateral support walls  168 ,  169 , and the front face  170  of the central column  160  provide a load path that is configured to distribute loads in the directions of arrows A, such as in a vertical direction. Similarly, the outer extension beam  188  of the outboard flange  162  and the inner extension beam  198  of the inboard flange  164  provide load paths that are configured to distribute loads in the direction of arrows A. Additionally, the lower ledge  184  and upper ledge  186  of the inboard flange  164 , the base  166  and the top ledge  172  of the central column  160 , and the lower ledge  196  and the upper ledge  210  of the inboard flange  164  provide loads paths that are configured to distribute loads in the directions of arrows B, which are orthogonal to the directions of arrows A, such as in a horizontal direction. Further, the front support braces  200  and  212  of the inboard flange  164  are configured to distribute shear loads. The front support braces  200  and  212  provide integrated structures that are configured to react to lateral loads, for example. 
     As shown in  FIGS.  6 - 10   , the pivot fitting  120  includes the central column  160 , the outboard flange  162 , and the inboard flange  164 . As such, the pivot fitting  120  includes three separate and distinct pieces. In this manner, the pivot fitting  120  provides redundant load paths, so that if an anomaly arises in one of the pieces (such as a crack), a robust and reliable load path is still provided by one or both of the other pieces. 
       FIG.  11    illustrates an isometric rear view of the aft fuselage section  104  having the pivot fittings  120   a  and  120   b , according to an example of the present disclosure. In order to assemble the aft fuselage section, the pivot fittings  120   a  and  120   b  are first secured to the upper sill beam  114  and the lower sill beam  118  before the horizontal stabilizer  100  is positioned within the stabilizer channel  106 . As noted, the upper sill beam  114 , the lower sill beam  118 , and the pivot fittings  120   a  and  120   b  are machined (such as via drilling) to form various through-holes, and the various fasteners  146  (shown in  FIG.  5   , for example) are inserted and engaged to secure the pivot fittings  120   a  and  120   b  to the forward section  102  (such as via the upper sill beam  114  and the lower sill beam  118 ) before the forward section  102  is secured to a bulkhead and/or an aft section. As such, the various operations, such as drilling through-holes, inserting fasteners (and optionally shims), engaging the fasteners to secure components together, and the like can be performed by one or more individuals outside of the aft fuselage section  104  at ergonomically comfortably positions. Thus, as shown in  FIG.  11   , the pivot fittings  120   a  and  120   b  are secured to the forward section  104  and confirmed to be properly positioned and fastened in relation to the forward section  104  before the forward section  102  is secured to the aft section (and optionally before the horizontal stabilizer is positioned within the stabilizer channel  106 ). 
     In at least one example, the front joint  102  arrives at a location for final assembly with the pivot fittings  120   a  and  120   b  temporarily attached to the upper sill beam  114  and the lower sill beam  118 . The pivot fittings  120  and  120   b , the upper sill beam  114 , and the lower sill beam  118  have already been drilled to provide respective aligned, deburred through-holes at full size. 
       FIG.  12    illustrates an isometric rear view of the aft fuselage section  104  with the pivot fittings  120   a  and  120   b  (shown in  FIG.  1   ) removed, according to an example of the present disclosure. Referring to  FIGS.  11  and  12   , after the pivot fittings  120   a  and  120   b  are securely coupled to the forward section  102  to ensure proper positioning, tolerances, and the like, the pivot fittings  120   a  and  120   b  are removed to provide an unimpeded path into the stabilizer channel  106 . 
       FIG.  13    illustrates an isometric rear view of the horizontal stabilizer  100  separated from the forward section  102  of the aft fuselage section  104 , according to an example of the present disclosure. Referring to  FIGS.  11 - 13   , after the pivot fittings  120   a  and  120   b  are removed from the forward section  102 , the pivot fittings  120   a  and  120   b  are pivotally coupled to rear surfaces  240  of the horizontal stabilizer  100 . For example, spherical bearings at the rear surfaces  240  are pivotally secured to the bearing slots  176  (shown in  FIG.  7   ) of the pivot fittings  120   a  and  120   b . After the pivot fittings  120   a  and  120   b  are pivotally secured to the horizontal stabilizer  100 , the horizontal stabilizer  100  is moved into the stabilizer channel  106  of the forward section  102  in the direction of arrow  242  until the pivot fittings  120   a  and  120   b  are realigned with the upper sill beam  114  and the lower sill beam  118  (such that the respective through-holes are aligned), and then an individual can secure the pivot fittings  120   a  and  120   b  to the forward section  102 , by way of the upper sill beam  114  and the lower sill beam  118 , via the fasteners  146 . In this manner, the pivot fittings  120   a  and  120   b  are secured to the forward section  102 , and the horizontal stabilizer  100  is secured to the pivot fittings  120   a  and  120   b  within the stabilizer channel  106 , thereby providing a sub-assembly that can be secured to a bulkhead and an aft section. No drilling is required at this point. Instead, the drilling previously occurred prior to the final assembly process. 
     As described herein, the fittings  120   a  and  120   b  (which are temporarily secured to the upper sill beam  114  and the lower sill beam  118 ) are configured to be removed from the upper sill beam  114  and the lower sill beam  118 . The horizontal stabilizer  100  is then coupled to the fittings  120   a  and  120   b . The horizontal stabilizer  100  (having the fittings  120   a  and  120   b  coupled thereto) then moved into the forward section  102  (such as into the stabilizer channel  106 ). The fittings  120   a  and  120   b  are then re-secured to the upper sill beam  114  and the lower sill beam  118  to secure the horizontal stabilizer  100  within the stabilizer channel  106  of the forward section  102 . 
       FIG.  14    illustrates an isometric rear view of the sub-assembly  250  of the aft fuselage section  104 , according to an example of the present disclosure. The sub-assembly  250  includes the horizontal stabilizer  100  within the stabilizer channel  106 , and pivotally secured to the forward section  102  by the pivot fittings  120   a  and  120   b . As shown, an individual  252  is outside of the aft fuselage section  104  and can operate to fasten the upper sill beam  114  and the lower sill beam  118  to the pivot fittings  120   a  and  120   b  by vertically inserting fasteners and torquing the fasteners to securely fasten the pivot fittings  120   a  and  120   b  to the forward section  102 . 
       FIG.  15    illustrates an isometric rear view of a completed aft fuselage  104  section, according to an example of the present disclosure. After the sub-assembly  250  has been formed, as described above, the aft section  270 , which can include a bulkhead (or optionally, the bulkhead is first secured to the sub-assembly  250 ) is secured to the sub-assembly  250 . 
       FIG.  16    illustrates a flow chart of a method of forming an aft fuselage section, according to an example of the present disclosure. Referring to  FIGS.  4 - 16   , at  300 , the forward section  102  is operated on to secure pivot fittings  120   a  and  120   b  thereto. For example, one or more individuals outside of the aft fuselage section  104  perform various operations, such as drilling through-holes, aligning pivot fittings  120   a  and  120   b  in relation to the upper sill beam  114  and the lower sill beam  118 , inserting fasteners into aligned through-holes, torquing the fasteners to securely fasten the pivot fittings  120   a  and  120   b  to the upper sill beam  114  and the lower sill beam  118 , and/or the like, to secure the pivot fittings  120   a  and  120   b  to the forward section  102 . In this manner, the positioning, tolerances, and securing of the pivot fittings  120   a  and  120   b  in relation to the forward section  102  are determined and set before the horizontal stabilizer  100  is coupled to the forward section  102  and the forward section  102  is secured to the aft section  270 . 
     At  302 , the pivot fittings  120   a  and  120   b  are removed from the forward section  102  to provide an impeded path for the horizontal stabilizer  100  into the stabilizer channel  106  of the forward section  102 . At  304 , the pivot fittings  120   a  and  120   b  are pivotally secured to the horizontal stabilizer  100 . At  306 , the horizontal stabilizer  100 , which now has the pivot fittings  120   a  and  120   b  pivotally secured thereto, is moved into the stabilizer channel  106  of the forward section  102 . At  308 , the pivot fittings  120   a  and  120   b  are then secured to the forward section  102  (such as by the upper sill beam  114  and the lower sill beam  118 ) to form the sub-assembly  250 . 
     Optionally, at  310 , a bulkhead is secured to the aft section  270  or the sub-assembly  250 . At  312 , the aft section  270  is then secured to the sub-assembly  250 , thereby completing the aft fuselage section  104 . 
     Referring to  FIGS.  4 - 16   , the pivot fitting  120 , such as the pivot fittings  120  and  120   b , enables streamlined assembly of the aft fuselage section  104 . In particular, the pivot fitting  120  is configured to be secured to the front joint  102  before the front joint  102  is secured to the aft section  270 . The pivot fitting  120  allows individuals to work outside of the aft fuselage section  104 , away from confined spaced, to complete integration of the horizontal stabilizer  100  to the aft fuselage section  104 . 
     The pivot fittings  120   a  and  120   b  are secured to the upper sill beam  114  and the lower sill beam  118  outside of the aft fuselage section  104 , and away from confined spaces such as above and below the horizontal stabilizer  100 . It has been found that this results in a 95% reduction in confined space work and a significant improvement in ergonomics. Factory flow is also improved greatly because there is no drilling required to join the pivot fittings  120   a  and  120   b  to the fuselage, as the through-holes have been formed prior to the final assembly process. Further, the pivot fittings  120   a  and  120   b  provide improved structural load paths, such as in vertical, horizontal, lateral, and shear directions. 
       FIG.  17    illustrates an isometric front view of an aircraft  410 , according to an example of the present disclosure. The aircraft  410  includes a propulsion system  412  that includes engines  414 , for example. Optionally, the propulsion system  412  may include more engines  414  than shown. The engines  414  are carried by wings  416  of the aircraft  410 . In other embodiments, the engines  414  may be carried by a fuselage  418  and/or an empennage  420 . The empennage  420  also supports a horizontal stabilizer  422  and a vertical stabilizer  424 . 
     The horizontal stabilizer  422  is an example of the horizontal stabilizer  100 , shown in  FIGS.  4  and  13 - 15   . The fuselage  418  includes an aft fuselage section, such as the aft fuselage section  104  shown in  FIGS.  4 ,  5 , and  11 - 15   . The fuselage  418  of the aircraft  410  defines an internal cabin  430 , which includes a flight deck or cockpit, one or more work sections (for example, galleys, personnel carry-on baggage areas, and the like), one or more passenger sections (for example, first class, business class, and coach sections), one or more lavatories, and/or the like. 
     The aircraft  410  shown in  FIG.  17    is merely exemplary. It is to be understood that the aircraft  410  can be sized, shaped, and configured differently than shown. 
     Further, the disclosure comprises examples according to the following clauses:
     Clause 1. A system for forming an aft fuselage section of an aircraft, the system comprising:
   a forward section having a stabilizer channel, wherein the forward section comprises an upper sill beam and a lower sill beam; and   one or more pivot fittings securely fastened between the upper sill beam and the lower sill beam, wherein the one or more pivot fittings are configured to pivotally couple to a horizontal stabilizer within the stabilizer channel.   
   Clause 2. The system of Clause 1, wherein the one or more pivot fittings comprise:
   a first pivot fitting at a first side of the forward section; and   a second pivot fitting at a second side of the forward section, wherein the second side is opposite from the first side.   
   Clause 3. The system of Clauses 1 or 2, wherein each of the upper sill beam and the lower sill beam comprises:
   a joint panel that mounts to a rear face of the forward section; and   a fitting panel that mounts to the one or more pivot fittings.   
   Clause 4. The system of Clause 3, wherein the joint panel is perpendicular to the fitting panel.   Clause 5. The system of any of Clauses 1-4, wherein the one more pivot fittings are securely fastened to the forward section, and the horizontal stabilizer is pivotally coupled to the one or more pivot fittings before the forward section is secured to an aft section.   Clause 6. The system of any of Clauses 1-5, wherein each of the one or more pivot fittings comprises:
   a central column;   an outboard flange; and   an inboard flange.   
   Clause 7. The system of Clause 6, wherein the central column comprises:
   a base;   lateral support walls extending upwardly from the base;   a front wall extending upwardly from the base, wherein a bearing slot is formed in the front wall, and wherein the bearing slot is configured to retain a spherical bearing of the horizontal stabilizer; and   a top ledge connected to upper portions of the lateral support walls and the front wall,   wherein the base secures to the lower sill beam through a first plurality of fasteners, and wherein the top ledge secures to the upper sill beam through a second plurality of fasteners.   
   Clause 8. The system of Clause 7, wherein the outboard flange comprises a lower ledge connected to an upper ledge by an outer extension beam, wherein the lower ledge secures to the lower sill beam through a third plurality of fasteners, and wherein the upper ledge secures to the upper sill beam through a fourth plurality of fasteners.   Clause 9. The system of Clause 8, wherein the extension beam comprises an inboard surface and an outboard surface opposite from the inboard surface, wherein the inboard surface abuts against one of the lateral support walls of the central column.   Clause 10. The system of any of Clauses 7-9, wherein the inboard flange comprises:
   a lower panel inwardly extending from a lower portion of an inboard surface of an inner extension beam, wherein the lower panel connects to a front support brace that angles upwardly and inwardly to connect to a central portion of the inner extension beam; and   an upper panel inwardly extending from an upper portion of the inboard surface of the inner extension beam, wherein the upper panel connects to a front support brace that angles downwardly and inwardly to connect to the central portion.   
   Clause 11. The system of Clause 10, wherein the inner extension beam includes the inboard surface and an outboard surface opposite from the inboard surface, and wherein the outboard surface abuts against one of the lateral support walls of the central column.   Clause 12. The system of any of Clauses 1-11, wherein the one or more fittings are temporarily attached to the upper sill beam and the lower sill beam before the horizontal stabilizer is coupled to the one or more pivot fittings.   Clause 13. The system of Clause 12, wherein the one or more fittings are configured to be removed from the upper sill beam and the lower sill beam, wherein the horizontal stabilizer is configured to be coupled to the one or more fittings, wherein the horizontal stabilizer is configured to be moved into the stabilizer channel of the forward section, and wherein the one or more fittings are configured to be re-secured to the upper sill beam and the lower sill beam to secure the horizontal stabilizer within the stabilizer channel of the forward section.   Clause 14. The system of Clauses 12 or 13, wherein a sub-assembly includes the one or more fittings secured to the upper sill beam and the lower sill beam, and the horizontal stabilizer coupled to the one or more fittings within the stabilizer channel, wherein a bulkhead is secured to an aft section or the sub-assembly, and wherein the sub-assembly is secured to the aft section.   Clause 15. A method for forming an aft fuselage section of an aircraft, the method comprising:
   fastening one or more pivot fittings securely between an upper sill beam and a lower sill beam of a forward section; and   coupling a horizontal stabilizer within a stabilizer channel of the forward section to the one or more pivot fittings.   
   Clause 16. The method of Clause 15, wherein said fastening and said coupling occur before securing the forward section to an aft section.   Clause 17. The method of Clauses 15 or 16, further comprising:
   temporarily attaching the one or more fittings to the upper sill beam and the lower sill beam before said coupling;   removing one or more fittings from the upper sill beam and the lower sill beam;   coupling the horizontal stabilizer to the one or more fittings outside of the stabilizer channel;   moving the horizontal stabilizer into the stabilizer channel of the forward section; and   re-securing the one or more fittings to the upper sill beam and the lower sill beam to secure the horizontal stabilizer within the stabilizer channel of the forward section.   
   Clause 18. The method of any of Clauses 15-17, further comprising:
   forming a sub-assembly including the one or more fittings secured to the upper sill beam and the lower sill beam, and the horizontal stabilizer coupled to the one or more fittings within the stabilizer channel;   securing a bulkhead to an aft section or the sub-assembly; and   securing the sub-assembly is secured to the aft section.   
   Clause 19. A pivot fitting for coupling a horizontal stabilizer to a forward section of an aft fuselage section of an aircraft, the pivot fitting comprising:
   a central column;   an outboard flange; and   an inboard flange.   
   Clause 20. The pivot fitting of Clause 19,
   wherein the central column comprises:
   a base;   lateral support walls extending upwardly from the base;   a front wall extending upwardly from the base, wherein a bearing slot is formed in the front wall, and wherein the bearing slot is configured to retain a spherical bearing of the horizontal stabilizer; and   a top ledge connected to upper portions of the lateral support walls and the front wall,   wherein the base secures to the lower sill beam through a first plurality of fasteners, and wherein the top ledge secures to the upper sill beam through a second plurality of fasteners,   
   wherein the outboard flange comprises a lower ledge connected to an upper ledge by an outer extension beam, wherein the lower ledge secures to the lower sill beam through a third plurality of fasteners, and wherein the upper ledge secures to the upper sill beam through a fourth plurality of fasteners, and   wherein the inboard flange comprises:
   a lower panel inwardly extending from a lower portion of an inboard surface of an inner extension beam, wherein the lower panel connects to a front support brace that angles upwardly and inwardly to connect to a central portion of the inner extension beam; and   an upper panel inwardly extending from an upper portion of the inboard surface of the inner extension beam, wherein the upper panel connects to a front support brace that angles downwardly and inwardly to connect to the central portion.   
   
   

     As described herein, examples of the present disclosure provide a system and a method for efficiently and effectively joining a horizontal stabilizer to an aft fuselage section of an aircraft. Further, examples of the present disclosure provide a simpler and easier method for joining the horizontal stabilizer to the aft fuselage section. Additionally, examples of the present disclosure provide a more ergonomic method for securing the horizontal stabilizer to the aft fuselage section. 
     While various spatial and directional terms, such as top, bottom, lower, mid, lateral, horizontal, vertical, front and the like can be used to describe examples of the present disclosure, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations can be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like. 
     As used herein, a structure, limitation, or element that is “configured to” perform a task or operation is particularly structurally formed, constructed, or adapted in a manner corresponding to the task or operation. For purposes of clarity and the avoidance of doubt, an object that is merely capable of being modified to perform the task or operation is not “configured to” perform the task or operation as used herein. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described examples (and/or aspects thereof) can be used in combination with each other. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the various examples of the disclosure without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various examples of the disclosure, the examples are by no means limiting and are exemplary examples. Many other examples will be apparent to those of skill in the art upon reviewing the above description. The scope of the various examples of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims and the detailed description herein, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. 
     This written description uses examples to disclose the various examples of the disclosure, including the best mode, and also to enable any person skilled in the art to practice the various examples of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various examples of the disclosure is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if the examples have structural elements that do not differ from the literal language of the claims, or if the examples include equivalent structural elements with insubstantial differences from the literal language of the claims.