Abstract:
A sealing assembly is provided in an airframe of aircraft. The sealing assembly includes, but is not limited to a resilient and yet stiff enough bellows body that is attachable to the fuselage of the aircraft and is further attachable to a center wing box of the aircraft. The sealing assembly seals off a gap between the fuselage and the center wing box so as to allow maintaining pressure in the fuselage if the fuselage is pressurized. The bellows body is a composite and is designed to sustain exposure to tear and wear and exposure to a high and low temperatures as well as exposure to chemicals used during operation of the aircraft.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/EP2010/054512, filed Apr. 6, 2010, which was published under PCT Article 21(2) and which claims priority to European Patent Application No: 09 157 424.4 filed 6 Apr. 2009 and of U.S. Provisional Patent Application No. 61/167,010 filed 6 Apr. 2009, the disclosure of which applications is hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The technical field relates to the field of aeronautics. More particularly the technical field relates to a sealing assembly in an aircraft attachable to the airframe of an aircraft. 
       BACKGROUND 
       [0003]    The need for reliable air transport means is ever increasing. Large cargo aircraft or cargo haulers have been devised in order to meet such demands for air transport. 
         [0004]    Aircraft makers having distributed manufacturing facilities have found aircraft of the detached wing type to be useful. Detached wing type airframes have the wing structure detached from the fuselage, rather than having the wing structure integrally formed with the fuselage. This type of airframe allows manufacturing the wing structure in one manufacturing facilities whereas the fuselage structure can be manufactured elsewhere. The airframe may then be assembled by mounting the wing structure to the fuselage at yet another manufacturing facility. 
         [0005]    The wing structure, fuselage and the empennage, make up the major components of the airframe. Those components are assembled in a manner so as to arrive at a structure providing the maximum amount of stability and reliability. For example, it is imperative to allow relative displacements between the airframe components in order to better absorb and propagate forces and so obtain a favorable behavior of the airframe to strain occurring during critical phases of aircraft operation. The landing phase may be one example of such a critical phase. 
         [0006]    The need for stable and resilient airframe design holds particularly true in case of cargo aircrafts, which are used for example in military missions for troop and heavy equipment deployment. The requirement to cope with a payload in the range of tens of tons combined with the need for performing challenging flight maneuvers in possibly adverse weather conditions subjects the airframe to high tensile and compressive forces. 
         [0007]    Designing the airframe to such high standards on stability and reliability often poses challenges to the equally important requirement to ensure that the fuselage stays pressurized during all flight conditions. This is because, especially in airframes of the detached wing type in high or low wing constructions, gaps within the airframe may be necessitated due to those design requirements. A variable geometry aircraft seal for swing-wing aircraft is disclosed in U.S. Pat. No. 4,029, 272. 
         [0008]    There is therefore a need for reliable sealing means to seal gaps in the airframe designs of the detached wing type. In addition, other needs, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
       SUMMARY 
       [0009]    In addressing at least parts of the above needs a sealing assembly is provided that comprises a bellows body. The bellows body is attachable or couplable to the airframe and is suitable to reliably seal off one or more gaps, openings or apertures or other pressure escapes in the airframe. In accordance with one embodiment, the bellows body of the sealing assembly is arranged and mounted between the wing structure of the airframe and the fuselage of the airframe. 
         [0010]    More particularly, the airframe is of the detached wing type and the bellows body is attached to both, the center wing box of the wing structure and the upper portions of the center fuselage. The center wing box and upper portions of center fuselage are arranged at a distance to each other thus defining a gap in the wing carry-through section of the airframe. The gap can thus be sealed off by using the sealing assembly according to the invention. 
         [0011]    The bellows body can be thought as an elongated sealing strip manufactured from a material having resilient or elastomeric consistency. Preferably the bellows body has a flat, curved or wavy cross-section with two length-wise side portions, one of the two length-wise side portions, edges or flap being attachable to the centering box and the other side portion, edge or flap being attachable to the fuselage. 
         [0012]    However, it will be understood by those skilled in the art that the sealing assembly is also attachable to other structures in the airframe defining other gaps. The sealing assembly may for example be attachable to two structures in the fuselage or in the empennage or to interface structures between the empennage and the fuselage. 
         [0013]    Although in circumstances attaching the sealing assembly direct to the airframe may be conceivable, mounting members are used for indirect attachment of the sealing assembly&#39;s bellows body to the airframe structures. This indirect way of attaching allows a more flexible construction, essentially implementing a “welted” construction principle. The mounting may be thought to serve as a “welt” for attaching the bellows body to attachment points in the airframe. This welted construction allows the sealing assembly to better compensate relative displacement between the airframe structures that are likely to occur during operation of the aircraft. 
         [0014]    According to one embodiment the mounting members have contoured portions in order to receive and accommodate the side portions of the bellow body when so attached to the airframe. According to one embodiment, the contoured portions are arranged so as to match an outline of the respective surfaces of side portions of the bellow body. This allows for a snug and tight fit of the bellows body, thus providing even better sealing properties. The cabin pressure can be thus maintained even when the airframe needs to sustain relatively large relative displacements of the airframe structures to which the bellow body is attached. 
         [0015]    According to another embodiment, the contoured portions are designed not only to ensure better sealing properties, but to provide a guiding function for a deflection which the so attached bellows body may undergo during operation of the aircraft. Deflection therefore occurs in a controlled manner rather than having the bellows body “wobble” uncontrollably. 
         [0016]    According to yet another embodiment the contoured portions of the mounting members have crimped terminal portions. Those terminal portions are crimped so as to curl away from the bellows body when the bellow body is so attached to the airframe. The crimped terminal portions of the contoured portion prevents the bellow body from damage should the bellows body become deflected to such a degree that it makes contact with the contoured portion. The otherwise possibly sharp edges of the contoured portions can thus be prevented from cutting into the bellows body. 
         [0017]    Mounting members having the contoured portions with the crimped edges are preferably arranged as J- or L-aluminum profiled bars. However, the exact shape of the aluminum profile bar may depend on the exact spatial relationship between the airframe structures defining the gap to be sealed. 
         [0018]    According to yet another embodiment the bellows assembly further comprises a retainer member. The retainer members can be arranged as U profile aluminum bars arranged in such a manner that the each of the side portions of the bellows body is firmly sandwiched between one of the retainer members and the contoured portion of one of the mounting members. The end portions of the bellows body, the mounting members and the retainer members each have a series of holes arranged therein which are brought into registry when attaching the bellows body in order to pass bolts through the holes received on the other sides in sealed nuts to firmly affix and hold this three-part sandwich structure in place. 
         [0019]    According to a further embodiment the mounting member has a drainage arrangement comprising for example a number of additional holes for draining the mounting member. Condense water or other liquids that may accumulate in the channel-like structures formed by the contoured portions can this be carried off 
         [0020]    According to yet another embodiment the drainage arrangement comprises hose fittings in registry with those additional holes. The hose arrangement has a hose attached to any one of the hose fittings in order to allow the water or other accumulated liquids to drain in a controlled manner. 
         [0021]    According to one embodiment the bellows body is arranged as a composite material in a plurality of alternately stacked layers. The layers comprise layers of woven polyester fabric, layers of polyester, layers of silicon and layers of glass fiber. The polyester layer and the woven polyester fabric provide a support structure for the bellows body. During flight operations and when the cabin is pressurized, pressure exerted on the bellows body from the inside of the cabin bulges the bellows body outwardly due to pressurized environment within the fuselage. The polyester structure ensures that this bulging out and deformation of the bellows body occurs in a controlled manner rather than the bellow body, due to its resilient characteristic, ballooning in an uncontrolled way. The silicon layers add the required resiliency and suppleness whereas the glass fiber provides stiffness. 
         [0022]    According to one embodiment, the layers are not only stacked but also laid out side by side inside and across the length of the bellows body. This vertical and horizontal arrangement of the layers allows for a better way of localizing desired properties where they are most needed: suppleness and resilience in or around the center portion and more stiffness in or around the two end portions of the bellows body. For example, according to one embodiment, the bellows body has two end portions that are joinable by overlapping the two end portions when the bellow body is attached to the airframe. The stiffness at the ends portions allows for a better fit of the bolts that are used to join the overlapped end portions. 
         [0023]    The desired stiffness at the end portions for a firm fit of the nut-and-bolt joint. The stiffness so required at the end portions can thus be provided without comprising the desired resiliency of the bellow body required at the center portion thanks to the thicker silicon kernel layer embedded in the center portion of the bellows body. 
         [0024]    In other words, the layers are so arranged that the amount of glass fiber is increased at the end portion of the bellows body or the bellows body sections whereas the amount of silicon is increased around the center portion of the bellows body or bellows body section. This converse distribution of the amounts of glass fiber and of the amounts of silicon may also be achieved by using glass fiber layers having different densities. 
         [0025]    According to one embodiment the bellow body is arranged or formed by joining two or more bellow body sections and their respective end portions. This “modular” construction of the bellows body comprising a number of bellows body section facilitates maintenance in case bellows body incurs local damage. In this case only the specific bellows body section concerned needs replacement rather than replacing the entire bellows body. 
         [0026]    According to yet another embodiment the end portions are chamfered, beveled or have a step-profile to ensure uniform overall thickness of the bellow body when the end portions of bellows body or sections thereof are joined by overlapping. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The invention will be described in detail hereinafter with reference to the drawings, in the figures like numerals designate like parts, and the figures are not to scale, where: 
           [0028]      FIG. 1  shows a high wing aircraft having a detached wing structure; 
           [0029]      FIG. 2  shows a plan view of the aircraft of  FIG. 1 ; 
           [0030]      FIG. 3  is a cross-section view of the fuselage and wing structure in the aircraft along line  3 - 3  in  FIG. 2 ; 
           [0031]      FIG. 4  is a perspective, partly cut-away view of the wing carry-through section in the fuselage of the aircraft in  FIG. 1 ; 
           [0032]      FIG. 5  is another perspective, partly cut-away view on the wing carry-through section of  FIG. 4 ; 
           [0033]      FIG. 6  is a close up sectional view on the sealing assembly according to the invention in  FIG. 3 ; 
           [0034]      FIG. 7  is a close up sectional view of a mounting member of the sealing assembly in  FIG. 6 ; 
           [0035]      FIG. 8  is a perspective view taken from a point within the center fuselage on the sealing assembly attached to the airframe; 
           [0036]      FIG. 9  is a perspective view on the bellows body of the sealing assembly partly cut away; and 
           [0037]      FIG. 10  is a length-wise cross-section view of a section of the bellows body in the sealing assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description 
         [0039]    Reference is now made to  FIG. 1  showing a high wing aircraft  100  of the detached wing type. The aircraft  100  has a wing structure  105  that is detached from the fuselage  110 . In other words, the wing structure  105  is not integrally formed with the fuselage  110 . The wing structure  105  is mounted on a central portion, the center fuselage, of the fuselage  110 . 
         [0040]      FIG. 2  is a plan view of the high wing aircraft  100  in  FIG. 1 .  FIG. 2  affords a better overall view on the major components of the airframe  106  of aircraft  100 . The airframe  106  comprises the empennage  101 , fuselage  110  and the wing structure  105 . The wing structure  105  is mounted at the center portion and on top of the fuselage  110 . The wing structure  105  in detached wing type aircraft is a one-piece structure, the “wings” of the aircraft being formed by the wing structure  105  extending to the left and the right of the fuselage  110 . The aircraft also has a fairing  109  arranged on top of the wing structure  105 . 
         [0041]      FIG. 3  shows a cross-section along the line  3 - 3  in  FIG. 2 . The cross-section being defined by a plane passing through the root wing portion of the airframe  106 .  FIG. 3  shows clearly how the wing structure  105  and the fuselage  110  are arranged as two separate components of the airframe  106 . The wing structure  105  abuts on mounting heads  107  arranged on the fuselage  110 . The wing structure  105  is firmly bolted to the mounting heads  107  and held in place on top of the fuselage  110  by means of the mounting heads  107 . 
         [0042]    The fuselage  110  has a substantially cylindrical shape.  FIG. 3  also shows a carry-through section  120  for partly receiving the center wing box  108  of the wing structure  105 . The carry-through section  120  is a cut-out in the cylindrical fuselage  110 . The wing carry-through section  120  is defined by a distance d between the center wing box  108  of the wing structure  105  and the upper edges of semi ring frames  115 . There are a number of semi- or open semi ring frames  115  arranged side-by-side, the number of semi rings frames  115  making up the center portion of the fuselage  110 . The center wing box  108  does not about the semi ring frames  115 . The detached wing type construction results in a gap of width d in the airframe  106  which is sealed off by means of the sealing assembly  200 . The sealing assembly  200  is attached to the center wing box  108  and a C-beam element  112  disposed on the upper edges of the semi ring frames  115  so as to cap those edges and to so provide sound support for the sealing assembly  200 . The sealing assembly ensures the fuselage  110  remains pressurized during operation of the aircraft  100 . 
         [0043]    A perspective view on the carry-through section  120  is provided by  FIG. 4 . For clarity, the wing structure  105 , including the center wing box  108 , and the mounting heads are  107  are cut away. The cylindrical shape of the fuselage  110  outside the carry-trough section  120  is defined by ring frames  117 . The rings frames  117  are similar to the semi ring frames  115 , the later one having their center portions cut out so as to define the carry-through section  120 . The wing carry-through section  120  has a rectangular periphery which is defined by two C-beams  112  arranged opposite to each other and two further C-beams  116  arranged in span-wise direction. Only one of the C-beams  112  is shown in the perspective view afforded by  FIG. 4 . The rectangular periphery has rounded corners in order to facilitate mounting of the sealing assembly  200  thereto. The sealing assembly is arranged all around the periphery and has one of its side portions or lower edge attached to the upper surfaces of the C-beams  112 , 116  making up the periphery and the other side, or upper edge potion attached to substantially to those portions or regions of the center wing box  108  facing those upper surfaces of the C-beams  112 ,  116 . The exact points of attachment may however differ for other airframes having somewhat different geometries. 
         [0044]      FIG. 4  shows how the bellows body  201  is laid out when attached to the fuselage  110  and the center wing box  108 , both are components of the airframe  106 . The bellows body  201 , essentially a strip or band, has its upper and lower edges attached to the center wing box  108  and the fuselage  110 , respectively. The two or more end portions of the bellows body  201  are arranged in one or more overlaps  205  so that the bellows body  201 , when so arranged and attached, assumes the shape of a closed band or closed strip. The bellows body  201  assumes a curved cross section due to the pressure inside the pressurized area PA when the fuselage  110  is pressurized. 
         [0045]      FIG. 5  affords another perspective view of the wing carry-through section  120 . The perspective view is taken from a point inside the fuselage  110  and approximately underneath the wing carry-through section  120 . Again, as in  FIG. 4 , the wing structure  105  is cut-away to better show the rectangular periphery around which the bellows body  201  is laid out as a sealing band. 
         [0046]      FIG. 6  is a close up of the sealing assembly  200  as shown in  FIG. 3 . The cross-sectional view of the sealing assembly  200  as shown in  FIG. 5  is exemplary and substantially the same all around the periphery. The sealing assembly  200  comprises a bellows body  201 . The bellows body  201  is a polyester-glass fiber-silicon composite and is arranged as an elongate strip, which is mounted all around the rectangular periphery by means of the mounting members  210   a  and  210   b.  The dashed line in  FIG. 5  demarks the wing area WA from the center fuselage area CFA. 
         [0047]    The sealing assembly  200  allows pressurizing the pressurized area PA versus the non-pressurized area NPA to the left and outside of the fuselage  110 . The sealing assembly  200  is not attached direct to the center wing box  108  and/or the C-beam  112 . Attachment of the bellows body  201  is by means of the two mounting members  210   a  and  210   b  which are substantially similar. The bellows body  201  has a curved cross-section and has the two side portions  202   a  and  202   b.  The bellows body may be formed from two or more bellows body sections. The bellows body sections are joined to one another at their respective end portions so as to form a closed strip or closed band, or lop or ring. Reference to the side portions  202   a  and  202   b  and the end portions are therefore construed also as a reference to the respective side portions or end portions of the bellows body sections. The width of the bellows body is larger than the width of the gap, but is in the range of about 200-400 mm. The bellows body has a total length corresponding to the perimeter of the periphery and is about 12 meters. Again, the exact numbers are understood to differ depending on the geometry of the airframe. 
         [0048]    As mentioned earlier, the bellows body  201  has preferably a curved cross-section to better sustain the pressure exerted on the bellows body  201  from the pressure inside the pressure area PA. The bellows body  201  may be extruded in shape to have the curved cross-section prior to mounting. Alternatively, the bellows body  201  may have a flat cross-section. In this case the width is chosen so that the bellows body is attached by way of the mounting members  210   a,b  with sufficient slack rather than stretched taut. The bellows body  210 , when so attached, will then assume the curved cross-section as shown in  FIG. 5  when the fuselage  110  is pressurized. 
         [0049]    The mounting members  210   a, b  are arranged substantially as L- or J-profiled bars made from aluminum. The profiled mounting members  210   a  and  210   b  are also arranged in two or more profile sections having a total length of about the perimeter of the periphery. The members  210   a,b  or sections thereof are laid out one by one around the rectangular periphery of the carry-through section  120 . Those sections of the profiled mounting members  210   a, b  that come to be laid out at the corners have a curvature corresponding to the curvature of the rounded corners. 
         [0050]    The mounting members  210   a,b  each have a contoured portion  213   a,b  and a mounting portion  211   a,b.  An angle between the contoured portion  213   a, b  and mounting portions  211   a, b  may be so arranged such as to correspond to the relative spatial relationship between the upper surface of the C-beam  112  and the lower surface of the center wing box  108  to which the sealing assembly is attachable to. This allows aligning the bellows body in relation to those spatial relationships. If the sealing assembly  200  is attachable to other parts or structures defining a gap in the airframe  106  the angle may be manufactured to the local geometry. 
         [0051]    The upper mounting member  210   b  on top of  FIG. 5  has a larger angle than the lower mounting member  210   a.  Each of the mounting portions  211   a,b  of the mounting members  210   a,b  are attachable by suitable fixing means, such as rivets, to the center wing box  108  and the C-beam  112 , respectively. 
         [0052]    The sealing assembly  200  further comprises retainer members  215   a,b.  The retainer members  215   a  and  b  are arranged as U-profile bars made from aluminum. Similar to the mounting members  210   a,b  the retainers  215   a,b  may also have two or more sections, the sum of the lengths of each one of those sections totaling to about the perimeter of the periphery or substantially equal to the sum of the lengths of the profiled mounting members  210   a,b.    
         [0053]    The first end second end portions  202   a  and  202   b  of the bellows body  201  or of the bellows body sections are laid out to be brought into contact with the contoured portions  213   a,    213   b  respectively. The end portions  202   a,    202   b  are then sandwiched between the retainers  215   a,    215   b  and the contoured portions  213   a,    213   b  of the lower mounting member  210   a  and upper mounting member  210   b,  respectively. This sandwiched arrangement of the end portions  202   a,b  in between the respective contoured portion  213   a,b,  and the retainers  215   a,b  are then firmly held in place and affixed by means of a bolt  220   a,b  and a sealed nut  221   a,b.    
         [0054]    The contoured portions  213   a,b,  the end portions  202   a,b  and the retainers  220   a,b  each have a series of holes arranged therein which are brought in the registry with one another in order for the bolts  220  to pass through those holes. The threaded portions of the bolts are received by and threaded into the sealed nuts  221   a, b,  the heads of the bolts snugly abutting the horizontal surface of the U-profile retainers  215   a,b.  The sealed nuts are arranged on the side of the bellows body facing into the non-pressurized area NPA with the bolts  220   a,b  coming from the pressurized area PA. 
         [0055]    The contoured members  213   a,  when the bellows body  201  is so attached, outline the cross-section form of the end portions  202   a, b.  The contoured portions thus not only enhance sealing but also allow guiding the deflection of the bellows body during operation of the aircraft. Deflection may be caused by relative displacements of the C-beam  112  and the center wing box  108  during challenging flight conditions of the aircraft and/or in adverse weather conditions. The contoured portions  213   a,b  have crimped terminal portions which are so crimped so as to curl away from the bellows body. Damage to the bellows body  201  can be thus prevented should the bellows body come into contact with the portion  213   a  or  b  while undergoing such deflections. 
         [0056]    According to one embodiment, the contoured portion  213   b  has a drainage arrangement in form of drain holes  214  arranged along the contoured portion  213   b.  Those drain holes  214  allow draining condense water or fuel dripping from the center wing box  108 . 
         [0057]      FIG. 7  is a close up of the mounting member  210   a.  In one embodiment the draining arrangement  240  further comprises one or more hose fitting  223  each arranged in registry with one the drain holes  214 . A hose  224  is attached to the hose fitting  223 . The hose  224  drains by way of a lead-through in the C-beam  112  into the non-pressurized area NPA. The lead through is furnished with a sealing  225  to not compromise pressurization of the fuselage  110 . The draining arrangement  240  allows by way of the hose  224  to drain accumulated condensed water or fuel  230  in the trough -like arrangement between the C-beam  112  and the contoured portion  213   a.  The water  230  can be drained back into the non-pressurized area NPA and thrown clear in a controlled manner. 
         [0058]      FIG. 8  is a perspective view on the sealing assembly  200  attached to the center wing box  108 , the C-beams  112  and the C-beams  116  running in span-wise direction.  FIG. 8  shows the bellows body  201  arranged all around the periphery of the rectangular periphery of the wing carry-through section.  FIG. 8  also affords a view on how the elongate bellows body  201  when laid out and attached assumes the loop or ring shape. The Bellows body  201  of the sealing assembly  200  depicted in  FIG. 8  comprises two bellow body sections joined at an overlap  205 . The other overlap is not shown in the perspective view afforded by  FIG. 8 . 
         [0059]      FIG. 9  shows a close up of that overlap  205  with cutaways. The end portion  203 , b of the respective bellows body sections are arranged in an overlapping manner. Each of the end portions or edges  203   a  and  b  has holes arranged therein which are brought into registry. The two end portions  203   a  and  203   b  are held in place by bolts receivable in nuts. According to one embodiment, the two end portions  203   a  and  203   b  are not only bolted but also glued together to form a fluid-tight bond. In this a dual affixing is affected, that is bolting and gluing, and the use of sealed nuts can be dispensed with at the overlap  205 , thus driving down manufacturing costs. 
         [0060]    In order to prevent the bolts cutting into the bellows body  201  during deflection of the bellows body the holes in the end portions  203   a  and  203   b  are furnished with aluminum grommets. The end portion are chamfered, beveled or have a “step” profile to ensure that the overall thickness of the bellows body is substantially constant. A thickening of the bellows body at the overlaps  205  can thus be avoided. 
         [0061]      FIG. 10  shows a length-wise cross-section through a bellows body  201  section having the two end portions  301   a  and  301   b.  The holes in each of the end portion  301   a  and  b  are not shown for clarity. The bellows body or the bellow body sections as depicted in  FIG. 9  is arranged as a composite in a number of layers or lamina. The body section has a total width D of about 3 mm. The carrier substrate is arranged as three polyester fabric  405  layers and a layer of woven polyester fabric  401 . On the pressurized side PA, one of those polyester layers  405  is the outermost layer. The outermost layer on the non-pressurized area NPA is formed by a low friction silicon layer  420  of about 0.14 mm thickness. This thin low friction silicon layer is designed to prevent damage of the bellows body and allows maintaining integrity of the bellows body should the bellow body come into contact with internal structure during operation of the aircraft. The bellows body would “slip off” the internal structure and thus prevent the structure cutting into the body. 
         [0062]    Between the polyester fabric layers  405  there are arranged silicon layers  415  of about 1.5 mm thickness each. They account for the resilient character of the bellow body. As can be seen there is also a thicker silicon layer having a thickness of about 0.93 mm arranged in a center portion of the cross-section of the silicon body section. The thick silicon layer provides a silicon “kernel”  410  and does not extend all the way to the end portion  301   a, b.  To the left and right of the silicon kernel  410 , there are arranged layers of glass fiber  425 . In the embodiment shown in  FIG. 9  there are arranged four layers of glass fiber each having a thickness of about 0.4 mm. 
         [0063]    The amount of silicon in the region around the end portion  301   a, b  is therefore decreased, whereas the amount of glass fiber in that region is increased, The opposite holds true for the center portion of the bellows body  201  or the section thereof where the amount of silicon is increased whereas the amount of glass fiber is decreased. 
         [0064]    This converse distribution across the lengthwise cross-section of silicon and glass fiber results in the bellows body  201  to be more supple and flexible in its center portion and stiffer due to the high amount of glass fiber therein in regions around the end portion  301   a  and  301   b.  The regions around or at the end portions  301   a  and  b  having the high amount of glass fiber therein have each a width which is taken in relation to a width of the head of the bolt used to join the bellow body sections. In this way it is ensured that the heads of the bolts abut the bellows body section where the amount of glass fiber is increased. In this way the necessary reinforcement required at the end portion can be provided without compromising the suppleness required at the center portion of the bellows body  210 . Because the sections have different layers at their outermost sides, that is the low friction silicon layer on the one side and the outermost one of the polyester layers  405  on the other side, the chamfering of the bellows body sections must be executed in opposite direction to ensure that the low friction silicon layer and the outermost one of polyester layers  405  come to lie on different sides when joining the bellows body sections. 
         [0065]    The composite structure of the bellows body  201  allows securing a number of desirable properties conducive to safe aircraft operation. The silicon-polyester-glass fiber composite layer structure of the bellows body  201  allows withstanding cabin and fairing pressures. The bellows body  201  is “high tear and wear” and sustains even comparably large deformations and deflections between the center wing box  108  and the fuselage  110 . Further, the bellows body  201  also sustains impact of water, fuel, deicing and hydraulic fluids, for example Skydrol. The bellows body  201  is usable in temperature ranges between about −55° up to about +80°. Further, the bellows body  201  has an electrical conductivity in the range between about 10 and about 20 MOhm. It allows safe drainage of static electricity caused by dripping fuel from the center wing box  108  onto the bellows body  201 . 
         [0066]    The bellows body  201  has been designed on the assumption of the following boundary conditions: cabin normal pressure is about 550 mbar (limit load); cabin burst pressure is about two times 550 mbar equals about 1100 mbar (ultimate load); the WFF leak pressure is about −100 mbar (ultimate load); the cabin negative pressure equals about −75 mbar (ultimate load); the normal for teak pressure is 483 mbar (limit load); the bellows body  201  is snap through proof at about −80 mbar (limit load). 
         [0067]    The bellows body  201  as used in the sealing assembly  200  according to an embodiment allows maintaining a pressurized atmosphere in the fuselage  110  during relative displacement in the airframe according to the following table: 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Relative Displacement [mm] in airframe sustained during 
               
               
                 flight operation 
               
             
          
           
               
                 z-vertical 
                 x-parallel 
                 y-lateral 
               
               
                   
               
               
                 +10/−17 
                 +/−7 
                  +/−8 
               
               
                 +21/−24 
                 +/−7 
                 +/−10 
               
               
                 +30/−30 
                 +/−12  
                 +/−12 
               
               
                   
               
             
          
         
       
     
         [0068]    While the foregoing summary and written description enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed. 
         [0069]    In addition it should be pointed out that “comprising” does not exclude other elements or steps, and “a” or “one” does not exclude a plural number. Furthermore, it should be pointed out that features or steps which have been described with reference to one of the above exemplary embodiments can also be used in combination with other features or steps of other exemplary embodiments described above.