Sawtooth fitting

Abstract

The invention relates to a serrated fitting, and discloses a serrated fitting and a method for installing a fixed length roller tray segment across an integration zone of an aircraft fuselage. The serrated fitting includes a first surface for attachment to a fixed length roller tray segment. The serrated fitting also includes a serrated surface for engagement with a serrated plate attached to a floor beam of the aircraft. A fastener connects the serrated surface to the serrated plate and the floor beam through a pre-drilled hole in the floor beam. The pre-drilled hole is greater than the diameter of the fastener to accommodate a cumulative tolerance between joined fuselage sections at the fuselage integration zone.

Description

Technical Field

[0001] The present disclosure relates generally to serrated fittings and more particularly to a no-drill solution for supporting installation of fixed-length roller tray segments of a cargo handling system across a fuselage integration area having large manufacturing tolerances. Background Art

[0002] Freight aircraft often incorporate continuous roller pallets for cargo handling. Roller pallets consist of multiple segments, where each segment is of fixed length. In some cases, roller pallet segments can span fuselage locations with circumferential joints. Circumferential joints can also be called integration zones. Integration zones are locations where two adjacent fuselage sections are joined. At these locations, assembly tolerances accumulate.

[0003] The installation of a continuous roller pallet cargo handling system uses discrete roller pallet attachment fittings at each end or along the length of a fixed length roller pallet section that is fastened to pre-installed floor beams. In the fuselage integration area, the exact distance between floor beams is unknown due to the assembly tolerance stack-up between fuselage sections.

[0004] Given these assembly tolerances, existing solutions defer installation (i.e., drilling and filling) of the roller tray attachment fittings to the floor beam until after the circumferential joints are installed on the aircraft during final assembly. Aircraft manufacturers drill holes in the aircraft substructure (e.g., floor beams) to attach fixed-length roller tray segments during final assembly after the circumferential joints of the fuselage have been assembled. Post-final assembly drilling of floor beams is a significant foreign object debris (FOD) and cost issue if any systems such as electrical, fuel, or environmental control (ECS) have been previously installed in the fuselage below the drilling location.

[0005] Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above as well as other possible issues. Summary of the invention

[0006] One illustrative embodiment of the present disclosure provides a serrated fitting for mounting a fixed length roller tray segment of an aircraft. The serrated fitting includes a first surface and a serrated surface opposite the first surface. The first surface is connected to the fixed length roller tray segment. The serrated surface is used to engage with a serrated plate attached to a floor beam pre-installed in the aircraft. A fastener connects the serrated surface to the serrated plate and the floor beam through a pre-drilled hole in the floor beam. The size of the pre-drilled hole is axially aligned with the longitudinal axis of the fixed length roller tray segment. The size is larger than the diameter of the fastener.

[0007] Another illustrative embodiment of the present disclosure provides a fixed-length roller pallet mounting system, which includes a fixed-length roller pallet segment of an aircraft, a serrated fitting, a serrated plate, and a fastener. The serrated fitting is connected to the fixed-length roller pallet segment. The serrated plate is connected to a floor beam of the aircraft. The serrated surface of the serrated fitting engages the serrated plate. The fastener connects the serrated surface of the serrated fitting to the serrated plate and the floor beam of the aircraft through a pre-drilled hole in the floor beam.

[0008] Another illustrative embodiment of the present disclosure provides a method for installing a fixed length roller tray segment across an aircraft fuselage integration region. A first set of floor beams is installed in a first aircraft fuselage section. A second set of floor beams is installed in a second aircraft fuselage section, wherein at least one of the first set of floor beams or the second set of floor beams includes a pre-drilled hole. The first aircraft fuselage section is joined to the second aircraft fuselage section at the fuselage integration region. A serrated fitting is connected to the fixed length roller tray segment. A serrated plate is connected to the first set of floor beams or the second set of floor beams having a pre-drilled hole. The serrated plate surrounds the pre-drilled hole. A serrated surface of the serrated fitting engages the serrated plate. The serrated fitting is fastened to the first set of floor beams or the second set of floor beams with a fastener through the pre-drilled hole. The size of the pre-drilled hole is axially aligned with the longitudinal axis of the fixed length roller tray segment and the size is greater than the diameter of the fastener.

[0009] The features and functions can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The novel features which are believed to be characteristic of the illustrative embodiments are set forth in the appended claims. However, the illustrative embodiments and their preferred modes of use, further objects and features thereof will be best understood by reference to the following detailed description of illustrative embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

[0011] Figure 1 is a diagram of an aircraft according to an illustrative example;

[0012] Figure 2 is an illustration of a block diagram of a manufacturing environment according to an illustrative embodiment;

[0013] Figure 3 is a diagram of a cargo handling system according to an illustrative embodiment;

[0014] Figure 4 is a diagram of a cargo handling system according to an illustrative embodiment;

[0015] Figure 5 is an illustration of a fixed length roller pallet mounting system according to an illustrative embodiment;

[0016] Figure 6 is an exploded view of a fixed length roller tray mounting system according to an illustrative embodiment;

[0017] Figure 7 is an illustration of an isometric view of a serrated fitting and a serrated plate according to an illustrative embodiment;

[0018] Figure 8 is an illustration of a fixed length roller pallet mounting system according to an illustrative embodiment;

[0019] Fig. 9 is an illustration of a flow chart of a process for installing a fixed length roller tray segment spanning an aircraft fuselage integration area in accordance with an illustrative embodiment;

[0020] Fig.10 is a block diagram of an aircraft manufacturing and service method according to an illustrative embodiment; and

[0021] Fig.11 is an illustration of a block diagram of an aircraft in which illustrative embodiments may be implemented. DETAILED DESCRIPTION

[0022] The illustrative embodiments recognize and take into account one or more different considerations.For example, the illustrative embodiments recognize and take into account that the installation of a continuous roller pallet cargo handling system utilizes discrete fixed-length roller pallet segments.

[0023] The illustrative embodiments also recognize and take into account that the installation of fixed length roller tray segments may span the circumferential joint or integration area of ​​two joined fuselage sections. Due to manufacturing variations, the spacing between the floor beams of two joined fuselage sections may not be consistent and vary within acceptable tolerances.

[0024] The illustrative embodiments also recognize and take into account that because the exact distance between floor beams may not be known prior to joining fuselage sections, existing installation techniques attach fittings to the floor beams after the circumferential joints are installed on the aircraft during final assembly, which requires the aircraft manufacturer to drill holes in the aircraft substructure during final assembly in order to attach the fixed-length roller tray segments.

[0025] The illustrative embodiments also recognize and take into account that such final post-assembly drilling in the floor beams is a significant FOD issue for any systems (eg, electrical, fuel, or ECS) previously installed in the fuselage below the drilling location.

[0026] Thus, the illustrative embodiments provide a serrated fitting for installing fixed length roller tray segments across a fuselage integration zone in final assembly. The serrated plate engagement and oversized pre-drilled holes allow for drill-free installation of fixed length roller tray segments and corresponding serrated fittings in a fuselage circumferential integration zone having floor beam to floor beam distance variations. The load path of the fixed length roller tray segment passes through the serrated fitting, bypassing fasteners used to attach the serrated fitting and the final fixed length roller tray segment to the aircraft floor beams, while also accounting for accumulated tolerances between joined fuselage sections at the fuselage integration zone.

[0027] Referring now to the drawings, and in particular to Figure 1 , depicts a diagram of an aircraft according to an illustrative example. In this illustrative example, aircraft 100 has wing 102 and wing 104 attached to fuselage 106. Aircraft 100 includes engine 108 attached to wing 102 and engine 110 attached to wing 104.

[0028] Fuselage 106 has a tail section 112 . Horizontal stabilizer 114 , horizontal stabilizer 116 , and vertical stabilizer 118 are attached to tail section 112 of fuselage 106 .

[0029] Aircraft 100 is an example of an aircraft in which a fixed length roller pallet of a cargo handling system may be installed according to an illustrative example. For example, a cargo area located in fuselage 106 of aircraft 100 may have a cargo handling system attached to floor beams of the aircraft. After the fuselage sections are joined, fixed length roller pallet segments of the cargo handling system may be attached to the floor beams, wherein the fixed length roller pallet segments span the fuselage integration area of ​​the joined fuselage sections. The fixed length roller pallet mounting system including the serrated fittings allows the fixed length roller pallet to be attached to the appropriate location of the floor beams and accounts for tolerances between the joined fuselage sections.

[0030] Figure 1 The illustration of aircraft 100 is not meant to imply physical or architectural limitations to the manner in which the illustrative examples may be implemented. For example, while aircraft 100 is a commercial aircraft, aircraft 100 may be a military aircraft, a rotorcraft, a helicopter, an unmanned aerial vehicle, or any other suitable aircraft.

[0031] Although the illustrative examples are described with respect to an aircraft, the illustrative examples are applicable to other types of platforms as well. The platform may be, for example, a mobile platform, a fixed platform, a land-based structure, a water-based structure, or a space-based structure. More specifically, the platform may be an aircraft, a surface ship, a tank, a personnel carrier, a train, a spacecraft, a space station, a satellite, a submarine, a car, a power plant, a bridge, a dam, a house, a manufacturing facility, a building, a tool, a mechanical structure, or some other suitable platform or structure to which a fixed-length roller pallet segment is to be mounted.

[0032] Now go to Figure 2 , an illustration of a block diagram of an aircraft manufacturing environment is depicted according to an illustrative example. Aircraft manufacturing environment 200 includes aircraft 202 and fixed-length roller pallet mounting system 204 .

[0033] In this illustrative example, aircraft 202 includes first fuselage section 206 and second fuselage section 208. First fuselage section 206 is joined to second fuselage section 208 at fuselage integration area 210. First fuselage section 206 includes first set of floor beams 212, and second fuselage section 208 includes second set of floor beams 214. In this illustrative example, aircraft 202 is in final assembly when first fuselage section 206 is joined to second fuselage section 208. Due to allowable tolerances in fuselage integration area 210, the distance between the floor beams of first set of floor beams 212 and the floor beams of second set of floor beams 214 is unknown prior to final assembly. Floor beam 220 represents a floor beam from first set of floor beams 212 or second set of floor beams 214. Floor beam 220 includes pre-drilled holes 222. Prior to final assembly, or before the first fuselage section 206 is joined to the second fuselage section 208, pre-drilled holes 222 are drilled in the floor beams 220. Pre-drilling the pre-drilled holes 222 prior to joining the first fuselage section 206 to the second fuselage section 208 prevents foreign debris, such as drill cuttings, from interfering with any systems already installed in the fuselage sections. In other words, there is no drilling of holes in the floor beams after the fuselage sections are joined together. The pre-drilled holes 222 are present before the fuselage sections are joined together in final assembly.

[0034] The pre-drilled hole 222 has a dimension 224. Dimension 224 is the fore-aft dimension and must be larger than the diameter of the fastener that will be used with the pre-drilled hole 222. The pre-drilled hole 222 is typically round or slotted, but can be any shape that includes a dimension that is larger than the diameter of the fastener. In other words, dimension 224 of the pre-drilled hole 222 must be of sufficient size to account for all applicable manufacturing and assembly tolerances. Dimension 224 is axially aligned or parallel to the longitudinal axis of the fixed length roller tray segment 230 to be attached. Dimension 224 is axially aligned or parallel to the longitudinal axis of the fuselage segment. Dimension 224 will account for distance variations between floor beams to which the fixed length floor tray segment is attached. Dimension 224 will be large enough to accommodate longitudinal tolerance stack-ups in the fuselage integration area 210 between the first fuselage segment 206 and the second fuselage segment 208. Dimension 224 will allow for fore-aft position adjustment of the fixed length roller tray segment relative to the floor beam.

[0035] As used herein, when used in reference to an item, a “set” refers to one or more items. For example, a “set of floor beams” is one or more of floor beams 220 .

[0036] As used herein, when used with a list of items, the phrase "at least one of" means that different combinations of one or more of the listed items may be used, and only one of each item in the list may be required. In other words, "at least one of" means any combination of items and numbers of items that can be used in the list, but not all items in the list are required. An item may be a specific object, thing, or category.

[0037] For example, but not limited to, "at least one of item A, item B, or item C" may include item A, item A and item B, or item B. This example may also include item A, item B, and item C, or item B and item C. Of course, any combination of these items may exist. In some illustrative examples, "at least one of..." may be, for example, but not limited to, two of item A; one of item B; ten of item C; four of item B and seven of item C; or other suitable combinations.

[0038] As used herein, a first component "connected to" or "coupled to" or "associated with" a second component means that the first component can be directly or indirectly connected to the second component. A connection is a physical association. In other words, there can be additional components between the first component and the second component. When there are one or more additional components between the two components, the first component is considered to be indirectly connected to the second component. When the first component is directly connected to the second component, there are no additional components between the two components.

[0039] For example, a first component may be considered physically connected to a second component by at least one of being fixed to the second component, bonded to the second component, mounted to the second component, welded to the second component, fastened to the second component, or connected to the second component in some other suitable manner. The first component may also be connected to the second component using a third component. The first component may also be considered physically connected to the second component by being formed as a part of the second component, an extension of the second component, or both.

[0040] In this illustrative example, fixed length roller pallet mounting system 204 includes fixed length roller pallet segment 230 , serrated fitting 232 , serrated plate 234 , and fastener 236 .

[0041] The fixed length roller pallet segment 230 is one segment of a complete cargo handling system installed in the cargo hold of the aircraft 202. The fixed length roller pallet segment 230 may, but need not, span the fuselage integration area 210. The fixed length roller pallet segment 230 has a longitudinal axis 240. The longitudinal axis 240 is longitudinally axially aligned with the first fuselage section 206 and the second fuselage section 208. Although one fixed length roller pallet segment 230 is depicted, the fixed length roller pallet mounting system 204 may have more than one fixed length roller pallet segment 230 for installation with the serrated fitting 232. For example, the fixed length roller pallet mounting system 204 may include any number of fixed length roller pallet segments to be installed across the cargo area floor of the aircraft.

[0042] A fixed length roller tray segment 230 of a cargo handling system installed in a cargo hold of an aircraft 202 has a load path 242. The load path 242 is a result of movement of cargo loaded on the cargo handling system during operation of the aircraft 202. Fore-aft and / or lateral forces generated by the movement of cargo are transferred from the fixed length roller tray segment of the cargo handling system to the floor beams of the aircraft via the load path 242.

[0043] Load path 242 represents fore-aft and / or lateral loads caused by cargo movement supported by the cargo handling system. Vertical tension loads, such as when the aircraft is in a sharp descent, are not represented by the illustrated load path 242. Load path 242 originates at fixed length roller pallet segment 230. By using serrated fitting 232, load path 242 is directed from fixed length roller pallet segment 230 through serrated fitting 232 and serrated plate 234 to a floor beam, such as floor beam 220, to which fixed length roller pallet segment 230 is attached. Load path 242 does not reach a floor beam, such as floor beam 220, through fastener 236 for attached serrated fitting 232 and ultimately fixed length roller pallet segment 230.

[0044] The serrated fitting 232 includes a first surface 244. The first surface 244 defines an overhang 246. The serrated fitting 232 is connected to the fixed length roller pallet segment 230 at the first surface 244 by a fastener 248 that cooperates with the overhang 246. The fastener 248 can be any type of fastener, including, for example, a tension stud. Other structural arrangements are possible without the overhang and tension stud combination, as long as the first surface 244 includes a surface area whose minimum area is sized to be sufficient to carry the expected load from the cargo supported by the cargo handling system.

[0045] The serrated fitting 232 includes a serrated surface 250. The serrated surface 250 is located on the side of the serrated fitting 232 opposite the first surface 244. The serrated surface 250 has a surface area 252. The 2D shape of the serrated surface 250 is typically polygonal, however, shapes such as circular or oval are sufficient as long as most of the surface area 252 is available for engagement with the serrated plate 234. In a typical sense, a majority is defined to mean at least more than half of the surface area 252, such as at least 51% to 100% of the surface area 252 is available for engagement with the serrated plate 234. The surface area 252 is designed to meet the load transfer requirements from the cargo supported by the cargo handling system.

[0046] The serrated plate 234 is connected to the floor beam 220. The serrated plate 234 is connected to the floor beam 220 before final assembly, in other words, the serrated plate 234 is pre-attached to the floor beam 220 before final assembly. The serrated plate 234 can be connected to the floor beam 220 with fasteners that are not commonly used with fixed-length roller tray segments 230, for example, or the serrated plate 234 can be connected to the floor beam 220 with adhesives. The serrated plate 234 can be integrally formed with the floor beam 220. The serrated plate 234 includes a pre-drilled hole 254. The pre-drilled hole 254 has a size 256. The size and shape of the pre-drilled hole 254 and the size 256 generally match the pre-drilled hole 222 and size 224 in the floor beam 220. The pre-drilled hole 254 is generally round or slot-shaped, but can be any shape including a size that is larger than the diameter of the fastener 236. In other words, the size 256 of the pre-drilled hole 254 must be of sufficient size to account for all applicable manufacturing and assembly tolerances. The serrated plate 234 is connected to the floor beam 220 with the pre-drilled holes 254 aligned with the pre-drilled holes 222 .

[0047] Fastener 236 connects serrated fitting 232 to serrated plate 234. Fastener 236 has diameter 258. Diameter 258 is significantly smaller than dimension 256 and dimension 224. If the cross-section of fastener 236 is not typically circular, the largest dimension of the non-circular cross-section must be significantly smaller than dimension 256 and dimension 224. In other words, there is a clearance fit between fastener 236 and pre-drilled hole 222 and pre-drilled hole 254 in the direction of dimension 224 and dimension 256, respectively, which allows fastener 236 to be inserted into pre-drilled hole 222 and pre-drilled hole 254 without interfering with floor beam 220 and serrated plate 234.

[0048] The serrations of the serrated surface 250 of the serrated fitting 232 engage the serrations of the serrated plate 234. The engagement of the serrations prevents fore-and-aft movement of the serrated fitting 232 relative to the serrated plate 234 in the direction of either dimension 256 or dimension 224. The engagement of the serrations also helps prevent lateral movement of the serrated fitting 232 relative to the serrated plate 234. The placement of the serrated fitting 232 relative to the serrated plate 234 is adjustable because the diameter 258 is smaller than both dimension 256 and dimension 224. The adjustable placement of the serrated fitting 232 relative to the serrated plate 234 through the length of both dimension 256 and dimension 224 is an illustrative example of how the fixed-length roller pallet mounting system 204 accommodates manufacturing variations caused by the spacing between the floor beams of two joined fuselage sections, which may not be uniform.

[0049] Next reference Figure 3-Figure 4 , depicts an illustration of a cargo handling system according to an illustrative embodiment. In this illustrative example and the following illustrative examples, the same reference numerals may be used in more than one of the figures. Reference numerals are repeated in different figures to represent the same elements / components in different figures. Figure 3-Figure 4 The components shown in Figure 2 An example of a physical implementation of first fuselage section 206, second fuselage section 208, fuselage integration region 210, first set of floor beams 212, second set of floor beams 214, and floor beams 220 are shown in block form in FIG.

[0050] As shown, the cargo handling system 300 includes fixed length roller pallet segments 320, 322 mounted to a first set of floor beams 312 in a first fuselage section 302 and fixed length roller pallet segments 324, 326 mounted to a second set of floor beams 314 in a second fuselage section 304. A serrated fitting 310 or standard fitting is positioned between each fixed length roller pallet segment and the corresponding floor beam. A standard fitting (in other words, a fitting that is not the subject of the present disclosure) can replace the serrated fitting 310 in this illustrated example because the fixed length roller pallet segments 320, 322, 324, 326 do not span the fuselage integration area. However, the serrated fitting 310 is also operable in this case. The serrated fitting 310 can be used at each end of any fixed length roller pallet segment or along its length, in other words, the serrated fitting 310 can be used at any floor beam position where there is a tolerance stack-up.

[0051] At final assembly, first fuselage section 302 is ready to be joined to second fuselage section 304. Prior to final assembly, first set of floor beams 312 are pre-installed in first fuselage section 302. Second set of floor beams 314 are pre-installed in second fuselage section 304 prior to final assembly. Due to acceptable manufacturing tolerances 308, distance 306 between floor beams 316 of first fuselage section 302 and floor beams 318 of second fuselage section 304 is not known until after final assembly.

[0052] Once the first fuselage section 302 is joined to the second fuselage section 304, as shown in FIG. Figure 4 As shown, fixed length roller tray segment 402 is connected to and between floor beam 316 and floor beam 318. Serrated fittings 404 and 406 connect fixed length roller tray segment 402 to floor beam 316 and floor beam 318, respectively. Serrated fittings 404 and 406 are located at pre-drilled holes in floor beams 316, 318. The dimension length of the pre-drilled holes in longitudinal direction 410 allows the fittings to move laterally relative to the floor beams to accommodate manufacturing tolerances 308 during final assembly. In a minimum implementation scenario, only one serrated fitting, serrated fitting 404 or serrated fitting 406, is required. Factors considered in determining whether to use one or two serrated fittings include excessive integration tolerances due to having adjustability at both ends of fixed length roller tray 402, versatility of maintenance, assembly cost, etc.

[0053] Next reference Figure 5-Figure 7 , an illustration of a fixed length roller pallet mounting system 500 is depicted in accordance with an illustrative embodiment.

[0054] Figure 5 yes Figure 4An enlarged view of inset 408. As shown, after final assembly, fixed length roller tray segment 502 is attached to floor beam 504 via serrated fitting 506. Prior to final assembly, fixed length roller tray segment 510 is pre-attached to floor beam 504 via fitting 512. Fitting 512 may be considered an example of a standard fitting and not the subject of the present disclosure.

[0055] The first surface 520 of the serrated fitting 506 is connected to the fixed length roller pallet segment 502 via a fastener 522 that engages an overhang 524. The fastener 522 can be any type of fastener, including, for example, a tension stud. Other structural arrangements are possible without the overhang 524 and fastener 522 combination, as long as the first surface 520 includes a surface area whose minimum area is sized to be sufficient to carry the expected load from the cargo supported by the cargo handling system. The serrated fitting 506 includes a serrated surface 526.

[0056] The serrated plate 528 is connected to the floor beams 504. The serrated plate 528 is pre-attached to the floor beams 504 prior to final assembly. The serrated plate 528 can be connected to the floor beams 504 by fasteners 546, 548. Alternatively, in a non-limiting example, the serrated plate 528 can be connected to the floor beams 504 with an adhesive, or formed integrally with the serrated plate 528. The serrated plate 528 includes a pre-drilled hole 530. The pre-drilled hole 530 has a size 532. The size and shape of the pre-drilled hole 530 and the size 532 generally match the pre-drilled hole 540 and the size 542 in the floor beam 504.

[0057] Fastener 536 connects serrated fitting 506 to serrated plate 528. Fastener 536 has diameter 538. Diameter 538 is significantly smaller than dimension 532 and dimension 542 to allow fastener 536 to be placed along the length of dimension 532 and dimension 542.

[0058] The teeth of the serrated surface 526 engage the teeth of the serrated plate 528. The engagement of the serrations prevents the serrated fitting 506 from moving fore and aft relative to the serrated plate 528 in directions 534. The engagement of the serrations also helps prevent lateral movement of the serrated fitting 506 relative to the serrated plate 528. The placement of the serrated fitting 506 relative to the serrated plate 528 is adjustable because the diameter 538 is smaller than both the dimension 532 and the dimension 542. The adjustable placement of the serrated fitting 506 relative to the serrated plate 528 by the length of the dimensions 532 and the dimension 542 accommodates manufacturing variations caused by the spacing between the floor beams 316, 318 of the two joined fuselage sections 302, 304 at the time of final assembly, which spacing may vary at each fuselage integration area.

[0059] The serrated fitting 506 may be referred to as a split fitting or a roller tray end fitting. The split fitting works in conjunction with a standard fitting, such as fitting 512. Fitting 512 connects a fixed length roller tray segment 510 to a floor beam 504. The fixed length roller tray segment 510 does not span the fuselage integration region. The serrated fitting 506 connects a fixed length roller tray segment 502 to a floor beam 504, wherein the fixed length roller tray segment 502 spans the fuselage integration region. The serrated fitting 506 accommodates the accumulated tolerances between the joined fuselage sections at the fuselage integration region.

[0060] The load path 544 of the fitting 512 is shown passing through the fasteners connecting the fitting 512 to the floor beam 504. The path of the load path 544 passes through the fitting because the fasteners have an interference fit with the floor beam and, due to the lack of serrations, the fasteners provide the only barrier to movement between the fitting and the floor beam.

[0061] In contrast, the load path 550 of the fixed length roller pallet mounting system 500 passes through the serrated fitting 506 and around the fastener 536. The engagement of the serrations of the serrated surface 526 and the serrations of the serrated plate 528 provides the load path 550.

[0062] Load paths 550 represent fore-aft and / or lateral loads caused by cargo movement supported by the cargo handling system. Vertical tension loads, such as when the aircraft is in a sharp descent, are not represented by the illustrated load paths 550. Load paths 550 originate at fixed length roller pallet segments 502. By using serrated fittings 506, load paths 550 are directed from fixed length roller pallet segments 502 through serrated fittings 506 and serrated plates 528 to floor beams 504. Load paths 550 do not reach floor beams 504 through fasteners 536, which are used to attach serrated fittings 506 and ultimately fixed length roller pallet segments 502.

[0063] Next reference Figure 8 , an illustration of a fixed length roller pallet mounting system 800 is depicted in accordance with an illustrative embodiment.

[0064] As shown, after final assembly, the fixed length roller tray segment 802 is attached to the floor beam 804 via a serrated fitting 806. The serrated fitting 806 may be referred to as a one-piece fitting or an intermediate fitting. The fixed length roller tray segment 802 may or may not span the fuselage integration area. The serrated fitting 806 replaces the Figure 5-Figure 7 506 and doubles the surface area of ​​the serrated assembly 506. Certain elements of the serrated assembly 806 perform in a similar manner to the elements of the serrated assembly 506 previously described, however some elements may be repeated.

[0065] The first surface 820 of the serrated fitting 806 is connected to the fixed length roller tray segment 802 via a fastener 822 that engages an overhang 824. The fastener 822 can be any type of fastener, including, for example, a tension stud. Other structural arrangements are possible without the combination of the overhang 824 and the fastener 822. The serrated fitting 806 includes a serrated surface 826.

[0066] The serrated plate 828 is connected to the floor beam 804. The serrated plate 828 is pre-attached to the floor beam 804 prior to final assembly. The serrated plate 828 may be connected to the floor beam 804 by fasteners 846, 848. Alternatively, in a non-limiting example, the serrated plate 828 may be connected to the floor beam 804 with an adhesive, or may be formed integrally with the floor beam 804. The serrated plate 828 includes pre-drilled holes 830, 831. The pre-drilled hole 830 has a size 832, and the pre-drilled hole 831 has a size 833. The size and shape of the pre-drilled holes 830, 831 and the sizes 832, 833 generally match the pre-drilled hole 840 and size 842 and the pre-drilled hole 841 and size 843 in the floor beam 804, respectively.

[0067] Fasteners 836, 837 connect the serrated fitting 806 to the serrated plate 828. Fastener 836 has a diameter 838. Fastener 837 has a diameter 839. Diameters 838, 839 are significantly smaller than dimensions 832, 842 and dimensions 833, 843 to allow fasteners 836, 837 to be placed along the length of dimensions 532, 533, 542, 543.

[0068] The teeth of the serrated surface 826 engage the teeth of the serrated plate 828. The engagement of the serrations prevents fore-and-aft movement of the serrated fitting 806 relative to the serrated plate 828 in directions 834. The engagement of the serrations also helps prevent lateral movement of the serrated fitting 806 relative to the serrated plate 828. The placement of the serrated fitting 806 relative to the serrated plate 828 is adjustable. The adjustable placement of the serrated fitting 806 relative to the serrated plate 828 by the lengths of the dimensions 532, 533, 542, 543 accommodates manufacturing variations caused by the spacing between the floor beams of the two joined fuselage sections during final assembly, which spacing may vary at each fuselage integration area.

[0069] Next reference Fig. 9 , an illustration of a flowchart of a process 900 for installing a fixed length roller tray segment spanning an aircraft fuselage integration area is depicted in accordance with an illustrative embodiment. Fig. 9 The method shown can be used with Figure 2-Figure 8 For use in conjunction with the fixed length roller pallet mounting system shown.

[0070] The process begins by installing a first set of floor beams in a first aircraft fuselage section (operation 902). The process continues by installing a second set of floor beams in a second aircraft fuselage section (operation 904). At least one of the first set of floor beams or the second set of floor beams includes a pre-drilled hole. At operation 906, the process joins the first aircraft fuselage section to the second aircraft fuselage section at a fuselage integration region. At operation 908, the process connects a serrated fitting to a fixed length roller pallet segment. At operation 910, the process connects a serrated plate to the set of floor beams having the pre-drilled holes, whether the first set of floor beams or the second set of floor beams. The serrated plate surrounds the pre-drilled hole. At operation 912, the process engages a serrated surface of the serrated fitting with the serrated plate. At operation 914, the process fastens the serrated fitting to the first set of floor beams or the second set of floor beams with a fastener through the pre-drilled hole. The size of the pre-drilled hole is axially aligned with the longitudinal axis of the fixed length roller pallet segment and the size is greater than the diameter of the fastener.

[0071] In some alternative implementations of the illustrative examples, one or more functions noted in the blocks may not be necessary or may not be in the order noted in the drawings. For example, in some cases, two blocks shown in succession may be performed substantially simultaneously, or the blocks may sometimes be performed in the reverse order, depending on the functions involved. In addition, other blocks may be added in addition to the blocks shown in the flowchart or block diagram.

[0072] Illustrative embodiments of the present disclosure may be used in Fig.10 Aircraft manufacturing and service method 1000 is shown and Fig.11 The invention is further described in the context of the aircraft 1100 shown. Fig.10 , an illustration of a block diagram of an aircraft manufacturing and service method is depicted in accordance with an illustrative embodiment. During pre-production, aircraft manufacturing and service method 1000 may include Fig.11 Specification and design 1002 of aircraft 1100 and procurement of materials 1004.

[0073] During production, Fig.11 Component and subassembly manufacturing 1006 and system integration 1008 of aircraft 1100. Thereafter, Fig.11 The aircraft 1100 in can be certified and delivered 1010 to be put into service 1012. While serving the customer 1012, Fig.11 The aircraft 1100 is scheduled for routine maintenance and service 1014, which may include reconditioning, reconfiguration, refurbishment, and other maintenance, service, or inspection.

[0074] The devices of the present disclosure may be installed on an aircraft during component and subassembly manufacturing 1006. In addition, the devices of the present disclosure may be retrofitted to an aircraft during routine maintenance and service 1014. Fig.11On the plane at 1100, as Fig.11 A portion of a modification, reconfiguration, or refurbishment of aircraft 1100.

[0075] Each process of the aircraft manufacturing and service method 1000 can be performed or implemented by a system integrator, a third party, an operator, or some combination thereof. In these examples, the operator may be a customer. For the purpose of this specification, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors; a third party may include, but is not limited to, any number of suppliers, subcontractors, and vendors; an operator may be an airline, a leasing company, a military entity, a service organization, etc.

[0076] Reference now Fig.11 , depicts an illustration of a block diagram of an aircraft in which an illustrative embodiment may be implemented. In this example, aircraft 1100 is Fig.10 1000 is a method of manufacturing and servicing an aircraft in the art and may include an airframe 1102 having a plurality of systems 1104 and an interior 1106. Examples of systems 1104 include one or more of a propulsion system 1108, an electrical system 1110, a hydraulic system 1112, and an environmental system 1114. Any number of other systems may be included. Although an aerospace example is shown, different illustrative embodiments may be applied to other industries, such as the automotive industry.

[0077] The apparatus and methods embodied herein can be used to Fig.10 During at least one of the phases of aircraft manufacturing and service method 1000. In one illustrative example, Fig.10 The components or subassemblies produced in 1006 may be manufactured in a manner similar to Fig.10 The components or subassemblies are manufactured in the same manner as those produced when aircraft 1100 is in service 1012. As another example, during a production phase (e.g., Fig.10 In the component and subassembly manufacturing 1006 and system integration 1008), one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized. Fig.10 1012, during maintenance and service 1014 (including inspection), or both. Using a number of different illustrative embodiments can significantly speed up the assembly of aircraft 1100, reduce the cost of aircraft 1100, or both speed up the assembly of aircraft 1100 and reduce the cost of aircraft 1100.

[0078] The description of different illustrative embodiments is presented for the purpose of illustration and description and is not meant to be exhaustive or limited to the embodiments of the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. In addition, different illustrative embodiments may provide different features compared to other desired embodiments. The selected one or more embodiments are selected and described in order to best explain the principles of the embodiments, practical applications, and to enable other persons of ordinary skill in the art to understand the disclosure of various embodiments with various modifications suitable for the intended specific use.

Claims

1. A serrated fitting (232) for mounting a fixed length roller tray segment (230) of an aircraft (202), the serrated fitting (232) comprising: a first surface (244) for connection to the fixed-length roller tray segment (230); and a serrated surface (250) opposite the first surface (244), the serrated surface (250) being adapted to engage a serrated plate (234) attached to a floor beam (220) pre-installed in the aircraft (202); wherein a fastener (236) connects the serrated surface (250) to the serrated plate (234) and the floor beam (220) through a pre-drilled hole (222) in the floor beam (220), the pre-drilled hole (220) having a dimension (224) axially aligned with a longitudinal axis (240) of the fixed-length roller tray segment (230), and wherein the dimension (224) is greater than a diameter (258) of the fastener (236).

2. The serrated accessory of claim 1, wherein a majority of the surface area (252) of the serrated surface (250) engages the serrated plate (234).

3. The serrated fitting of claim 1, wherein the fixed-length roller tray segment (230) spans a fuselage integration area (210) of the aircraft (202), and wherein the serrated fitting (232) is a split serrated fitting comprising a first portion (506) connected to the fixed-length roller tray segment (230) and a second portion (512) connected to a second fixed-length roller tray segment (510) that does not span the fuselage integration area (210) of the aircraft (202).

4. The serration fitting of claim 1, wherein the serration fitting (232) is positioned between the fixed length roller tray segment (230) and the floor beam (220) of the aircraft (202).

5. The serrated accessory of claim 1, wherein the serrated accessory (232) is positioned between the fixed length roller tray segment (230) and the serrated plate (234).

6. The serrated accessory of claim 1, wherein the first surface (244) includes an overhang (246) sized for a second fastener (248) for connecting the first surface (244) to the fixed-length roller tray segment (230).

7. The serration fitting of claim 1, wherein a load path (550) of the fixed length roller tray segment (230) passes through the serration fitting (232).

8. The serrated accessory of claim 7, wherein the load path (550) of the fixed-length roller tray segment (230) bypasses the fastener (236).

9. A fixed-length roller tray mounting system (204), comprising: a fixed length roller tray segment (230) of the aircraft (202) connected to the serrated fitting (232); a serrated plate (234) connected to a floor beam (220) of the aircraft (202); and The serrated surface (250) of the serrated fitting (232) engages with the serrated plate (234), wherein the serrated fitting (232) is connected to the serrated plate (234) and the floor beam (220) of the aircraft (202) with fasteners (236) through pre-drilled holes (222) in the floor beam (220).

10. The system of claim 9, wherein the fixed-length roller tray segment (230) spans a fuselage integration area (210) of the aircraft (202), and wherein the serrated fitting (232) is a split serrated fitting comprising a first portion (506) connected to the fixed-length roller tray segment (230) and a second portion (512) connected to a second fixed-length roller tray segment (510).

11. The system of claim 9, wherein the pre-drilled hole (222) includes a dimension (224) axially aligned with a longitudinal axis (240) of the fixed-length roller tray segment (230), and wherein the dimension (224) provides a clearance fit with the fastener (236).

12. The system of claim 9, wherein a majority of the surface area (252) of the serrated surface (250) engages the serrated plate (234).

13. The system of claim 9, wherein the serrated fitting (232) is positioned between the fixed-length roller tray segment (230) of the aircraft (202) and the floor beam (220) of the aircraft (202).

14. The system of claim 9, wherein the serrated fitting (232) is positioned between the fixed length roller tray segment (230) and the serrated plate (234) of the aircraft (202).

15. The system of claim 9, wherein a load path (550) of the fixed-length roller tray segment (230) of the aircraft (202) bypasses the fastener (236).

16. The system of claim 15, wherein the load path (550) of the fixed-length roller tray segment (230) of the aircraft (202) also passes through the serrated fitting (232).

17. A method for installing a fixed length roller pallet segment across an aircraft fuselage integration area, the method comprising: installing (902) a first set of floor beams (212) in a first aircraft fuselage section (206); installing (904) a second set of floor beams (214) in a second aircraft fuselage section (208), wherein at least one of the first set of floor beams (212) or the second set of floor beams (214) includes pre-drilled holes (222); joining (906) the first aircraft fuselage section (206) to the second aircraft fuselage section (208) at a fuselage integration region (210); connecting (908) a serrated fitting (232) to a fixed length roller tray segment (230); connecting (910) a serrated plate (234) to the first set of floor beams (212) or the second set of floor beams (214) having the pre-drilled holes (222), the serrated plate (234) surrounding the pre-drilled holes (222); engaging (912) the serrated surface (250) of the serrated fitting (232) with the serrated plate (234); and The serrated fitting (232) is fastened (914) to the first set of floor beams (212) or the second set of floor beams (214) with a fastener (236) through the pre-drilled hole (222), wherein the pre-drilled hole (222) has a dimension (224) axially aligned with a longitudinal axis (240) of the fixed-length roller tray segment (230), and wherein the dimension (224) is greater than a diameter (258) of the fastener (236).

18. The method of claim 17, wherein the serrated fitting (232) is positioned between the fixed length roller tray segment (230) and the serrated plate (234).

19. The method of claim 17, wherein a load path (550) of the fixed-length roller tray segment (230) bypasses the fastener (236).

20. The method of claim 19, wherein the load path (550) of the fixed-length roller tray segment (230) passes through the serrated fitting (232).

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