Patent Publication Number: US-2022227470-A1

Title: Pressure bulkhead assembly methods and systems

Description:
PRIORITY 
     This application claims priority from U.S. Ser. No. 63/139,369 filed on Jan. 20, 2021. 
    
    
     FIELD 
     The present disclosure relates generally to methods and systems for joining structural components and, more particularly, to methods and systems for joining structural components associated with a pressure bulkhead assembly of an aircraft. 
     BACKGROUND 
     Pressure bulkheads are often used in aircraft to separate a pressurized section of a fuselage from an unpressurized section. In some applications, the pressure bulkhead may be mounted within the fuselage and attached to the outer skin of one or more sections of the fuselage. In some instances, the pressure bulkhead is mounted to the aircraft using a plurality of angled members, referred to herein as splice angles, and stringer end fittings. 
     The splice angles and the pressure bulkhead are typically assembled on a drill jig using assembly jig tooling. In particular, the pressure bulkhead is initially joined with the splice angles. Subsequently, holes are drilled through the pressure bulkhead and the splice angles while both are temporarily joined to each other. However, the use of drill jigs to drill such primary structural joints may result in oversized holes, may require multiple measurement and alignment steps, and/or may require the pressure bulkhead and the splice angles to be repeatedly placed and removed from the jig, with any or all leading to production lags. The use of drill jigs may also lead to design of shims or spacers larger than desired. Also, the flexibility of carbon fiber materials that make up some of the pressure bulkhead components can make it harder to machine the surface of the pressure bulkhead and holes when the pressure bulkhead is attached to the jig. 
     Thus, there is a need for an assembly method for pressure bulkheads that reduces installation time, increases the accuracy of the size of the hole, increases the accuracy of the location of the hole, reduces labor, is readily automated, and minimizes wastage of parts. Accordingly, those skilled in the art continue with research and development efforts in the field of pressure bulkhead assembly. 
     SUMMARY 
     Disclosed are examples of a method of making a pressure bulkhead assembly, a system for making a pressure bulkhead assembly, and a pressure bulkhead assembly for an aircraft. The following is a non-exhaustive list of examples, which may or may not be claimed, of the subject matter according to the present disclosure. 
     In an example, the disclosed method includes steps of: (1) determining first locations of a plurality of first holes, pre-drilled in an aft pressure bulkhead; (2) determining first orientations of the plurality of first holes in the aft pressure bulkhead; (3) determining a first surface profile of a first interface surface of the aft pressure bulkhead; (4) determining a second surface profile of a second interface surface of each one of a plurality of splice angles that corresponds to an associated portion of the first interface surface of the aft pressure bulkhead, wherein the plurality of splice angles is configured to be coupled to the aft pressure bulkhead; (5) determining second locations and second orientations of a plurality of second holes to be drilled in the plurality of splice angles, wherein the plurality of second holes correspond to the plurality of first holes in the aft pressure bulkhead; and (6) drilling the plurality of second holes in each one of the plurality of splice angles at the second locations and the second orientations. 
     In an example, the disclosed system includes a spatial relation apparatus including a measurement machine and a computer system having a memory storing a program and a processor. The processor is configured to execute the program to perform the steps of: (1) determine first locations of a plurality of first holes, pre-drilled in an aft pressure bulkhead; (2) determine first orientations of the plurality of first holes in the aft pressure bulkhead; (3) determine a first surface profile of a first interface surface of the aft pressure bulkhead; (4) determine a second surface profile of a second interface surface of each one of a plurality of splice angles that corresponds to an associated portion of the first interface surface of the aft pressure bulkhead, wherein the plurality of splice angles is configured to be coupled to the aft pressure bulkhead; and (5) determine second locations and second orientations of a plurality of second holes to be drilled in the plurality of splice angles, wherein the plurality of second holes correspond to the plurality of first holes in the aft pressure bulkhead. The system also includes a Computer Numerically Controlled machine configured to drill the plurality of second holes in each one of the plurality of splice angles at the second locations and the second orientations. 
     In an example, the disclosed pressure bulkhead assembly includes an aft pressure bulkhead including a first interface surface and a plurality of first holes pre-drilled through the first interface surface. The pressure bulkhead assembly also includes a plurality of splice angles configured to be coupled to the aft pressure bulkhead. Each one of the plurality of splice angles includes second interface surface and a plurality of second holes drilled through the second interface surface and corresponding to a portion of the plurality of first holes in the aft pressure bulkhead. The plurality of second holes is drilled by a Computer Numerically Controlled machine executing a validated Network Computer program based on second locations and second orientations of the plurality of second holes to be drilled in each one of the plurality of splice angles. The second locations and the second orientations of the plurality of second holes are determined based on a virtual overlay of a first three-dimensional profile of the aft pressure bulkhead and a second three-dimensional profile of each one of the plurality of splice angles. The first three-dimensional profile of the aft pressure bulkhead is determined by determining first locations and first orientations of the plurality of first holes in the aft pressure bulkhead and determining a first surface profile of the first interface surface of the aft pressure bulkhead. The second three-dimensional profile of each one of the plurality of splice angles is determined by determining a second surface profile of the second interface surface of each of the splice angles. 
     Other examples of the disclosed method, system and structural assembly will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic, perspective view of an example of a pressure bulkhead assembly; 
         FIG. 2  is a schematic illustration of an example of an aircraft that includes the pressure bulkhead assembly; 
         FIG. 3  is a schematic, cut away, perspective view of an example of a portion of the pressure bulkhead assembly coupled to a fuselage of the aircraft; 
         FIG. 4  is a flowchart of an example of a method of making the pressure bulkhead assembly; 
         FIG. 5  is a schematic block diagram of an example of a system for making the pressure bulkhead assembly; 
         FIG. 6  is a schematic, cut away, perspective view of an example of a portion of an inner surface of an aft pressure bulkhead of the pressure bulkhead assembly; 
         FIG. 7  is a schematic, cut away, perspective view of an example of a portion of an outer surface of the aft pressure bulkhead pressure bulkhead assembly; 
         FIG. 8  is a schematic, perspective view of an example of a splice angle configured to be installed on the aft pressure bulkhead to form the pressure bulkhead assembly; 
         FIG. 9  is a schematic illustration of an example of the aft pressure bulkhead being measured by a measurement machine; 
         FIG. 10  is a schematic illustration of an example of the splice angles being measured by a measurement machine; 
         FIG. 11  is a schematic, perspective view of an example of the splice angle shown in  FIG. 8  with a second plurality of holes drilled therein; 
         FIG. 12  is a schematic illustration of an example of an assembly jig; 
         FIG. 13  is a schematic illustration of an example of the aft pressure bulkhead mounted on the assembly jig shown in  FIG. 12 ; 
         FIG. 14  is a schematic illustration of an example of a three-dimensional virtual overlay of the aft pressure bulkhead and the splice angle; 
         FIG. 15  is a schematic illustration of an example of a transformation of hole locations from a curved shim profile to a flat shim profile; 
         FIG. 16  is a schematic, plan view of an example of a shim of the pressure bulkhead assembly with third holes drilled therein; 
         FIG. 17  is a schematic illustration of an example of the plurality of splice angles and the aft pressure bulkhead mounted on the assembly jig shown in  FIG. 12 ; and 
         FIG. 18  is a flow diagram of an aircraft manufacturing and service methodology. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description refers to the accompanying drawings, which illustrate specific examples described by the present disclosure. Other examples having different structures and operations do not depart from the scope of the present disclosure. Like reference numerals may refer to the same feature, element, or component in the different drawings. Throughout the present disclosure, any one of a plurality of items may be referred to individually as the item and a plurality of items may be referred to collectively as the items and may be referred to with like reference numerals. Moreover, as used herein, a feature, element, component or step preceded with the word “a” or “an” should be understood as not excluding a plurality of features, elements, components or steps, unless such exclusion is explicitly recited. 
     Illustrative, non-exhaustive examples, which may be, but are not necessarily, claimed, of the subject matter according the present disclosure are provided below. Reference herein to “example” means that one or more feature, structure, element, component, characteristic, and/or operational step described in connection with the example is included in at least one aspect, embodiment, and/or implementation of the subject matter according to the present disclosure. Thus, the phrases “an example,” “another example,” “one or more examples,” and similar language throughout the present disclosure may, but do not necessarily, refer to the same example. Further, the subject matter characterizing any one example may, but does not necessarily, include the subject matter characterizing any other example. Moreover, the subject matter characterizing any one example may be, but is not necessarily, combined with the subject matter characterizing any other example. 
     Referring to  FIG. 1 , by way of examples, the present disclosure is directed to a pressure bulkhead assembly  150  that includes an aft pressure bulkhead  110  and a plurality of splice angles  130 . Referring generally to  FIG. 4 , by way of examples, the present disclosure is directed to a method  1000  of installing the plurality of splice angles  130  on the aft pressure bulkhead  110  to make the pressure bulkhead assembly  150 . Referring generally to  FIG. 5 , by way of examples, the present disclosure is also directed to a system  200  for installing the plurality of splice angles  130  on the aft pressure bulkhead  110  to make the pressure bulkhead assembly  150 . In one or more examples, the method  1000  is implemented using the system  200 . 
     Examples of the system  200  and method  1000 , described herein, use measurements of locations and orientations of pre-drilled full-size holes in the aft pressure bulkhead  110 , measurements of surface profiles of the aft pressure bulkhead  110 , and measurements of surface profiles of the splice angles  130  to determine locations and orientations of full-size holes to be drilled in the splice angles  130 . Examples of the system  200  and method  1000 , described herein, also facilitate drilling the full-size holes in the splice angles  130  at the determined locations and orientations. The full-size holes that are drilled in the splice angles  130  correspond to the pre-drilled full-size holes in the aft pressure bulkhead  110 . Examples of the system  200  and method  1000 , described herein, also facilitate installation of the splice angles  130  on the aft pressure bulkhead  110  using a plurality of fasteners inserted through aligned pairs of full-size holes in the splice angles  130  and full-size holes in the aft pressure bulkhead  110 . 
     Furthermore, examples of the system  200  and method  1000 , described herein, also facilitate identifying dimensions of gaps formed between the aft pressure bulkhead  110  and the splice angles  130  and forming shims  140  based on those gap dimensions. Examples of the system  200  and method  1000 , described herein, further facilitate determining locations and orientations of full-size holes to be drilled in the shims  140  and drilling the full-size holes in the shims  140  at the determine locations and orientations. Examples of the system  200  and method  1000 , described herein, additionally facilitate installing the shims  140  between the aft pressure bulkhead  110  and the splice angles  130 . 
     Referring now to  FIG. 1 , which schematically illustrates an example of the pressure bulkhead assembly  150 . The pressure bulkhead assembly  150  includes, or is formed of, the aft pressure bulkhead  110  and the splice angles  130 , installed on (e.g., fastened to) the aft pressure bulkhead  110 . The splice angles  130  are positioned adjacent to one another and are joined to the aft pressure bulkhead  110 . The splice angles  130  form a circumferential surface  152 . The circumferential surface  152  has a nominal shape  154 . 
     The aft pressure bulkhead  110  may take the form of a panel, a disk or a dome (e.g., be dome-shaped). Accordingly, the aft pressure bulkhead  110  may also be referred to as an aft pressure bulkhead dome or as an aft pressure bulkhead panel. For simplicity, the aft pressure bulkhead may also be referred to herein or in the accompanying figures as “APB”. Generally, the pressure bulkhead assembly  150  is sized and shaped for placement inside a fuselage  156  of an aircraft  104  ( FIG. 2 ) such that the aft pressure bulkhead  110  separates a pressurized portion of an interior  172  ( FIG. 2 ) of the aircraft  104  (e.g., a pressurized cabin) from an unpressurized portion of the interior  172  and the splice angles  130  form a pressure seal. In one or more examples, the pressure bulkhead assembly  150  is attached to a skin  170  ( FIG. 2 ) of the fuselage  156  via the splice angles  130 . 
     The aft pressure bulkhead  110  and the splice angles  130  may be formed of any suitable material. For example, the aft pressure bulkhead  110  and the splice angles  130  may be formed of a composite material. The material of the aft pressure bulkhead  110  and the material of the splice angles  130  may be the same or different. 
     Referring now to  FIG. 2 , which schematically illustrates an example of an aircraft  104  in which pressure bulkhead assembly  150  is used. The pressure bulkhead assembly  150  divides a pressurized side of the aircraft  104  from an unpressurized side of the aircraft  104 . The splice angles  130  ( FIG. 1 ) are installed on the aft pressure bulkhead  110  ( FIG. 1 ) on the pressurized side of the aft pressure bulkhead  110 . As an example, the aircraft  104  includes a fuselage  156  and wings  108  attached to and outwardly extending from the fuselage  156 . The fuselage  156  includes a plurality of fuselage sections (e.g., barrel sections). The fuselage  156  (e.g., each fuselage section) has skin  170 , coupled to an airframe  158 , that forms an exterior of the aircraft  104 . The pressure bulkhead assembly  150  separates a first fuselage section  174  (e.g., pressurized side) from a second fuselage section  176  (e.g., unpressurized side) in an aft portion of the fuselage  156 . For example, in  FIG. 3 , arrow  250  indicates a direction of a forward (e.g., pressurized) portion of the aircraft  104 . 
     Referring now to  FIG. 3 , which schematically illustrates an example of a portion of the pressure bulkhead assembly  150  attached to the first fuselage section  174  and the second fuselage section  176 , viewed from within the fuselage  156 . The splice angles  130  overlap a skin-first portion  178  of the skin  170  of the first fuselage section  174  and a skin-second portion  180  of the skin  170  of the second fuselage section  176 . The splice angles  130  are attached (e.g., fastened by a plurality of fasteners) to the skin-first portion  178  and to the skin-second portion  180 . In this manner, the splice angles  130  join the aft pressure bulkhead  110 , the first fuselage section  174  and the second fuselage section  176  together. Accordingly, the splice angles  130  may also be referred to as skin splice angles. 
     As an example, during fabrication of the aircraft  104 , the pressure bulkhead assembly  150  is attached to the second fuselage section  176  by fastening the splice angles  130  to the skin-second portion  180 . The first fuselage section  174  is then positioned adjacent to the second fuselage section  176  such that the splice angles  130  overlap the skin-first portion  178 . The pressure bulkhead assembly  150  is attached to the first fuselage section  174  by fastening the splice angles  130  to the skin-first portion  178 . The nominal shape  154  ( FIG. 1 ) of the circumferential surface  152 , formed by the splice angles  130 , is complementary to the barrel shape of the skins  170  of the first fuselage section  174  and the second fuselage section  176 . Accordingly, the splice angles  130  are positioned on the pressurized side of the aft pressure bulkhead  110  and are configured to form a pressure seal for the fuselage  156  ( FIG. 2 ) between the first fuselage section  174  and the second fuselage section  176 . 
     In one or more examples, shims (not shown in  FIG. 3 ) may be positioned between the circumferential surface  152  of the splice angles  130  and the skin-first portion  178  and/or the skin-second portion  180  to fill any gaps that exist between the splice angles  130  and the skin-first portion  178  and/or the skin-second portion  180 , for example, in areas where the nominal shape  154  of the circumferential surface  152  does not match the barrel shape of the first fuselage section  174  and/or the second fuselage section  176 . 
     Referring now to  FIG. 4 , which illustrates an example of the method  1000 ,  FIGS. 6 and 7 , which schematically illustrate examples of a portion of the aft pressure bulkhead  110  and  FIG. 8 , which schematically illustrates an example of the splice angle  130 . 
     In one or more examples, the method  1000  includes a step of (block  1002 ) making, or forming, the aft pressure bulkhead  110 . The aft pressure bulkhead  110  is initially fabricated, or otherwise made, with a plurality of first holes  112  ( FIGS. 6 and 7 ). For example, the aft pressure bulkhead  110  may be attached to an assembly jig (e.g., assembly jig  240  shown in  FIG. 12 ) for drilling the first holes  112 . The first holes  112  are pre-drilled in the aft pressure bulkhead  110  and are full-size holes configured to receive a corresponding fastener. Accordingly, the first holes  112  may also be referred to herein as pre-drilled full-size holes or first fastener holes. The first holes  112  are drilled at pre-defined locations  182  ( FIGS. 6 and 7 ) on the aft pressure bulkhead  110 . The pre-defined locations  182  of the first holes  112  (e.g., the pre-defined location  182  of each one of the first holes  112 ) refer to the pre-determined, actual (e.g., physical, real world) locations of the first holes  112  on the aft pressure bulkhead  110 , as drilled. 
     Referring to  FIGS. 6 and 7 , the aft pressure bulkhead  110  includes a first surface  111  (e.g., as shown in  FIG. 6 ) and a second surface  119  (e.g., as shown in  FIG. 7 ), opposite the first surface  111 , and a thickness  113 . The first surface  111  may be an inner mold line (IML) of the aft pressure bulkhead  110  and the second surface  119  may be an outer mold line (OML) of the aft pressure bulkhead  110 . Accordingly, the first surface  111  may also be referred to as an inner surface and the second surface  119  may also be referred to as an outer surface. With the pressure bulkhead assembly  150  installed within the fuselage  156  of the aircraft  104  (e.g., as shown in  FIG. 3 ), the first surface  111  is on a pressurized side of the aft pressure bulkhead  110  and the second surface  119  is on the unpressurized side of the aft pressure bulkhead  110 . 
     The first surface  111  includes, or forms, a first interface surface  115  (e.g., an aft pressure bulkhead-interface surface). The first interface surface  115  is located adjacent to a peripheral edge of the aft pressure bulkhead  110  and extends along an approximately circular path. The first interface surface  115  forms a mating contact surface that mates with the splice angles  130  during installation of the splice angles  130  on the aft pressure bulkhead  110 . In other words, the first interface surface  115  is configured to receive the splice angles  130 . 
     The first holes  112  are drilled through the thickness  113  of the aft pressure bulkhead  110  (e.g., extending between the first surface  111  and the second surface  119 ). The pre-defined locations  182  of the first holes  112  locate the first holes  112  through the first interface surface  115 , for example, along an approximately circular path proximate (e.g., at or near) the peripheral edge of the aft pressure bulkhead  110 . Only some of the first holes  112  are shown in  FIGS. 6 and 7  (e.g., first holes  112  in a section of the aft pressure bulkhead  110 ) for the purpose of clarity of illustration. While not explicitly illustrated in  FIGS. 6 and 7 , it should be understood that the first holes  112  may extend around an entirety of the aft pressure bulkhead  110  (e.g., as shown in  FIG. 1 ). 
     In one or more examples, the method  1000  includes a step of (block  1004 ) making the splice angles  130  ( FIG. 8 ). The splice angles  130  are initially fabricated, or otherwise made, without a plurality of holes. 
     Referring briefly to  FIG. 8 , in one or more examples, the splice angle  130  includes a flange  186  and a skin splice  188  that extends from the flange  186  at an oblique angle. The flange  186  includes, or forms, a second interface surface  131  (e.g., a splice angle-interface surface). The second interface surface  131  forms a mating contact surface that mates with the first interface surface  115  of the aft pressure bulkhead  110  during installation of the splice angles  130  on the aft pressure bulkhead  110 . The skin splice  188  includes, or forms, an arcuate segment of the circumferential surface  152  (e.g., shown in  FIG. 1 ). The splice angle  130  includes a first mating edge  190  and a second mating edge  192 , opposite the first mating edge  190 . During installation of the splice angles  130  on the aft pressure bulkhead  110 , the first mating edge  190  of one of the splice angles  130  abuts the second mating edge  192  of a directly adjacent one of the splice angles  130 . 
     In one or more examples, the splice angles  130  may be fabricated with pilot holes  194  drilled through the skin splice  188 . The pilot holes  194  are drilled at locations that approximately correspond to locations where full-size holes will be drilled through the skin splice  188  of the splice angle  130 , the skin-first portion  178  and the skin-second portion  180  during installation of the pressure bulkhead assembly  150  in the fuselage  156  (e.g., as shown in  FIG. 3 ). 
     Referring again to  FIG. 4 , in one or more examples, the method  1000  includes a step of (block  1006 ) measuring the first holes  112  in the aft pressure bulkhead  110 , a step of (block  1008 ) measuring the first interface surface  115  of the aft pressure bulkhead  110  and a step of (block  1010 ) measuring the second interface surface  131  of the flange  186  of the splice angles  130  (e.g., of each one of the splice angles  130 ). 
     Referring to  FIG. 5 , the system  200  is configured to make accurate measurements of the aft pressure bulkhead  110  and the splice angles  130 , process those measurements, machine the splice angles  130  (e.g., drill holes in the splice angles  130 ) and machine the shims  140  that comply with required tolerances, when needed. 
     In one or more examples, the system  200  includes a spatial relation apparatus  202 . The spatial relation apparatus  202  includes a measurement machine, such as a Coordinate Measurement Machine (CMM)  204 , and a computer system  206  (e.g., controller). The measurements taken by the CMM  204  are sent to the computer system  206 . The computer system  206  provides the interface for a user to execute a measurement plan, process the measurements, and provide the processed measurements in an .XML format to an on demand emergent manufacturing (ODEM) application  220 . 
     The computer system  206  includes a processor  208  and a memory  210 . The memory stores one or more programs, such as, for example, a spatial analyzer program  212 . The processor  208  executes the spatial analyzer program  212  to facilitate the spatial relation apparatus  202  in providing an interface for a user to execute the measurement plan, process the measurements, and provide the processed measurements, as described in the method  1000 , to the ODEM application  220 . In one or more examples, the processor  208  executes the spatial analyzer program  212  to direct the CMM  204  to execute operational steps (e.g., blocks  1006 - 1010 ) of the method  1000 . For example, the processor  208  executes the spatial analyzer program  212  to perform an operational step of implementing a first measurement model (e.g., 3D seed model) of the aft pressure bulkhead  110  that includes a plurality of first measurement points for each one of the first holes  112  and for portions of the first interface surface  115 , adjacent to the first holes  112 , and a second measurement model (e.g., 3D seed model) for each one of the splice angles  130  that includes a plurality of second measurement points for portions of the second interface surface  131 . The processor  208  then executes the spatial analyzer program  212  to perform further operational steps (e.g., blocks  1012 - 1026  and  1030 ) of method  1000 . The ODEM application  220  generates network computer (NC) programs  224  and then validates the network computer (NC) programs (generates validated network computer (NC) programs  224 ) to enable drilling full-size holes in the splice angles  130 , machining or fabricating necessary shims  140 , and drilling full-size holes in the shims  140  (e.g., blocks  1028  and  1032 ) when provided with the compatibly-formatted .XML measurement files and 3D seed models from the spatial analyzer program  212 . Each hole to be drilled will have an XYZ point to be drilled and an associated plane, which determines the orientation of the hole to be drilled. 
     The CMM  204  is configured to measure an object in a three-dimensional (3D) coordinate system, often in comparison to a computer aided design (CAD) model of the object. For example, the CMM  204  makes measurements of the aft pressure bulkhead  110  and of the splice angles  130  for drilling a plurality of second holes  132  in the splice angles  130  and, optionally, adding the shims  140  and drilling a plurality of third holes  142  in the shims  140  as necessary to fill the gaps between the aft pressure bulkhead  110  and the splice angles  130 . 
     The CMM  204  may be any suitable metrological machine. The CMM  204  may be a Portable Coordinate Measuring machine. In one or more examples, the CMM  204  may be an articulated measurement arm  205 , such as a ROMER arm machine (e.g., as shown in  FIG. 9 ). For example, the CMM  204  includes a robotic arm that operates in 3D space with six or seven joints, having six degrees of freedom, which means that the robotic arm can move in three-dimensional space forward/backward, up/down, left/right combined with rotation about three perpendicular axes (roll, yaw, pitch). The movement along each of the three axes is independent of each other and independent of the rotation about any of these axes, having the six degrees of freedom. 
     In one or more examples, the CMM  204  may be mounted on a support platform adjacent to the structures being measured (e.g., the aft pressure bulkhead  110  and/or the splice angles  130 ) to take measurements of selected areas on the respective structures. In one or more examples, the CMM  204  may be mounted on, or otherwise form a component of, the assembly jig  240  (e.g.,  FIG. 12 ). 
     Referring now to  FIG. 9 , which schematically illustrates an example of the CMM  204  taking measurements of selected areas (e.g., the first holes  112  and the first interface surface  115 ) on the aft pressure bulkhead  110 . Generally, the CMM  204  is positioned adjacent to the aft pressure bulkhead  110  to be measured, such that the articulated measurement arm  205  can take measurements of the location and orientation of the first holes  112  and the first interface surface  115 . In one or more examples, the aft pressure bulkhead  110  may be mounted on the assembly jig  240  (e.g., as shown in  FIG. 13 ) for taking measurements by the CMM  204 . 
     Referring now to  FIG. 10 , which schematically illustrates an example of the CMM  204  taking measurements of selected areas (e.g., the second interface surface  131 ) on the splice angles  130 . Generally, the CMM  204  is positioned adjacent to the splice angles  130  to be measured, such that the articulated measurement arm  205  can take measurements of the second interface surface  131 . In one or more examples, the plurality of splice angles  130  may mounted on the assembly jig  240  (e.g.,  FIG. 12 ) and positioned adjacent to one another to form the circumferential surface  152  having the nominal shape  154  for taking measurements of each one of the splice angles  130  by the CMM  204 . Alternatively, in one or more examples, each one of the splice angles  130  may be mounted to support tooling for taking measurements by the CMM  204 . 
     Accordingly, the system  200  may be configured to generate a plurality of NC programs for drilling the plurality of second holes  132  in the splice angles  130  based on obtained measurements. 
     It should be appreciated that other suitable types of coordinate measurement machines with sufficient accuracy may be used to take measurements of the selected areas of the structure being measured (e.g., aft pressure bulkhead  110  and splice angles  130 ), such as a handheld measuring device or a laser scanner. Further, it should be appreciated that the system  200  may use different coordinate measurement machines to take measurements of the aft pressure bulkhead  110  and the splice angles  130 . 
     The computer system  206  may include a measurement software platform. The measure software platform may be any suitable type that includes programs that help take and process measurements. In one or more examples, the measurement software platform includes, or takes the form of, the spatial analyzer program  212  (may also referred to herein as spatial analyzer). 
     In one or more examples, the spatial analyzer program  212  may be adapted (e.g., programmed) to link a three-dimensional (3D) measurement seed model. For example, the system  200  may also include 3D measurement seed models that correspond to the aft pressure bulkhead  110  and the splice angles  130  in nominal configurations that include interfacing surfaces, nominal full-size holes, directions and surface geometry. As an example, for the aft pressure bulkhead  110 , the corresponding measurement seed model may identify the first surface  111 , the second surface  119 , the first interface surface  115  and the first holes  112  (e.g., as shown in  FIGS. 6 and 7 ). As an example, for each one of the splice angles  130 , the corresponding measurement seed model may identify the flange  186 , the skin splice  188  and the second interface surface  131  (e.g., as shown in  FIG. 8 ). 
     In one or more examples, for each selected area to be measured, the spatial analyzer program  212  may operate to lead the CMM  204  (e.g., under automated computer control or under operator control) through the measurements and processing needed resulting in the coordinate system transform from an as-mounted CMM coordinate system to a 3D NC seed model in a nominal coordinate system for each one of the aft pressure bulkhead  110  and the splice angles  130 . 
     In one or more examples, the system  200  provides the processed measurements in the .XML format to the on demand emergent manufacturing (ODEM) application  220 . The ODEM application  220  generates and then validates a network computer (NC) program  222  to drill the second holes  132  (e.g., full-size holes) in the splice angles  130  and, optionally, to fabricate (e.g., machine and drill full-size holes in) the shims  140 , as necessary, when provided with the compatibly formatted .XML measurement files and NC seed models. Each hole to be drilled will have an XYZ point to be drilled and an associated plane, which determines the orientation of the hole to be drilled. The ODEM application  220  also monitors the fabrication status of the drilled or machined part. 
     The ODEM application  220  may also transfers the network computer programs to a server that includes setup files that reflect the allowable tolerances of the drilled holes and shims and the quality assurance provisions per product definition data along with measurement plans, index plans, and installation plans. 
     In one or more examples, the system  200  also includes a 5-axis Computer Numerically Control (CNC) milling machine  230 , or equivalent. The CNC machine  230  includes a network computer (NC) controller  232  that receives the NC programs  224 . The system  200  takes measurements, processes the measurements in accordance with the requirement document in an .XML format. The ODEM application  220  then updates the NC seed model with the .XML formatted data, and then automatically creates the requisite NC program  224 . 
     The CNC machine  230  drills the second holes  132  in the splice angles  130  (e.g.,  FIG. 11 ) and, optionally, machines the shims  140  and drills the third holes  142  in the shims  140  (e.g.,  FIG. 16 ), based on the NC programs  222 . For example, each one the splice angles  130  may be secured and indexed on a drill fixture. The CNC machine  230  drills the second holes  132  in each one the splice angles  130  based on the NC programs  224 . Similarly, each one the shims  140  may be secured and indexed on a drill fixture. The CNC machine  230  drills the third holes  142  in each one the shims  140  based on the NC programs  224   
     Referring now to  FIGS. 4, 6 and 7 , in one or more examples, the method  1000  includes a step of (block  1012 ) determining first locations  184  (e.g., aft pressure bulkhead hole locations) of the plurality of first holes  112  at the pre-defined locations  182  on the aft pressure bulkhead  110 . The first locations  184  represent the determined (e.g., measured) locations of the first holes  112 . 
     In an example, as illustrated in  FIG. 6 , the step of (block  1012 ) determining a first one of the measured first locations  184  of a first one of the first holes  112  includes a step of determining a first measured location  114  of a first hole  112   a . The first hole  112   a  is an example of one of the plurality of first holes  112 . For example, a first hole center  117  of the first hole  112   a  along the first surface  111  of the aft pressure bulkhead  110  is measured (e.g., block  1006 ), for example, by the CMM  204  (e.g.,  FIGS. 5 and 9 ), relative to an origin O in an example three-dimensional Cartesian coordinate system XYZ. As an example, the first measured location  114  of the first hole center  117  of the first hole  112   a  is measured as x1, y1, z1 in the XYZ coordinate system. 
     In an example, as illustrated in  FIG. 7 , the step of (block  1012 ) determining the first one of the measured first locations  184  of the first one of the first holes  112  also includes a step of determining a second measured location  118  of the first hole  112   a . For example, a second hole center  121  of the first hole  112   a  along the second surface  119  of the aft pressure bulkhead  110  is measured (e.g., block  1006 ), for example, by the CMM  204  (e.g.,  FIGS. 5 and 9 ), relative to the origin O in an example three-dimensional Cartesian coordinate system XYZ. As an example, the second measured location  118  of the second hole center  121  of the first hole  112   a  is measured as x2, y2, z2 in the XYZ coordinate system. 
     It can be appreciated that the origin O (e.g., as shown in  FIGS. 6 and 7 ) may be chosen for convenience, such as at an outer peripheral edge of the aft pressure bulkhead  110 . In other instances, the origin O may be chosen at a different location or in other instances, the measurement is made using a different coordinate system, such as a polar or spherical coordinate system, without departing from the scope of the present disclosure. 
     In one or more examples, the method  1000  includes a step of (block  1014 ) determining first orientations  116  (e.g., aft pressure bulkhead hole orientations) of the plurality of first holes  112  on the aft pressure bulkhead  110 . The first orientations  116  represent the determined (e.g., measured) orientations of the first holes  112 . 
     In an example, as illustrated in  FIGS. 6 and 7 , the step of (block  1012 ) determining the first one of the first orientations  116  of the first one of the first holes  112  includes a step of determining a first orientation  116   a  of the first hole  112   a . Determination of the first orientation  116   a  uses the first measured location  114  (e.g., indicated by x1, y1, z1 in the XYZ coordinate system) of the first hole center  117  of the first hole  112   a  (e.g., as shown in  FIG. 6 ) and the second measured location  118  (e.g., indicated by x2, y2, z2 in the XYZ coordinate system) of the second hole center  121  of the first hole  112   a  (e.g., as shown in  FIG. 7 ). Based on the first measured location  114  of the first hole center  117  and the second measured location  118  of the second hole center  121 , the first orientation  116   a  of the first hole  112   a  is determined by the angle θ made along a plane  123  between the first hole center  117  and the second hole center  121  across the thickness  113  of the aft pressure bulkhead  110  (e.g., as shown in  FIG. 7 ). 
     For example, in accordance with the method  1000 , the computer system  206  processes the measurements to determine the relative location and orientation of the first hole  112   a . The measurement step (e.g., block  1006 ) and determination steps (e.g., block  1012  and block  1014 ) are repeated for each one of the first holes  112  in the aft pressure bulkhead  110 . 
     Referring now to  FIGS. 4 and 6 , in one or more examples, the method  1000  includes a step of (block  1016 ) determining a first surface profile  125  (e.g., a first interference surface profile) of the first interface surface  115  of the aft pressure bulkhead  110  (e.g., a portion of the first surface  111  of the aft pressure bulkhead  110 ) that is to mate with the second interface surface  131  of a corresponding one of the splice angles  130  (e.g.,  FIG. 8 ). 
     In an example, the first interface surface  115  of the aft pressure bulkhead  110  is scanned and a three-dimensional (3D) scan of the first interface surface  115  (e.g., first interference surface scan) is generated and stored. The 3D scan may be processed to generate the first surface profile  125 . For example, the 3D scan produces 3D point cloud surface profile data for the first interface surface  115 . In an example, the first interface surface  115  of the aft pressure bulkhead  110  is measured (e.g., scanned) by the CMM  204 . 
     In one or more examples, the 3D scan of the first interface surface  115  is compared to a corresponding surface in the 3D seed model, to a nominal model of the aft pressure bulkhead  110  or to as-designed dimensions derived from drawings associated with the aft pressure bulkhead  110  to identify the measurement capability of the measurement machine performing the 3D scan, to ensure that the measurement process resulted in no errors, to ensure proper alignment has been achieved and/or to confirm no anomalies are present. 
     Referring now to  FIG. 12 , which schematically illustrate an example of the assembly jig  240  and  FIG. 13 , which schematically illustrates an example of the aft pressure bulkhead  110  mounted on the assembly jig  240 . In one or more examples, during the measuring steps (block  1006  and block  1008 ) and the determining steps (block  1012 , block  1014  and block  1016 ), the aft pressure bulkhead  110  is mounted on the assembly jig  240  in a position corresponding to an assembly position of the aft pressure bulkhead  110 . In one or more examples, the method  1000  includes a step of securing the aft pressure bulkhead  110  on the assembly jig  240  in a position resembling a final assembly position of the aft pressure bulkhead  110  for assembly of the pressure bulkhead assembly  150  prior to the steps of (block  1006  and block  1008 ) measuring the first holes  112  and the first interface surface  115  and the steps of (block  1012 , block  1014  and block  1016 ) determining the first locations  184  and the first orientations  116  of the first holes  112  in the aft pressure bulkhead  110  and the first surface profile  125  of the aft pressure bulkhead  110 . For example, the aft pressure bulkhead  110  is supported by an aft pressure bulkhead stand  244  ( FIG. 12 ) and is secured to the assembly jig  240  such that the aft pressure bulkhead  110  has negligible freedom of movement while measuring the aft pressure bulkhead  110  and determining the measured first locations  184  and first orientations  116  of the first holes  112  and/or the first surface profile  125  of the first interface surface  115 . 
     In one or more examples, the assembly jig  240  is support tooling that includes a plurality of segmented frames  246  that form a substantially circular shape. The aft pressure bulkhead stand  244  is positioned within, such as at an approximate center of, the circular shape of the segmented frames  246 . In one or more examples, the CMM  204  (e.g.,  FIG. 9 ) is also positioned within the circular shape of the segmented frames  246  for taking measurements of the aft pressure bulkhead  110 . 
     Referring now to  FIGS. 4 and 8 , in one or more examples, the method  1000  includes a step of (block  1018 ) determining a second surface profile  135  (e.g., a second interface surface profile) of the second interface surface  131  of the splice angle  130  (e.g., of each of the splice angles  130 ) to be coupled to the aft pressure bulkhead  110 . As described above, the splice angles  130  are initially fabricated without full-size pre-drilled holes (e.g., without the plurality of second holes  132 ), as illustrated by example in  FIG. 8 . 
     In an example, the second interface surface  131  of the splice angle  130  is scanned and a three-dimensional (3D) scan of the second interface surface  131  (e.g., second interface surface scan) is generated and stored. The 3D scan may be processed to generate the second surface profile  135 . For example, the 3D scan produces 3D point cloud surface profile data for the second interface surface  131 . In an example, the second interface surface  131  of the each one of the splice angles  130  is measured (e.g., scanned) by the CMM  204 . 
     In one or more examples, the 3D scan of the second interface surface  131  is compared to a corresponding surface in the 3D seed model, to a nominal model of the splice angles  130  or to as-designed dimensions derived from drawings associated with the splice angles  130  to identify the measurement capability of the measurement machine performing the 3D scan, to ensure that the measurement process resulted in no errors, to ensure proper alignment has been achieved and/or to confirm no anomalies are present. 
     Referring to  FIGS. 1, 9 and 10 , as described above, in one or more examples, the measured first locations  184  and first orientations  116  of the first holes  112  in the aft pressure bulkhead  110 , the first surface profile  125  of the first interface surface  115  of the aft pressure bulkhead  110  and the second surface profile  135  of the second interface surface  131  of the splice angles  130  are measured and determined (e.g., blocks  1006 - 1018 ) using a measurement machine, such as the CMM  204  and the computer system  206 . In one or more examples, the CMM  204  is mounted on a stable platform that prevents the CMM  204  from rocking or otherwise moving in order to take accurate measurements (e.g., as shown in  FIGS. 9 and 10 ). In one or more examples, the CMM  204  implements a measurement plan outlined by the spatial analyzer program  212 , as described above. 
     Referring to  FIGS. 4 and 5 , in one or more examples, in one or more examples, the method  1000  includes a step of (block  1020 ) generating a first 3D profile  214  representing the aft pressure bulkhead  110  and a step of (block  1022 ) generating a second 3D profile  216  representing the splice angles  130  (e.g., each one of the splice angles  130 ). 
     In one or more examples, the computer system  206  ( FIG. 5 ) may execute a software application (e.g., the spatial analyzer program  212 ) to generate the first 3D profile  214  of the aft pressure bulkhead  110  and the second 3D profile  216  of the splice angles  130  (e.g., each one of the splice angles  130 ). The first 3D profile  214  of the aft pressure bulkhead  110  may be generated using the measured first locations  184  and first orientations  116  of the first holes  112  and the 3D scan of the first interface surface  115 . The second 3D profile  216  of each one of the splice angles  130  may be generated using the 3D scan of the second interface surface  131 . In an example, the first 3D profile  214  is a digital scan or virtual 3D model that represents the surface of the aft pressure bulkhead  110 . In an example, the second 3D profile  216  is a digital scan or virtual 3D model that represents the surface of the splice angle  130 . 
     In one or more examples, the method  1000  includes a step of (block  1024 ) virtually overlaying, or aligning, the first 3D profile  214  of the aft pressure bulkhead  110  with the second 3D profile  216  of each of the splice angles  130  and a step of (block  1026 ) determining second locations  134  (e.g., splice angle hole locations) and second orientations  136  (e.g., splice angle hole orientations) of the plurality of second holes  132  to be drilled in each one of the splice angles  130  (e.g., as shown in  FIG. 11 ). The second locations  134  represent the determined locations and orientations of the second holes  132  to be drilled in the splice angles  130 . 
     In one or more examples, the first 3D profile  214  of the aft pressure bulkhead  110  is determined by the spatial analyzer program  212  of the system  200  that uses the measured first locations  184  and first orientations  116  of the first holes  112  in the aft pressure bulkhead  110  and the first surface profile  125  of the first interface surface  115  of the aft pressure bulkhead  110  measured by the CMM  204 . For example, the aft pressure bulkhead  110  is measured and scanned by the CMM  204 , and the spatial analyzer program  212  generates the first 3D profile  214  for the aft pressure bulkhead  110  based on the 3D cloud surface profile data. 
     In one or more examples, the second 3D profile  216  of each one of the splice angles  130  is similarly determined by the spatial analyzer program  212  using the second surface profile  135  of the second interface surface  131  associated with a corresponding portion of the first interface surface  115  of the aft pressure bulkhead  110 . For example, each splice angle  130  is scanned by the CMM  204 , and the spatial analyzer program  212  determines the second 3D profile  216  for each splice angle  130  based on the 3D cloud surface profile data. 
     In one or more examples, the spatial analyzer program  212  of the system  200  performs the virtual overlaying step (block  1024 ), for example, generates a virtual overlay  138  (e.g., as shown in  FIG. 14 ), by virtually aligning the first interface surface  115  of the aft pressure bulkhead  110 , represented by the first 3D profile  214 , with the corresponding second interface surface  131  of each of the splice angles  130 , represented by the second 3D profile  216 . Based on virtual overlaying the first 3D profile  214  of the aft pressure bulkhead  110  with the second 3D profile  216  of each of the splice angles  130 , the spatial analyzer program  212  determines the second locations  134  (e.g., indicated by x3, y3, z3 in  FIG. 11 ) and second orientations  136  of the second holes  132  to be drilled in each one of the splice angles  130  corresponding to the first holes  112  in the aft pressure bulkhead  110 . 
     The step of (block  1026 ) determining the second locations  134  and the second orientations  136  of the plurality of second holes  132  to be drilled in each one of the splice angles  130  includes a step of determining locations and orientations of a drilling axis relative to the second 3D profile  216  of the splice angle  130  for drilling the second holes  132  in the splice angles  130 . Accordingly, the second location  134  and the second orientation  136  of each one of the second holes  132 , for example, determined by the spatial analyzer program  212 , provides locations and orientations of a center bore axis of the second holes  132  in the splice angles  130  after drilling along the drilling axis, such that during fabrication of the pressure bulkhead assembly  150  ( FIG. 1 ) the first holes  112  in the aft pressure bulkhead  110  coaxially align with the second holes  132  in the splice angles  130 . 
     In one or more examples, the step of (block  1026 ) determining the second locations  134  and the second orientations  136  of the plurality of second holes  132  to be drilled in each one of the splice angles  130  includes a step of modifying, or adjusting, a location and/or orientation of at least one of the splice angles  130  relative to the aft pressure bulkhead  110  during, or following, the step of virtually overlaying the first 3D profile  214  of the aft pressure bulkhead  110  with the second 3D profile  216  of each of the splice angles  130 . For example, the second 3D profiles  216  of the splice angles  130  may be arranged, or virtually positioned, adjacent to one another such that the second 3D profiles  216  form a virtual representation of the circumferential surface  152  having the nominal shape  154 . The second 3D profile  216  representing at least one of the splice angles  130  and the first 3D profile  214  representing the aft pressure bulkhead  110  may be translated or rotated relative to each other to optimize the mating interface between the first interface surface  115  of the aft pressure bulkhead  110  and the second interface surfaces  131  of the splice angles  130 . Once the locations and orientations of the splice angles  130  are optimized, a virtual overlay  138  of the first 3D profile  214  and the second 3D profile  216  is fixed and the second locations  134  and second orientations  136  of the second holes  132  may be determined based on the determined first locations  184  and first orientations  116  of the first holes  112 . 
     While the example of the method  1000  describes steps of generating (block  1020  and block  1022 ) and overlaying (block  1024 ) the first 3D profile  214  of the aft pressure bulkhead  110  and the second 3D profile  216  of the splice angles  130  for determining (block  1026 ) the second locations  134  and second orientations  136  of the second holes  132  to be drilled in each of the splice angles  130 , in other examples, the second locations  134  and second orientations  136  of the second holes  132  may be determined in other suitable manners. For example, in some examples, a least-squares method or other best fit optimization may be employed to best fit the first interface surface  115  represented by the first 3D profile  214  and the second interface surface  131  represented by the second 3D profile  216  for determining the second locations  134  and second orientations  136  of the second holes  132  to be drilled in each of the splice angles  130  that align with the first holes  112  in the aft pressure bulkhead  110 . 
     Referring now to  FIGS. 4 and 5  and to  FIG. 11 , which schematically illustrates an example of the splice angle  12  with the second holes  132  drilled therein. In one or more examples, the method  1000  includes a step of (block  1028 ) drilling the second holes  132  in the splice angles  130 . The second holes  132  are drilled at the second locations  134  (e.g., indicated by x3, y3, z3 in  FIG. 11 ) and second orientations  136 , as determined after virtual overlaying (e.g., block  1024 ). 
     In one or more examples, the step of ( 1028 ) drilling the second holes  132  in the splice angles  130  includes a step of creating a program to drill the second holes  132  in the splice angles  130  that align with the measured first locations  184  and first orientations  116  of the first holes  112  (pre-drilled holes) in the aft pressure bulkhead  110  based on the determined second locations  134  and second orientations  136  of the second holes  132  to be drilled in the splice angles  130 . In an example, the CNC machine  230  ( FIG. 5 ) may drill the second holes  132  in the splice angles  130  based on the created program. 
     In one or more examples, the method  1000  includes a step of (block  1030 ) determining (e.g., estimating) gaps between the first interface surface  115  of the aft pressure bulkhead  110  and the second interface surface  131  of the splice angles  130 . It can be appreciated that the gaps may be formed due to manufacturing tolerances for the aft pressure bulkhead  110  and the splice angles  130 . 
     In one or more examples, when the spatial analyzer program  212  overlays the first 3D profile  214  of the aft pressure bulkhead  110  with the second 3D profile  216  of each of the splice angles  130 , the spatial analyzer program  212  further estimates gaps between the first 3D profile  214  and the second 3D profile  216 . The estimated gaps are representative of the gaps between the first interface surface  115  of the aft pressure bulkhead  110  and the second interface surface  131  of the splice angles  130 . The estimated gaps are used to determine shimming required to fill any gaps between the first interface surfaces  115  of the aft pressure bulkhead  110  and the corresponding second interface surfaces  131  of the splice angles  130  during the overlay. 
     In one or more examples, the spatial analyzer program  212  also minimizes the gaps and, thus, the shimming requirements by adjusting the position of the second 3D profile  216  of one or more of the splice angles  130  relative to the first 3D profile  214  of the aft pressure bulkhead  110  during the step of virtual overlay and alignment (e.g., block  1024 ), as described above. For example, this gap minimization step is performed before the step of (block  1026 ) determining the second locations  134  and second orientations  136  of the second holes  132 . 
     In one or more examples, in order to determine the shimming and/or spacing requirement, the spatial analyzer program  212  of system  200  determines a set of deviations or gaps between the first interface surface  115  of the aft pressure bulkhead  110  and the corresponding second interface surfaces  131  of the splice angles  130  during overlay and compares the set of deviations with design allowances for deviations in design or nominal 3D profiles of the aft pressure bulkhead  110  and the splice angles  130 . The set of deviations between the first interface surface  115  of the aft pressure bulkhead  110  and the corresponding second interface surfaces  131  of the splice angles  130  includes, for example, dimensional and surface profile information. The set of deviations that exceed (e.g., greater than) the design allowances determines mating surfaces and profiles for potential shimming for the joint between the aft pressure bulkhead  110  and the splice angles  130 . 
     Referring now to  FIGS. 4 and 5 , in one or more examples, the method  1000  includes a step of (block  1032 ) making the shims  140  used to fill the gaps between the aft pressure bulkhead  110  and the splice angles  130 . For example, the CNC machine  230  ( FIG. 5 ) may machine the shims  140  and drill the third holes  142  in the shims  140 . 
     Referring now to  FIG. 14 , which schematically illustrates an example of a portion of the virtual overlay  138  (e.g., a joint interface) between the aft pressure bulkhead  110 , represented by the first 3D profile  214 , and the splice angle  130 , represented by the second 3D profile  216 . In one or more examples, when the first 3D profile  214  of the aft pressure bulkhead  110  is overlaid with the second 3D profile  216  of the splice angle  130 , any deviations  143  (e.g., gaps) exceeding design allowances for deviations are used to determine an outline  141  and a third surface profile  145  of the shim  140  used to fill the gap between the first interface surface  115  and the second interface surface  131 . 
     Referring to  FIG. 15 , which schematically illustrates a profile transform of the third surface profile  145  of the shim  140 , as determined during overlay of the first 3D profile  214  with the second 3D profile  216 , to a fourth surface profile  146  of the shim  140  for machining the shim  140 . In one or more examples, the spatial analyzer program  212  ( FIG. 5 ) initially creates a virtual curved shim  140   a  (e.g., having a curved 3D surface profile) corresponding to the set of deviations  143  (e.g., gaps) determined during the overlay of first 3D profile  214  (e.g., aft pressure bulkhead scan) and the second 3D profile  216  (e.g., splice angle scan). The outline  141  and the third surface profile  145  for the curved shim  140   a  are determined based on the dimensional details of the set of deviations  143  and represent the length, width, thickness and surface geometry of the shim  140  to be machined to fill the gap between the aft pressure bulkhead  110  and the splice angles  130 . The spatial analyzer program  212  then transforms data for the determined set of deviations  143  from the virtual curved shim  140   a  to a virtual flat shim  140   b  (e.g., having a flat 2D shim surface) having the fourth surface profile  146 . The fourth surface profile  146  represents the surface profile of a stock shim prior to being machined to fill the gap between the aft pressure bulkhead  110  and the splice angles  130 . 
     Referring to  FIGS. 4, 5 and 15 , in one or more examples, the method  1000  includes a step of (block  1032 ) making the shims  140 . In one or more examples, the step of (block  1032 ) making the shims  140  includes a step of determining third locations  144  (e.g., shim locations) of the plurality of third holes  142  to be drilled in each one of the shims  140  ( FIG. 16 ). The third locations  144  of the third holes  142  correspond to the first locations  184  of the first holes  112  in the aft pressure bulkhead  110  and the second locations  134  of the second holes  132  in the splice angle  130 . 
     In one or more examples, the step of determining the third locations  144  of the third holes  142  to be drilled in the shims  140  is performed by the spatial analyzer program  212  ( FIG. 5 ). The spatial analyzer program  212  virtually overlays (e.g., block  1024 ) the first 3D profile  214  of the aft pressure bulkhead  110  with the second 3D profile  216  of the splice angle  130  such that the first holes  112  in the aft pressure bulkhead  110  and the second holes  132  in the splice angles  130  are aligned (e.g., approximately coaxially aligned within allowable tolerance). The spatial analyzer program  212  determines virtual third locations  144   a  ( FIG. 15 ) in three-dimensional space (e.g., in a three-dimensional coordinate system indicated by x4a, y4a, z4a in  FIG. 15 ) for the third holes  142  on the third surface profile  145  of the curved shim  140   a . The spatial analyzer program  212  then transforms the third surface profile  145  of the curved shim  140   a  to the fourth surface profile  146  that is flat, or planar, and that represents the flat shim  140   b  (e.g., having a flat or planar surface profile) and transforms the virtual third locations  144   a  of the third holes  142  on the curved shim  140   a  to virtual third locations  144   b  in two-dimensional space (e.g., in a two-dimensional coordinate system indicated by y4, z4 in  FIG. 15 ) of the third holes  142  on the flat shim  140   b.    
     Referring now to  FIGS. 4 and 5  and to  FIG. 16 , which schematically illustrates an example of the shim  140  with the third holes  142  drilled therein. For example, the CNC machine  230  ( FIG. 5 ) may drill the second holes  132  in the splice angles  130 . 
     In one or more examples, the step of (block  1032 ) making the shims  140  includes a step of drilling the third holes  142  in the shims  140  at the determined third locations  144  (e.g., indicated by y4, z4 in  FIG. 16 ). As expressed above, in one or more examples, the third holes  142  are drilled in the shims  140  having an approximately flat configuration (e.g., a stock shim), such as the flat shim  140   b  having the fourth surface profile  146 , and the third locations  144  correspond to the virtual third locations  144   b  ( FIG. 15 ). In these examples, the step of (block  1032 ) making the shims  140  also includes a step of machining the shim  140  to form the third surface profile  145  of the shim  140  needed to fill the gap between the first interface surface  115  of the aft pressure bulkhead  110  and the second interface surface  131  of the splice angle  130 . In other examples, the shim  140  may be machined to form the third surface profile  145  of the shim  140  needed to fill the gap between the first interface surface  115  of the aft pressure bulkhead  110  and the second interface surface  131  of the splice angle  130  before the third holes  142  are drilled in the shim  140 . In these examples, the third locations  144  correspond to the virtual third locations  144   a  ( FIG. 15 ). 
     Accordingly, in one or more examples, the step of determining the third locations  144  of the third holes  142  to be drilled in the shim  140  includes a step of determining the virtual third locations  144   a  of the third holes  142  relative to the third surface profile  145 , a step of transforming the third surface profile  145  to the fourth surface profile  146  that is flat, or planar, and a step of determining the virtual third locations  144   b  of the third holes  142  relative to the fourth surface profile  146 . In other words, the virtual third locations  144   b  are used as the third locations  144  for drilling the third holes  142 . The step of drilling the third holes  142  in the shim  140  at the third locations  144  includes a step of drilling the third holes  142  at the virtual third locations  144   b  in a stock shim having the fourth surface profile  146 . 
     In one or more examples, the step of drilling the third holes  142  in the shim  140  includes a step of creating a program to drill the third holes  142  in the shim  140  that align with the measured first locations  184  and first orientations  116  of the first holes  112  (pre-drilled holes) in the aft pressure bulkhead  110  and the second holes  132  (drilled or to be drilled) in a corresponding one of the splice angles  130 , based on the determined third locations  144  of the third holes  142  to be drilled in the shim  140 . In an example, the CNC machine  230  ( FIG. 5 ) may drill the third holes  142  in the shims  140  based on the created program. 
     Referring to  FIG. 5 , in one or more examples, in accordance with the method  1000 , a set of .XML measurement files is generated incorporating the determinations of the second locations  134  and second orientations  136  of the second holes  132  to be drilled in the splice angles  130 , the outlines  141  and the third surface profiles  145  of the shims  140  to be machined and the determinations of the third locations  144  of the third holes  142  to be drilled in the shims  140 . In an example, the spatial analyzer program  212  generates the set of .XML files and transmits the set of .XML files to the On-Demand Emergent Manufacturing (ODEM) application  220  ( FIG. 5 ). The ODEM application  220  then generates the plurality of network computer (NC) programs  222  for drilling the second holes  132  in the splice angles  130 , for machining the shims  140  to fill the gaps and for drilling the third holes  142  in the shims  140 . The NC programs  222  are then validated, and the ODEM application  220  then transfers a set of validated NC programs  224  to the CNC machine  230  or equivalent. The NC controller  232  receives the validated NC programs  224  and the CNC machine  230  drills the second holes  132  in the splice angles  130 , machines the shims  140 , and drills the third holes  142  in the shims  140  based on the set of validated NC programs  224 . 
     Referring now to  FIGS. 4 and 5  and to  FIG. 17 , which schematically illustrates an example of the plurality of splice angles  130  and the aft pressure bulkhead  110  mounted on the assembly jug  240  for assembly of the pressure bulkhead assembly  150  ( FIG. 1 ). In one or more examples, the method  1000  includes a step of (block  1034 ) assembling the pressure bulkhead assembly  150 . 
     In one or more examples. once the second holes  132  are drilled in the splice angles  130 , the shims  140  are machined and the third holes  142  are drilled in the shims  140 , the splice angles  130  and the shims  140 , as needed to fill the gaps, are position at corresponding locations on the aft pressure bulkhead  110  such that the third holes  142  in the shims  140  and the second holes  132  in the splice angles  130  are aligned with the first holes  112  in the aft pressure bulkhead  110 . Fasteners  196  ( FIG. 5 ) are installed through the aligned first holes  112  in the aft pressure bulkhead  110 , third holes  142  in the shims  140  and second holes  132  in the splice angles  130  to secure the splice angles  130  and the shims  140  to the corresponding location of the aft pressure bulkhead  110 . 
     For example, as illustrated in  FIG. 17 , the splice angles  130  are mounted on the assembly jig  240  so that the splice angles  130  are positioned adjacent to one another to form the circumferential surface  152  having the nominal shape  154 . In one or more examples, the assembly jig  240  includes a plurality of force assemblies  248 , configured to apply clamping pressure to mating edges of the splice angles  130  and to index the mating edges of two adjacent splice angles  130 . The aft pressure bulkhead  110  is positioned, indexed and secured over the splice angles  130  by the assembly jig  240 . 
     The pressure bulkhead assembly  150  may include any number of splice angles  130  needed to form the circumferential surface  152  and for attachment of the pressure bulkhead assembly  150  the fuselage  156 . In an example, thirty-two splice angles  130  are coupled to the aft pressure bulkhead  110  to form the pressure bulkhead assembly  150 . 
     The shims  140  (not visible in  FIG. 17 ) are positioned between the second interface surface  131  (e.g., as shown in  FIG. 8 ) of each splice angle  130  and the first interface surface  115  (e.g., as shown in  FIG. 6 ) of the aft pressure bulkhead  110  to fill any gaps between the splice angles  130  and the aft pressure bulkhead  110 . The shims  140  maintain the nominal shape  154  when the splice angles  130  are joined to the aft pressure bulkhead  110 . 
     The aft pressure bulkhead  110  is positioned so that the second interface surface  131  mates with a corresponding portion (e.g., section) of the first interface surface  115  and that the first holes  112  the aft pressure bulkhead  110 , the second holes  132  in the splice angles  130  (e.g., as shown in  FIG. 11 ) and the third holes  142  in the shims  140  (e.g., as shown in  FIG. 16 ) are aligned with each other. The fasteners  196  ( FIG. 5 ) are sent through the aligned set of holes to join the aft pressure bulkhead  110 , the splice angles  130  and the shims  140  together to form the pressure bulkhead assembly  150 . The fasteners  196  may take any desirable form, such as permanent fasteners. 
     Referring now to  FIGS. 2 and 18 , examples of the method  1000 , the system  200  and the pressure bulkhead assembly  150  may be related to, or used in the context of, an aircraft manufacturing and service method  1100 , as shown in the flow diagram of  FIG. 18  and the aircraft  104 , as schematically illustrated in  FIG. 2 . For example, the aircraft  104  and/or the aircraft production and service methodology  1100  may utilize the pressure bulkhead assembly  150  made according to the method  1000  and/or using the system  200  described with respect to  FIGS. 1 and 3-17 . 
     Referring to  FIG. 2 , examples of the aircraft  104  may include an airframe  158  that forms the wings  108  and the fuselage  156  having the interior  172 . The aircraft  104  also includes a plurality of high-level systems  160 . Examples of the high-level systems  160  include one or more of a propulsion system  162 , an electrical system  164 , a hydraulic system  166 , and an environmental system  168  (e.g., environmental control system). In other examples, the aircraft  104  may include any number of other types of systems, such as a communications system, a flight control system, a guidance system, a weapons system, and the like. 
     Referring to  FIG. 18 , during pre-production, the method  1100  includes specification and design of the aircraft  104  (block  1102 ) and material procurement (block  1104 ). During production of the aircraft  104 , component and subassembly manufacturing (block  1106 ) and system integration (block  1108 ) of the aircraft  104  take place. Thereafter, the aircraft  104  goes through certification and delivery (block  1110 ) to be placed in service (block  1112 ). Routine maintenance and service (block  1114 ) includes modification, reconfiguration, refurbishment, etc. of one or more systems of the aircraft  104 . 
     Each of the processes of the method  1100  illustrated in  FIG. 18  may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include, without limitation, any number of spacecraft manufacturers and major-system subcontractors; a third party may include, without limitation, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on. 
     Examples of the pressure bulkhead assembly  150 , the system  200  and the method  1000  shown and described herein may be employed during any one or more of the stages of the manufacturing and service method  1100  shown in the flow diagram illustrated by  FIG. 18 . In an example, implementations of the pressure bulkhead assembly  150 , the system  200  and the method  1000  may form a portion of component and subassembly manufacturing (block  1106 ) and/or system integration (block  1108 ). For example, production of the pressure bulkhead assembly  150 , made using the system  200  or according to the method  1000 , or production of the aircraft  104  that includes the pressure bulkhead assembly  150  may correspond to component and subassembly manufacturing (block  1106 ). Further, the pressure bulkhead assembly  150 , made using the system  200  or according to the method  1000 , may be utilized in a manner similar to components or subassemblies prepared while the aircraft  104  is in service (block  1112 ). Also, the pressure bulkhead assembly  150 , made using the system  200  or according to the method  1000 , may be utilized during system integration (block  1108 ) and certification and delivery (block  1110 ). Similarly, implementations of the pressure bulkhead assembly  150 , made using the system  200  or according to the method  1000 , may be utilized, for example and without limitation, while the aircraft  104  is in service (block  1112 ) and during maintenance and service (block  1114 ). 
     Although an aerospace example is shown, the examples and principles disclosed herein may be applied to other industries, such as the automotive industry, the space industry, the construction industry, and other design and manufacturing industries. Accordingly, in addition to aircraft, the examples and principles disclosed herein may apply to structural component assemblies and systems and methods of making the same for other types of vehicles (e.g., land vehicles, marine vehicles, space vehicles, etc.) and stand-alone structures. 
     As used herein, a system, apparatus, device, structure, article, element, component, or hardware “configured to” perform a specified function is indeed capable of performing the specified function without any alteration, rather than merely having potential to perform the specified function after further modification. In other words, the system, apparatus, device, structure, article, element, component, or hardware “configured to” perform a specified function is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the specified function. As used herein, “configured to” denotes existing characteristics of a system, apparatus, structure, article, element, component, or hardware that enable the system, apparatus, structure, article, element, component, or hardware to perform the specified function without further modification. For purposes of this disclosure, a system, apparatus, device, structure, article, element, component, or hardware described as being “configured to” perform a particular function may additionally or alternatively be described as being “adapted to” and/or as being “operative to” perform that function. 
     Unless otherwise indicated, the terms “first,” “second,” “third,” etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to, e.g., a “second” item does not require or preclude the existence of, e.g., a “first” or lower-numbered item, and/or, e.g., a “third” or higher-numbered item. 
     As used herein, the phrase “at least one of”, when used with a list of items, means different combinations of one or more of the listed items may be used and only one of each item in the list may be needed. For example, “at least one of item A, item B, and item C” may include, without limitation, item A or item A and item B. This example also may include item A, item B, and item C, or item B and item C. In other examples, “at least one of” may be, for example, without limitation, two of item A, one of item B, and ten of item C; four of item B and seven of item C; and other suitable combinations. As used herein, the term “and/or” and the “/” symbol includes any and all combinations of one or more of the associated listed items. 
     For the purpose of this disclosure, the terms “coupled,” “coupling,” and similar terms refer to two or more elements that are joined, linked, fastened, attached, connected, put in communication, or otherwise associated (e.g., mechanically, electrically, fluidly, optically, electromagnetically) with one another. In various examples, the elements may be associated directly or indirectly. As an example, element A may be directly associated with element B. As another example, element A may be indirectly associated with element B, for example, via another element C. It will be understood that not all associations among the various disclosed elements are necessarily represented. Accordingly, couplings other than those depicted in the figures may also exist. 
     As used herein, the term “approximately” refers to or represent a condition that is close to, but not exactly, the stated condition that still performs the desired function or achieves the desired result. As an example, the term “approximately” refers to a condition that is within an acceptable predetermined tolerance or accuracy, such as to a condition that is within 10% of the stated condition. However, the term “approximately” does not exclude a condition that is exactly the stated condition. As used herein, the term “substantially” refers to a condition that is essentially the stated condition that performs the desired function or achieves the desired result. 
       FIGS. 1-3 and 5-17 , referred to above, may represent functional elements, features, or components thereof and do not necessarily imply any particular structure. Accordingly, modifications, additions and/or omissions may be made to the illustrated structure. Additionally, those skilled in the art will appreciate that not all elements, features, and/or components described and illustrated in  FIGS. 1-3 and 5-17 , referred to above, need be included in every example and not all elements, features, and/or components described herein are necessarily depicted in each illustrative example. Accordingly, some of the elements, features, and/or components described and illustrated in  FIGS. 1-3 and 5-17  may be combined in various ways without the need to include other features described and illustrated in  FIGS. 1-3 and 5-17 , other drawing figures, and/or the accompanying disclosure, even though such combination or combinations are not explicitly illustrated herein. Similarly, additional features not limited to the examples presented, may be combined with some or all of the features shown and described herein. Unless otherwise explicitly stated, the schematic illustrations of the examples depicted in  FIGS. 1-3 and 5-17 , referred to above, are not meant to imply structural limitations with respect to the illustrative example. Rather, although one illustrative structure is indicated, it is to be understood that the structure may be modified when appropriate. Accordingly, modifications, additions and/or omissions may be made to the illustrated structure. Furthermore, elements, features, and/or components that serve a similar, or at least substantially similar, purpose are labeled with like numbers in each of  FIGS. 1-3 and 5-17 , and such elements, features, and/or components may not be discussed in detail herein with reference to each of  FIGS. 1-3 and 5-17 . Similarly, all elements, features, and/or components may not be labeled in each of  FIGS. 1-14 , but reference numerals associated therewith may be utilized herein for consistency. 
     In  FIGS. 4 and 18 , referred to above, the blocks may represent operations, steps, and/or portions thereof and lines connecting the various blocks do not imply any particular order or dependency of the operations or portions thereof. It will be understood that not all dependencies among the various disclosed operations are necessarily represented.  FIGS. 4 and 18  and the accompanying disclosure describing the operations of the disclosed methods set forth herein should not be interpreted as necessarily determining a sequence in which the operations are to be performed. Rather, although one illustrative order is indicated, it is to be understood that the sequence of the operations may be modified when appropriate. Accordingly, modifications, additions and/or omissions may be made to the operations illustrated and certain operations may be performed in a different order or simultaneously. Additionally, those skilled in the art will appreciate that not all operations described need be performed. 
     Further, references throughout the present specification to features, advantages, or similar language used herein do not imply that all of the features and advantages that may be realized with the examples disclosed herein should be, or are in, any single example. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an example is included in at least one example. Thus, discussion of features, advantages, and similar language used throughout the present disclosure may, but do not necessarily, refer to the same example. 
     The described features, advantages, and characteristics of one example may be combined in any suitable manner in one or more other examples. One skilled in the relevant art will recognize that the examples described herein may be practiced without one or more of the specific features or advantages of a particular example. In other instances, additional features and advantages may be recognized in certain examples that may not be present in all examples. Furthermore, although various examples of the pressure bulkhead assembly  150 , the system  200  and the method  1000  have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.