Abstract:
A system and method for installing a window panel assembly into an aircraft is disclosed. In one embodiment, the system has a retaining device having an outside edge that is sealed against an inboard surface of the aircraft skin. A biasing member is mounted to an inboard edge of the retaining device, and a plurality of protrusions (which are secured onto the biasing member) press against the window panel. This pushes the window panel outward, maintaining a seal around the edge of the window.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to the field of aircraft design. More specifically, the invention relates to the field of aircraft window design and installation. 
         [0003]    2. Description of the Related Art 
         [0004]    Windows have been installed in aircraft for years. However, traditional aircraft window installation is difficult and time consuming. Each window installation requires an installer to hold a window in place while managing ten or more spring clips or other fastener to secure the window in place. Each spring clip or other fastener must be separately secured. Depending on the situation, it may require more than one installer per window—one to hold the window in place while the other secures the clips or fasteners—increasing the time and cost of installing the windows on an aircraft. 
         [0005]    Additionally, fasteners typically used to hold aircraft window assemblies in place include rivets or other mechanical fasteners. These fasteners are visible from the outside, detracting from the ideally smooth overall appearance of the aircraft. 
         [0006]    Further, the pressures that an aircraft withstands at a higher altitude cause the fasteners to shift. Many times, this will cause the paint on the outside of the aircraft to crack and eventually flake off. When the paint flakes off, it exposes the material underneath to the harsh elements—both on the ground and at elevated altitudes. This can cause corrosion of the material, leading to much larger issues. Furthermore, the chipping of paint decreases the aesthetic appeal of the aircraft making it appear old and run-down. This can cause major concern to passenger, even if the aircraft is in prime flying condition. Therefore, aircraft owners and operators incur a large expense in maintaining the paint on the aircraft to both protect it from corrosion and to maintain a clean image with consumers. 
       SUMMARY 
       [0007]    The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below. 
         [0008]    In an embodiment, a system for installing a window panel into an aperture defined into an aircraft skin is disclosed. The system includes a retaining device having an outside edge sealed against an inboard surface of the aircraft skin, a biasing member mounted on an inboard edge of the retaining device, and a plurality of protrusions secured onto the biasing member, the protrusions pressing against an inboard surface of the outside edge of the window panel, thus compelling the window panel outward, maintaining the seal against an inboard surface of the retaining device. 
         [0009]    In another embodiment, an aircraft window assembly is disclosed, having a retaining device that includes a cross-member; an outside edge extending perpendicular in both directions from the cross member, wherein the outside edge is autoclave bonded to an inboard surface of the aircraft skin; an inside edge extending perpendicular in one direction from the cross-member, having a plurality of apertures for receiving mechanical fasteners; a receiving area defined between the cross member and the outside edge of the retaining device; and a plurality of structural members extending between the outside edge and the inside edge of the receiving area, perpendicular to the cross-member, wherein the outside edge of the retaining device is sealed against an inboard surface of the aircraft skin. The assembly further includes a window panel inserted into the receiving area of the retaining device; a biasing member, further comprising a plurality of apertures, wherein the plurality of apertures correspond to the plurality of apertures in the inside edge of the retaining device; and a plurality of protrusions having a one-bend “J” configuration secured onto the biasing member, wherein the bends of the protrusions extend toward the center of the biasing member, and wherein the protrusions press against an inboard surface of the outside edge of the window panel, thus compelling the window panel outward. 
         [0010]    In still another embodiment, a method of installing a window assembly is disclosed, consisting of the steps of (1) securing a retaining device onto an inboard surface of an aircraft skin, wherein the retaining device is configured to fit around the perimeter of an aperture cut into the aircraft skin; (2) securing a plurality of protrusions having a one-bend “J” configuration around the perimeter of a biasing member, wherein the biasing member is configured to sit atop the retaining device, and wherein the bends of the protrusions extend toward the center of the biasing member; (3) placing a seal around the perimeter of a receiving area of the biasing member; (4) receiving a window panel into the receiving area of the retaining device such that it sits atop the seal; (5) placing the biasing member with the plurality of protrusions attached thereto atop the retaining device; (6) aligning apertures in the biasing member with apertures in the retaining device; and (7) securing the biasing member to the retaining device. 
         [0011]    Further embodiments and aspects will become apparent by reference to the drawings and by study of the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0012]    Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein: 
           [0013]      FIG. 1  is an illustration of an installed window assembly from the outside of an aircraft; and 
           [0014]      FIG. 2  is a perspective view of a window assembly according to an embodiment; 
           [0015]      FIG. 3A  is an illustration of the cross-section of the window frame of  FIG. 2 ; 
           [0016]      FIG. 3B  is a perspective view of the window frame assembly of  FIG. 2 ; 
           [0017]      FIG. 4A  is a side view of a spring clip; 
           [0018]      FIG. 4B  is a side view of the biasing member of  FIG. 4A ; 
           [0019]      FIG. 5A  is a rear view of a biasing member having spring clips attached thereto; 
           [0020]      FIG. 5B  is a front view of the biasing member of  FIG. 5A ; 
           [0021]      FIG. 5C  is an illustration of an installed window assembly from the inside of the aircraft. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Embodiments of the present invention provide a window assembly  100  and method of installation. A representative window frame assembly  100  includes a window frame  105 , a window  110 , a seal  120 , and a biasing member  130  (spring clip band) with spring clips  140  attached thereto. According to some embodiments, the window frame assembly  100  may be provided for use on an aircraft. However, it will be understood that while the invention herein is described primarily in relation to its use on an aircraft, the window frame assembly  100  may also be provided for use on other structures requiring an airtight pressure seal around the window. 
         [0023]    In an exemplary embodiment, at least one window cutout  5 ,  10 ,  20  is provided in the skin  160  of the fuselage of an aircraft for accepting the window frame assembly  100 . As is further described in detail below, the window frame  105  is bonded to the inside face of the skin  160  removing the need for mechanical fasteners. A seal  120  placed around the inside edge  230  of the window frame  105  is held into place by the window  110  and the spring plate band  130  having springs  140  attached thereto, thereby creating an airtight pressure seal. Alternatively, the seal  120  may be bonded to the window  110 . The spring plate band  130  may be coupled to the window frame  105  using any suitable means. In a preferred embodiment, the spring plate band  130  is mechanically coupled to the window frame  105  to facilitate easy removal and replacement of the window. 
         [0024]    Referring now to the figures,  FIG. 1  is an illustration of the outside of an aircraft showing various exemplary configurations of window cutouts  5 ,  10 ,  20 . Window cutouts may have many configurations, including ovular, as shown at  5  or rectangular, as shown at  10  and  20 . 
         [0025]      FIG. 2  is a perspective view of a window frame assembly  100  according to one embodiment. The window frame assembly  100  includes a window frame  105 , a window  110 , a seal  120 , a spring clip band  130  with at least one spring clip  140  attached thereto, and at least one bolt  150  and nutplate  155  for securing the band  130  to the frame  105 . The window frame  105  provides structural support for the window  110  and the spring clip band  130  having spring clips  140  attached thereto. 
         [0026]    With references to  FIGS. 3A-B , the window frame  105  includes an outer flange  210 , an inner flange  220 , and a cross-member  215 . The inner flange  220  extends in one perpendicular direction from the cross-member  215 , while the outer flange  210  extends in both perpendicular directions from the cross-member  215 , parallel to the inner flange  220 . A window receiving area  250  is defined in the space between the inside face  230  of the outer flange  210  and the cross member  215 . An opening  260  for receiving fasteners is defined between the outer flange  210 , the inner flange  220 , and the cross member  215 . Walls  270  may be interspersed between the outer member  210  and the inner member  220  to further define individual compartments  260  for receiving mechanical fasteners through apertures  240  in the inner member  220  while allowing the frame  105  to maintain structural stability at high pressures and flight loads. 
         [0027]    The shape and dimensions of the outer flange  210  of the window frame  105  may correspond to the dimensions of the window cutout  5 ,  10 ,  20  such that the outer flange  210  rests flush against the inside skin of the aircraft  160  ( FIG. 2 ). In other words, the inner diameter of the outer flange  210  may be substantially equal to the diameter of the window cutout  5 ,  10 ,  20 , while the outer diameter of the outer flange  210  is greater than the diameter of the window cutout  5 ,  10 ,  20 . The window frame  105  may be formed of any suitable material. In an embodiment, the window frame  105  is formed from integrally stiffened aluminum, but it may also be formed from any other acceptable material including titanium, magnesium, or the like. 
         [0028]    The window frame  105  may be secured to the structure  160  through autoclave bonding, thereby eliminating the need for mechanical fasteners between the window frame  105  and the structure  160 . Any known and widely acceptable method for autoclave bonding that produces a bonded product consistent with professional specifications may be used. An example of such a method may be found in U.S. Pat. No. 8,182,640. 
         [0029]    Referring back to  FIG. 2 , a seal  120  may be placed around the inner edge  230  of the outer flange  210  of the frame  105  to provide a substantially airtight seal around the periphery of the window  110 . With the seal  120  in place, the window  110  may be received into the window receiving area  250  ( FIG. 3B ). The outer face of the window presses against the seal  120  to hold the seal  120  in place. Alternatively, the seal  120  may be bonded directly to the window  110  before installation of the window  110 . The spring clip band  130  having spring clips  140  attached thereto is then fastened adjacent to the inner flange  220  of the window frame  105  to secure the window  110  in place, as described in further detail below. 
         [0030]    In an embodiment, the spring clip band  130  is comprised of a generally planar strip of material with dimensions substantially corresponding to the inner flange  220  of the window frame  105 . The spring clip band  130  may be placed adjacent to the inner flange  220  of the window frame. Apertures  141  ( FIG. 4A ) in the spring clip band  130  align with the apertures  240  ( FIG. 3B ) in the window frame  105 . In alternate embodiments, the spring clip band  130  may be rectangular, ellipsoidal, et cetera, as the window cutout  5 ,  10 ,  20 , and thus the window frame  105 , requires. 
         [0031]    Spring clips  140  attached to the spring clip band  130  provide support for the window  110 . The spring clips  140  may be attached to the band  130  using known techniques, including mechanical fasters, such as rivets, or chemical bonding prior to the band  130  being secured to the frame  105 . Preassembling the clips  140  to the band  130  aids ease of final installation of the window frame assembly  100 . The spring clips  140  are fastened to the band  130  such that the clip  140  engages the window  110  and holds it securely in place, when secured to the window frame  105 . 
         [0032]    In terms of configuration, in one embodiment, the spring clips  140  may have a downwardly extending portion  142  for abutting the spring clip band  130 , leading to an outwardly extending portion  143  that leads to and terminates with an upwardly extending portion  144 , as shown, for example, in  FIG. 4A . It may be preferable for the downwardly extending portion of the spring clip  140  to be substantially planar such that the spring clip  140  rests flush against the spring clip band  130 . In other embodiments, the spring clip  140  may include a downwardly extending portion  142  leading to and terminating with an outwardly extending portion  143 . 
         [0033]    In embodiment, the outwardly extending portion  143  may conclude with a contact member (not shown) for abutting the window  110 . The contact member may be, for example, a plastic covering that allows the spring clip  140  to touch the window  110  without scratching the glass, and preventing the clip  140  from slipping. In a further embodiment, the spring clip  140  may use a single bend design extending from a downwardly extending portion  142 , comprising a substantially “J” cross-section, as shown in  FIGS. 4A-B . Apertures  141  in the downwardly extending portion of the spring clip  140 , indicated by broken lines in  FIG. 4A , align with apertures  240  ( FIG. 5A ) in the spring clip band  130  allowing for the spring clip band  130  to be fastened to window frame  105 . 
         [0034]    The shape, positioning, and number of the clips  140  may vary. Various shapes of spring clips  140  have traditionally been used in the industry. In addition to the “J” configuration described herein, other spring clips  140  such as flat springs, “L”-shaped springs, and springs having other bending configurations may be used, as appropriate. 
         [0035]    Referring to  FIGS. 5A-B , it can be seen that the clips  140  are spaced apart around the band  130  so as to apply pressure uniformly about the engaged edge of the window  110 . Also, certain clips  140  may be oppositely positioned across the window  110  from others so that both sides of the window  110  are borne against. For example, clip  140   a  is located almost directly across the window edge from corresponding clip  140   b . Similarly, clip  140   c  is directly across from corresponding clip  140   d . It will be recognized from  FIGS. 5A-C  that the spaced-apart relationship of the corresponding clip pairs presents, in the disclosed embodiments, a clocked appearance. By clocked, it is not meant that any particular spacing is required, but rather that the spaced apart relationship is one that provides reasonably uniform support about the outside edge of the window  110 . 
         [0036]    Different numbers of oppositely disposed clips  140  may be used to hold the window in place, so long that they substantially hold the window  110  in place during and after installation. It should be noted that in alternative embodiments, it may be suitable to have no more than two substantially oppositely positioned spring clips  140  attached to the spring clip band  130 . Alternatively, additional spring clips  140  could be used to hold the window  110  in place. 
         [0037]    With the spring clips  140  fastened to the biasing member  130 , the seal  120  and the window  110  may be received into the receiving area  250  ( FIG. 3B ) of the frame  105  and held in place. The biasing member  130  may then be fastened to the inner flange  220  of the window frame  105  using mechanical fasteners, such as a bolt  150 , for example, as shown in  FIG. 2 . A nutplate  155  may be pre-secured to the outboard edge of the inner flange  220  around the aperture  240  using any appropriate method. Pre-securing the nutplate  155  to the inner flange  220  further aids in the installation process, allowing the nutplate  155  to accept the bolt  150  as the bolt  150  is inserted into the assembly, rather than requiring a separate step of inserting the bolt  150  through the apertures  141 ,  240  in the spring clip  140  and the frame  130 , respectively, and securing the nutplate or nut  155  to the bolt  150 . Alternately, the mechanical fastener may be a screw and a nutplate, a pin, or a screw and nut. Additionally, the nutplate or nut may be replaced by a threaded hole in the window frame configured for receiving a bolt or screw. 
         [0038]    As the biasing member  130  is attached to the window frame  105 , the outwardly and/or upwardly extending portion of the spring clip  140  comes into contact with the window  110  and presses against the window  110 , holding the seal  120  and the window  110  in place.  FIG. 5C  illustrates an installed aircraft window assembly  100  from inside the cabin of the aircraft. 
         [0039]    The pressure exerted on the window  110  by the spring clips  140 , once the biasing member  130  has been securely fastened to the window frame  105 , is sufficient to provide a pressure and weather seal, as illustrated by the skewed clip  140  in  FIG. 2 . 
         [0040]    In addition to the ease of installation that the present invention provides, the window frame assembly  100  is easily disassembled when replacement of parts becomes necessary. There are numerous reasons why a window  110  or seal  120  may need to be replaced. For window assemblies  100  that include spring clips  140  that are each separately attached to the frame, this is a time consuming and often frustrating task. The present invention allows for the spring clips  140  to be removed all at once by releasing the biasing member  130 . The window  110  may be easily removed from the window receiving area  250  and the window  110 , seal  120 , or both may be easily replaced. The biasing member  130  may then be re-attached to the window frame  105  and the window frame assembly  100  is again complete. 
         [0041]    Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of the present invention. Embodiments of the present invention have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from its scope. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from the scope of the present invention. 
         [0042]    It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.