Abstract:
Evacuation slide systems including a slide pack comprising a packboard coupled to an aircraft door, a girt bar coupled to an aircraft floor when the aircraft door is armed, and a restraint coupled to the packboard and the girt bar are detailed. The restraint controls a speed at which the aircraft door opens when the aircraft door is armed until the aircraft door has traveled beyond a predetermined distance.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/763,056, filed Feb. 11, 2013, and entitled “Aircraft Emergency Evacuation Systems Door Restraint Lanyard,” the entire contents of which application are incorporated herein by this reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This application relates to systems for evacuating passenger vessels such as aircraft and more particularly, but not exclusively, to door restraint lanyards for door-mounted inflatable evacuation slides. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 7,467,764 to Hintzman discusses certain conventional emergency evacuation slide assemblies. As noted in the Hintzman patent:
       Door-mounted emergency evacuation slides are typically contained within an enclosure mounted to the interior surface of the aircraft exit door. Opening of the door in the “armed” position causes the slide to be pulled downward out of the enclosure into a position immediately outboard of and below the door exit opening. The evacuation slide is then rapidly inflated to form a structure sufficiently rigid to enable the airline passengers to escape.
 
See Hintzman, col. 1, 11. 14-21. The contents of the Hintzman patent are incorporated herein in their entirety by this reference.
       
 
         [0005]    While opening of the door in the armed position is the conventional method of activating evacuation systems, in certain cases, the door may open too rapidly. As a result, a reliable method of slowing the speed at which the door opens is needed so that the release cable may be pulled to release the pack, which also does not interfere with the slide deployment. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides an inflatable evacuation slide system comprising a slide pack comprising a packboard coupled to an aircraft door, a girt bar coupled to an aircraft floor when the aircraft door is armed, and a restraint coupled to the packboard and the girt bar. 
         [0007]    In some embodiments, the restraint controls a speed at which the aircraft door opens when the aircraft door is armed until the aircraft door has traveled beyond a predetermined distance. In other embodiments, the restraint dissipates energy generated by an outward movement of the aircraft door when the aircraft door is armed until the outward movement of the aircraft door exceeds a predetermined distance. 
         [0008]    The restraint may be formed of webbing sewn with loops and no back stitch, wherein the restraint controls the speed at which the aircraft door opens by breaking the loops in the webbing. The restraint may also be formed of high strength hook-and-loop materials. 
         [0009]    In yet other embodiments, the restraint comprises an energy absorbing portion that slows the outward movement of the aircraft door when the aircraft door is armed and/or breaks when the outward movement of the aircraft door exceeds a predetermined distance. 
         [0010]    The system may further comprises a door bustle coupled to the packboard, wherein the aircraft door has traveled beyond the predetermined distance when an inside edge of the door bustle vertically clears a door sill of the aircraft. In other embodiments, the predetermined distance is approximately 7 inches. 
         [0011]    Other objects, features, and advantages of the present invention will be apparent to those skilled in the appropriate field with reference to the remaining text and the drawings of this application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  schematically illustrates portions of a slide pack consistent with the present invention. 
           [0013]      FIG. 2  schematically illustrates a side view of the slide pack of  FIG. 1  with the aircraft door closed and armed. 
           [0014]      FIG. 3  schematically illustrates a side view of the slide pack of  FIG. 1  with the aircraft door opening in an armed state and positioned at the point that tension is beginning to be applied to the restraint. 
           [0015]      FIG. 4  schematically illustrates a side view of the slide pack of  FIG. 1  with the aircraft door opening in an armed state and positioned with the inside edge of the door bustle clearing a vertical sill of the aircraft. 
           [0016]      FIG. 5  schematically illustrates a perspective view of the slide pack of  FIG. 1  with the aircraft door closed and armed. 
           [0017]      FIG. 6  schematically illustrates an exemplary embodiment of a restraint used with the slide pack of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Detailed in  FIGS. 1-6  are portions of an exemplary inflatable evacuation slide pack  10 . Pack  10  may include packboard  12  and release assembly  14  (or other structure) suitable for attachment to pack release cable  18  and inflation cable  22 . Cables  18  and  22  are shown as being connected to ring  30 ; in turn, ring  30  preferably connects to a girt bar  16  of an aircraft or any other mechanism or object suitable for tensioning cables  18  and  22  when pack  10  is to be deployed (as, for example, when an “armed” aircraft door  26  opens). Pack  10  additionally may include an inflatable evacuation slide  24 . 
         [0019]    The packboard  12  may be mounted to an interior surface of the aircraft door  26 . A door bustle  28  may be attached over the pack  10 . When the aircraft door  26  is opened in the armed condition, the evacuation slide  24  drop away from the packboard  12 . As the evacuation slide  24  drops away from the aircraft door  26 , a fixed end of the evacuation slide  24  is secured to the aircraft floor  20  by the girt bar  16 . 
         [0020]    In certain cases, the speed at which the aircraft door  26  opens in the armed condition may need to be controlled (i.e., slowed down). To slow down the opening speed of the aircraft door  26 , a restraint  32  may be used. The critical time period in which the speed of the aircraft door  26  opening needs to be controlled is typically between when the aircraft door  26  starts to open by rotating outward until an inside edge  34  of the door bustle  28  vertically clears a door sill  36  of the aircraft (as indicated by the dashed vertical line in  FIG. 4 ). 
         [0021]    As illustrated in  FIGS. 2-5 , a first end  38  of the restraint  32  may be attached to a fixed point on the girt bar  16  since the girt bar  16  is engaged and disengaged from the aircraft floor  20  as the aircraft door  26  is armed and disarmed. A second end  40  of the restraint  32  may be attached to an outboard surface  42  of the packboard  12 . In other embodiments, the second end  40  may be attached to any suitable location on the packboard  12 , including but not limited to an inboard surface, a lower surface, embedded within a recess within the packboard  12  or other locations. 
         [0022]    In certain embodiments, the outboard surface  42  is inwardly spaced apart from the girt bar  16  by a distance X. In certain embodiments, the distance X is approximately 2.25 inches. However, a person of ordinary skill in the art will understand and appreciate that the distance between the girt bar  16  and the outboard surface  42  may be any suitable distance, and may include circumstances where the girt bar  16  is positioned inwardly relative to the outboard surface  42  of the packboard  12 . 
         [0023]    In the embodiments where the outboard surface  42  is positioned inwardly of the girt bar  16 , the aircraft door  26  must travel outwardly a distance that is approximately twice the distance X before the restraint  32  is placed under tension by the movement of the aircraft door  26 . In other words, as shown in  FIG. 3 , the outboard surface  42  must be outwardly spaced apart from the girt bar  16  by a distance X′, where X′ is approximately the same magnitude as distance X. Therefore, in the embodiments where the distance X is approximately 2.25, the total distance traveled by the aircraft door  26  is approximately 4.5 inches before the restraint  32  is placed under tension. 
         [0024]    In the embodiments where the girt bar  16  is positioned inwardly relative to the outboard surface  42  of the packboard  12 , the restraint  32  may be placed under tension approximately as soon as the aircraft door  26  begins to move outwardly or very shortly thereafter, depending on the amount of slack that is provided in the restraint  32  between the girt bar  16  and the outboard surface  42  when the aircraft door  26  is closed. 
         [0025]    Once the restraint  32  is placed under tension by the outward movement of the aircraft door  26 , the restraint  32  comprises an energy absorbing portion  44  that begins to exert a resistive force on the aircraft door  26 , thus slowing down the movement of the aircraft door  26  by dissipating the aircraft door&#39;s  26  energy. The restraint  32  slows the movement of the aircraft door  26  by an amount that provides sufficient time for the release cable  18  to be pulled, which releases the evacuation slide  24 . The restraint  32  is further designed so that the restraint  32  breaks away or detaches when the inside edge  34  of the door bustle  28  reaches the door sill  36 . As illustrated in  FIG. 4 , the total distance between the point where the restraint  32  is placed under tension and the inside edge  34  of the door bustle  28  reaching the door sill  36  is represented by a predetermined distance Y. In certain embodiments, the predetermined distance Y is approximately 7 inches. However, a person of ordinary skill in the art will understand and appreciate that the predetermined distance may be any suitable distance, and may depend on the relative location of the girt bar  16 , the location of the outboard surface  42  when the aircraft door  26  is closed, and the distance between the girt bar  16  and the door sill  36 . 
         [0026]    The energy absorbing portion  44  of the restraint  32  may be configured with a frangible design. In these embodiments, the energy absorbing portion  44  is designed to break when a sufficiently high strain is placed on the restraint  32 , and could have the effect of almost stalling the aircraft door  26  before breaking. Thus, in these embodiments, the energy absorbing portion  44  may create a sufficiently large shock load on the aircraft door  26  that may damage its opening mechanism, which could in turn prevent the evacuation slide  24  from deploying. 
         [0027]    In other embodiments, the energy absorbing portion  44  of the restraint  32  may dissipate energy slowly over a brief period of time, which may provide a smaller (or minimal) shock load on the aircraft door  26 . An exemplary embodiment of such a restraint  32  is shown in  FIG. 6 . In these embodiments, the restraint  32  is formed of webbing that is sewn with loops (similar to carpet) with no back stitch and includes a shock absorber with a woven inner core that smoothly expands to dissipate energy. In certain embodiments, the restraint  32  may be able to dissipate the load over the entire predetermined distance Y. In other embodiments, the restraint  32  dissipates the load over approximately one-half the predetermined distance Y. In certain embodiments, the restraint  32  is configured to have lengths of webbing sewn together to dissipate the energy by breaking the stitching or may comprise a high strength hook-and-loop design (i.e., Velcro). The restraint  32  may be positioned between the outboard surface  42  and the girt bar  16  in a location that does not interfere with the deployment of the evacuation slide  24 , which may be particularly important for embodiments where the restraint  32  dissipates the energy but remains connected to the outboard surface  42  and the girt bar  16 . 
         [0028]    The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention.