Abstract:
A device is used to plug an opening in a structure having a front side and a back side. The device includes a removable plug body for plugging the opening, and a retainer that is expandable into engagement with the back side of the structure to retain the plug in the opening. Means coupled with the retainer and the plug is provided for expanding the retainer.

Description:
TECHNICAL FIELD 
     This disclosure generally relates to closures for openings, and deals more particularly with a device for plugging and sealing an opening in a structure, such as an exterior access opening in an aircraft panel. 
     BACKGROUND 
     Vehicles such as aircraft are often provided with exterior access openings in order to allow service personnel to access interior components for, without limitation, inspection, maintenance and/or adjustment. These access openings may be located in aerodynamic exterior surfaces, and therefore may be plugged with covers that are preferably as flush as possible with the skin of the aircraft in order to reduce turbulent airflow over the opening. 
     Known covers for access openings in aircraft structures may include a plug having a separately installed sleeve which may render this type of plug difficult to install multiple applications with differing surface contours. Another type of known plug employs glue to hold the plug in the opening, however these glued plugs may not be easily removed, and may require cleaning and the use of additional glue during reinstallation. 
     Accordingly, there is a need for an access opening plug that is adapted for use with structures having a variety of contours, and which is self-retaining in the opening, without the use of glue. There is also a need for a plug of the type mentioned above which may be easily and quickly removed and reinstalled entirely from one side of the opening. 
     SUMMARY 
     The disclosed embodiments provide a relatively simple self retaining aerodynamic plug for plugging and sealing access openings in a structure, such as those used in commercial and military aircraft. The plug may be easily and quickly installed from one side of the opening, and may not require the assembly of parts for its installation. The disclosed access opening plug has an outer surface that extends substantially flush with the skin or other outer surface of the structure so as to maintain aerodynamic airflow over the access opening. The plug may be especially suitable for plugging relative small openings, and be installed or removed using a simple tool such as a screwdriver to turn a screwdrive. The screwdrive compresses and expands a retainer into engagement with the backside of the structure in order to draw the plug tightly down into a recess in the structure. The retainer may comprise a compressible O-ring seal which may create a relatively tight seal around the entire opening between the plug and the structure. 
     According to one disclosed embodiment, a device is provided for plugging an opening in a structure having first and second opposite sides. The device includes a removable plug body for plugging the opening and a retainer that is expandable into engagement with the second side of the structure for retaining the plug in the opening. Means coupled with the retainer and the plug are provided for expanding the retainer. The plug may include tapered sides which engage a chamfered edge surrounding the opening. An outer surface of the plug body covers the opening and extends substantially flush with the first side of the structure. 
     According to another embodiment, a device is provided for sealing an opening in a structure having a first side and a second side. The device includes a plug body disposed in the opening and engaging the first side of the structure. Means coupled with the plug body are provided for retaining the plug body in the opening, including a compressible member that expands laterally when compressed to seal against the second side of the structure. Means are provided for compressing the compressible member and for drawing the compressible member down against the second side of the structure. The plug body may be recessed within the structure and includes an outer surface that is substantially flush with the first side of the structure. The means for compressing the compressible member includes a screw drive extending through the plug body and which is accessible from the first side of the structure. 
     According to a further embodiment, a device is provided for plugging an access opening in an aircraft structure. The device includes a removable plug for plugging the opening from a front side of the structure, and a retainer on the back side of the structure that is displaceable between a first position allowing the plug body to be removed from the opening and a second position retaining the plug body in the opening. A drive is provided for coupling the plug body with the retainer and for displacing the retainer between the first and second positions thereof. The drive extends through the plug body and is accessible from the front side of the structure. 
     According to still another embodiment, a method is provided of installing a plug within an opening in a structure. The method includes placing a plug body in the opening from a front side of the structure and accessing a screwdrive from the front side of the structure. The screwdrive is used to displace a seal on the back side of the structure, and the displaced seal is used to retain the plug body in the opening. Using the screwdrive to deform the seal may include compressing the seal between the plug body and a plate. 
     The disclosed embodiments satisfy the need for a plug that may be used to plug and seal an access opening which may be used with a wide range of structural surface contours, and which may be easily installed or removed with simple tools, without the need for glue. 
    
    
     
       BRIEF DESCRIPTION OF THE ILLUSTRATIONS 
         FIG. 1  is an illustration of a perspective view of a typical flap track fairing having access openings sealed by plugs according to the disclosed embodiments. 
         FIG. 2  is an illustration of an isometric view showing the plug about to be inserted into an access opening from the front side of a structure. 
         FIG. 3  is an illustration of an isometric view of the plug of  FIG. 2 , better showing components on the back side of the plug. 
         FIG. 4  is an illustration of an isometric view of the plug body. 
         FIG. 5  is an illustration of an isometric view of the plug body similar to  FIG. 4 , but viewed from a different angle. 
         FIG. 6  is an illustration of an isometric view of the retainer plate and the nut plate. 
         FIG. 7  is an illustration of another isometric view of the retainer plate and the nut plate, similar to  FIG. 6 , but viewed from a different angle. 
         FIG. 8  is an illustration of a sectional view taken along the line  8 - 8  in  FIG. 3 , but showing the plug having been installed in the opening, before being sealed. 
         FIG. 9  is an illustration of a sectional view similar to  FIG. 8 , but taken along the line  9 - 9  in  FIG. 3 . 
         FIG. 10  is an illustration of the area designated as “A” in  FIG. 8 . 
         FIG. 11  is an illustration of an isometric view of the front surface of the structure and the outer, flush surface of the plug body. 
         FIG. 12  is an illustration of a sectional view similar to  FIG. 8 , but showing the O-ring retainer having been compressed to retain and seal the plug body within the access opening. 
         FIG. 13  is an illustration of a sectional view similar to  FIG. 9 , but showing the O-ring retainer having been compressed to retain and seal the plug body within the access opening. 
         FIG. 14  is an illustration of the area designated as “B” in  FIG. 13 . 
         FIG. 15  is an illustration of a flow diagram showing the steps of a method of installing a plug in an access opening according to the disclosed method embodiments. 
         FIG. 16  is an illustration of a flow diagram of aircraft production and service methodology. 
         FIG. 17  is an illustration of a block diagram of an aircraft. 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIG. 1 , the disclosed embodiments relate to a plug  20  for plugging and sealing openings  22  in a structure  24 . In the illustrated embodiment, the structure  24  comprises a slat track fairing which protects and streamlines a mechanism  26  controlling wing slats (not shown) on an aircraft (not shown). However, the plug  20  may be used to plug and seal openings  22  in a variety of other structures, particularly in so called blind side applications where the plug  20  must be installed entirely from only one side of the structure  24 . In the illustrated embodiment, the structure  24  includes first and second opposite sides which may also be respectively referred to herein as front side  24   a  and the backside  24   b . In aircraft applications, the openings  22  are sometimes referred to as access openings which allow service personnel to access components such as the mechanism  26 , inside a structure  24  for purposes of inspection, maintenance, or adjustment. For example, service personnel may remove plug  20   a  in order to adjust or tighten a bolt  28  forming part of the mechanism  26 . In some cases, the plug  20  and the corresponding opening  22  may be relatively small, measuring for example, and without limitation, approximately one inch in diameter. While the plugs  20  and the access openings  22  are shown as being substantially circular, other plug geometries may be possible. 
     Attention is now generally directed to  FIGS. 2-11  which illustrate additional details of the plug  20 . As shown in  FIGS. 2 and 3 , the plug  20  broadly comprises a plug body  30 , an O-ring retainer  32  and a screwdrive  36  that are concentrically aligned and keyed together to prevent their relative rotation. The plug body  30  has the general shape of a truncated cone with tapered sides  56 . The tapered sides  56  are adapted to engage and seat on a chamfered edge  58  ( FIG. 2 ) of the structure  24  surrounding the opening  22 . The chamfered edge  58  allows the plug body  30  to be recessed within the structure  24  so that the outer surface  64  lies substantially flush with the front side  24   a  of the structure  24  (see  FIG. 11 ). 
     The O-ring retainer  32  is donut shaped and may have a substantially circular cross section. The O-ring retainer  32  is sleeved over and bears against the tapered sides  56  of the plug body  30 . The O-ring retainer  32  may be formed of any suitable plastically deformable material which expands laterally as it is compressed. 
     The screwdrive  36  broadly comprises a screw  38 , a nut plate  40  and a retainer plate  34 . The screw  38  extends axially through a central opening  55  ( FIG. 5 ) in the plug body  30  and, as shown on  FIG. 10 , includes male threads  48  that are received by female threads  50  in the nut plate  40 . As seen in  FIGS. 6 and 7 , the nut plate  40  includes a threaded nut  42  and laterally extending flanges  44  which are secured to the retainer plate  34  by rivets  46 , or other fasteners. A cotter pin  52  ( FIGS. 2 and 3 ) or similar retainer extends through a key hole  54  ( FIGS. 8 and 9 ) in one end  38   a  of the screw  38  in order to limit the travel of the nut plate  40  relative to the screw  38 . The other end  38   b  of the screw  38  is flared within the plug body  30  and includes a tool feature  66  adapted to receive a tool (not shown) for rotating the screw  38 . In the illustrated example, the tool receiving feature  66  is a cross slot adapted to receive a screwdriver head (not shown), however a variety of other tool receivers features may be used. 
     Referring to  FIGS. 8 and 9 , the O-ring retainer  32  is captured between the tapered sides  56  of the plug body  30  and the retainer plate  34 . The diameter of the retainer plate  34  is slightly less than the diameter of the plug body  30 . Similarly, in its uncompressed state, the O-ring retainer  32  is also slightly smaller in diameter than the maximum diameter of the plug body  30 . As will be discussed below in more detail, rotation of the screw  38  by a tool (not shown) draws the retainer plate  34  toward the plug body  30 , thereby compressing the O-ring retainer  32  (see  FIGS. 12 and 13 ), and causing the O-ring retainer to expand laterally. Rotation of the retainer plate  34  relative to the plug body  30  is prevented by a pair of spaced apart lugs  62  ( FIGS. 6 and 7 ) which are secured to the retainer plate  34  and into a slot  65  ( FIG. 5 ) in the plug body  40 . 
     As shown in  FIGS. 2 ,  4 ,  8  and  11 , the outer face  64  of the plug body  30  may include a pair of spaced apart recesses  60  adapted to receive a spanner tool (not shown). The spanner tool may be used to hold the plug body  30  against rotation as the screw  38  is being rotated during the plug installation. 
     Referring to  FIG. 2 , in use, the plug  20  is readied for installation by adjusting the screwdrive  36  such that the O-ring retainer  32  is substantially uncompressed. The plug  20  is aligned with the opening  22  on the front side  24   a  of the structure  24 . The plug  20  may then be moved axially into the opening  22  until the tapered sides  56  of the plug body  30  seat against the chamfered edge  58  around the opening  22 , as shown in  FIGS. 8 and 9 . A tool (not shown) may then inserted into the tool receiver  66  and used to turn the screwdrive  36 . The screwdrive  36  draws the nut plate  40 , and thus the retainer plate  34  toward the plug body  30 , thereby compressing the O-ring retainer  32 , as shown in  FIGS. 12 and 13 . 
     Referring particularly to  FIG. 14 , as the O-ring retainer  32  is compressed against the tapered sides  56  of the plug body  30 , the O-ring retainer  32  expands from a first position shown at  32   a , laterally outward a distance D to a second position  32   b  so as to overlie and be compressed against the inside surface  24   b  of the structure  24 . As seen in  FIGS. 12 ,  13  and  14 , in the fully installed position of the plug  20 , the O-ring retainer  32  forms a seal between the tapered sides  56  of the plug body  30  and the inside surface  24   b  of the structure  24  surrounding the opening  22 , while also functioning to retain the plug body  30  within the opening  22  due to the interfering overlap of the retainer  32  and the inside surface  24   b  of the structure  24 . 
     In order to remove the plug  20  to gain access to the opening  22 , a tool (not shown) may be inserted into the tool receiver  66  and rotated in a direction opposite of that during the installation process. The retainer plate  34  is displaced away from the inside surface  24   b  of the structure  24 , allowing the O-ring retainer  32  to spring back to its normal, substantially uncompressed state shown in  FIGS. 8 and 9 . As the O-ring retainer  32  decompresses, it contracts laterally inwardly to clear the structure  24 , thereby allowing the plug  20  to be removed from the opening  22 . 
       FIG. 15  graphically illustrates the steps of a method of installing a plug  20  within an access opening  22 . Beginning at step  68 , the plug  20  is placed within the opening  22  from the front side  24   a  of the structure  24 . Next, at  70 , the screwdrive  36  is accessed from the front side  24   a  of the structure  24 . As previously indicated, a tool (not shown) may be inserted into the tool recess  66  in order to turn the screw  38 . As shown at  72 , the screwdrive  36  is used to displace the O-ring retainer  32  by compressing and thereby laterally expanding the O-ring retainer  32 . At  74 , the displaced and expanded O-ring retainer  32  is used to retain the plug body  30  within the opening  22 . 
     Embodiments of the disclosure may find use in a variety of potential applications, particularly in the transportation industry, including for example, aerospace, marine and automotive applications. Thus, referring now to  FIGS. 16 and 17 , embodiments of the disclosure may be used in the context of an aircraft manufacturing and service method  76  as shown in  FIG. 16  and an aircraft  78  as shown in  FIG. 17 . During pre-production, exemplary method  76  may include specification and design  80  of the aircraft  78  and material procurement  82  in which the disclosed plug  20  may be specified for use in plugging various access openings in the aircraft  78 . During production, component and subassembly manufacturing  84  and system integration  86  of the aircraft  78  takes place. The disclosed method may be used to install the plug  20  in openings in the aircraft  78  during these production processes where the installation must be conducted from only one side of the opening. The plug  20  may assembled and integrated with other subassemblies. Thereafter, the aircraft  78  may go through certification and delivery  88  in order to be placed in service  90 . While in service by a customer, the aircraft  78  is scheduled for routine maintenance and service  92  (which may also include modification, reconfiguration, refurbishment, and so on). The disclosed method  76  may be used to install the plug  20  in openings in the aircraft  78  during the maintenance and service  92 . 
     Each of the processes of method  76  may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on. 
     As shown in  FIG. 17 , the aircraft  78  produced by exemplary method  76  may include an airframe  94  with a plurality of systems  96  and an interior  98 . The disclosed plug  20  may form part of, or may be installed on the airframe  94 . Examples of high-level systems  96  include one or more of a propulsion system  102 , an electrical system  104 , a hydraulic system  106 , and an environmental system  108 . Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the marine and automotive industries. 
     The plug  20  and plug installation method embodied herein may be employed during any one or more of the stages of the production and service method  76 . For example, components or subassemblies corresponding to production process  84  may incorporate the plug  20 . Also, one or more method embodiments, or a combination thereof may be utilized during the production stages  84  and  86 , for example, by substantially expediting assembly of or reducing the cost of an aircraft  78 . Similarly, the disclosed plug and installation method may be utilized while the aircraft  78  is in service, for example and without limitation, as well as during maintenance and service  92 . 
     Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.