Abstract:
The invention relates to the installation of pipes, for example aircraft fuel pipes and fuel systems, in an aircraft. The invention further relates to guidance tool for restricting the potential angular misalignment between the axial centrelines of a pipe end and corresponding socket arrangement during a pipe installation process. The guidance tool may comprise a sleeve and a clamp. The clamp may be configured to removably engage the sleeve with an external surface of a pipe end, such that at least part of the sleeve and pipe end may be inserted into a corresponding socket arrangement.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention concerns a tool for use in aircraft construction. More particularly, but not exclusively, this invention concerns a tool and method for installation of a pipe end within a socket, wherein the pipe end and the socket are part of an aircraft fuel system. 
         [0002]    In a typical aircraft fuel pipe system installation process, the fuel pipe connectors comprising pipe-end receiving socket arrangements are installed in the aircraft structure prior to the fuel pipes being installed. An aircraft engineer may then manually install the fuel pipes by pushing the fuel pipe ends into the fuel pipe connectors. During this push-fit installation, it is important that the angular misalignment between the axial centrelines of the pipe end and the socket is minimised in order to avoid damage to the pipe end or the socket arrangement. Damage to the pipe end or the socket arrangement may include damage to a seal between the pipe end and the socket arrangement. Damage to the pipe end or the socket arrangement during the installation process may lead to potentially costly and hazardous fuel leakages during use of the aircraft. 
         [0003]    Typically, the tolerance level required is no more than ±2 degrees angular misalignment between the axial centrelines of the pipe end and the socket arrangement. However, it may be difficult to measure and/or monitor the accuracy achieved during the push fit process. Additionally, it is desirable to maintain a gap between the end of the pipe end and the socket arrangement, that allows the pipe end to float in a longitudinal direction when installed in the socket arrangement. In the aircraft industry this is typically known as the coupling gap. 
         [0004]    The present invention seeks to mitigate the above-mentioned problems. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides, according to a first aspect, a guidance tool for restricting the potential angular misalignment between the axial centrelines of a pipe end and corresponding socket arrangement during a pipe installation process, the guidance tool comprising: 
         [0006]    a sleeve; and 
         [0007]    a clamp; wherein the clamp is configured to removably engage the sleeve with an external surface of a pipe end, such that at least part of the sleeve and pipe end may be inserted into a corresponding socket arrangement. 
         [0008]    The guidance tool, when engaged with a pipe end, restricts the potential angular misalignment between the axial centrelines of a pipe end and corresponding socket arrangement when the pipe end is pushed into the socket arrangement. The sleeve reduces the free space between the external surface of a pipe end and the internal surface of a corresponding socket arrangement, the free space which may allow angular misalignment of the pipe end and socket arrangement beyond the desired tolerance levels during the pipe installation process. The sleeve may remove substantially all of the free space between the external surface of a pipe end and the internal surface of a corresponding socket arrangement during installation of the pipe end into the socket arrangement. 
         [0009]    The clamp may be configured to allow removal of the sleeve from engagement with the external surface of a pipe end, once the pipe end has been inserted into a corresponding socket arrangement. 
         [0010]    The sleeve may be approximately cylindrical. The sleeve may comprise a first half and a second half, the first half and second half being distinct and separate elements. The first half and the second half of the sleeve may be connected to each other by a hinge. 
         [0011]    The clamp may be approximately cylindrical. The clamp may comprise a first half and second half, the first half and second half being distinct and separate elements. The clamp may comprise a locking mechanism to maintain the sleeve in removable engagement with a pipe end when the locking mechanism is in the locked position. The locking mechanism may allow removal of the sleeve from removable engagement with a pipe end when the locking mechanism is in the unlocked position. The locking mechanism may be one or more fasteners. The one or more fasteners may be quick release fasteners, for example spring loaded fasteners. The one or more fasteners may be a screw, Allen bolt, or any other suitable joining means. The clamp may comprise a first half and a second half, the first half and second half connected to each other by a hinge. The first half and second half of the clamp may respectively include a first protrusion and second protrusion, such that bringing the first protrusion and second protrusion into contact locks the clamp. A clip may maintain the first protrusion and second protrusion in contact with each other. Alternatively, an engineer may hold the first protrusion and second protrusion together during the installation process in order to lock the clamp into position. In such an arrangement, the clamp may be easily unlocked by releasing the first protrusion and second protrusion, thereby allowing easy removal of the installation device from a pipe end and socket arrangement when connecting the two. The external surface of the clamp may include features configured to allow an engineer to hold the clamp together. The external surface of the clamp may include gripping portions. 
         [0012]    The clamp may be arranged to limit the extent to which the sleeve may be inserted into the socket arrangement. The clamp may be arranged to abut the socket arrangement when the pipe end is in the desired installed position. 
         [0013]    The clamp and the sleeve may be separable and distinct elements. Alternatively the clamp and the sleeve may be integrated such that they are not separable. A first half of the sleeve may be integrated with a first half of the clamp and the second half of the sleeve may be integrated with the second half of the clamp. The integrated halves may be formed by a single moulding or machining process. 
         [0014]    The guidance tool may comprise a material chosen to be softer than the material from which the pipe end and socket arrangement the guidance tool is designed to be used with is made of. The guidance tool may comprise a plastics material. The plastics material may be nylon or any other suitable material. The softer material may reduce the possibility that the guidance tool damages a pipe end or socket arrangement during the installation process. The guidance tool may comprise a low-friction material. A low-friction material may facilitate the installation of the pipe end and guidance tool within the socket arrangement. 
         [0015]    The guidance tool may be arranged for use with single or double walled pipe ends and single or double walled socket arrangements. The clamp and/or the sleeve may include sections of material that have been removed in order to avoid damage to features of pipe ends or socket arrangements, for example bonding lugs. 
         [0016]    A second aspect of the invention provides a pipe end and a guidance tool removably engaged with the pipe end, the guidance tool as substantially described with respect to the first aspect of the invention. 
         [0017]    A third aspect of the invention provides a pipe end fitting and a guidance tool removably engaged with the pipe end, the invention further including a socket arrangement, whereby the pipe end and guidance tool at least partially extend into the socket arrangement. 
         [0018]    A fourth aspect of the invention provides a method of installing a pipe end into a socket arrangement in an aircraft structure, the method comprising the steps of: 
         [0019]    removably engaging a guidance tool according to a first aspect of the invention with the pipe end; 
         [0020]    inserting the pipe end and guidance tool at least partially into the socket arrangement; and 
         [0021]    removing the guidance tool from the pipe end. 
         [0022]    The guidance tool may be as described with respect to any of the first, second, or third aspects of the invention. 
         [0023]    Removably engaging a guidance tool with the pipe end may comprise the step of locking the guidance tool to the pipe end fitting. The step of locking the guidance tool to the pipe end fitting may comprise the use of quick release fasteners. The step of locking the guidance tool to the pipe end fitting may comprise an installation engineer physically biasing the guidance tool into contact with the pipe end during the installation process. Removing the guidance tool from the pipe end may comprise unlocking the guidance tool. The guidance tool may be removed from the pipe end by sliding it away from and out of the socket arrangement, then opening the guidance tool to allow it to be fully removed from the pipe end. The guidance tool may be opened by being split into two or more parts. The guidance tool may comprise a hinge allowing expansion of the tool without the tool being fully split into two or more parts. This may reduce the possibility of parts of the guidance tool being lost. 
         [0024]    A fifth aspect of the invention provides an aircraft, the aircraft comprising a pipe structure constructed according to the method described above or using a guidance tool as described above with regards to any aspect of the invention. 
         [0025]    It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0026]    Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: 
           [0027]      FIG. 1  shows a cross-section view of a guidance tool and fuel pipe coupling according to a first embodiment of the invention; 
           [0028]      FIG. 2  shows an exploded view of the guidance tool according to the first embodiment of the invention; 
           [0029]      FIG. 3  shows an isometric view of the guidance tool according to the first embodiment of the invention; 
           [0030]      FIG. 4  shows an isometric view of a guidance tool according to a second embodiment of the invention; 
           [0031]      FIG. 5  shows an isometric view of a guidance tool according to a third embodiment of the invention; 
           [0032]      FIG. 6  shows an isometric view of a clamp for use with a guidance tool according to a fourth embodiment of the invention; 
           [0033]      FIGS. 7A and 7B  show a pipe connection method according to a fifth embodiment of the invention; and 
           [0034]      FIG. 8  shows an aircraft comprising a fuel system including a fuel pipe connection according to a sixth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]      FIG. 1  shows a fuel pipe coupling in an aircraft, the fuel pipe coupling comprising a pipe end  100 , a socket arrangement  102 , and a guidance tool  104 . The pipe end  100  is partially inserted within the socket arrangement  102 . The guidance tool  104  comprises a sleeve  106  and a clamp  108 . The sleeve  106  is held in removable engagement with the outer surface of the pipe  100  by the clamp  108 . As can be seen in  FIG. 1 , the sleeve  106  is at least partially inserted into the socket  102  such that it removes part of the free space between the outer surface of the pipe  100  and the inner surface of the socket arrangement  102 . This free space is to allow slight angular movement of the pipe coupling when the aircraft is in the air. Such angular movement may be caused by vibration of the aircraft during flight. However, during the pipe installation process, when the pipe end  100  is inserted into the socket arrangement  102 , the free space may allow angular misalignment of the axial centrelines of the fuel pipe  100  and socket arrangement  102  to an extent where the fuel pipe coupling is damaged. The damage may be to the seal  110  located between the far end of the pipe end  100  and the socket arrangement  102 , or other elements of the fuel pipe coupling. 
         [0036]    The arrangement as described for  FIG. 1  allows the pipe end  100  to be inserted into the socket arrangement  102  with the potential for angular misalignment between the axial centrelines of the pipe end  100  and the socket arrangement  102  restricted to no more than ±2 degrees, due to the removal of the free space by the sleeve  106  as described above. The clamp  108  abuts the socket arrangement  102  limiting the distance the sleeve  106  may be inserted into the socket arrangement  102 . The clamp  108  may also be used to control the gap between the end of the pipe end  100  and the socket arrangement  102 , such that the pipe end  100  and socket arrangement  102  are joined with a coupling gap. 
         [0037]      FIG. 2  shows the guidance tool  104  in greater detail than in  FIG. 1 . The sleeve  106  comprises a first half  106 ′ and a second half  106 ″. It can be seen that the two halves,  106 ′ and  106 ″, when put together, form a sleeve with a cylindrical inner surface. The cylindrical inner surface is shaped and sized to engage with the pipe end  102 . The first half of the sleeve  106 ′ includes a cut-out portion  113  where the sleeve material has been removed. The cut-out portion  113  is arranged to prevent the sleeve  106  from fouling features of the pipe end  100  or socket arrangement  102  such as bonding lugs during the installation process and removal of the sleeve  106 . The clamp  108  comprises a first half  108 ′ and a second half  108 ″. The clamp  108  may be placed around the sleeve  106  and locked in position to removably engage the sleeve with the pipe end  100 . In this embodiment the clamp is locked in position by use of the quick-release fasteners  116 . The sleeve includes a flange portion  112  against which the clamp  108  is arranged to abut, and a male insert  114  located on the outer surface of the sleeve  106  arranged to engage with a female insert on the inner surface of the clamp  108  to ensure the correct location of the clamp  108 . 
         [0038]      FIG. 3  shows the guidance tool as shown in  FIGS. 1 and 2 , where the first half  106 ′ and second half  106 ″ of the sleeve  106  are in contact with each other, and the clamp  108  is locked in position around the sleeve  106 . 
         [0039]      FIG. 4  shows a guidance tool  200  according to a second embodiment of the invention. The sleeve  206  is essentially the same as the sleeve  106 . The clamp  208  comprises a first half  208 ′ and a second half  208 ″ that are joined via a hinge arrangement  210 . Each half of the clamp  208 ′,  208 ″ includes a protrusion  212 ′,  212 ″, approximately opposite the hinge arrangement  210 . The two protrusions  212 ′,  212 ″, may be held together manually to lock the clamp  208  in position on the sleeve  206 . Such an arrangement may increase the ease of use of the guidance tool as no additional fastening mechanism is required. Additionally, the two halves of the clamp,  208 ′,  208 ″, are connected together by the hinge arrangement  210 , reducing the possibility of losing one half of the clamp. In alternative embodiments, the two protrusions  212 ′,  212 ″, may be locked together using a clip or other suitable mechanical locking mechanism. 
         [0040]      FIG. 5  shows a guidance tool  300  according to a third embodiment of the invention. In this embodiment the guidance tool comprises a first half  302  and a second half  304 , each half comprising a single moulded piece combining both the function of a sleeve and clamping arrangement. Functionally, the guidance tool is fastened to a pipe end in the same way as the guidance tool substantially as described with reference to  FIG. 4 . The guidance tool  300  includes a fastener  308  arranged to lock the first half  302  and second half  304  together. Providing two, one-piece, halves that are hinged together reduces the possibility of losing parts of the guidance tool and may increase the ease of use of the tool during a pipe fitting operation. The first half  302  and second half  304  each include a U-grip  306 , the U grips  306  configured such that when the clamp is fastened around a pipe end, the U-grips compress the sleeve arrangement onto the surface of the pipe end. 
         [0041]      FIG. 6  shows a clamp  400  according to a fourth aspect of the invention. The clamp  400  is approximately oval shaped and comprises a first half  402  and a second half  404 , the two halves  402 ,  404 , connected together by a hinge arrangement  406  and a fastening arrangement  408 . Each half  402 ,  404 , includes a female insert  410  to allow the clamp to be located on a suitable sleeve. Providing an oval clamp  400  as shown in  FIG. 4 , may allow the clamp to be used with a number of different sized sleeves, each sleeve being specifically sized for a certain pipe end diameter. The sleeves for use with the oval clamp may include a standard size male part for insertion into the female insert  410 . The female insert  410  may be arranged to receive a number of different sized shims in order that the clamp  400  may be used on different sized sleeves. Providing an adjustable clamp as shown in  FIG. 6  may increase the versatility of the clamp such that it may be used in a variety of guidance tool configurations, each configuration specific to a particular pipe end or socket diameter. 
         [0042]      FIGS. 7A and 7B  show a pipe installation method according to a fifth aspect of the invention.  FIG. 7A  show a guidance tool  700  fastened to a pipe end  702  prior to the pipe end  702  being manually inserted into a socket arrangement  704 . In this case the socket arrangement  700  corresponds to that described in relation to the first embodiment of the invention but it will be appreciated any of the described guidance tools may be used. Once the guidance tool  700  has been fastened to the pipe end  702 , the pipe end  702  and guidance tool  700  are partially inserted into the socket arrangement  704 , as shown in  FIG. 7B . Once the pipe end  702  is properly located in the socket arrangement  704 , the guidance tool is removed from the pipe end fitting  702 , in this case by removing the fasteners from the clamp and sliding the sleeve away from the socket arrangement  704  and out of engagement with the pipe end  702 . 
         [0043]      FIG. 8  shows an aircraft  800  including a fuel pipe system including a fuel pipe coupling  802  that has been installed using a guidance tool according to any of the above described embodiments of the invention. 
         [0044]    Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. 
         [0045]    Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.