Abstract:
An inflatable evacuation slide system includes a slide pack that is ejected from its enclosure by means of an ejection bag, which inflates rapidly to force the evacuation slide out of the enclosure. The high accelerations imposed on the uninflated evacuation slide by the ejection bag make the slide prone to tearing on the edge of the fuselage as the slide pack is forced through the opening. Accordingly, the enclosure is provided with a chafing skirt, which comprises a flexible collar that deploys outward from the enclosure and lays flat against the aircraft fuselage to provide a smooth transition region between the enclosure and the aircraft skin.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to emergency evacuation equipment for aircraft, in particular to inflatable aircraft evacuation slides. 
   The requirement for reliably evacuating airline passengers in the event of an emergency is well-known. A conventional method of quickly evacuating a large number of passengers from an aircraft is to provide multiple emergency exits, each of which is equipped with an inflatable evacuation slide. 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. Over-wing evacuation slides are typically mounted outside the pressurized aircraft fuselage in a compartment located within the wing-to-fuselage fairing. If an over-wing exit is opened, a signal is generated that causes the over-wing evacuation slide inflation system to begin inflation. In response to the inflation pressure signal, pneumatic locks are released, which allow the evacuation slide compartment cover to fall away. The expanding evacuation slide then is forced out of the compartment either by the action of the slide itself inflating or in some cases by means of a separate ejection bag that inflates and forces the uninflated evacuation slide horizontally out of the storage compartment prior to the inflation thereof. 
   Fuselage mounted evacuation slides present special difficulties. As with door-mounted and over-wing-mounted evacuation slides, weight and storage volume are of great concern. The requirement that the evacuation slide be fuselage-mounted, however, imposes an additional constraint in that since the evacuation slide compartment intrudes into the pressure hull of the aircraft, the compartment opening must be minimized to avoid placing undue stress on the aircraft skin and supporting airframe. The minimum opening constraint, in turn, causes difficulty in the rapid deployment of the evacuation slide, which must be forced through this minimal opening without tearing on the surrounding aircraft skin. 
   SUMMARY OF THE INVENTION 
   The present invention comprises an inflatable evacuation slide system for mounting to the airframe of an aircraft. According to an embodiment of the present invention, the evacuation slide system comprises a packboard compartment comprising a rigid enclosure that is mounted to the fuselage of the aircraft. The enclosure has a cover panel that is released prior to deployment of the inflatable evacuation slide. An inflatable evacuation slide or combination evacuation slide/raft is stored in an uninflated condition within the rigid enclosure. An ejection bag, which comprises an inflatable pillow is located within the rigid enclosure behind the stored evacuation slide. In response to the aircraft exit door being opened in the armed condition, a signal is sent to the gas generator (which may be any source of inflation gas, including stored gas, pyrotechnic, or hybrid gas generator) to begin the inflation process. Gas pressure from the gas generator operates the pneumatic locks to release the cover panel as inflation gases begin to flow to the ejection bag and the inflatable evacuation slide. The ejection bag inflates rapidly to force the evacuation slide out of the rigid enclosure prior to inflation thereof. Because of the high accelerations imposed on the uninflated evacuation slide by the ejection bag, the evacuation slide is prone to tearing on the edge of the fuselage opening as it is forced through. Accordingly, the enclosure is provided with a chafing skirt attached to the inner surface of the rigid enclosure. The chafing skirt comprises a flexible hat-section collar that deploys outward from the enclosure and lays flat against the aircraft fuselage to provide a smooth transition region between the enclosure and the aircraft skin. The transition region enables the rapid deployment of the evacuation slide through the minimal sized opening without damage. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     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: 
       FIG. 1  is a perspective view of an inflatable evacuation slide system incorporating features of the present invention. 
       FIG. 2  is an enlarged perspective view of a portion of the inflatable evacuation slide system of  FIG. 1 . 
       FIG. 3  is a partial perspective view of the inflatable evacuation slide system of  FIG. 1  showing certain details of construction. 
       FIG. 4  is a plan view of the inflatable evacuation slide system of  FIG. 1  viewed from outside the aircraft. 
       FIG. 5  is a cross-sectional view of the inflatable evacuation slide system of  FIG. 1  showing the inflatable evacuation slide in its stored, uninflated condition. 
       FIG. 6  is a cross-sectional view of the inflatable evacuation slide system in the initial stages of deployment. 
       FIG. 7  is a partial perspective view of a chafing skirt in accordance with the illustrative embodiment. 
       FIG. 8  is a plan view of the chafing skirt of  FIG. 7  prior to assembly. 
       FIG. 9  is a cross-sectional view showing details of assembly of the chafing skirt of  FIG. 7 . 
   

   DETAILED DESCRIPTION 
   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 detail. 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. 
   With reference to  FIGS. 1-5 , emergency evacuation slide system  10  comprises an inflatable evacuation slide  11  which comprises a conventional flexible panel that defines a slide surface having a head end and a foot end supported by a plurality of inflatable tubular members that extend from the head end toward the foot end of the slide. Inflatable evacuation slide  11  is stored in a folded, uninflated condition referred to as a slide pack  12  contained within a rigid enclosure or packboard  14 . Packboard  14  is closed by means of a packboard cover panel  16 , which is mounted to packboard  14  along the lower edge by means of a tongue  18  formed in packboard cover panel  16 , which engages a groove  20  formed along the lower edge of packboard  14 . Packboard cover panel  16  is retained to packboard  14  along the upper edge by means of a plurality of pneumatic locks  22 . Tongue  18  and groove  20  cooperate to form a detachable hinge which, in cooperation with pneumatic locks  22 , allow packboard cover panel  16  to open and fall away from packboard  14  when pneumatic locks  22  are actuated. 
   The folded, uninflated evacuation slide  12  is held within packboard  14  by means of a slide pack soft cover  24 . Soft cover  24  comprises one or more fabric panels  26  and  28 , which are attached to the inner surface  30  of packboard  14 . The proximal edges  32  and  34  of fabric panels  26  and  28  include a plurality of grommets. Fabric panels  26  and  28  are laced together by means of speed-lacing  38  which is threaded through grommets  36 . Thus laced together, fabric panels  26  and  28  form a barrier that holds slide pack  12  within packboard  14  spaced apart from cover panel  16  so that slide pack  12  is incapable of pressing against cover panel  16  during normal storage. An ejection bag  58  is disposed within packboard  14  immediately behind slide pack  12 . As explained more fully hereinafter, ejection bag  58  is used to rapidly push slide pack  12  out of packboard  14  during deployment. 
   Emergency evacuation slide system  10  further includes an inflation source  40 . Inflation source  40  may comprise a stored cold gas, a pyrotechnic gas generator or any other source of inflation gas known in the art, but preferably comprises a hybrid gas generator such as the gas generator disclosed in U.S. Pat. No. 5,988,438 to Lewis et al. the specification of which is incorporated herein by reference. 
   Emergency evacuation slide system  10  further includes one or more chafing skirts  42  and  44 . With further reference to  FIGS. 7-9 , each of chafing skirts  42  and  44  comprises a flexible fabric flange section  46  and a flexible fabric throat section  48 . Flange section  46  comprises an arcuate sector  50  formed of a flexible fabric material, preferably a polyurethane coated, low coefficient of friction fabric with a single-ply plain weave, high tenacity, 840 denier nylon base cloth, which is commonly used in the industry for fabrication of evacuation slide surfaces and other evacuation slide parts. Throat section  48  comprises a rectangular section  52  also composed of a polyurethane coated, aluminized nylon fabric. Two of arcuate sectors  50  and one rectangular section  52  are butt-spliced together as shown in  FIG. 9  by means of two strips  54  and  56  of polyurethane coated nylon fabric scam tape. Strips  54  and  56  may be any variety of seam tape commonly used in the fabrication of evacuation slides, however, preferably strips  54  and  56  are made from type  3454  seam tape manufactured by Uretek, Inc. The joining of arcuate sectors  50  with rectangular section  52  forms chafing skirt  42  into a flattened bell or partial hat-section collar which causes flange section  46  to lay flat against the aircraft fuselage  60  when deployed. 
   As shown most clearly in  FIGS. 2 and 4 , chafing skirt  42  is stored by folding flange section  46  inward on top of itself so that it lays against the surface of soft cover  24 . A safety loop  62  of light gage thread is then stitched through the fold and attached to pack lacing  68 . 
   In operation, when an aircraft emergency exit door is opened in the armed condition, a signal is sent to inflation source  40 . In response to the signal, a valve is opened, which begins the flow of inflation gases to the slide pack components. In response to the pressure signal, the pneumatic locks  22  release cover panel  16  which falls and/or is pushed away by the moving slide pack  12 . Simultaneously, a pyrotechnic cord cutter (not shown) cuts the speed lacing  38  holding together the fabric panels  26  and  28  of soft cover  24 . This allows fabric panels  24  and  26  to fall away from each other thereby releasing slide pack  12  to move. Also simultaneously, inflation gases entering ejection bag  58  cause the rapid expansion of ejection bag  58  which in turn, forces slide pack  12  rapidly out of packboard  14 . The force of ejection bag  58  breaks safety loops  62 , which allows chafing skins  42  and  44  to deploy prior to slide pack  12  exiting packboard  14 . Because of the high acceleration forces, slide pack  12  is highly prone to chafing and/or tearing on the corners  64  of aircraft fuselage  60 . Chafing skirts  42  and  44 , however, prevent damage to slide pack  12  by deploying outward from packboard  14  and assuming their hat-section configuration, prior to slide pack  12  coming into contact with fuselage  60 . In the illustrative example, the width of flange section  46  is approximately six inches as compared with the flange area  66  of packboard  14  which is approximately two inches in width, however, the width of flange section  46  may be any width provided it is sufficiently wide to deploy under the urging of slide pack  12  and extend over the edge  64  of aircraft fuselage  60 . 
   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. Accordingly, it is intended that the invention shall be limited only to the extent required by the appended claims and the rules and principals of applicable law. As used herein unless otherwise specifically defined, the terms “substantially” or “generally” when used with mathematical concepts or measurements mean within plus or minus ten degrees of angle or within ten percent of the measurement, whichever is greater.