Abstract:
A design and installation method are provided to improve access to equipment mountable on aircraft equipment racks, including installing modified equipment rack framework on the aircraft, preassembling the equipment on a separate equipment package, providing separate matable hinge units on both the framework and equipment package, and temporarily supporting the equipment package in a hanging position from the equipment rack by matably joining the separate hinge units. Wiring the equipment from adjacent wireway banks is performed in the hanging position, followed by rotating the equipment package about an axis of rotation formed by the joined hinge units into a fixed stowed position, and fastening the equipment package to the equipment rack framework to complete the installation.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the design, construction, and method of installation of equipment on equipment racks, and more particularly to the design, construction, and method of installation of equipment on aircraft equipment racks using hinge members to improve access to system connections. 
     BACKGROUND OF THE INVENTION 
     The aircraft industry currently employs overhead racks attached to frames or frame structure to support equipment packages adjacent to the aircraft&#39;s frames. These racks are typically installed by fastener attachment to the frames, or associated frame structure, prior to installation of the equipment packages. Wiring supporting the equipment packages is typically located in wire hangers supporting wiring banks and brought to general locations where the equipment packages will be located. The individual pieces of equipment are then mounted on the preinstalled racks and typically bolted in position. Following equipment installation on the rack assemblies, an installation mechanic will pull the wiring from the adjacent wiring banks to make connections into the equipment packages. A drawback of the existing rack system is that access for this type of installation is often difficult due to the structure of the rack assembly itself. Access for this type of installation is often made more difficult on existing aircraft, where in addition to the original wiring banks, structure of the rack assembly, and installed equipment, other equipment and structure may have been installed or retrofitted during the service life of the aircraft. 
     Existing rack assembly designs employ various structural members to support the equipment. Structural members may comprise vertical rails formed of angle shapes and U-shaped channels, flat plate forming equipment shelves, adjustable mounting fittings such as turnbuckle assemblies to locate the racks, and mechanical fasteners to join these members to themselves and the aircraft structure. Generally, aircraft safety requirements provide that additional support structure must be utilized to restrain motion of the rack assemblies. This additional support structure usually comprises diagonal support braces and additional stiffener members. A drawback is that installation of this additional structure, in addition to the vertical supports typically used to support the weight of the rack assembly and equipment package to the aircraft structure, provides a difficult access path for mechanics to reach the equipment to make the wiring and other equipment connections. 
     On wide body aircraft there is generally sufficient space in the overhead compartments for additional wiring and components for retrofit on the aircraft following initial construction. An example of this includes antenna system installation, which requires, in addition to the two antennas, power converters and power supplies for each. The power converters and power supplies have the additional restriction that their location must be within about two feet of each antenna. Such retrofit requires sufficient space for the equipment structure, the equipment, the necessary wiring, and any mechanical connections. Retrofitting this antenna equipment on existing aircraft, within the space limitation discussed above, must be performed within time constraints of aircraft down time, and with the drawback that surrounding structure and components could limit access into an existing design equipment rack. 
     There is a need for a less expensive and simpler method to provide the mechanic access to new installation or retrofitted equipment packages to make wiring and mechanical connections. A simpler structural design requiring fewer parts and a method of providing access for wiring interconnect to equipment before it is positioned and fastened to the rack assembly is desirable. 
     SUMMARY OF THE INVENTION 
     The present invention addresses these needs and past design drawbacks by providing a rack installation method and design that permits access to the associated equipment for interconnection activity prior to positioning the equipment in its final fixed position. The rack assembly and method of installation of the present invention relies on material forms such as flat sheet or plate metal, unshaped channel, angle shapes, and fasteners. At least one male hinge is incorporated in the rack structure which allows the equipment weight to be temporarily supported by the rack structure and provides an accessible equipment orientation for wiring. The male hinge(s) extends outwardly from the main body of the rack structure, permitting an equipment package to initially hang supported by the male hinge(s) along one of the package sides, vertically below the rack structure, and rotated about 90 degrees down from its final fixed position. This package position provides ease of access for a mechanic to reach the equipment electrical and mechanical connections. The mechanic can then perform cabling interconnect activities with unobstructed access to the equipment packages and greater access to the adjacent cable banks. When interconnect activities are complete and testing performed, the mechanic rotates the package about 90 degrees to its final fixed position. 
     The equipment package comprises the necessary equipment pre-mounted on a flat plate structure of suitable material for strength and weight, optional stiffener member(s), pre-bored equipment fastener holes which may be through bores or threaded bores, and at least one female hinge member. The at least one female hinge member comprises at least one opening in the flat plate to receive the at least one male hinge of the rack structure. A rod of about one quarter inch (0.64 mm) diameter spans the female hinge opening(s) and provides the axis of rotation for the equipment package about the male hinge(s). 
     In another aspect of the invention, a plurality of quick turn, eg. one-quarter turn, fasteners are provided to improve both installation and subsequent removal of the equipment package. These fasteners permit a single mechanic to swing the equipment package up to its installed position and, while holding the package in position, fasten the package to the rack structure. The rack structure is provided with mating fastener ports for the one-quarter turn fasteners. Similarly, for subsequent maintenance work, a single mechanic can support the weight of the equipment package while simultaneously releasing the quarter-turn fasteners. 
     The hinge(s) may also be reversed, wherein the male hinge(s) form a structural part of the equipment package, and the female hinge(s) form a structural part of the rack structure. Additionally, the hinge design may be varied in the form of a male pin which slides into the female hinge, or a door hinge design employing female type hinge members on both the rack structure and the flat plate of the equipment package may be used with a separate male pin joining the two female hinges. The female hinge(s) may also incorporate flat or rolled plate in place of the tack welded rod to simplify the hinge design. 
     In another aspect of the invention, an upper plate, forming a drip shield for the equipment package below, may form an integral part of the rack structure, or the drip shield may be incorporated as the flat plate of the equipment package. 
     The equipment package may also comprise a box-like enclosure surrounding the equipment mounted therein. In this aspect of the invention the equipment package, when swung up to its installed position, contacts an opposed plate section mounted to the rack structure, providing total enclosure of the equipment. Wiring clearance openings are employed for this aspect, with the potential for hermetically sealing the enclosure. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a partial perspective view of the invention showing the equipment support plate in the working suspended position; 
     FIG. 2 is a partial perspective view of the arrangement of FIG. 1 showing both the equipment support plate and typical equipment in the stored fixed position; 
     FIG. 3A is a section view taken along section line I—I of FIG. 1, showing an exemplary hinge design; 
     FIG. 3B is a plan view of the female hinge design plate and rod assembly of FIG. 3A; 
     FIG. 3C is an elevational view of the female hinge design taken along section line II—II of FIG. 3B; 
     FIG. 4 is a section view showing an alternative hinge design reversing the orientation of the male hinge of FIG. 3A; 
     FIG. 5 is a plan view of an equipment plate similar to FIG. 3B, eliminating the rod; 
     FIG. 6 is a perspective view of a rack design having a drip tray; 
     FIG. 7 is a perspective view of an alternative rack design providing for complete enclosure of the equipment and a further alternative hinge design; 
     FIG. 8A is a section view taken along section line I—I of FIG. 1, similar to FIG. 3A, showing rolled plate replacing the rod and tack weld of FIG. 3A; 
     FIG. 8B is a plan view of the female hinge design of FIG. 8A; and 
     FIG. 8C is an elevational view of the female hinge design taken along section line III—III of FIG.  8 B. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     FIG. 1 shows rack assembly  100  in accordance with a preferred embodiment of the present invention, disposed between aircraft frames  102  and  104 , inboard intercostal  106 , and outboard intercostal  108 . Rack assembly  100  is shown having long vertical rails  110  on the inboard side of rack assembly  100 , and short vertical rails  112  on the outboard side of rack assembly  100 . Two diagonal stiffeners  114  (only the inboard stiffener is shown in FIG. 1 for clarity) are used to minimize forward/aft deflections of rack assembly  100 . Similarly, two diagonal braces  116  (only the forward brace is shown in FIG. 1 for clarity) are used to minimize inboard/outboard deflections of rack assembly  100 . 
     Forward angle  118  and aft angle  120  form the lower forward and aft corners respectively of rack assembly  100 . Channel member  122  forms the lower outboard corner member of rack assembly  100 . A modified channel, forming a hinge channel  124  is shown in FIG. 1, as the lower inboard corner member of rack assembly  100 . Hinge channel  124  has at least one and preferably two male hinge members  126  extending inboard from the lower inboard corner of rack assembly  100 . For clarity, two male hinge members  126  will be described in further detail. Plate  128  provides at least one and preferably two female hinge members  130 . For clarity, two female hinge members  130  will be described in further detail. Female hinge members  130  each comprise an opening in plate  128 , and are together spaced and sized to accept male hinge members  126 . A space envelope for equipment  132  supported by rack assembly  100  is shown attached to plate  128 . 
     FIG. 1 further shows plate  128  in a working suspended position, wherein female hinge members  130  rotatably engage male hinge members  126 , and the weight of plate  128  with attached equipment  132  is gravity suspended from both the male hinge members  126  and hinge channel  124 . From the working suspended position shown in FIG. 1, a mechanic can pull connecting ends of adjacently supported wireway wires (not shown) directly to equipment  132 , or through one or more clearance openings  134  provided in plate  128  for this purpose. 
     Referring to FIG. 2, upon completion of wiring and system interconnections to equipment  132  in the working suspended position previously shown in FIG. 1, plate  128  with supported equipment  132  is rotated about ninety (90) degrees, about axis of rotation A, to the stored fixed position shown in FIG.  2 . In the stored fixed position, the mechanic fastens plate  128  to both forward angle  118  and aft angle  120  using mechanical fasteners  136 . Mechanical fasteners for fastening plate  128  are preferably one-quarter (¼) turn fasteners, but may be of any suitable type of removable fastener including screws, bolts, and studs with nuts. Quarter turn fasteners are preferred to permit one hand operation by a mechanic who simultaneously manually supports plate  128 . Forward angle  118  and aft angle  120  are both pre-machined to accept mechanical fasteners  136 , with fastener spacing corresponding to fastener spacing on plate  128 . 
     Referring now to FIGS. 3A,  3 B, and  3 C, an example of a hinge combination is shown. FIG. 3A is a section view taken along Section line I—I of FIG.  1 . FIG. 3B is a plan view of plate  128 . FIG. 3C is an elevational view of plate  128  taken along Section line II—II of FIG.  3 B. FIG. 3A shows male hinge member  126  fastened to the outward facing flange of long vertical rail  110  by at least one fastener  138 . Fastener  138  may be a bolt, rivet, or hole filling fastener. Plate  128  is shown in FIG. 3A in the stored fixed position. A rod  140  is tack welded to plate  128  providing axis of rotation “A” for plate  128 . This detail is better shown in FIGS. 3B and 3C. 
     FIG. 3B shows at least one and preferably two cutouts  142  machined in plate  128 , each having a width “W” equaling the width of male hinge member  126  plus clearance for rotation. Cutouts  142  permit plate  128 , with any associated pre-mounted equipment  132 , to extend over the looped free end, as shown in FIG. 1, of male hinge member  126 . Height “X” of cutout  142  is determined by the material thickness of male hinge member  126  plus a clearance allowance. Typical locations for mechanical fasteners  136  are also shown. The length of rod.  140  is about equal to the width “Y” of plate  128 . Rod  140  length may be shorter than width “Y” of plate  128 , providing the length of rod  140  provides for. at least a tack weld at tack weld positions  146  and  148  respectively. 
     FIG. 3C shows the positioning of rod  140  on plate  128  and one of a plurality of supporting tack welds  144  attaching rod  140  to plate  128 . 
     FIG. 4 is a section view similar to FIG. 3A, but with the orientation of male hinge member  126  reversed from the FIG. 3A orientation. The principal difference between FIGS. 3A and 4 is the method of installation differs in that plate  128  in FIG. 4 would be initially hung from male hinge member  126  by inserting rod  140  end of plate  128  into. the clearance area “Z” provided between forward, angle.  118  and male hinge member  126 , and simultaneously into a similar clearance area between aft angle  120  and male hinge member  126  (not shown). 
     FIG. 5 is a plan view of plate  228  showing cutouts  242 , both similar to plate  128  and cutouts  142  of FIG.  3 B. FIG. 5 differs from FIG. 3B as an example of a simplified version of manufacturing female hinge members. Rod  140  is omitted from the modified female hinge members  230 . Plate  228  has cutouts  242  sized similarly to cutouts  142  of FIG. 3B, however, cutouts  242  are spaced to retain thickness “T” as a substitute for rod  140 . The axis of rotation “B” of plate  228  is about the center of thickness “T”. 
     Referring now to FIG. 6, structural members of rack assembly  300  are similar to members shown in FIG. 1, as rack assembly  100 , and therefore only the differences will be discussed in further detail herein. Rack assembly  300  provides a pre-positioned drip tray  302 , providing overhead protection of equipment  304  mounted on plate  306 . Drip tray  302  comprises an assembly of top plate  308 , first and second side walls  310  and  312 , respectively, end wall  314 , and hinge channel  316 . Inside corner brackets (not shown) or similar hardware may be used to join or reinforce the corner joints of drip tray  302 . Also, first and second side walls,  310  and  312 , respectively, and end wall  314  may be bent from a single piece of material and subsequently joined to hinge channel  316 . 
     Plate  306 , has rod  318  and one or more cutouts  320  at a first end of plate  306 , similar to the configuration shown in FIG.  3 B. At the opposed second end of plate  306 , latch plate  322  is mounted, providing a surface for location of mechanical fasteners  324 , which are similar to mechanical fasteners  136 . 
     Functionally, plate  306 , having rod  318  and one or more cutouts  320 , similar to the configuration shown in FIG. 3B, will be initially hung in a working suspended position. Upon completion of wiring interconnections, the mechanic will swing plate  306  about ninety (90) degrees about axis of rotation “C” to a fixed supported position of plate  306 , similar to FIG.  2 . Mechanical fasteners  324  join with pre-located fastener mating holes  326  in end wall  314  to join latch plate  322  with end wall  314  in the fixed supported position. 
     Referring now to FIG. 7, another version of the present invention is shown. In this configuration, rack assembly  400  provides a box structure having one open end, and within the box, equipment is pre-mounted. A flat plate is pre-mounted to the rack structure in the aircraft, similar to the attachment of drip tray  302  of FIG.  6 . The box structure is hinged to the flat plate, such that when rotated to the fixed stored position, the equipment is completely enclosed. An alternate hinge detail Is also shown in FIG. 7. A description of the preferred use of two hinges is provided. 
     Structural members of rack assembly  400  are similar to members shown in FIG. 1, rack assembly  100 , and therefore only the differences will be discussed in further detail herein. Rack assembly  400  provides a pre-positioned plate  402 , providing overhead protection of equipment  404  mounted therefrom in box structure  406 . Box structure  406  comprises an assembly of bottom plate  408 , first side wall  410  and second side wall  412 , and first end wall  414 , and second end wall  416 . Inside corner brackets (not shown) or similar hardware may be used to join or reinforce the corner joints of box structure  406 . Also, first and second side walls,  410 ,  412 , together with first and second end walls  414 ,  416  may be bent from a single piece of material. A reinforcing flange  418  provides perimeter stiffness for box structure  406 . Reinforcing flange  418  may be formed of a separate piece and subsequently fastened or tack welded to first and second side walls  410  and  412 , and first and second end walls  414  and  416 , or reinforcing flange  418  may be formed from the material of first and second side walls  410  and  412 , and first and second end walls  414  and  416 , and bent or rolled to form the flange shape shown. 
     Plate  402  has at least one and preferably two female hinge member(s)  420  attached or integrally formed at a first end of plate  402 . At the opposed second end of plate  402 , latch plate  422  is disposed, perpendicular to plate  402 . Latch plate  422  provides a surface for location of mechanical fasteners  424 , which are similar to mechanical fasteners  136 . 
     Box structure  406  provides at least one and preferably two male hinge member(s)  426  disposed on an outward facing surface of first end wall  414 , adjacent to reinforcing flange  418 . Male hinge members  426  are dimensionally positioned to slidably engage female hinge members  420  via hinge pin  428 . Hinge plate  430  fixedly supports hinge pin  428 , and hinge plate  430  itself is then fixedly attached to first end wall  414  with fasteners (not shown). 
     Functionally, box structure  406  will be initially hung in a working suspended position by slidably engaging male hinge members  426  and female hinge members  420 . Upon completion of wiring interconnections, the mechanic will swing box structure  406  about ninety (90) degrees about axis of rotation D to a fixed supported position of box structure  406 , similar to FIG.  2 . Mechanical fasteners  424  join with pre-located fastener mating holes  432  in second end wall  416  to join latch plate  422  of plate  402  to second end wall  416  and thus fasten box structure  406  in the fixed supported position. Additionally, one or more wiring through bores  434  are provided to route equipment wiring (not shown) into box structure  406 . Wiring through bores  434  may be subsequently hermetically sealed. Box structure  406  and equipment  404  together form an equipment package. 
     Referring now to FIGS. 8A,  8 B, and  8 C, a further example of a hinge combination is shown. FIG. 8A is a section view taken along Section line I—I of FIG. 1, similar to FIG.  3 A. FIG. 8B is a plan view of plate  528  (similar to plate  128 ). FIG. 8C is an elevational view of plate  528  taken along Section line III—III of FIG.  8 B. FIG. 8A shows male hinge member  126  fastened to the outward facing flange of long vertical rail  110  by at least one fastener  138  as previously described for FIG.  3 A. Plate  528  is shown in FIG. 8A in the stored fixed position. A rolled end section  540  (substituted for rod  140  of FIG.  3 A), is rolled from extra stock length provided on plate  528  for this purpose. Rolled end section  540  provides. axis of rotation “E” for plate  528  as shown in FIG.  8 B. 
     FIG. 8B shows at least one and preferably two cutouts  542  formed in plate  528 , each having a width “W′”, similar to width “W” of FIG. 3B, equaling the width of male hinge member  126  plus clearance for rotation. Cutouts  542  permit plate  528 , with any associated pre-mounted equipment  132 , to extend over the looped free end, (similar to plate  128  as shown in FIG.  1 ), of male hinge member  126 . Height “X′” of cutout  542 , similar to height “X” of FIG. 3B, is determined by the material thickness of male hinge member  126  plus a clearance allowance. Typical locations for mechanical fasteners  136  are also shown. The length of rolled end section  540  is about equal to the width “Y′” of plate  528 . The width “Y” of plate  128  and the width “Y′” of plate  528  are about equal. 
     FIG. 8C shows the positioning and detail of rolled end section  540  on plate  528 . Diameter “F” of rolled end section  540  is about equal to the diameter of rod  140  plus the thickness (not shown) of plate  128  of FIG.  3 A. 
     The plate thickness for plate  128  and plate  528 , the dimensions of diameter “F” and the diameter of rod  140 , and the curvature of male hinge member  126  may be varied to suit a weight of any given equipment package. 
     The invention provides the advantages of an improved method of installing equipment racks on aircraft, by providing a temporary support position accessible for wiring equipment connections. A single mechanic can both support and mount equipment, thus reducing installation time and cost. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. For example, locations of the male and female hinges may be reversed, alternatives other than those described herein for a design of a male or female hinge section may be employed, or the hinges may be located on any of the sides formed by the rack structure, eg. the hinges may be located to center the axis of rotation of the equipment package on the forward, aft, inboard, or outboard facing side of the rack structure to suit accessibility to the equipment. Fastener location may also vary to suit accessibility to the fasteners or for surrounding installation clearance. Such variations are not to be regarded as a departure from the spirit and scope of the invention.