Patent Publication Number: US-11396357-B2

Title: Aircraft security door and method and apparatus for security door handling

Description:
FIELD 
     Aspects of the present disclosure provide a method and apparatus for transfer of objects to and from an aircraft. More specifically, implementations disclosed herein relate to an aircraft security door as well as handling an aircraft security door. 
     BACKGROUND 
     The present disclosure relates to an aircraft security door, and more specifically, to methods and apparatus for handling an aircraft security door. Aspects of the disclosure may also be applicable to moving other objects to and from an aircraft with improved safety. 
     Whenever there is a need to load or unload parts or equipment to or from an aircraft, the item is typically carried by hand up or down a stairway, often referred to as an aircraft service stair, or the item is lifted to the aircraft directly by a forklift and pallet or other means. 
     Conventionally, aircraft security doors, which are utilized during servicing of aircraft, are lifted using a pallet and forklift to the platform of the aircraft service stair. The security door is laid down on the pallet which is lifted to the platform, and personnel then move the security door from the pallet onto the platform. The security door typically has a weight that is greater than about 180 pounds, which typically requires more than one person to transfer the door from the pallet to the platform. 
     This method of transfer introduces numerous difficulties, due to, for example, reduced space on the platform, and the weight of the doors. Further, laying the door down on the pallet and/or moving the door from the pallet to the platform may damage the door. 
     SUMMARY 
     The present disclosure provides an aircraft security door as well as methods and apparatus for handling an aircraft security door. 
     In one implementation, a bridge crane for supporting an aircraft security door on an aircraft service stair is provided. The bridge crane includes a frame supported by a plurality of posts, two first rail members coupled to the frame that extend in an X direction in a substantially parallel relationship, wherein first ends of each of the first rail members are coupled to a first end rail extending in a Y direction and second ends of each of the first rail members are coupled to a second end rail extending in the Y direction, the Y direction substantially orthogonal to the X direction, each of the first and second end rails being substantially parallel to each other, a trolley positioned on a trolley frame that is movable along the first rail members in the X direction and the Y direction, and a brake assembly for immobilizing the trolley frame relative to the first rail members and the first and second end rails. 
     In another implementation, a bridge crane for supporting an aircraft security door on an aircraft service stair is provided. The bridge crane includes a frame supported by a plurality of posts, two first rail members coupled to the frame that extend in an X direction in a substantially parallel relationship, wherein ends of each of the first rail members are coupled to an end rail extending in a Y direction, which is substantially orthogonal to the X direction, each of the end rails being substantially parallel to each other, a trolley positioned on a trolley frame that is movable along the first rail members in the X direction and the Y direction, and a brake assembly for immobilizing the trolley frame relative to the first rail members and the end rails, the brake assembly including a locking bracket that is coupled to a sidewall of the trolley frame and a plurality of pins that selectively interact with the locking bracket. 
     In another implementation, a method for installing an aircraft security door onto an aircraft is disclosed that includes transferring the aircraft security door to an aircraft service stair, supporting the aircraft security door by a bridge crane coupled to the aircraft service stair, positioning the aircraft service stair in proximity to a fuselage of the aircraft adjacent to an opening in the fuselage, positioning the aircraft security door relative to the opening using the bridge crane, and securing the aircraft security door to the opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. 
         FIGS. 1A-1G  are various views of an aircraft security door. 
         FIG. 2  is an enlarged perspective view of a portion of a fuselage of an aircraft and a portion of the aircraft security door is shown in an opening of the fuselage. 
         FIG. 3A  is a perspective view of the aircraft security door coupled to a transport pallet. 
         FIG. 3B  is a perspective view of the aircraft security door on the transport pallet being transferred to a platform of an aircraft service stair. 
         FIG. 3C  is an enlarged perspective view of the transfer process of  FIG. 3B . 
         FIG. 3D  shows the transport pallet to the platform of the aircraft service stair. 
         FIGS. 4A-4C  are various perspective views showing handling procedures of the aircraft security door on the aircraft service stair. 
         FIG. 5A  is an isometric view of the bridge crane shown on the aircraft service stair of  FIGS. 4A-4C . 
         FIG. 5B  is an enlarged perspective view of the trolley of the bridge crane of  FIG. 5A . 
         FIG. 5C  is an enlarged perspective view of the trolley frame of the bridge crane of  FIG. 5A . 
         FIG. 5D  is a side view of the brake assembly of the bridge crane. 
         FIG. 5E  is a bottom perspective view of the brake assembly of the bridge crane. 
         FIG. 5F  is a cross-sectional view of a portion of the brake assembly along lines  5 F- 5 F of  FIG. 5D . 
         FIG. 6A  is an isometric view of the transport pallet of  FIGS. 3A-3D . 
         FIG. 6B  is an elevation view of the transport pallet of  FIG. 6A . 
         FIG. 6C  is an isometric view of the transport pallet with the folding structure in an upright position to support the aircraft security door. 
         FIG. 6D  is a top plan view of the transport pallet and the aircraft security door shown in  FIG. 6C . 
         FIG. 6E  is a sectional view of the transport pallet and the aircraft security door along lines  6 E- 6 E of  FIG. 6D . 
         FIG. 6F  is an enlarged view of a portion of the transport pallet and the aircraft security door shown in  FIG. 6E . 
         FIGS. 7A and 7B  are perspective views of the transport pallet showing operation of the folding structure. In  FIG. 7A , the folding structure is in an upright position to support the aircraft security door (not shown) and the folding structure is shown in a stowed position in  FIG. 7B . 
         FIGS. 7C-7D  are enlarged views of portions of the second railing showing coupling interfaces of the folding structure. 
         FIGS. 8A and 8B  show another portion of the installation system and/or installation method configured to transfer the aircraft security door to an aircraft and couple the aircraft security door thereto as described herein, continued from  FIGS. 3A-4C  above. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides an aircraft security door as well as methods, systems and apparatus for improved handling of an aircraft security door. 
       FIGS. 1A-1G  are various views of an aircraft security door  100 . The aircraft security door  100  is utilized to temporarily couple to a fuselage of an aircraft (not shown) to provide ingress and egress to the aircraft during servicing of the aircraft in lieu of utilizing the flight door of the aircraft. For example, when servicing the aircraft, service personnel enter and exit the aircraft multiple times. Aircraft flight doors are expensive to maintain and replace and opening and closing the flight door damages components on the flight door, such as seals and/or latches. Damage to these components reduces the lifetime of the flight door. However, utilizing the aircraft security door  100  as described herein, a comfortable atmosphere can be maintained in the aircraft during servicing while allowing ease of entry and exit to service personnel. For example, while the aircraft security door  100  is not pressurizable like the flight door, climate controls on the aircraft can be utilized to heat or cool the aircraft during servicing with minimal thermal losses through the aircraft security door  100 . In addition, security of the aircraft being serviced is maintained utilizing the aircraft security door  100  as described herein. 
     The aircraft security door  100  includes a door panel  105  that is hingedly coupled to a frame  110 . The frame  110  is a multi-component assembly that includes a base portion  112 , a roof portion  113 , and side portions  114  on each side of the base portion  112  and the roof portion  113 . The base portion  112  includes a plurality of tubular members  109 A and  1098  aligned along a width of the aircraft security door  100 . As shown in  FIG. 1G , the base portion  112  extends along a lateral direction (a Y-X plane) a first depth D, and the roof portion extends along the lateral direction a second depth D′, with the second depth D′ being greater than the first depth D. Each of the side portions  114  includes a jamb, such as a first jamb  115  and a second jamb  116  positioned on opposing sides of the door panel  105 . Each of the first jamb  115  and the second jamb  116  are coupled to the tubular member  109 A. Each of the side portions  114  includes an arc-shaped member  119 . The arc-shaped member  119  is curved to match a contour of an aircraft fuselage (not shown). For example, the arc-shaped member  119  includes a concave shape that substantially matches a convex shape of the fuselage. A water/pressure tight seal (not shown) is provided between the arc-shaped member  119  and the fuselage when the aircraft security door  100  is installed. The arc-shaped member  119  of the aircraft security door  100  is sized to accommodate both wide-body and narrow-body aircraft. The door panel  105  includes a sliding member  107  that opens and closes relative to an opening in the door panel  105 . The sliding member  107  may be opened manually by moving the sliding member  107  laterally or vertically. A transparent window  108  (shown in  FIG. 1D ) is positioned behind the sliding member  107 . Sliding the sliding member  107  to expose the transparent window  108  is utilized to identify personnel through the door panel  105 . The transparent window  108  may be a shatter resistant glass or plastic material. 
     The door panel  105  is coupled to the first jamb  115  by a hinge  117 . The hinge  117  may be a continuous hinge or a piano hinge. The hinge  117  allows the door panel  105  to rotate about a rotational axis  118  (shown in  FIG. 1A ) to allow the door panel  105  to open and close relative to the second jamb  116 . In the closed position as shown, the door panel  105  is secured by a plurality of locking devices such as a first lock member  120  and a second lock member  122 . 
     The aircraft security door  100  is configured to be the weakest point of entry to an aircraft. For example, while the aircraft security door  100  as described herein may be locked to prevent ingress to the interior of the aircraft, the first lock member  120  and the second lock member  122  can be breached if sufficient force is used. While unauthorized access to the aircraft is not preferred, allowing access to unauthorized persons through the aircraft security door  100  prevents damage to other portions of the aircraft by the unauthorized persons. However, unauthorized access through the aircraft security door  100  will be evident by one or both of the first lock member  120  and the second lock member  122 . Further, security cameras trained on the aircraft security door  100  are used to capture images of the unauthorized persons entering and/or exiting the aircraft. 
     One or both of the first lock member  120  and the second lock member  122  comprise tamper evident locks  124  that may be utilized to indicate unauthorized access to the aircraft. The first lock member  120  may be a combination lock  126  having a handle  128 . The first lock member  120  may be a high security pedestrian door lock that has a keypad or biometric device that restricts access to all but authorized personnel. The second lock member  122  may be a sliding deadbolt lock that can be secured in a locked position by a tamper evident locking device, such as a padlock seal, a security seal or a security padlock. However, both of the first lock member  120  and the second lock member  122  can be breached upon application of sufficient force to allow access to unauthorized personnel. This makes the aircraft security door  100  the easiest point of entry to the aircraft and prevents damage to other parts of the aircraft when unauthorized persons attempt to enter the aircraft. Further, any fasteners that are accessible on outwardly facing sides or surfaces of the frame  110  are tamper proof fasteners (described in more detail below) which makes the aircraft security door  100  more difficult to breach. For example, the construction of the aircraft security door  100  is configured to make an attempted breach by opening the door panel  105  (e.g., breaking in to the aircraft via a breach of one or both of the lock members  120  and  122 ). 
     The side portions  114  as well as the door panel  105  include one or more vents  130 . The vents  130  prevent over-pressurization in the fuselage of the aircraft. Each of the side portions  114  includes a utility pass-through box  132 . Each utility pass-through box  132  includes a cover  133 . The cover  133  is opened to access an opening  134  (shown in  FIG. 1E ) formed through each of the side portions  114 . Each utility pass-through box  132  is utilized to route wires or cables through the side portions  114 , if necessary. The side portions  114  as well as the door panel  105  include one or more handles  136 . Each of the handles  136  are utilized to position and/or move the aircraft security door  100  during installation and removal. The handles  136  on the door panel  105  are recessed or flush pull handles  138  that are recessed into the door panel  105 . The handles  136  on the side portions  114  are one or a combination of rigid pull handles  140  and folding pull handles  142 . Each of the side portions  114  includes a first or exterior surface  144  and a second or interior surface  146  (both shown in  FIG. 1E ). The side portions  114  include one or more folding pull handles  142  on each of the exterior surface  144  and the interior surface  146 . 
     The majority of the aircraft security door  100  is made of metallic materials that resist corrosion, such as aluminum and stainless steel. The frame  110  is either welded or coupled together using fasteners, such as bolts or screws. Portions of the fasteners comprise tamper proof security screws  123 . For example, the fasteners for the hinge  117  and the vents  130 , as well as any fasteners that are accessible on the outwardly facing surfaces of the door panel  105  and the side portions  114 , are tamper proof security screws  123 . 
     Each of the side portions  114  includes one or more hook points  148 . Each of the hook points  148  are utilized to secure the aircraft security door  100  to a transfer pallet (not shown but described in detail below). For example, when the aircraft security door  100  is transferred, tie-down straps are coupled between the transfer pallet and the aircraft security door  100  to secure the aircraft security door  100  to the pallet. 
     In some implementations, transfer wheels  150  are coupled to the frame  110 . The transfer wheels  150  aid in moving the aircraft security door  100  and/or positioning of the aircraft security door  100  during installation or removal of the aircraft security door  100 . 
     The base portion  112  of the aircraft security door  100  includes a floor portion  152 . The floor portion  152  includes a ramp  154 . The ramp  154  has a portion  156  that extends into the aircraft (not shown). 
     The roof portion  113  includes a slanted roof panel  158 . The slanted roof panel  158  is angled to allow water, such as rain, to flow off a lower side of the roof portion  113 . As shown in  FIG. 1F , the slanted roof panel  158  is slanted at an angle  160  of about 5 degrees to about 15 degrees relative to a plane of the base portion  112  (e.g., horizontal). 
     The roof portion  113  includes one or more storage blocks shown as long storage blocks  162  and short storage blocks  164 . The storage blocks  162 ,  164  are utilized to store the aircraft security door  100  when the aircraft security door  100  is not in use. The heights of the storage blocks  162 ,  164  are different in order to account for the angle  160  of the slanted roof panel  158 . Therefore, when the aircraft security door  100  is stored in an upside down orientation, the base portion  112  is coplanar with horizontal. The storage blocks  162 ,  164  may be made of a thermoplastic material or a foam material. The storage blocks  162 ,  164  are removably fastened to the frame  110  to facilitate removal, if desired. While not shown, storage blocks may be included on the base portion  112 . 
     The roof portion  113  also includes a hoist ring  166 . The hoist ring  166  is utilized to transfer and/or position the aircraft security door  100  during installation or removal. The hoist ring  166  is configured to couple to a hook (not shown) that is utilized to suspend, lift and/or lower the aircraft security door  100 . The hoist ring  166  is located at a position that is the center of gravity of the aircraft security door  100 . Therefore, the aircraft security door  100  may be suspended and/or moved in a balanced upright orientation. 
     The aircraft security door  100  is attached to the aircraft using a plurality of clamps and hooks. The clamps and hooks are shown as first clamp devices  168  and second clamp devices  170  in  FIGS. 1D-1G  and  FIG. 2 . 
       FIG. 2  is an enlarged perspective view of a portion of a fuselage  200  of an aircraft  205 . A portion of the aircraft security door  100  is shown in an opening  210  of the fuselage  200 . In  FIG. 2 , the perspective view is from the vantage point looking out from the opening  210 . One of the first clamp devices  168  and one of the second clamp devices  170  is shown coupled to the fuselage  200 . The first clamp devices  168  are configured as a safety latch that rotates about a rotational axis  215 . Each of the first clamp devices  168  include an L-shaped hook  220  that is configured to fix the aircraft security door  100  onto the fuselage  200 . The first clamp devices  168  may include a locking mechanism  225  that prevents the L-shaped hook  220  from moving in the rotational axis  215 . 
     However, the aircraft security door  100  may move slightly relative to the opening  210 , and the second clamp devices  170  are utilized to further fix the aircraft security door  100  to the fuselage  200 . Each of the second clamp devices  170  are locking clamps, such as locking toggle clamps. Each of the second clamp devices  170  include a series of levers and pivot points operable by a movable handle  230 . Movement of the handle  230  applies a force against the fuselage  200  via an adjustable spindle  235  to clamp the aircraft security door  100  onto the aircraft  205 . However, movement of the handle  230  in an opposite direction releases the adjustable spindle  235  from the aircraft  205 . 
       FIGS. 3A-4C  are various schematic views showing a portion of an installation system and/or installation method configured to transfer the aircraft security door  100  to an aircraft and couple the aircraft security door  100  thereto as described herein.  FIGS. 3A-3D  show the aircraft security door  100  being transferred to an aircraft service stair;  FIGS. 4A-4C  show handling methods for the aircraft security door  100  when it is on the aircraft service stair; and  FIGS. 8A-8B  show the aircraft security door  100  being installed on the fuselage of an aircraft. 
     In  FIG. 3A , the aircraft security door  100  is shown coupled to a transport pallet  300 . The transport pallet  300  is disposed on a forklift  305  that moves the transport pallet  300  about the aircraft  205 . The aircraft security door  100  as well as the transport pallet  300  is foreign object debris (FOD) compliant in order to creation of reduce foreign object damage from portions of the aircraft security door  100  and/or the transport pallet  300 . 
     The transport pallet  300  includes a first railing  310  and a second railing  315 . The first railing  310  is fixed to a base member  320  in an upright orientation. The first railing  310  may be utilized as a safety railing for personnel working on the base member  320 . The second railing  315  is utilized as a support member for the aircraft security door  100 . Straps  321 , coupled between the transport pallet  300  and the hook points  148 , are utilized to secure the aircraft security door  100  during transport. 
     The second railing  315  is fixed to the base member  320  by one or more hinge devices  322 . The hinge devices  322  comprise a folding structure  324  that allows the second railing  315  to fold into a stowed position. 
     The transport pallet  300  is made of aluminum materials to be lightweight and weather resistant. The base member  320  includes slots formed in sidewalls thereof that receive forks of the forklift  305 . 
       FIG. 3B  is a perspective view of the aircraft security door  100  on the transport pallet  300  being transferred to a platform  326  of an aircraft service stair  328 .  FIG. 3C  is an enlarged perspective view of the transfer process of  FIG. 3B . 
     The aircraft service stair  328  is similar to other stairways used in the aviation industry. The aircraft service stair  328  may be sized for a wide body aircraft or a narrow body aircraft. A bridge crane  330  that facilitates handling of the aircraft security door  100  is positioned on the platform  326 . 
     The aircraft service stair  328  is height adjustable and the platform  326  may be adjusted to a specific height for installation of the aircraft security door  100  in the opening  210  of the fuselage  200 . The forklift  305  lifts the transport pallet  300  and the aircraft security door  100  to this height and moves the transport pallet  300  laterally above an upper surface of the platform  326 . 
     In  FIG. 3D , the transport pallet  300  is transferred onto the platform  326  of the aircraft service stair  328 . The aircraft security door  100  remains in an upright orientation being secured to the second railing  315  and the transport pallet  300 . Personnel (not shown) that install the aircraft security door  100  may climb onto the platform  326  to secure the aircraft security door  100  to the bridge crane  330 . 
     Specifically, a hook  332  of the bridge crane  330  is coupled to the hoist ring  166  coupled to the aircraft security door  100 . The bridge crane  330 , which will be explained in detail in  FIGS. 5A-5F , is utilized to lift the aircraft security door  100  a small distance above the base member  320  of the transport pallet  300 . For example, the bridge crane  330  may lift the aircraft security door  100  only about 6 inches, or less, above the base member  320  if the transport pallet  300  to suspend the aircraft security door  100  above the transport pallet  300 . 
       FIGS. 4A-4C  are various perspective views showing handling procedures of the aircraft security door  100  on the aircraft service stair  328 . The platform  326  of the aircraft service stair  328  has a stair case side  400  and an aircraft side  405  opposite the stair case side  400 . 
     In  FIG. 4A , the transport pallet  300  is resting on the platform  326  of the aircraft service stair  328 . A safety net  410  is stretched across an opening formed on the aircraft side  405  of the platform  326 . The safety net  410  may be secured to side posts  415  of the platform  326  by a plurality of coupling members  420  in one implementation. Each of the plurality of coupling members  420  may be a combination of D-rings and snap hooks that are secured by personnel. In another implementation, the safety net  410  may be a curtain that is movably suspended by a top rail  425 . The curtain type safety net  410  may be secured using the plurality of coupling members  420 . 
     The transport pallet  300  is positioned on the platform  326  such that the first railing  310  is outside of the safety net  410 . However, the first railing  310  may be utilized as a safety railing when personnel are deploying the safety net  410 . After the safety net  410  is installed, and the aircraft security door  100  is suspended by the bridge crane  330 , the transport pallet  300  may be removed from the platform  326  by the forklift  305  (not shown). To remove the transport pallet  300 , the second railing  315  is folded to a stowed position via the folding structure  324  (The folding structure is explained in more detail in  FIGS. 7A and 7B ). 
     A gap  430  is provided between the safety net  410  and a surface  435  of the platform  326 . The gap  430  is sized to allow the transport pallet  300 , with the second railing  315  in a stowed position, to be move under the safety net  410  using the forklift  305  (not shown). The transport pallet  300  may then be stored on the aircraft service stair  328  which is shown in  FIG. 8A . 
       FIG. 4C  shows the aircraft security door  100  suspended by the bridge crane  330 . The aircraft security door  100  cab be lifted or lowered (in the Z direction) relative to the surface  435  of the platform  326 , as well as rotated about a rotational axis  440  of the hook  332  of the bridge crane  330 . The bridge crane  330  also includes a trolley structure  450  that enables movement of the hook  332 , with the aircraft security door  100  suspended thereon, laterally (in an X-Y plane). 
       FIG. 5A  is an isometric view of the bridge crane  330  with the aircraft security door  100 . The aircraft security door  100  is shown suspended from the hook  332  of the trolley structure  450 . 
     The bridge crane  330  includes a frame  500  that is supported by a plurality of support members  505 , such as posts. Each of the support members  505  include a mounting plate  510  that may be used to couple the frame  500  to the surface  435  of the platform  326  (shown in  FIG. 4B ). The frame  500  also includes two first rail members  515  that extend in the X direction in a substantially parallel relationship. Ends of each of the first rail members  515  are coupled to one or both of the support members  505  and an end rail  520  extending in the Y direction. A trolley  525  is positioned on a trolley frame  530  that is movable along the first rail members  515  in the X direction. 
     The trolley frame  530  includes two second rail members  535  that support the trolley  525 . The second rail members  535  extend in the Y direction in a substantially parallel relationship and the trolley  525  is also movable in the Y direction. Each end of the second rail members  535  are coupled to a rolling member  540 . The rolling members  540  are movably coupled to the two first rail members  515  and allow the trolley frame  530  to roll along the two first rail members  515  in the X direction. 
     On one short side of the frame  500 , two cross members  507  are provided between two of the support members  505 . Additionally, a cradle assembly  508  is shown on the short side of the frame  500 . The cradle assembly  508  engages a lower portion of the aircraft security door  100  when the aircraft security door  100  is positioned adjacent thereto. The cradle assembly  508  is a channel that is sized to receive a portion of the tubular member  109 A of the aircraft security door  100  in a manner similar to the cradle  625  shown in  FIG. 6F . While not explained in detail, the cradle assembly  508  is constructed similarly to the cradle  625  described in  FIG. 6F . 
     When the aircraft security door  100  is positioned as shown in  FIG. 5A , the aircraft security door  100  is in a “locked” or “docked” position on the bridge crane  330 . This “locked” or “docked” position allows the bridge crane  330  and the aircraft security door  100  to be moved (using a forklift and/or rolling movement of the aircraft service stair  328  (not shown) between aircraft and/or a hangar and an aircraft. A plurality of door blocks  509  are utilized between the support members  505  and corners of the aircraft security door  100 . The door blocks  509  are utilized as a guide as well as cushioning members to prevent damage to the aircraft security door  100 . Each of the door blocks  509  may be made of a polymeric material, such as a polyoxymethylene (POM) material. 
       FIG. 5B  is an enlarged perspective view of the trolley  525  on the second rail members  535 .  FIG. 5C  is an enlarged perspective view of the trolley frame  530 . The trolley  525  includes a hoist  545  that is coupled to the hook  332 . The hoist  545  includes a lead screw  556  and a gear motor  558 . The lead screw  556  is coupled to the hook  332  by a swivel connector  547  (shown in  FIG. 5C ). The gear motor  558  is coupled to a shaft  560  and a pulley  562 . The chain  550  is coupled to the pulley  562 . Rotation of the pulley  562  rotates the shaft  560  and the gear motor  558  moves the lead screw  556  (and the hook  332 ) up or down (depending on the direction of rotation of the pulley  562 ). For example, the chain  550  has a first hanging portion  564 A and a second hanging portion  564 B. When the first hanging portion  564 A is pulled downward, the pulley  562  (and the shaft  560 ) is rotated in a clockwise direction. Alternatively, when the second hanging portion  564 B is pulled downward, the pulley  562  (and the shaft  560 ) is rotated in a counter-clockwise direction. Thus, personnel can raise or lower the aircraft security door  100  in the Z direction by pulling the respective hanging portions of the chain  550  down. When the chain  550  is not pulled, the gear motor  558  does not allow the shaft  560  to move, which facilitates stable suspension of the aircraft security door  100 . 
     The hoist  545  is a simple mechanism and is constructed and/or operated with no cables. 
     The trolley  525  includes two rolling members  566  that allow the trolley  525  to roll along a length of the second rail members  535 . Each of the rolling members  566  includes rollers  568 . While not shown, the rolling members  540  on the trolley frame  530  are constructed similarly to the rolling members  566 , and include rollers  568 . The trolley structure  450  also includes a brake assembly  570 . The brake assembly  570  is coupled to a sidewall  572  of the trolley structure  450  and is configured to lock the trolley structure  450  in the X and Y directions by coupling with the end rail  520 . 
     In order to place the tubular member  109 A of the aircraft security door  100  into the cradle assembly  508  of  FIG. 5A , the aircraft security door  100  is lifted by the hoist  545  to clear an angled sidewall  511  of the cradle assembly  508 . The aircraft security door  100  is then guided toward the support members  505  and the door blocks  509 . Thereafter, the aircraft security door  100  may be lowered into the cradle assembly  508  by the hoist  545 . Tie-down straps, such as the straps  321  (shown in  FIG. 3A ), may be used to secure the aircraft security door  100  to the frame  500 . For example, tie-down straps may be coupled between the support members  505  and the hook points  148  (shown in  FIG. 5A ) to secure the aircraft security door  100  during transport. 
       FIGS. 5D and 5E  are various views of the brake assembly  570 .  FIG. 5D  is a side view of the brake assembly  570  and  FIG. 5E  is a bottom perspective view of the brake assembly  570 . 
     The brake assembly  570  includes a locking bracket  574  that is coupled to the sidewall  572  of the trolley structure  450 . The brake assembly  570  also includes a locking mechanism  576  coupled to the end rail  520 . The locking mechanism  576  is fixed to the end rail  520 . The locking bracket  574  is fastened to the sidewall  572  of the trolley structure  450  and moves with the trolley structure  450  when not locked in by the locking mechanism  576 . However, when the locking bracket  574  is engaged by the locking mechanism  576 , the trolley structure  450  is in a “docked” or “locked” position. 
     The locking mechanism  576  includes a plurality of pins  578  that are movable in the Z direction into and out of engagement with the locking bracket  574 . The plurality of pins  578  include a spring loaded mechanism adapted to engage the pins with the locking bracket  574 . One or more pull cords  594  are coupled with the locking mechanism  576  to facilitate movement of the pins  578  into and out of engagement with the locking bracket  574 . 
       FIG. 5F  is a cross-sectional view of one of the pins  578  that are engaged with a notch  580  formed in the locking bracket  574  along lines  5 F- 5 F of  FIG. 5D . 
     In one implementation, the end rail  520  is a strut made of an aluminum material having a structural shape as shown in  FIG. 5F . The structural shape shown in  FIG. 5F  is marketed by the Bosch Group as struts sold under the tradename REXROTH®. Other structural members of the frame  500  may be the same as the end rail  520 , such as the support members  505 , the first rail members  515  and the second rail members  535 . 
     The pins  578  (only one is shown in  FIG. 5F ) are movably disposed in openings  582  (only one is shown) in a circular web  584  of the end rail  520 . When the pins  578  engage with the notch  580  as shown in  FIG. 5F , the trolley  525  is laterally fixed relative to the end rail  520  and the frame  500 . 
     The end rail  520  also includes grooves  586 A- 596 D formed between corner structures  588 . The rollers  568  of the rolling members  566  of the trolley  525  include a ridge that is sized to fit into the groove  586 A. The ridge of the rollers  568  and the groove  586 A facilitate alignment of the trolley  525  during relative movement thereof. 
     To disengage the pins  578  and allow lateral movement of the trolley  525  relative to the end rail  520 , the locking mechanism  576  is utilized. Referring to  FIGS. 5D and 5E , the locking mechanism  576  includes a pull cord  594  operably coupled to each of the pins  578 . When the pull cords  594  are pulled downward by personnel, the pins  578  move downward in the direction of arrow A, thereby releasing the pins  578  from the notch  580  in the locking bracket  574 . Thus, the trolley  525  is able to move laterally as long as the pull cords  594  are pulled or held downward by personnel to disengage the pins  578  from the respective notch  580 . 
       FIG. 6A  is an isometric view of the transport pallet  300  of  FIGS. 3A-3D .  FIG. 6B  is an elevation view of the transport pallet  300  of  FIG. 6A . In  FIGS. 6A and 6B , the folding structure  324  is in an upright position such that the second railing  315  is rigidly fixed to the base member  320 . 
     The base member  320  includes two short sides  600 A on opposing ends thereof and two long sides  600 B on opposing ends thereof. The first railing  310  is provided on one of the long sides  600 B along a length thereof and the second railing  315  is foldable in a transverse relation to one of the long sides  600 B. 
     The base member  320  includes a first plate or top plate  605  and a second plate or bottom plate  608  in a spaced apart relation to the top plate  605 . Multiple slots  610  are formed between the top plate  605  and the bottom plate  608  to receive forks from a forklift (not shown). The slots  610  are provided on the short sides  600 A and the long sides  600 B. 
     Anchor points  612  are also shown on two first rigid support members  614  of the second railing  315 . The anchor points  612  are utilized to attach the straps  321  (shown in  FIG. 3A ). One set of hinge devices  322  are coupled between the top plate  605  and each of the first rigid support members  614 . 
       FIGS. 6C-6E  are various views of the transport pallet  300  supporting the aircraft security door  100  of  FIGS. 1A-1G .  FIG. 6C  is an isometric view of the transport pallet  300  with the folding structure  324  in an upright position to support the aircraft security door  100 .  FIG. 6D  is a top plan view of the transport pallet  300  and the aircraft security door  100  shown in  FIG. 6C .  FIG. 6E  is a sectional view of the transport pallet  300  and the aircraft security door  100  along lines  6 E- 6 E of  FIG. 6D . 
     The aircraft security door  100  rests on the transport pallet  300  and is secured in an upright position by the second railing  315 . The second railing  315  includes a pad  615 , made of foam rubber or other elastic material, to protect the aircraft security door  100 . 
     Referring to  FIG. 6E , the base portion  112  of the aircraft security door  100  rests on a raised support member  620 . The raised support member  620  is coupled to the top plate  605  of the transport pallet  300 . Details of the interface between the aircraft security door  100  and the raised support member  620  are discussed in  FIG. 6F . 
       FIG. 6F  is an enlarged view of a portion of the transport pallet  300  and the aircraft security door  100  shown in  FIG. 6E . The raised support member  620  includes a cradle  625  that supports and holds the aircraft security door  100  relative to the transport pallet  300 . The cradle  625  is a channel that is sized to receive a portion of the tubular member  109 A of the aircraft security door  100 . The cradle  625  includes an angled sidewall  511  that is angled about 45 degrees relative to a plane of the top plate  605 . The cradle  625  also includes a backstop sidewall  635  that is angled about 90 degrees from a plane of the top plate  605 . The backstop sidewall  635  prevents movement of the aircraft security door  100  towards the second railing  315 . The angled sidewall  511  also prevents movement of the aircraft security door  100  away from the second railing  315  while also permitting removal of the aircraft security door  100  with little effort. The cradle  625  is made of a polymeric material, such as an ultra-high molecular weight (UHMW) plastic material. 
       FIGS. 7A and 7B  are perspective views of the transport pallet  300  showing operation of the folding structure  324 . In  FIG. 7A , the folding structure  324  is in an upright position to support the aircraft security door  100  (not shown) and the folding structure  324  is shown in a stowed position in  FIG. 7B .  FIGS. 7C-7D  are enlarged views of portions of the second railing  315  showing coupling interfaces of the folding structure  324 . 
     The folding structure  324  of the second railing  315  includes the first rigid support members  614  and two second rigid support members  700 . A first coupling interface  705  is shown in  FIG. 7C . The first coupling interface  705  includes a pair of ears  710  extending from a lateral support member  715  coupled to the first rigid support members  614 . The first coupling interface  705  also includes a fastener  720  that interfaces with openings formed in the ears  710  and an opening in the second rigid support members  700 . In some implementations, the fastener  720  may be a bolt or a pin securable by a retaining pin or clip. In other implementations, the fastener  720  is a pin having a push button retainer, and the pin is leashed to the second railing  315  (to prevent foreign object debris). 
       FIG. 7D  shows a second coupling interface  725  of the folding structure  324 . The second coupling interface  725  also comprises one of the hinge devices  322  of the folding structure  324 . The second coupling interface  725  comprises a support member  730  that is coupled to the top plate  605  of the transport pallet  300 . A gusset  735  is coupled to the support member  730 . The gusset  735  and the second rigid support member  700  each include an opening that is sized to receive a fastener  740 , such as a bolt and a nut. 
     Referring to  FIG. 7B , the second railing  315  is folded into a stowed position by removing the first coupling interfaces  705  between the first rigid support members  614  and the second rigid support members  700 , and rotating the first rigid support members  614  along a rotational axis  745 . Similarly, the second rigid support members  700  are rotatable in a rotational axis  750  such that the second rigid support members  700  lay on top of a portion of the first rigid support members  614 . In the stowed position, the folding structure  324  has a height  755  (measured from the bottom plate  608 ) of about 17 inches to about 18 inches. The height  755  corresponds to the gap  430  provided between the safety net  410  and a surface  435  of the platform  326  (shown in  FIGS. 4A and 4B ). 
       FIGS. 8A and 8B  show another portion of the installation system and/or installation method configured to transfer the aircraft security door  100  to an aircraft and couple the aircraft security door  100  thereto as described herein, continued from  FIGS. 3A-4C  above. The aircraft service stair  328  has the aircraft security door  100  secured thereon by the bridge crane  330 . The aircraft service stair  328  is moved toward the opening  210  (shown in  FIG. 8B ) of the fuselage  200  of the aircraft  205 . During movement of the aircraft service stair  328 , the aircraft security door  100  is secured by the bridge crane  330  and/or the brake assembly  570  (shown in  FIGS. 5D and 5E ). 
     In  FIG. 8B , the platform  326  of the aircraft service stair  328  is positioned in proximity to the aircraft  205 . The aircraft security door  100  is manipulated by personnel by moving the trolley structure  450  and/or hoist  545  of the bridge crane  330  to position the aircraft security door  100  relative to the opening  210  of the fuselage  200 . After positioning of the aircraft security door  100 , the aircraft security door  100  can be fastened to the opening  210  of the fuselage  200  as shown and described in  FIG. 2 .