Abstract:
A tank is coupled to a body assembly of the fuselage of an aircraft with a lug of the tank mounted on a pin coupled to a body assembly. The pin is marked using a special tool with a first location mark and a second location mark. The lug of the tank may be mounted on the pin. To verify that the tank is correctly located on the pin, the position of the lug may be compared to two marks disposed on the pin. When the respective marks are visible on either side of the lug, the tank is properly aligned on the pin and the tank can be secured to the body assembly. The process is particularly helpful when the pin is located in an area that is inaccessible for direct observation or measurement after the tank is in place.

Description:
FIELD 
       [0001]    This disclosure relates generally to aircraft manufacture and more particularly to locating a tank in a fuselage of an aircraft. 
       BACKGROUND 
       [0002]    Aircraft are often provided with tanks in the main fuselage of the aircraft for holding various liquids, such as fuel or water. These tanks may be used to extend the range of the aircraft, for mid-air fueling of other aircraft, for transporting supplies to land operations, or other activities. Mounting such a tank in a body assembly, that is, a section of the fuselage, involves sliding the tank into place so that holes in mounting lugs on the tanks are placed over pins coupled to mounts of the body assembly. The tanks generally match the outline of the body so that there are often only a few inches or less of gap between the body assembly and the tank. Because of this, the far end of the tank and the far end mounts with their associated pins are not accessible after the tank is place. 
         [0003]    The tank should be properly located with respect to the mounts, that is, that the tank lugs are preferably located within a narrow range of acceptable distances from the mounts brackets on their respective pins. However, because the far end, or distal end, pins and lugs are blocked by the tank itself, this critical distance cannot be measured directly by manufacturing personnel at the time of installation or verified by inspectors. 
         [0004]    A prior art method of ensuring that the distal end lugs are properly located on their respective pins involves measuring a mounting gap on the proximal end of the fuel tank, using a specially manufactured caliper to measure a distance to the distal end lug, measuring a distance between body-assembly mounts, and mathematically calculating the mounting gap on the distal end. This process is time consuming and is susceptible to both measurement errors and calculation errors. 
       SUMMARY 
       [0005]    In an embodiment, a method of attaching a tank with a lug onto a pin of a body assembly of an aircraft fuselage includes disposing a first location mark on the pin, disposing a second location mark on the pin, and mounting the lug onto the pin between the first location mark and the second location mark. The method may also include determining that the lug has no overlap with the first location mark and determining that the lug has no overlap with the second location mark. When no overlap exists, the method may further include attaching the tank to the body assembly. 
         [0006]    In another embodiment, a fuselage of an aircraft may include a body assembly including a tank mount having a pin, the pin including a first indicator and a second indicator, the first indicator separate from the second indicator. The body may also include a tank having a lug, the lug placed on the pin so that the lug is between the first and second indicators and non-overlapping with either the first indicator or the second indicator. 
         [0007]    In yet another embodiment, a method of mounting a tank in a body assembly of an aircraft fuselage includes coupling a lug of the tank to a pin of a mount of the body assembly, the pin having a first location mark and a second location mark. The method may include determining that the lug lies completely between the first location mark and the second location mark and may conclude by securing the tank to the body assembly when the lug lies completely between the location marks. 
         [0008]    The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    For a more complete understanding of the disclosed methods and apparatuses, reference should be made to the embodiment illustrated in greater detail on the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a top view of a portion of an aircraft; 
           [0011]      FIG. 2  is view of a section of a fuselage of the aircraft; 
           [0012]      FIG. 3  depicts a view of the inside of the fuselage; 
           [0013]      FIG. 4  illustrates the use of a remote camera in the fuselage; 
           [0014]      FIG. 5  is a top view of a tool in accordance with the current disclosure; 
           [0015]      FIG. 6  is a perspective view of the tool of  FIG. 5 ; 
           [0016]      FIG. 7  is a top view of the tool of  FIG. 5  placed on a pin of a mount; and 
           [0017]      FIG. 8  is an illustration of operations performed by one embodiment of mounting a tank to a body assembly in accordance with the current disclosure. 
       
    
    
       [0018]    It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein. 
       DETAILED DESCRIPTION 
       [0019]    Tanks in airplane fuselage can carry tens of thousands of pounds of fuel or other liquids yet still must accommodate changes in temperature, changes in air pressure, and high G forces. To accommodate this potentially harsh environment, a tank may be mounted with lugs on pins rather than bolted directly to a body assembly of the fuselage. This lug and pin arrangement allows for a degree of expansion and contraction as the environment changes. However, the lug must be initially placed at a prescribed location on the pin with a high tolerance so that these expansion and contraction changes are fully accommodated. For example, if a tank is mounted at one end of the pin, expansion may damage the lug, the tank, or the tank mount on which the pin is located. 
         [0020]      FIG. 1  is a view of a portion of an aircraft  90  having a fuselage  100 . The fuselage  100  includes a body assembly  103  and a tank  102  disposed inside the fuselage  100 . The tank  102  has a distal end  105  and a proximal end  106 . In the embodiment illustrate, the distal end  105  is facing rearward, or toward the tail-end of the fuselage  100 . In such an embodiment, the tank  102  may be installed from the front. In other embodiments, the tank  102  may be mounted from the tail-end of the fuselage  100  so that the distal end  105  is forward of the proximal end  106 . The problem remains the same in both embodiments, that is, that the distal end  105  is not accessible for visual inspection. In an embodiment, additional tanks  130  and  132  may be installed in addition to tank  102 . The installation of these additional tanks may benefit from the techniques described below caused by obstructed access for inspection after installation. 
         [0021]      FIG. 2  is a view of a section of a fuselage  100  with a tank  102 , such as a fuel tank, and a body assembly  103 . The tank  102  may include lugs  104 ,  107 , with the lug  104  at a distal end  105  of the tank  102  and the lug  107  at the proximal end  106  of the tank  102 . 
         [0022]    The body assembly  103  may include a proximal tank mount  110  with a pin  108 . The lug  107  may be placed over the pin  108  to secure a portion of the proximal end  106  of the tank  102  to the body assembly  103 . Similarly, a distal tank mount  114  holds a pin  112  onto which the lug  107  is placed to capture the far end  105  of the tank  102 . The lug  104  must be a prescribed distance  116  from the tank mount  114  within a certain tolerance. In an embodiment which installs three consecutive body tanks, the prescribed distance is 0.6130±0.1250 for the most forward tank left hand side, 0.7413±0.1500 for right hand side; 0.6488±0.1500 for the mid tank left hand side, 0.7413±0.1500 for right hand; and 0.6488±0.1500 for the most aft tank. 
         [0023]    A first location mark  118  and a second location mark  120  can be disposed on the pin  112  so that the distance  116 , with allowable tolerances, lies between the two marks  118 ,  120 . Because of the placement of the first location mark  118  and the second location mark  120 , correct placement of the lug  104  may be verified visually by simply observing that the lug  104  is between the two marks  118  and  120  and has no overlap with either mark  118 ,  120 . That is, if the lug  104  is touching either mark  118  or  120 , the lug  104  and, therefore the tank  102 , are incorrectly placed and an adjustment to the placement needs to be made before securing the tank  102 . 
         [0024]      FIG. 3  depicts a view of the inside of the body assembly  103  looking toward the proximal end  106  of the tank  102 . The proximal tank mount  110  is shown with the pin  108  coupling the lug  107 . As is illustrated in  FIG. 3 , the distal end  105  of the tank  102  and its lug  104  are not accessible to a person because of the small size of the gap  122  between the tank  102  and the body assembly  103 . This makes direct measurement of the distance  116  virtually impossible. Prior art attempts to take indirect measurements through the gap  122  were difficult and time consuming. 
         [0025]      FIG. 4  is illustrates the use of an instrument  160  with an image sensor  162  such as a camera attached to the instrument  160  via a cable  164 . In an embodiment, the image sensor may be a boroscope that relays an optical image to the instrument  160 . The image sensor  162  may be fed through the gap  122  to allow visual inspection of the location of the lug  104  on the pin  112  by allowing visual inspection of the location of the lug  104  relative to the first location mark  118  and the second location mark  120 . In an embodiment, the camera may take a photograph or image of each side of the lug  104  to show whether there is any overlap of the lug  104  on either location mark  118 ,  120 . When there is no overlap, the lug  104  is properly placed. The instrument  160  may be used again after the tank  102  is mechanically fixed to the body assembly  103  to verify that no shifting occurred during the attachment process. The instrument  160  may be capable of producing a photograph or image of lug placement. The instrument  160  may also be capable of storing and sending a copy of such a photograph or image to a quality control group or to a manufacturing database for archiving. 
         [0026]      FIGS. 5-7  depict a tool  140  that may be used to mark the pin  112  with the first location mark  118  and the second location mark  120 .  FIG. 5  is a top view of the tool  140 . The tool  140  may include a base  142  and a flange  144 . In the embodiment illustrated, a first aperture  146  may be formed in the base  142 . The flange  144  may be split at the base  142  to form a second aperture  148 . A span  152  between the apertures  146  and  148  is centered at the distance  116  and is as wide as the allowable tolerance for the placement of the lug  104 . Other arrangements of apertures  146  and  148  may be used that meet the distance and tolerance requirements for the lug  104  to be properly placed during tank  102  assembly. 
         [0027]    As illustrated in the perspective view of the tool  140  in  FIG. 6 , the base  142  may be a cylindrical section with an inside radius  150  that generally matches an outer radius of the pin  112  so that the tool  140  rests snugly on the pin  112  during use. Each mounting point for each tank  102 ,  130 ,  132  may require a separate tool due to variations in specified gap distances and tolerances. In this case, the tool  140  may include markings (not depicted) to indicate for which specific pin the tool  140  is designed for. 
         [0028]      FIG. 7  shows the tool  140  coupled to the pin  112  with the flange  144  placed against a face of the distal tank mount  114 . In this position, the first and second location marks  118 ,  120  can be marked using a special permanent ink on the pin  112  through the apertures  146  and  148 , respectively. Other marking techniques such as painting, scoring, or etching may be used. A distance  154  is a nominal mounting distance plus acceptable tolerance for placing the lug  104 . A second distance  156  is the nominal mounting distance minus the acceptable tolerance. After the marks  118 ,  120  are in place, the tool  140  may be removed and the tank  102  may be placed on the pin  112  as discussed above. 
         [0029]      FIG. 8  is a flowchart  200  of a method of attaching a tank  102  having a lug  104  onto a pin  112  of a body assembly  103 . At block  202 , a pin  112  of a tank mount  114  of a body assembly  103  may be marked with a first location mark  118  and a second location mark  120 . The marks  118 ,  120  may be made by marking with a permanent ink using a suitable marker or may be painted, for example, using a spray paint. The location of the marks  118 ,  120  may be set using a tool  140 . The tool  140  may be placed on the pin  112  with a flange  144  of the tool  140  seated against the rear tank mount  114 . After the first location mark  118  and the second location mark  120  are placed using the apertures  146  and  148 , respectively, the tool  140  may be removed prior to installation of the tank  102 . 
         [0030]    In other embodiments, the marks  118 ,  120  may be labels placed on the pin. In yet another embodiment, the marks  118 ,  120  may be etched or milled onto a surface of the pin  112  either prior to or after assembly in the distal tank mount  114 . 
         [0031]    At block  204 , a lug  104  of the tank  102  may be mounted on to the pin  112  so that the lug  104  is between the first location mark  118  and the second location mark  120 . 
         [0032]    A determination may be made that the lug  104  is not overlapped with the first location mark  118  at block  206 . As discussed above, an image sensor  162  such as a camera or boroscope may be fed through the gap  122  between tank  102  and the body assembly  103  to determine the placement of the lug  104  relative to the first location mark  118 . 
         [0033]    At block  208 , a determination may be made that the lug  104  is not overlapped with the second location mark  120 . This may require some adjusting of the location of the image sensor  162  compared to determining if there is no overlap with the first location mark  118 . If, at block  210  the lug  104  overlaps either location mark  118 ,  120  based on the determinations at blocks  206  and  208 , the process may follow the ‘yes’ branch continue at block  214  and the tank  102  may be adjusted to correct the placement of the lug  104  on the pin  112  between the two location marks  118 ,  120 . If, at block  210 , no overlap exists, execution may take the ‘no’ branch block  212  and the tank  102  may be attached to the body assembly  103  using struts or other mechanisms (not depicted). In some embodiments, the location of the lug  104  may be re-confirmed after the tank  102  is attached to the body assembly  103 . 
         [0034]    The ability to make a simply visual inspection of the placement of the tank lug  104  on the pin  112  improves manufacturing cycle time and reduces the possibility of making an error in measurement or calculation compared to the previous process. The ability to photograph the placement provides a mechanism to use photographic evidence to document proper placement of the tank  102  by either manufacturing or quality control personnel. The use of a simple tool  140  for providing the marks  118  and  120  increases reliability and accommodates, through the use of multiple tools, changes for different tank types and mounting requirements. 
         [0035]    While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.