Abstract:
A method and apparatus for defueling an aircraft. The apparatus includes a defueling fitting comprising one or more structural connectors, which may include one or more suction cups. The one or more structural members are attached to a mount. The mount may be of any shape, including generally straight, angled, polygonal, or circular. An actuator assembly is attached to the mount for opening an aircraft defueling valve. The first and second suction cups are operatively connected to a vacuum source to connect the defueling fitting to an aircraft body, with the actuator assembly positioned at the aircraft defueling valve. The defueling fitting facilitates safe and convenient defueling of certain aircraft that have recessed or covered fuel drain valves. For example, the Boeing C-17 has fuel drain valves that are recessed behind doors, heretofore presenting a great obstacle to appropriate defueling. The defueling fitting described herein may be used in small and tight spaces, even when other conventional defueling fittings are not helpful.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to aircraft equipment, and more particularly to a method and apparatus for defueling an aircraft.  
       BACKGROUND OF THE INVENTION  
       [0002]     Generally, aircraft often need to be defueled prior to performing certain types of maintenance or repairs. There are generally three stages of aircraft defueling: pumping (removing the majority of fuel from the aircraft fuel cells), bottom sumping (removing most of the remaining fuel from the bottom of the fuel cells—traditionally done by some type of gravity feed), and depuddling (which involves removing the small puddles remaining in the fuel cells). A number of aircraft defueling systems have traditionally been available to handle the various stages of aircraft defueling. At some point, however, most defueling systems require some type of gravity feed, resulting in low drain rates and long drain times. In fact, for many large aircraft, depending on the amount of fuel remaining in the tanks, it can take up to several hours to fully defuel the aircraft using a gravity dependent system.  
         [0003]     More recent defueling systems include a vacuum assist to increase the defueling rate. Vacuum assist defueling systems can evacuate airplane fuel tanks in a fraction of the time normally allocated to a gravity system. Nevertheless, many vacuum assist systems are useful only with specific fuel drain configurations. Thus, the use of such vacuum assist systems is limited to certain aircraft and certain personnel trained to match an inventory of attachments with the design requirements of fuel drain systems of particular aircraft.  
         [0004]     Accordingly, a universal coupler described in U.S. Pat. No. 5,117,876 (“the &#39;876 patent), which is incorporated in its entirety herein by this reference, is intended for use with nearly all aircraft. However, certain aircraft, such as the Boeing C-17, include a door housing the fuel drain valve. The location of the door and the recessed valving prevents use of a universal coupler similar to what is shown and described in the &#39;876 patent. The spacing about the door on the C17 is generally too small to accommodate the universal coupler of the &#39;876 patent. Therefore, there is a need for an aircraft defueling apparatus that can be used in a variety of environments, including relatively small, enclosed spaces, to minimize the risk of fuel leaks.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides a method and apparatus for defueling aircraft. The apparatus includes a defueling fitting comprising one or more structural connectors, which may include suction cups. The one or more structural members are attached to a mount. The mount may be configured in any desired shape, including a shape that is generally straight, angled, polygonal, or circular. An actuator assembly is attached to the mount for opening an aircraft drain valve. The first and second suction cups are operatively connected to a vacuum source to create a pressure differential for connecting the defueling fitting to an aircraft body, with the actuator assembly operatively positioned at the aircraft drain valve.  
         [0006]     The defueling fitting facilitates safe and convenient defueling of certain aircraft that have unique configurations, such as recessed or covered fuel drain valves. For example, the Boeing C-17 has fuel drain valves that are recessed behind doors, heretofore presenting a great obstacle to safely defueling. The defueling fitting described herein may be used in small and tight spaces, even when other conventional defueling fittings are not helpful.  
         [0007]     Other objects, features, and advantages of the invention will become apparent from the following detailed description of the invention with reference to the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Preferred embodiments of the invention are described below with reference to the accompanying drawings:  
         [0009]      FIG. 1  is a bottom view of an aircraft defueling fitting according to one embodiment of the present invention;  
         [0010]      FIG. 2  is an exploded side view, partly in section, of the aircraft defueling fitting of  FIG. 1 , shown in relation to a fuel tank drain valve mounted to a surface on an aircraft;  
         [0011]      FIG. 3  is a side elevation view, partly in section, of the aircraft defueling fitting of  FIG. 1  attached to a surface of an aircraft, and shown in schematic representation in relation to a tank and vacuum according to one embodiment of the present invention;  
         [0012]      FIG. 4  is a bottom view of an alternative embodiment of an aircraft defueling apparatus according to the present invention; and  
         [0013]      FIG. 5  is a bottom view of an alternative embodiment of an aircraft defueling apparatus according to the present invention. 
     
    
       [0014]     Throughout the drawings, identical reference numbers and descriptions indicate similar, but not necessarily identical elements.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     It is a very common procedure to defuel an aircraft prior to maintenance or repair. Most aircraft include one or more drain valves at low points of the fuel tanks to facilitate defueling. The drain valves are usually spring loaded “poppet” valves that are opened by the application of a force normal to the spring force. The drain valves of most aircraft are flush with the outside body of the aircraft and therefore readily accessible with few or no local obstructions. However, some aircraft include recessed fuel drain valves that are more difficult to access. Some recessed fuel drain valves are located adjacent or behind structures, such as doors, that are generally flush with the outside body of the aircraft. Such structures must sometimes be opened to gain access to the drain valve. For example, the Boeing C-17 is equipped with recessed fuel drain valves normally housed behind closed doors. Other fuel drain valves are placed in small or difficult-to-access locations that complicate the use of defueling fittings, because standard fittings will not fit over the drain valve in the spacing provided.  
         [0016]     Therefore, the present invention involves an aircraft defueling fitting and associated methods of defueling with features that facilitate defueling aircraft even in tight, recessed, and difficult-to-access spaces. The present invention more specifically involves a fitting that attaches to an aircraft body so that an actuator can be placed over the fuel drain valve. The actuator opens the fuel drain valve and allows fuel to drain from the associated fuel tank. The defueling fitting described herein can be used with any aircraft, including without limitation fixed wing aircraft (airplanes) and rotary wing aircraft (helicopters). Such aircraft are normally provided with one or more flush or recess-mounted fuel drains in the wings and/or fuselage.  
         [0017]     As used throughout the specification and claims, the term “plate” is used broadly to mean any object, the thickness of which is relatively small or shallow in comparison with the other dimensions of the item. A “plate” can also include a cup, especially a suction cup. “Flange” is also used broadly to mean a rim or plate used to hold an object in place or attach it to another object. “Circumference” means at or near a boundary line of a figure, area, or object. The term “baffle” means a usually static device that regulates or limits the flow of a fluid. The term “hub” is used broadly to indicate a central part or a receiver of other parts. “Vacuum” means lower pressure than local atmospheric pressure. The words “including” and “having,” as used in the specification, including the claims, have the same meaning as the word “comprising.” 
         [0018]     Turning now to the figures, and in particular to  FIGS. 1-2 , an aircraft defueling fitting  100  is shown according to principles of the present invention. The aircraft defueling fitting includes first and second structural connectors, which, according to  FIGS. 1-2 , comprise a first suction cup  102  and a second suction cup  104 . Each of the first and second suction cups  102 ,  104  comprises a plate  106  ( FIG. 2 ). The plate  106  shown in  FIG. 2  is a generally circular plate with a center  108 , a first surface  110 , a second surface  112 , and a circumferential edge  114 . According to the embodiment of  FIGS. 1-2 , the center  108  also defines a hole receptive of a fastener, for example a screw  116 . The plate  106  may be made of structural material such as aluminum, according to some embodiments; however, other materials such as different types of rubbers, plastics, ceramics, or composites may also be used.  
         [0019]     The plate  106  includes a second hole  118  spaced from the center  108 , a groove or trough  120  in the first surface  110 , and a seal disposed in the trough  120 . The trough  120  is preferably circumferential and continuous, but not necessarily so. The second hole  118  of  FIGS. 1-2  is a vacuum suction port that facilitates sealing the first surface  110  to an aircraft and prevents fluid leaks during aircraft defueling. According to  FIGS. 1-2 , the seal is a first elastomeric ring  122  and includes an exposed angled surface  124  seen most clearly in  FIG. 1 .  
         [0020]     The circumferential edge  114  comprises a concave surface  126  according to the embodiment of  FIGS. 1-2 . A second elastomeric ring  128  fits snugly around the plate  106  against the concave surface  126 .  
         [0021]     The first and second suction cups  102 ,  104  are connected to one another via a mount  130  extending therebetween. The mount  130  of  FIGS. 1-2  is a generally straight, elongated member comprised of structural materials such as aluminum. However, other suitable materials may also be used to construct the mount  130 . The mount  130  includes first and second holes  132 ,  134  at opposing ends thereof, through which the screws  116  or other fastener extends. The screws  116  attach the suction cups  102 ,  104  to the mount  130 . A gasket  136  may be disposed between the mount  130  and each of the suction cups  102 ,  104 .  
         [0022]     The aircraft defueling fitting  100  also includes an actuator assembly  140 . The actuator assembly  140  of  FIGS. 1-2  acts as a poppet valve opener and extends transversely from the mount  130 . As mentioned above, most aircraft are equipped with poppet drain valves to facilitate defueling. The actuator assembly  140  opens fuel tank drain valves when the properly aligned therewith. Details of engagement between the actuator assembly ( 140 ) and a poppet fuel tank drain valve are shown and discussed below with reference to  FIG. 3 .  
         [0023]     Referring again to  FIG. 2 , the actuator assembly  140  comprises a probe  142  with internal threading  144  and a tapered end  146 . The tapered end  146  includes a circumferential O-ring  148  and a recess  150  receptive of inserts  152  of various lengths. The actuator assembly also includes a hub  154  receptive of the probe  142 , and a hub gasket  156 . The hub  154  is flanged to facilitate connection to the mount  130 . Accordingly, one or more fasteners  158  may be inserted through holes  160  in the mount  130  to attach the hub  154  in an aperture  155  of the mount  130 . When the actuator assembly  140  is fully assembled, the probe  142  is inserted at least partially into the hub  154  (See  FIG. 3 ). The O-ring  148  seals an area or annulus between the hub  154  and the probe  142 . An internal baffle  162  of the hub  154  limits insertion of the probe into the hub  154 . However, one of the pin inserts  152  extends through the baffle  162  and through the hub  154 . The hub  154  includes a recess  164  receptive of the hub gasket  156 . The hub gasket  156  is preferably made of rubber or other sealing material.  
         [0024]     When the aircraft defueler fitting  100  is fully assembled, it may be used to effectively defuel an aircraft, including aircraft with covered and recessed fuel tank drain valves such as a poppet valve  166  shown in  FIGS. 2-3 . As shown in  FIG. 2 , some aircraft, such as the Boeing C-17 aircraft  168  shown, include an openable door  170  that covers and houses the poppet valve  166 . However, the actuator assembly  140  may be sized appropriately and fitted with one of the pin inserts  152  such that when the suction cups  102 ,  104  are connected to and seal against an outer surface  172  of the aircraft  168 , the poppet valve  166  is forced open by the insert  152  as shown in  FIG. 3 .  
         [0025]     One or more fluid passageways  174  through the actuator assembly  140  are open to a connecting hose  176  and in fluid communication with the poppet valve  166 . Therefore, when the poppet valve  166  is opened, fuel in the aircraft  168  is drained to a storage/vacuum assembly  178  which provides both a vacuum source and a holding tank. The suction cups  102 ,  104  and the actuator assembly  140  are operatively connected to a vacuum  179  provided by the storage/vacuum assembly  178 . The vacuum  179  creates a pressure differential to seal the suction cups  102 ,  104  against the surface of the aircraft. The vacuum  179  may also provide suction to the actuator assembly  140  for increased drain flow rates. Those skilled in the art will understand, however, that the vacuum  179  supplied to the suction cups  102 ,  104  and the actuator assembly  140  may be supplied by one or more vacuum generators, and that the vacuums  179  to each of the suction cups  102 ,  104  and the actuator assembly  140  may be independent or provided by a single source. The small actuator assembly  140  flanked by the suction cups  102 ,  104  allows easy and convenient access to tight or small areas, or recessed structures about an aircraft fuel drain valve (such as the ones associated with a Boeing C-17).  
         [0026]     While the aircraft defueler fitting  100  is shown with two suction cups  102 ,  104  and a generally straight mount  130 , other configurations are also contemplated and within the scope of the present invention. For example, with reference to  FIG. 4 , an alternate configuration for the defueler fitting  100  is shown. According to the embodiment of  FIG. 4 , the mount  130  is angled, with the actuator assembly  140  connected to the mount  130  at a vertex  180  of the generally V-shaped mount  130 . The actuator assembly  140  and the suction cups  102 ,  104  may remain, however, similar or identical to the assembly shown in  FIGS. 1-3 . Other configurations, including configurations with only one suction cup  102  ( FIG. 5 ) or more than two suction cups  102 ,  104  are also contemplated by the present invention. Furthermore, the mount  130  may be made of various shapes, including without limitation shapes that are round, polygonal, or any other suitable configuration. Accordingly, an aircraft fuel tank may be defueled by providing a defueling fitting according to principles described herein, and depressing an aircraft fuel drain valve, such as the poppet valve  166  shown in  FIG. 3 . Thus, leaks of any aircraft fuel are reduced or eliminated by the various gaskets, seals, and fittings of the defueler fitting  100  and all draining fuel is directed through the hose  176 .  
         [0027]     For some particular aircraft, such as the Boeing C-17 aircraft  168  ( FIGS. 2-3 ), defueling may include the steps of opening the fuel valve door  170 , attaching the two suction cups  102 ,  104  to the aircraft  168  adjacent to fuel valve door  170 , and depressing the poppet valve  166  with the actuator assembly  140  of defueler fitting  100 . The actuator assembly may need to be aligned with the poppet valve  166  for proper operation.  
         [0028]     While this invention has been described with reference to certain specific embodiments and examples, it will be recognized by those skilled in the art that many variations are possible without departing from the scope and spirit of this invention. The invention, as described by the claims, is intended to cover all changes and modifications of the invention which do not depart from the scope of the invention.