Abstract:
A method of lacing together two parts of an inflatable evacuation slide uses a single piece of cord that is passed through multiple pairs of apertures formed in the two parts to be joined. Thereafter, the loops formed by passing the cord through the multiple apertures are laced together and secured with a conventional key loop. In operation, once the key loop is released, since the lacing is composed of a single length of cord, rather than multiple independent loops, the tension in all of the lacing is released simultaneously thereby allowing the lacing to unravel reliably irrespective of the load on the lacing.

Description:
[0001]    This application claims priority of U.S. Provisional Application Serial No. 60/418,838, filed Oct. 15, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to emergency evacuation equipment for aircraft, in particular, to inflatable aircraft emergency evacuation slides.  
           [0003]    The conventional method of quickly evacuating a large number of passengers from an aircraft in an emergency is to provide multiple emergency exits, each of which is equipped with an inflatable evacuation slide. These inflatable evacuation slides are normally stored in an uninflated condition in a container, or slide pack, requiring a minimum of space in the interior of the aircraft. The slide pack is typically attached to a packboard mounted on or adjacent to the interior of the aircraft exit door. In a conventional aircraft evacuation slide system, the operation of which is described among other places in U.S. Pat. No. 4,441,582 to Ward, if the aircraft exit door is opened in the “armed” condition, the entire slide pack to falls to the sill of the aircraft. As the door is moved further away from the doorway the slide pack falls out of the doorway toward the ground. As the slide pack falls toward the ground, a lanyard is tensioned to withdraw a pin from the key loop of a series of interlaced loops commonly referred to as “daisy chain” lacing. Withdrawal of the pin from the key loop of the daisy chain lacing causes the lacing to unravel releasing the slide from the slide pack for inflation.  
           [0004]    Prior art methods of storing a fold uninflated evacuation slide within a pack closed by conventional daisy chains lacing have proved adequate for small to moderate sized inflation slides. Conventional daisy chain lacing, however, does not reliably release under the strain of large, tight slide packs or slides that have been stored for a protracted period of time. Accordingly, what is needed is a method of lacing an aircraft evacuation slide that reliably releases under all conditions.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is directed to a method of lacing together two parts of an inflatable evacuation slide in which a single piece of cord is passed through multiple pairs of apertures or grommets formed in the two parts to be joined. Thereafter, the loops formed by passing the cord through the multiple grommets are laced together and secured with a conventional key loop. In operation, once the key loop is released, since the lacing is composed of a single length of cord, rather than multiple independent loops, the tension in all of the lacing is released simultaneously thereby allowing the lacing to unravel reliably irrespective of the tension on the lacing or the duration of its storage prior to being released. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0006]    The present invention will be better understood from a reading of the following detailed description, taken in conjunction with the accompanying drawing figures in which like references designate like elements and, in which:  
         [0007]    [0007]FIG. 1 is a side view of an evacuation slide incorporating features of the present invention;  
         [0008]    [0008]FIG. 2 is a side view of an evacuation slide pack, portions of which are joined together by lacing incorporating features of the present invention;  
         [0009]    [0009]FIG. 3 is a partial perspective view of two portions of an evacuation slide joined by prior art daisy chain lacing;  
         [0010]    [0010]FIG. 4 is a partial perspective view of two portions of an evacuation slide joined by prior art lacing;  
         [0011]    [0011]FIG. 5 is a partial perspective view of two portions of an aircraft evacuation slide joined together by lacing incorporating features of the present invention;  
         [0012]    [0012]FIG. 6 is an enlarged perspective -view of a portion of the lacing shown in FIG. 5;  
         [0013]    [0013]FIG. 7 is a cross-sectional illustration of two parts of an aircraft evacuation slide joined together by lacing incorporating features of the present invention;  
         [0014]    [0014]FIG. 8 is a cross-section of two portions of an aircraft evacuation slide joined by an alternative embodiment of lacing incorporating features of the present invention;  
         [0015]    [0015]FIG. 9 is a cross-section of two portions of an aircraft evacuation slide joined by an alternative embodiment of lacing incorporating features of the present invention;  
         [0016]    [0016]FIG. 10 is a perspective view of an aircraft evacuation slide including a toe end compartment joined together by lacing incorporating features of the present invention; and  
         [0017]    [0017]FIG. 11 is a partial perspective view of an alternative hybrid lacing incorporating features of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0018]    The drawing figures are intended to illustrate the general manner of construction and are not necessarily to scale. In the detailed description and in the drawing figures, specific illustrative examples are shown and herein described in detailed. It should be understood, however, that the drawing figures and the detailed description are not intended to limit the invention to the particular form disclosed, but are merely illustrative and intended to teach one of ordinary skill how to make and/or use the invention claimed herein and for setting forth the best mode for carrying out the invention.  
         [0019]    With reference to FIGS. 1 and 2, an inflatable evacuation slide assembly  10  generally comprises a head end  12  and a foot end  14 . Head end  12  is configured to couple evacuation slide assembly  10  to an exit door  18  of an aircraft  20 , while foot end  14  is in contact with the ground  22  such that the slide assembly  10  provides a sloping surface to permit the rapid egress from passengers from aircraft  20 . The entire inflatable evacuation slide assembly  10  is preferably fabricated from an air impervious material such as a lightweight fabric that has been coated with an elastomer such as rubber or urethane. The various parts of the inflatable evacuation slide assembly  10  may be joined together with a suitable adhesive whereby the structure will form a unitary composite structure capable of maintaining its shape during operation. The entire structure of the inflatable evacuation slide assembly  10  is preferably formed such that all the chambers comprising the structure are interconnected pneumatically, such that a single pressurized gas source, such as compressed carbon-dioxide, nitrogen, or argon, output from a pyrotechnic gas generator, or a hybrid pyrotechnic/compressed gas generator may be utilized for its deployment.  
         [0020]    As shown in FIG. 2, evacuation slide assembly  10  is typically stored in a folded, uninflated condition within a slide pack  24  mounted to the interior surface  16  of aircraft door  18 . As the aircraft door is opened in the armed condition, the girt portion  26  of evacuation slide assembly  10 , which is secured to the aircraft door seal by girt bar  28 , pulls slide pack  24  off its mountings on interior surface  16  of door  18 . This allows slide pack  24  to begin to fall. After slide pack  24  has fallen a predetermined distance, a lanyard  30  attached to girt  26  withdraws a pin  32  from a key loop  34  which allows the lacing  36  to unravel thereby releasing the evacuation slide assembly  10  from the enclosure of slide pack  24 .  
         [0021]    With reference to FIGS. 3 and 4, a prior art “daisy chain” lacing for joining two parts of an inflatable aircraft evacuation slide comprises a plurality of fixed loops  38  and key loops  40  fastened to one end of a panel  44 . A like number of apertures  42  are formed in the opposite end of a panel  46  to be joined to panel  44 . The ends of panels  44  and  46  are lined up so that each of apertures  42  are positioned over one of loops  38  and  40 . Each of the loops  38 ,  40  are passed through apertures  42  in panel  46 . Beginning with the loop furthest from key loop  40  at each end, each loop is threaded through the adjacent outboard loop working inwardly toward key loops  40 . Key loops  40  are then held together by threading one through the other and then passing a pin  52  attached to a lanyard  54  through the resulting loop. Although there are numerous ways of securing the key loop of such a laced assembly, the basic principal of a plurality of individual loops threaded one through another is consistent throughout all prior art evacuation slide daisy chain style lacing.  
         [0022]    [0022]FIG. 5 is a perspective view of two parts of an inflatable aircraft evacuation slide joined together by means of lacing incorporating features of the present invention. As shown in FIG. 5, a first panel  58  has formed therein a plurality of apertures  62 , which in a preferred embodiment are provided with suitable grommets for reinforcement. A second panel  60  has a plurality of corresponding apertures  64  formed therein. (As used herein “corresponding apertures” means that the apertures in second panel  60  will line up with apertures  62  in first panel  58  to facilitate lacing the assembly together.) A length of cord  66  is fastened by suitable means (e.g., stitching) at one end  68  to second panel  60  and at a second end  74  to second panel  60 . A key loop  76  is formed by fastening a portion of cord  66  together with stitching  50  proximal second end  74 . Cord  66  may be any suitable length of cord made from natural or synthetic fibers, however, in the illustrative embodiment cord  66  is MIL-C-7515 nylon cord.  
         [0023]    With reference to FIG. 6, portions of cord  66  are threaded through apertures  64  of panel  60  to form a series of substantially equal size loops  78  (hereinafter referred to alternatively as “loops” or “breakaway loops”) and a substantially equally sized terminal loop  80 . Key loop  76  is also passed through one of apertures  64 .  
         [0024]    As shown in FIG. 7, each of loops  78  is threaded through apertures  62  of panel  58  and thereafter threaded through an adjacent loop  78  to form a chain of interlocked loops terminating in a terminal loop  80  through which is threaded key loop  76 . Alternatively, in lieu of anchoring terminal loop  80  to key loop  76 , terminal loop  80  could be anchored directly to panel  58  or  60  (e.g., by passing terminal loop  80  through a grommet and securing with a pin, passing terminal loop  80  through a cord cutter anchored to panel  58  or other conventional means) all within the scope of the present invention. Also, in lieu of using stitching  50 , key loop  76  may be formed by tying a knot in cord  66  proximal end  74 .  
         [0025]    With reference to FIGS. 8, 9 and  10 , according to another embodiment of the present invention, a bi-directional lacing in accordance with the present invention is used to close a compartment  98  at the foot end  14  of an evacuation slide assembly  10 . In the embodiment of FIGS. 8 and 9, cord  106  and cord  112  are threaded through a plurality of apertures  102  and  104  in panels  108  and  110  to form a series of loops  114  and  116  as well as key loops  118  and  120  (which, as noted hereinbefore, may be stitched or knotted). Key loops  118  and  120  are threaded through each other and secured with a pin  90  attached to a lanyard  92 . Alternatively, as shown in FIG. 9, ping  90  is replaced with a pyrotechnic cord cutter  122 . In operation, under the appropriate conditions, as the evacuation slide assembly  10  is deployed, a signal is sent to pyrotechnic cord cutter  122  which severs both of key loops  118  and  120 . Because cord  106  and cord  112  form all of the breakaway loops that form the breakaway lacing, once the key loops  118  and  120  are released the tension in the lacing is relieved simultaneously and uniformly rather than seriatim as in the prior art daisy uniformly and the lacing unravels immediately and more reliably than has been heretofore possible.  
         [0026]    With reference to FIG. 11, yet another alternative embodiment of a hybrid lacing comprising a combination of daisy chain loops and breakaway loops is shown. In the embodiment of FIG. 11, a plurality of conventional daisy chain loops  140  are threaded through corresponding apertures  142  in a panel  144  beginning at the outermost ends and working inward toward the center. The innermost of daisy chain loops  140  are then laced to the outermost of a plurality of breakaway loops  146 , which thereafter are threaded together as hereinbefore described. The innermost of breakaway loops  146  are secured to key loops  148  and  150 . Key loops  148  and  150  are then secured by pins  152  and  154  connected to a common lanyard  156 . A master loop  160  redundantly secures key loops  148  and  150  together. The purpose of master loop  160  is to prevent accidental unraveling of the lacing in the event pins  152  and  154  are inadvertently withdrawn. In normal operation, master loop  160  is severed by means of a pyrotechnic cord cutter THAT “arms” the lacing such that withdrawal of pins  152  and  154  will cause the lacing to unravel. Once the slide is in position for deployment pins  152  and  154  are withdrawn by means of common lanyard  156  which causes the breakaway lacing to unravel.  
         [0027]    Although certain illustrative embodiments and methods have been disclosed herein, it will be apparent from the foregoing disclosure to those skilled in the art that variations and modifications of such embodiments and methods may be made without departing from the spirit and scope of the invention. For example, a myriad of methods for securing the key loop of the breakaway lacing in accordance with the present invention are possible. Accordingly, it is intended that the invention shall be limited only to the extent require by the appended claims and the rules and principles of applicable law.