Patent Description:
Certain known aircraft, such as certain commercial jets, include a horizontal stabilizer secured to an aft or unpressurized fuselage section. <FIG> illustrates an isometric exploded view of a known aft fuselage section <NUM>. The aft or unpressurized fuselage section <NUM> includes a forward section <NUM>, a bulkhead <NUM>, and an aft section <NUM>.

Typically, pivot fittings <NUM> are secured to the bulkhead <NUM>. <FIG> illustrates an isometric front view of the bulkhead <NUM>. As shown, the pivot fittings <NUM> are secured to a front surface <NUM> of the bulkhead <NUM>. Separate and distinct beams <NUM> are coupled to one or both of the pivot fittings <NUM>. The beams <NUM> are separately positioned and secured to the bulkhead <NUM> and the pivot fitting(s) <NUM>. The beams <NUM> are typically necessary to react to lateral loads.

Referring to <FIG> and <FIG>, the bulkhead <NUM> is joined to the aft section <NUM>. The horizontal stabilizer <NUM> is then pivotally coupled to the pivot fittings <NUM>, such as through spherical bearings. After the horizontal stabilizer <NUM> is coupled to the bulkhead <NUM> through the pivot fittings <NUM>, and the bulkhead <NUM> is joined to the aft section <NUM>, the resulting sub-assembly <NUM> is then joined to the forward section <NUM>.

<FIG> illustrates an isometric internal view of the known aft fuselage <NUM> section during a manufacturing process. Referring to <FIG>, individuals <NUM> enter confined spaces of the aft fuselage section <NUM> to complete installation through various operations, including drilling through-holes, inserting shims, inserting and torquing fasteners, and the like. The individuals <NUM> drill various holes, connect shims, and couple various joints together through numerous fasteners. Typically, the individuals <NUM> perform such operations within confined spaces within the aft fuselage section <NUM>. As can be appreciated, performing such operations inside the confined spaces can be ergonomically challenging (as shown in <FIG>), as well as time and labor intensive.

Further, existing architecture for the aft fuselage section <NUM> includes a convoluted load path for the fuselage to support the horizontal stabilizer <NUM>. In general, the load of the horizontal stabilizer <NUM> is supported by intercostals and/or other such backup structure <NUM> in the aft fuselage section <NUM>, and these loads are transferred to the forward section <NUM> 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 <NUM> is time consuming due to tension bolt installation (torquing requirements), fay surface seal (dissimilar material), and debur (fatigue) requirements.

<CIT>, in accordance with its abstract, states a section having a vertical tail section and a horizontal tail section that are connected with one another. The horizontal tail section has front and rear end frames that include a wing unit. The frames are firmly connected with each other by torsion boxes and longitudinally reinforced braces. The boxes run symmetrical to a middle longitudinal plane of the rear section in a lower area of the horizontal section.

<CIT>, in accordance with its abstract, states an aircraft tail assembly that includes an aft fuselage section secured to a forward fuselage section, and includes a stiffener-reinforced pivot bulkhead defined by separate parts secured together by a first set of splices. A longeron extends longitudinally along the aft and forward fuselage sections, and includes a discontinuity adjacent a peripheral edge of the pivot bulkhead. The aircraft tail assembly includes a second set of splices that overlie the discontinuity. One of the second set of splices extends laterally over the longeron to bridge the discontinuity adjacent the peripheral edge of the pivot bulkhead, and another of the second set of splices extends longitudinally along the longeron to secure the longeron to the pivot bulkhead adjacent the discontinuity. A chord engages the peripheral edge of the pivot bulkhead to facilitate transfers of force loads from the bulkhead along a load path that includes the longerons and the splices.

<CIT>, in accordance with its abstract, states pivoting coupling system of a large dihedral empennage to the tail fuselage of an aircraft, in which the empennage comprises a right lateral box and a left lateral box arranged at a large dihedral angle in the tail fuselage of the aircraft. It further comprises a horizontal central box joining the lateral boxes, and which comprises a rear spar; and means of linkage for horizontally linking the central box to a frame structure of the tail fuselage of the aircraft, which allow the empennage to rotate vertically about a horizontal linkage shaft between a negative maximum angle of incidence and a positive maximum angle of incidence in response to the actuation of actuator means which are connected to the empennage and to a structural element of the fuselage of the aircraft.

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 according to claim <NUM>.

In at least one example, the one or more pivot fittings may 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, the one more pivot fittings may be securely fastened to the forward section, and the horizontal stabilizer may be 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 may include a central column, an outboard flange, and an inboard flange.

In at least one example, the central column may include a base. Lateral support walls may extend upwardly from the base. A front wall may extend upwardly from the base. A bearing slot may be formed in the front wall. The bearing slot may be configured to retain a spherical bearing of the horizontal stabilizer. A top ledge may be connected to upper portions of the lateral support walls and the front wall. The base may secure to the lower sill beam through a first plurality of fasteners, and the top ledge may secure to the upper sill beam through a second plurality of fasteners. In at least one example, the outboard flange may include a lower ledge connected to an upper ledge by an outer extension beam. The lower ledge may secure to the lower sill beam through a third plurality of fasteners, and the upper ledge may secure to the upper sill beam through a fourth plurality of fasteners. In at least one example, the extension beam may include an inboard surface and an outboard surface opposite from the inboard surface. The inboard surface may abut against one of the lateral support walls of the central column.

In at least one example, the inboard flange may include a lower panel inwardly extending from a lower portion of an inboard surface of an inner extension beam. The lower panel may connect to a front support brace that angles upwardly and inwardly to connect to a central portion of the inner extension beam. An upper panel may inwardly extend from an upper portion of the inboard surface of the inner extension beam. The upper panel may connect 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 may include the inboard surface and an outboard surface opposite from the inboard surface. The outboard surface may abut against one of the lateral support walls of the central column.

In at least one example, the one or more fittings may be 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 may be configured to be removed from the upper sill beam and the lower sill beam. The horizontal stabilizer may be configured to be coupled to the one or more fittings. The horizontal stabilizer may be configured to be moved into the stabilizer channel of the forward section. The one or more fittings may be 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 may include 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 may be secured to an aft section or the sub-assembly. The sub-assembly may be secured to the aft section.

Certain examples of the present disclosure provide a method for forming an aft fuselage section of an aircraft according to claim <NUM>.

In at least one example, said fastening and said coupling may occur before securing the forward section to an aft section.

In at least one example, the method may also include 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 may also include 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-assem bly is secured to the aft section.

Certain examples may provide a pivot fitting for coupling a horizontal stabilizer to a forward section of an aft fuselage section of an aircraft. The pivot fitting may include a central column, an outboard flange, and an inboard flange, as described herein.

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> illustrates an isometric rear view of a horizontal stabilizer <NUM> coupled to a forward section <NUM> of an aft fuselage section <NUM>, according to an example of the present disclosure. <FIG> illustrates a system <NUM> for securing the horizontal stabilizer to the forward section <NUM> of the aft fuselage section <NUM>. The system <NUM> is configured to form the aft fuselage section <NUM>, which includes an aft section (not shown) that is secured to the forward section <NUM>.

The forward section <NUM> includes a stabilizer channel <NUM> extending into the forward section <NUM> between an upper canopy <NUM>, a lower base <NUM>, and a main body <NUM>. An upper sill beam <NUM> is secured to a rear surface of the upper canopy <NUM> above an open end <NUM> of the stabilizer channel <NUM>. A lower sill beam <NUM> is secured to the rear surface of the lower base <NUM> above the open end <NUM> of the stabilizer channel <NUM>.

A first pivot fitting 120a is secured between the upper sill beam <NUM> and the lower sill beam <NUM>. A second pivot fitting 120b is secured between the upper sill beam <NUM> and the lower sill beam <NUM>. The first pivot fitting 120a is at one side (a first side) <NUM> of the forward section <NUM> (between respective first ends <NUM>, <NUM> of the upper sill beam <NUM> and the lower sill beam <NUM>), and the second pivot fitting 120b is at an opposite side (a second side) <NUM> of the forward section <NUM> (between respective second ends <NUM>, <NUM> of the upper sill beam <NUM> and the lower sill beam <NUM>).

As described herein, the system <NUM> for forming the aft fuselage section <NUM> of an aircraft includes the forward section <NUM> having the stabilizer channel <NUM>. The forward section <NUM> includes the upper sill beam <NUM> and the lower sill beam <NUM>. One or more pivot fittings 120a and/or 120b are securely fastened between the upper sill beam <NUM> and the lower sill beam <NUM>. The pivot fitting(s) 120a and/or 120b are configured to pivotally couple to the horizontal stabilizer <NUM> within the stabilizer channel <NUM>.

<FIG> illustrates an isometric rear view of the pivot fitting 120a secured to the upper sill beam <NUM> and the lower sill beam <NUM> of the forward section <NUM>, according to an example of the present disclosure. While the pivot fitting 120a is shown, the pivot fitting 120b shown in <FIG> is secured to the upper sill beam <NUM> and the lower sill beam <NUM> as shown in <FIG>.

The upper sill beam <NUM> includes a joint panel <NUM> and a fitting panel <NUM>. In at least one example, the joint panel <NUM> is orthogonal to the fitting panel <NUM>. That is, the joint panel <NUM> can be perpendicular to the fitting panel <NUM>. The joint panel <NUM> mounts onto and secures to a rear face <NUM> of the forward section <NUM> above the stabilizer channel <NUM> through a plurality of fasteners <NUM>. The fitting panel <NUM> mounts over an upper surface <NUM> of the pivot fitting 120a, and secures thereto through a plurality of fasteners <NUM>.

Similarly, the lower sill beam <NUM> includes a joint panel <NUM> and a fitting panel <NUM>. In at least one example, the joint panel <NUM> is orthogonal to the fitting panel <NUM>. That is, the joint panel <NUM> can be perpendicular to the fitting panel <NUM>. The joint panel <NUM> mounts onto and secures to a rear face <NUM> of the forward section <NUM> below the stabilizer channel <NUM> through a plurality of fasteners <NUM>. The fitting panel <NUM> mounts below a lower surface <NUM> of the pivot fitting 120a, and secures thereto through a plurality of fasteners <NUM>.

Notably, operations to form the through-holes for the various fasteners <NUM> (such as drilling), as well as inserting the fasteners <NUM> and torquing the fasteners to secure fastening positions occurs before the forward section <NUM> 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 <NUM>. 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 <NUM>).

As shown in <FIG>, the upper sill beam <NUM> and the lower sill beam <NUM> are securely fastened to the forward section <NUM>, via the fasteners <NUM>. The upper sill beam <NUM> and the lower sill beam <NUM> are secured to the pivot fittings 120a and 120b through vertical fasteners <NUM> (that is, an individual vertically inserts the fasteners <NUM>), which is an operation that can be performed while comfortably standing outside of the forward section <NUM>.

<FIG> illustrates an isometric rear view of a pivot fitting <NUM>, according to an example of the present disclosure. <FIG> illustrates an isometric front view of the pivot fitting <NUM> of <FIG> illustrates a first lateral view of the pivot fitting <NUM> of <FIG> illustrates a second lateral view of the pivot fitting <NUM> of <FIG> illustrates an isometric exploded rear view of the pivot fitting <NUM> of <FIG>. The pivot fittings 120a and 120b shown in <FIG> are configured as shown in <FIG>. For example, the pivot fitting 120a is configured as shown in <FIG>, and the pivot fitting 120b can be configured as a mirror image thereof.

Referring to <FIG>, the pivot fitting <NUM> includes a central column <NUM>, an outboard flange <NUM>, and an inboard flange <NUM>. The central column <NUM> includes a base <NUM>, lateral support walls <NUM>, <NUM> extending upwardly from the base <NUM>, a front wall <NUM> extending upwardly from the base <NUM>, and a top ledge <NUM> connected to upper portions of the lateral support walls <NUM> and the front wall <NUM>. A rear portion <NUM> of the central column <NUM> can be open. As shown and described herein, the base <NUM> secures to the lower sill beam <NUM> through a plurality (such as a first or second plurality) of fasteners <NUM>, and the top ledge <NUM> secures to the upper sill beam <NUM> through a plurality (such as the other of the first or second plurality) of fasteners <NUM>.

A bearing slot <NUM> is formed in the front wall <NUM>. The bearing slot <NUM> extends between opposed lateral fins <NUM> having bearing openings <NUM>. A bearing axis <NUM> is defined between the opposed bearing openings <NUM>. A spherical bearing of the horizontal stabilizer <NUM> (shown in <FIG>) is configured to be rotatably coupled to the bearing slot <NUM> between the opposed bearing openings <NUM>.

The outboard flange <NUM> includes a lower ledge <NUM> connected to an upper ledge <NUM> by an outer extension beam <NUM>. As shown and described herein, the lower ledge <NUM> secures to the lower sill beam <NUM> through a plurality of fasteners, and the upper ledge <NUM> secures to the upper sill beam <NUM> through a plurality of fasteners. The outer extension beam <NUM> includes an inboard surface <NUM> and an outboard surface <NUM> opposite from the inboard surface <NUM>. The inboard surface <NUM> abuts against the lateral support wall <NUM> of the central column <NUM>. A bearing opening <NUM> is formed through a spur <NUM> of the outer extension beam <NUM>. The bearing opening <NUM> is coaxially aligned with the bearing openings <NUM> of the central column <NUM>. The outboard flange <NUM> may or may not secure to the central column <NUM> through fasteners. Referring to <FIG>, in at least one example, the outboard flange <NUM> is not separately secured to the central column <NUM> through separate fasteners. Instead, the outboard flange <NUM> is fixed in relation to the central column <NUM> by way of the fasteners <NUM> that secure the pivot fitting <NUM> to the upper sill beam <NUM> and the lower sill beam <NUM>.

The inboard flange <NUM> includes a lower panel or ledge <NUM> inwardly extending from a lower portion of an inboard surface <NUM> of an inner extension beam <NUM>. The lower ledge <NUM> connects to a front support brace <NUM> that angles upwardly and inwardly to connect to a central portion <NUM> of the inner extension beam <NUM> below a bearing opening <NUM>, which is coaxially aligned with the bearing openings <NUM> of the central column <NUM>.

The inboard flange <NUM> also includes an upper panel or ledge <NUM> inwardly extending from an upper portion of the inboard surface <NUM> of the inner extension beam <NUM>. The upper ledge <NUM> connects to a front support brace <NUM> that angles downwardly and inwardly to connect to the central portion <NUM> of the inner extension beam <NUM> above the bearing opening <NUM>.

The inner extension beam <NUM> includes the inboard surface <NUM> and an outboard surface <NUM> opposite from the inboard surface <NUM>. The outboard surface <NUM> abuts against the lateral support wall <NUM> of the central column <NUM>. The inboard flange <NUM> may or may not secure to the central column <NUM> through fasteners. Referring to <FIG>, in at least one example, the inboard flange <NUM> is not separately secured to the central column <NUM> through separate fasteners. Instead, the inboard flange <NUM> is fixed in relation to the central column <NUM> by way of the fasteners <NUM> that secure the pivot fitting <NUM> to the upper sill beam <NUM> and the lower sill beam <NUM>.

The upper ledge <NUM> of the outboard flange <NUM>, the top ledge <NUM> of the central column <NUM>, and the upper ledge <NUM> of the inboard flange <NUM> provide flat surfaces that abut against a lower surface of the fitting panel <NUM> of the upper sill beam <NUM>, which allow for through-holes to be vertically drilled therethrough, and the fasteners <NUM> to be easily inserted (such as vertically inserted) and engaged from positions outside of the aft or unpressurized fuselage section <NUM>. Similarly, the lower ledge <NUM> of the outboard flange <NUM>, the base <NUM> of the central column <NUM>, and the lower ledge <NUM> of the inboard flange <NUM> also provide flat surfaces that abut against an upper surface of the fitting panel <NUM> of the lower sill beam <NUM>, which allow for through-holes to be vertically drilled therethrough, and the fasteners <NUM> to be easily inserted (such as vertically inserted) and engaged from positions outside of the aft fuselage section <NUM>.

The lateral support walls <NUM>, <NUM>, and the front face <NUM> of the central column <NUM> 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 <NUM> of the outboard flange <NUM> and the inner extension beam <NUM> of the inboard flange <NUM> provide load paths that are configured to distribute loads in the direction of arrows A. Additionally, the lower ledge <NUM> and upper ledge <NUM> of the inboard flange <NUM>, the base <NUM> and the top ledge <NUM> of the central column <NUM>, and the lower ledge <NUM> and the upper ledge <NUM> of the inboard flange <NUM> 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 <NUM> and <NUM> of the inboard flange <NUM> are configured to distribute shear loads. The front support braces <NUM> and <NUM> provide integrated structures that are configured to react to lateral loads, for example.

As shown in <FIG>, the pivot fitting <NUM> includes the central column <NUM>, the outboard flange <NUM>, and the inboard flange <NUM>. As such, the pivot fitting <NUM> includes three separate and distinct pieces. In this manner, the pivot fitting <NUM> 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> illustrates an isometric rear view of the aft fuselage section <NUM> having the pivot fittings 120a and 120b, according to an example of the present disclosure. In order to assemble the aft fuselage section, the pivot fittings 120a and 120b are first secured to the upper sill beam <NUM> and the lower sill beam <NUM> before the horizontal stabilizer <NUM> is positioned within the stabilizer channel <NUM>. As noted, the upper sill beam <NUM>, the lower sill beam <NUM>, and the pivot fittings 120a and 120b are machined (such as via drilling) to form various through-holes, and the various fasteners <NUM> (shown in <FIG>, for example) are inserted and engaged to secure the pivot fittings 120a and 120b to the forward section <NUM> (such as via the upper sill beam <NUM> and the lower sill beam <NUM>) before the forward section <NUM> 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 <NUM> at ergonomically comfortably positions. Thus, as shown in <FIG>, the pivot fittings 120a and 120b are secured to the forward section <NUM> and confirmed to be properly positioned and fastened in relation to the forward section <NUM> before the forward section <NUM> is secured to the aft section (and optionally before the horizontal stabilizer is positioned within the stabilizer channel <NUM>).

In at least one example, the front joint <NUM> arrives at a location for final assembly with the pivot fittings 120a and 120b temporarily attached to the upper sill beam <NUM> and the lower sill beam <NUM>. The pivot fittings <NUM> and 120b, the upper sill beam <NUM>, and the lower sill beam <NUM> have already been drilled to provide respective aligned, deburred through-holes at full size.

<FIG> illustrates an isometric rear view of the aft fuselage section <NUM> with the pivot fittings 120a and 120b (shown in <FIG>) removed, according to an example of the present disclosure. Referring to <FIG>, after the pivot fittings 120a and 120b are securely coupled to the forward section <NUM> to ensure proper positioning, tolerances, and the like, the pivot fittings 120a and 120b are removed to provide an unimpeded path into the stabilizer channel <NUM>.

<FIG> illustrates an isometric rear view of the horizontal stabilizer <NUM> separated from the forward section <NUM> of the aft fuselage section <NUM>, according to an example of the present disclosure. Referring to <FIG>, after the pivot fittings 120a and 120b are removed from the forward section <NUM>, the pivot fittings 120a and 120b are pivotally coupled to rear surfaces <NUM> of the horizontal stabilizer <NUM>. For example, spherical bearings at the rear surfaces <NUM> are pivotally secured to the bearing slots <NUM> (shown in <FIG>) of the pivot fittings 120a and 120b. After the pivot fittings 120a and 120b are pivotally secured to the horizontal stabilizer <NUM>, the horizontal stabilizer <NUM> is moved into the stabilizer channel <NUM> of the forward section <NUM> in the direction of arrow <NUM> until the pivot fittings 120a and 120b are realigned with the upper sill beam <NUM> and the lower sill beam <NUM> (such that the respective through-holes are aligned), and then an individual can secure the pivot fittings 120a and 120b to the forward section <NUM>, by way of the upper sill beam <NUM> and the lower sill beam <NUM>, via the fasteners <NUM>. In this manner, the pivot fittings 120a and 120b are secured to the forward section <NUM>, and the horizontal stabilizer <NUM> is secured to the pivot fittings 120a and 120b within the stabilizer channel <NUM>, 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 120a and 120b (which are temporarily secured to the upper sill beam <NUM> and the lower sill beam <NUM>) are configured to be removed from the upper sill beam <NUM> and the lower sill beam <NUM>. The horizontal stabilizer <NUM> is then coupled to the fittings 120a and 120b. The horizontal stabilizer <NUM> (having the fittings 120a and 120b coupled thereto) then moved into the forward section <NUM> (such as into the stabilizer channel <NUM>). The fittings 120a and 120b are then re-secured to the upper sill beam <NUM> and the lower sill beam <NUM> to secure the horizontal stabilizer <NUM> within the stabilizer channel <NUM> of the forward section <NUM>.

<FIG> illustrates an isometric rear view of the sub-assembly <NUM> of the aft fuselage section <NUM>, according to an example of the present disclosure. The sub-assembly <NUM> includes the horizontal stabilizer <NUM> within the stabilizer channel <NUM>, and pivotally secured to the forward section <NUM> by the pivot fittings 120a and 120b. As shown, an individual <NUM> is outside of the aft fuselage section <NUM> and can operate to fasten the upper sill beam <NUM> and the lower sill beam <NUM> to the pivot fittings 120a and 120b by vertically inserting fasteners and torquing the fasteners to securely fasten the pivot fittings 120a and 120b to the forward section <NUM>.

<FIG> illustrates an isometric rear view of a completed aft fuselage <NUM> section, according to an example of the present disclosure. After the sub-assembly <NUM> has been formed, as described above, the aft section <NUM>, which can include a bulkhead (or optionally, the bulkhead is first secured to the sub-assem bly <NUM>) is secured to the sub-assem bly <NUM>.

<FIG> illustrates a flow chart of a method of forming an aft fuselage section, according to an example of the present disclosure. Referring to <FIG>, at <NUM>, the forward section <NUM> is operated on to secure pivot fittings 120a and 120b thereto. For example, one or more individuals outside of the aft fuselage section <NUM> perform various operations, such as drilling through-holes, aligning pivot fittings 120a and 120b in relation to the upper sill beam <NUM> and the lower sill beam <NUM>, inserting fasteners into aligned through-holes, torquing the fasteners to securely fasten the pivot fittings 120a and 120b to the upper sill beam <NUM> and the lower sill beam <NUM>, and/or the like, to secure the pivot fittings 120a and 120b to the forward section <NUM>. In this manner, the positioning, tolerances, and securing of the pivot fittings 120a and 120b in relation to the forward section <NUM> are determined and set before the horizontal stabilizer <NUM> is coupled to the forward section <NUM> and the forward section <NUM> is secured to the aft section <NUM>.

At <NUM>, the pivot fittings 120a and 120b are removed from the forward section <NUM> to provide an impeded path for the horizontal stabilizer <NUM> into the stabilizer channel <NUM> of the forward section <NUM>. At <NUM>, the pivot fittings 120a and 120b are pivotally secured to the horizontal stabilizer <NUM>. At <NUM>, the horizontal stabilizer <NUM>, which now has the pivot fittings 120a and 120b pivotally secured thereto, is moved into the stabilizer channel <NUM> of the forward section <NUM>. At <NUM>, the pivot fittings 120a and 120b are then secured to the forward section <NUM> (such as by the upper sill beam <NUM> and the lower sill beam <NUM>) to form the sub-assembly <NUM>.

Optionally, at <NUM>, a bulkhead is secured to the aft section <NUM> or the sub-assembly <NUM>. At <NUM>, the aft section <NUM> is then secured to the sub-assembly <NUM>, thereby completing the aft fuselage section <NUM>.

Referring to <FIG>, the pivot fitting <NUM>, such as the pivot fittings <NUM> and 120b, enables streamlined assembly of the aft fuselage section <NUM>. In particular, the pivot fitting <NUM> is configured to be secured to the front joint <NUM> before the front joint <NUM> is secured to the aft section <NUM>. The pivot fitting <NUM> allows individuals to work outside of the aft fuselage section <NUM>, away from confined spaced, to complete integration of the horizontal stabilizer <NUM> to the aft fuselage section <NUM>.

The pivot fittings 120a and 120b are secured to the upper sill beam <NUM> and the lower sill beam <NUM> outside of the aft fuselage section <NUM>, and away from confined spaces such as above and below the horizontal stabilizer <NUM>. It has been found that this results in a <NUM>% 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 120a and 120b to the fuselage, as the through-holes have been formed prior to the final assembly process. Further, the pivot fittings 120a and 120b provide improved structural load paths, such as in vertical, horizontal, lateral, and shear directions.

<FIG> illustrates an isometric front view of an aircraft <NUM>, according to an example of the present disclosure. The aircraft <NUM> includes a propulsion system <NUM> that includes engines <NUM>, for example. Optionally, the propulsion system <NUM> may include more engines <NUM> than shown. The engines <NUM> are carried by wings <NUM> of the aircraft <NUM>. In other embodiments, the engines <NUM> may be carried by a fuselage <NUM> and/or an empennage <NUM>. The empennage <NUM> also supports a horizontal stabilizer <NUM> and a vertical stabilizer <NUM>.

The horizontal stabilizer <NUM> is an example of the horizontal stabilizer <NUM>, shown in <FIG> and <FIG>. The fuselage <NUM> includes an aft fuselage section, such as the aft fuselage section <NUM> shown in <FIG>, <FIG>, and <FIG>. The fuselage <NUM> of the aircraft <NUM> defines an internal cabin <NUM>, 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 <NUM> shown in <FIG> is merely exemplary. It is to be understood that the aircraft <NUM> can be sized, shaped, and configured differently than shown.

Further, the disclosure comprises the following non-limiting examples that are compatible with the claimed subject matter:
In the claimed system, the one more pivot fittings may be securely fastened to the forward section, and the horizontal stabilizer may be pivotally coupled to the one or more pivot fittings before the forward section is secured to an aft section.

In the claimed system, the one or more fittings may be 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.

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.

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, which is defined by the appended claims. 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. 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 <NUM> U. § <NUM>(f), unless and until such claim limitations expressly use the phrase "means for" followed by a statement of function void of further structure.

Claim 1:
A system (<NUM>) for forming an aft fuselage section (<NUM>) of an aircraft, the system (<NUM>) comprising:
a forward section (<NUM>) having a stabilizer channel (<NUM>), wherein the forward section (<NUM>) comprises an upper sill beam (<NUM>) and a lower sill beam (<NUM>);
a horizontal stabilizer (<NUM>) within the stabilizer channel (<NUM>); and
one or more pivot fittings (120a, 120b) securely fastened between the upper sill beam (<NUM>) and the lower sill beam (<NUM>), wherein the one or more pivot fittings (120a, 120b) are configured to pivotally couple to the horizontal stabilizer (<NUM>), and wherein each of the upper sill beam (<NUM>) and the lower sill beam (<NUM>) comprises:
a joint panel (<NUM>) that mounts to a rear face (<NUM>) of the forward section (<NUM>); and
a fitting panel (<NUM>) that mounts to the one or more pivot fittings (120a, 120b).