Abstract:
A floor system for a fuselage section of an aircraft is provided. The floor system has an essentially self-supporting design and is substantially mechanically separate from the fuselage section as primary structure. Consequent to the free or self-supporting design of the floor system in the fuselage cell, the layout of the floor system along an aircraft axis can be matched to customer specifications in a simple manner without reference to structural boundary conditions of the fuselage structure. A floor surface for the floor system is formed from a number of floor elements which can be fitted with functional elements, wherein filling of empty spaces or cavities can be achieved with a number of floor equalisation elements. As the floor elements have a relatively large support or fixing surface the loads induced by the functional elements are introduced into the floor system distributed over a large area such that the structural components thereof can be of a structurally lighter and thus weight-saving size.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT/EP 2009/050128 filed Jan. 7, 2009 and claims the benefit of U.S. Provisional Application No. 61/063,896, filed Feb. 7, 2008 and German Patent Application No. 10 2008 007 838.7, filed Feb. 7, 2008, the entire disclosures of which are herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a complex floor system for a fuselage airframe of an aircraft comprising a large number of floor members to form a floor surface. 
         [0003]    For reasons of comfort and due to use at high altitudes, to optimise use present-day passenger aircraft generally have compression-proof fuselage airframes, the internal pressure of which, at a flight altitude of, for example 12,000 m corresponds to an air pressure which prevails at approximately 1,800 m. The fuselage airframe of an aircraft is formed using a plurality of substantially barrel-shaped fuselage sections which are arranged in tandem and are connected by transverse butt straps. Each fuselage section is formed by a plurality of annular formers which are arranged in tandem and are covered on the outside with a fuselage cell skin. Running between the annular formers in the direction of a longitudinal axis of the aircraft are longitudinal reinforcing members, in particular stringers, which are attached to the inside of the fuselage cell skin over the periphery of the fuselage section preferably in a uniform spacing parallel to one another. The former spacing of a fuselage airframe is between 50 cm and 100 cm, depending on the type of aircraft and the structural loads. The stringers, the annular formers, the fuselage cell skin, the transverse butt straps as well as further components of the fuselage cell structure are generally formed using an aluminium alloy material. Alternatively, individual components (“hybrid construction method”) or all components can be produced using fibre-reinforced plastics materials, for example carbon fibre-reinforced epoxy resins. 
         [0004]    A floor of the passenger cabin is formed, inter alia, by a plurality of crossbars which are usually connected on either side to a respective annular former. The crossbars are usually supported downwards on either side by so-called Samer rods or other vertical struts, one end of which is connected to the end of a crossbar and the other end to an annular former. Attached to the crossbars is a plurality of longitudinal profiled parts which can be configured as seat rail profiled parts for receiving the seating. Floor plates are inserted and attached between the seat rail profiled parts to obtain a continuous, walkable and planar floor. The floor plates are usually formed using sandwich plates which are produced using fibre-reinforced plastics materials. The floor divides the fuselage airframe of the aircraft horizontally into the passenger compartment or, more specifically, the passenger cabin and the hold located below. In most cases, the interior layout of a fuselage airframe of an aircraft will not be changed for the entire service life, which can be as long as 30 years. However, an exception is the refitting of passenger aircraft into freight aircraft, which is a widespread practice and which, from the point of view of refit expense, is, however, almost comparable with a new construction. 
         [0005]    In aircraft accident situations, the seat rail profiled parts must be able to withstand mechanical forces in extreme cases ranging up to 20 g in the flight direction, so that the seat rail profiled parts have to be configured such that they are statically solid and consequently correspondingly heavy, which severely affects the payload of the aircraft. 
         [0006]    Furthermore, inter alia, the arrangement of passenger seats on conventional floor systems becomes inflexible thereby making it difficult to adapt the seating arrangement to customer-specific requirements. For example, the refitting of an existing seating arrangement of 2×3 rows of seats with one aisle into a seating arrangement of 3×2 rows of seats and two aisles requires a considerable refit expense, because the entire frame of the floor has to be modified. Alternatively, it would be possible to provide additional seat rail profiled parts to cover layout variations of this type, but this would increase the weight. Existing passenger seats which usually have four leg supports, at the ends of which the attachment points for the seat rail profiled parts are connected, cannot be secured to the seat rail profiled parts in random positions along the longitudinal axis of the aircraft due to the loads which are produced in an accident situation. 
       SUMMARY OF THE INVENTION 
       [0007]    The object of the invention is to avoid the disadvantages described above of the known embodiments of floor systems in respect of layout variants in the passenger cabin. 
         [0008]    This object is achieved by a floor system which has the features of claim  1 . 
         [0009]    Due to the fact that the floor system is configured to be substantially self-supporting and is substantially mechanically uncoupled from the fuselage airframe as a primary structure, the floor system can be modified substantially independently of static requirements or structural peripheral conditions of the fuselage airframe. Consequently, it is possible for the first time to adapt a layout of a passenger cabin of an aircraft to customer-specific special requests at a low refit expense. The mechanical loads emanating from the floor system are substantially exclusively introduced into the fuselage airframe or into the fuselage airframe structure, while conversely virtually no forces from the fuselage airframe are transferred into the self-supporting floor system. 
         [0010]    A development of the floor system provides that attached in a lower region of the fuselage airframe are at least two longitudinal supports, on which is arranged in each case at least one support member, in particular at least one lattice-type bracing, at least one crossbar for supporting and attaching the floor members being arranged in each case on the at least two opposing support members. As a result of this arrangement, loads emanating from the floor system parallel to a vertical axis (z-axis) of the aircraft are introduced in a statically advantageous manner via the support members directly into preferably two, preferably continuous lower (base) longitudinal supports which run in a uniform parallel spacing on both sides from a base line or crown line of the fuselage airframe and parallel to the x-axis and are attached in a lower region of the fuselage airframe (so-called “bilge”) inside the hold. In an alternative embodiment, both longitudinal supports can also be secured in the fuselage airframe running in unequal spacings parallel to the base line or the crown line of the fuselage airframe. The base line or the crown line passes through the lowest or highest point of a shape which is defined by the cross-sectional geometry of the fuselage airframe and which, in the simplest case, is a circle. The cross-sectional geometry can vary in portions along a longitudinal axis of the aircraft (x-axis) in the direction of flight. 
         [0011]    Crossbars which run in a parallel spacing with respect to one another are attached to the support members in each case parallel to a transverse axis of the aircraft (y-axis). In turn, attached to the crossbars are longitudinal profiled parts which run parallel to the x-axis of the aircraft, are preferably configured as seat rail profiled parts and on which are arranged floor members with optional functional members for providing a floor in the fuselage airframe. The floor members can be attached to the seat rail profiled parts using the same standard metal fittings which are usually used in civil aviation for attaching the seats in passenger cabins. 
         [0012]    Alternatively, any type of riveting, screwing, clamping or insertion members can be used. Furthermore, welded or adhesive bonded joints can optionally also be used. 
         [0013]    In the simplest case, each support member on the lower longitudinal supports is configured as a fixed vertical strut or as a longitudinally adjustable Samer rod which, in the normal flying state, primarily absorbs the forces arising from the floor parallel to the z-axis. However, for static reasons it will generally be necessary to reinforce two adjacent vertical struts in each case in a lattice-type manner by additional diagonal struts in order to also introduce forces which substantially arise parallel to the x-axis into the longitudinal supports located on the underside. Generally, it is not necessary to provide a vertical strut in the region of each annular former. Instead, it is usually sufficient to arrange merely one vertical strut on each fifth to tenth annular former. In a variant, on each of the two lower longitudinal supports, a lattice-type support member of this type extends over a total length of the longitudinal supports at a constant height. Alternatively, the support members can be configured as individual freestanding support members (“trestles”) which are arranged at a distance from one another on the longitudinal supports. Furthermore, upwards the support members can preferably have a respective continuous upper longitudinal support which runs substantially parallel to the two longitudinal supports arranged in the lower region of the fuselage airframe. Arranged on the upper longitudinal supports parallel to the y-axis are crossbars and, in turn, arranged on said crossbars parallel to the x-axis are longitudinal profiled parts to support and attach floor plates to provide a floor surface. 
         [0014]    In each case, horizontally running longitudinal struts with a smaller bending moment compared to the longitudinal supports and which, in conjunction with the optionally provided diagonal struts, form a lattice-type structure of the support members can optionally be provided in each case on the upper ends of respectively adjacent vertical struts. Where there is a sufficient inherent rigidity of the seat rail profiled parts or of the floor members, it is optionally possible to dispense with at least some of the longitudinal struts. 
         [0015]    In a further alternative embodiment, the crossbars can be directly connected to the upper ends of the vertical struts, the entire arrangement being stabilised in respect of forces acting parallel to the x-axis by the floor members which rest on and are attached to the crossbars. Due to the construction of the floor which is mechanically substantially uncoupled from the fuselage airframe according to the invention, it is even possible to make comprehensive changes to the floor without considering possible static requirements of the fuselage airframe, thereby simplifying the adaptation to customer-specific layout requests. 
         [0016]    According to a further advantageous configuration of the floor system, it is provided that the support members have differently fixed heights in relation to a z-axis (vertical axis of the aircraft). Consequently, for the first time it is possible to provide a floor in a fuselage airframe of a passenger or freight aircraft which is not a plane extending over the entire length of the aircraft. For example, in a front region of the fuselage airframe, the floor can be raised to increase the size of the hold, while in a rear region of the fuselage airframe the floor is lowered, forming a step, in order to increase the travel comfort for the passengers as a result of an increased cabin volume. 
         [0017]    A further advantageous configuration of the floor system provides that the support members can be vertically adjusted parallel to the z-axis. This measure further increases the flexibility of the floor system in respect of requested changes to the floor layout, since an adaptation of the floor level is realised in regions by a vertical adjustment, preferably made by motor or by hand, of the respective support members. A displacement of support members of a different height on the respective longitudinal support is no longer necessary. For example, in this case the support members can be configured as scissors which can be actuated by a motor, for example by an electromotive spindle drive (“scissor lift table”), in order to produce a preferably continuous vertical adjustment between the longitudinal supports and the crossbars. Scissor arrangements of this type with crossed struts are widely used in so-called “scissor tables” or lift tables. 
         [0018]    According to a further development of the floor system, it is provided that the support members can be moved and locked on the longitudinal supports parallel to a y-axis. This makes it easily possible to interchange the position on the longitudinal supports of higher support members with those of lower support members by transposing or moving them in order to reconfigure the layout of the floor at the lowest possible refit expense. In this variant, the longitudinal supports preferably have in the region of an upper side a rail-like guide means in which the support members are accommodated such that they can be moved and fixed parallel to the y-axis (i.e. along the x-axis). In this respect, it is possible for so-called “passing places” to be provided in the guide means to allow the support members to pass one another without having to be lifted out of the guide means—at least when the crossbars have been removed. In this respect, the support members can be attached to the longitudinal supports continuously or alternatively in grids. 
         [0019]    A further advantageous development of the floor system provides that at least one crossbar can be moved and locked on at least two support members parallel to the y-axis. This makes it possible for the floor to be specifically adapted to load conditions which have changed. For example, crossbars can be moved and locked parallel to the y-axis (i.e. along the x-axis) for local reinforcement in a region where, for example, a galley and/or a sanitary module are to be positioned on the floor. In this configuration, the support members attached to the longitudinal supports each have a continuous, upper longitudinal support, on which the ends of the crossbars are respectively accommodated in a movable and lockable manner. The crossbars are attached to the upper longitudinal supports by known screw, clamping or insertion connections which can be detached again if required. 
         [0020]    According to a development of the floor system, it is provided that at least two longitudinal profiled parts, in particular at least two seat rail profiled parts can be moved and locked on at least two crossbars parallel to the x-axis in order to attach thereto at least one functional member, in particular respectively at least one group of seats with at least two seats. Due to the longitudinal profiled parts which can be moved and fixed on the crossbars transversely to the longitudinal axis of the aircraft (i.e. parallel to the x-axis), the layout of seats on the floor can be changed easily and quickly. Thus, for example, it is possible by moving the longitudinal profiled parts or the seat rail profiled parts and by adding two further longitudinal profiled parts, to convert a seating arrangement with two rows of seats with in each case three seats and one centre aisle into a seating arrangement with three rows of seats with in each case two seats and two aisles. The longitudinal profiled parts are attached to and locked on the crossbars by suitable screw, clamping or insertion connections which can be detached if required. 
         [0021]    A further advantageous development of the floor system provides that at least one support member is connected at least in portions to the fuselage airframe by at least one side connection, in particular a framework, dampers, ropes or straps. This measure prevents the support members from tilting in the direction of the y-axis under the effect of transverse forces. To laterally couple the floor system with the fuselage airframe or with the annular formers attached on the inside in the fuselage airframe, pneumatically and/or hydraulically acting damping members for example can be used, the length of which can preferably be adjusted continuously for tolerance compensation. The ropes or straps are preferably formed from interlaced carbon fibres or carbon fibre strands. The framework preferably consists of reinforcing struts which, from a static viewpoint, are advantageously arranged triangularly. 
         [0022]    According to a further advantageous development, at least two opposing support members are reinforced in respect of forces acting parallel to the y-axis, in particular by triangular struts arranged on both sides in the region of overhanging ends of a crossbar resting on the two support members. Consequently, the floor system becomes substantially static independently of the surrounding fuselage airframe, in other words the entire floor system including the substructure and the floor positioned thereon or the floor members with the functional members stands “freely” in the fuselage airframe. 
         [0023]    A further advantageous configuration provides that at least two longitudinal supports are attached in an upper region of the fuselage airframe and in each case at least one support member, in particular at least one lattice-type bracing, is suspended from a respective longitudinal support and in each case at least one crossbar is arranged on the at least two support members in order to secure floor members. 
         [0024]    This configuration with floor members “suspended” from the crown region of the fuselage airframe is an “inverted” variant of the floor system. The advantage of this configuration is that, instead of being loaded in compression parallel to the z-axis, the support members are substantially only loaded in tension, so that the support members can be formed at least partially with weight-reducing ropes or straps. 
         [0025]    A development of a floor member for the floor system provides that the at least one floor member has at least one functional member, in particular a seat, a group of seats, a galley and/or a sanitary module. Compared to the conventional attachment of assemblies by discrete connection points, this arrangement achieves a more even load introduction, distributed over the surface of the floor member, into the entire floor system, thereby allowing a statically weight-saving configuration of the seat rail profiled parts and of the crossbars. Depending on the inherent rigidity or strength of a base plate of the floor member, said base plate can possibly take over, at least to some extent, the static function of the seat rail profiled parts and/or of the crossbars, no that in an ideal situation these become completely dispensable. Alternatively, regions of the floor system can be provided with floor members without functional members. 
         [0026]    Furthermore, the floor members can be positioned with integrated functional members in a spatially more flexible manner on the floor system and can also be assembled with less effort. 
         [0027]    Further advantageous embodiments of the floor system are set out in the further claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    In the drawings: 
           [0029]      FIG. 1  shows a floor frame, known from the prior art, for an aircraft. 
           [0030]      FIG. 2  shows a conventional seat for a passenger to be attached to the floor frame according to  FIG. 1 , 
           [0031]      FIG. 3  shows a floor system configured according to the invention, 
           [0032]      FIG. 4  shows a variant of the floor system, 
           [0033]      FIG. 5  shows a further variant of the floor system with a (fixed) height which differs in certain regions, 
           [0034]      FIG. 6  shows a further alternative variant of the floor system with the possibility of a level adjustment at least in certain regions, 
           [0035]      FIG. 7  shows a variant with longitudinal profiled parts, in particular seat rail profiled parts, which can be moved parallel to the x-axis, 
           [0036]      FIG. 8  shows two groups of seats as optional functional members of the floor system, 
           [0037]      FIG. 9  shows a variant with crossbars which can be moved and locked parallel to the y-axis, 
           [0038]      FIG. 10  shows an embodiment with (“trestle-shaped”) support members which can be moved and locked parallel to the y-axis, and 
           [0039]      FIG. 11  shows a “freestanding” floor system with additionally braced crossbars which overhang on both sides, 
           [0040]      FIG. 12  shows a “reverse” arrangement, i.e. a suspended variant of the floor system, 
           [0041]      FIG. 13  shows the floor system with two exemplary floor members, 
           [0042]      FIG. 14  shows a floor member with an adapter for attaching a functional member, in particular a group of seats, 
           [0043]      FIG. 15  shows a variant of a floor member which is progressively adjustable (in the direction of the x-axis), 
           [0044]      FIG. 16  shows a floor member with a galley as a functional member, 
           [0045]      FIG. 17  shows a floor member with an elevation (platform) for attaching a group of seats by means of an adapter, and 
           [0046]      FIG. 18  shows a group of two seats to be attached to the floor member according to  FIG. 17 . 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0047]    In assemblies which each have a relatively large number of functionally identical members, for example a support member configured as a lattice or the like to improve clarity, only one reference numeral will generally be provided—as long as reference is not made explicitly thereto in the associated description of the figure. 
         [0048]      FIG. 1  is a perspective view of a floor system according to the prior art. A fuselage airframe  100  of an aircraft (not shown) with a substantially circular cross-sectional geometry comprises, inter alia, a fuselage cell skin  101  with a plurality of annular formers arranged therein, of which only the foremost annular former  102  is provided with a reference numeral. A floor system  103  of the fuselage airframe  100  comprises, inter alia, a plurality of crossbars  104 . The crossbar  104  is connected on both sides to an annular former  102 . In addition, the crossbar  104  is supported downwards by two conventional Samer rods  105 ,  106  arranged between the crossbar  104  and the annular former  102 . Furthermore, attached to the crossbar  104  are a total of four seat rail profiled parts, of which only one seat rail profiled part  107  is provided with a reference numeral. Seats for the passengers are attached to the seat rail profiled parts. Inserted and attached between two seat rail profiled parts is a respective floor plate, of which only one floor plate  108  has been provided with a reference numeral. The floor plates form a continuous and planar floor  109  inside the fuselage airframe  100 , by which the fuselage airframe  100  is divided over its longitudinal extent into a passenger cabin  110  and a hold  111 . The spatial orientation of the components is indicated by a coordinate system  112  in  FIG. 1  and in all the following figures. An x-axis of the coordinate system  112  corresponds to a longitudinal axis of the aircraft (in the direction of flight), a y-axis corresponds to a transverse axis of the aircraft and the z-axis corresponds to a vertical axis of the aircraft, the z-axis being directed away from the ground. 
         [0049]      FIG. 2  is a simplified perspective view of a seat which is configured according to the prior art and is to be attached to standardised seat rail profiled parts. A seat  150  for a passenger has four legs or leg struts with in each case an attachment point arranged on the end, of which only legs  151  and  152  as well as attachment points  153  and  154  are visible here. The seat  150  is locked on the seat rail profiled part  155  through the attachment points  153  and  154  by means of conventional screw, clamping or insertion connections in a grid spacing of 2.54 cm. A spacing  156  between the attachment points  153 ,  154  parallel to the x-axis regulates the attachment possibilities for the seat, since as many crossbars as possible should run (parallel to the y-axis) in the region of attachment points  153 ,  154 , due to the high loads in accident situations. Furthermore, the spacing  156 , in conjunction with a centre of gravity (not shown) of the seat  150 , forms a significant lever by which considerable forces are introduced into the seat rail profiled part  155 , which accordingly must be of a solid configuration. 
         [0050]    In contrast to  FIG. 1 ,  FIG. 3  shows a floor system configured according to the invention. A floor system  202  is integrated into a fuselage airframe  200  with a fuselage cell skin  201 . The floor system  202  comprises, inter alia, two longitudinal supports  204  and  205  (platforms or base longitudinal supports) which run parallel to one another in a lower region  203  of the fuselage airframe  200 . Arranged on each longitudinal support  204 ,  205  is a lattice-type support member  206 ,  207  which, in the illustrated embodiment, extends over the entire length of each longitudinal support  204 ,  205 . 
         [0051]    The support members  206 ,  207  each have a plurality of vertical struts, of which two front vertical struts  208 ,  209  on longitudinal support  204  have a reference numeral. A diagonal strut  210  is arranged between the two vertical struts  208 ,  209  for reinforcement purposes. The same applies accordingly to the rest of the vertical struts. Arranged on upper ends of the vertical struts  208 ,  209 —as well as between all other respectively adjacent vertical struts—is a respective longitudinal strut  211  which runs parallel to the x-axis. The vertical struts  208 ,  209  can be of a rigid or resiliently damping configuration. If the vertical struts  208 ,  209  are rigid, they are formed, for example, by Samer rods which in any case allow a longitudinal adjustability parallel to the z-axis. Alternatively, the vertical struts  208 ,  209  can be formed by hydraulic and/or pneumatic damping members, optionally combined with spring members. Due to this configuration, upward and downward movements of the aircraft, in particular parallel to the z-axis, induced inter alia by turbulence, are compensated, thereby enhancing the passenger comfort. Alternatively, the hydraulic and/or pneumatic damping members can also be actively controlled, so that the floor surface of the floor system  202  can be actively stabilised in real time in its spatial position, in particular in relation to the xy-plane, based on, for example, data already present in the flight computer. For this purpose, the vertical struts can have actuators which can be moved parallel to the z-axis in particular. Any controllability of the damping members means in this connection that the damping members can be moved parallel to the z-axis and, furthermore, the damping and spring behaviour, controlled by a control means, can be actively adjusted as a function of the current flight data which can originate, for example, from the flight computer. Positioned on the support members  206 ,  207  running on both sides in the fuselage airframe  200  is also a plurality of crossbars, of which only one crossbar  212  has been given a reference numeral. The mutual spacing of the crossbars in the x-direction preferably corresponds to the spacings of the annular formers (not shown) which are connected to the fuselage cell skin  201 . In the illustrated embodiment of  FIG. 3 , an exemplary unilateral (asymmetrical) side connection  213  of the crossbar  212  to the fuselage airframe  200  is provided for lateral support. The unilateral side connection  213  is formed above the longitudinal support  204  on support member  206  with two preferably longitudinally adjustable Samer rods  214 ,  215  in the region of the first crossbar  212  and in the region of the fifth crossbar  216  in order to achieve in particular a stabilisation of the floor system  202  relative to loads acting parallel to the y-axis. A side connection of this type can also be provided on the side of the second longitudinal support  205 . The side connection  213  is usually only necessary on each fifth to tenth crossbar or annular former. The floor system  202  is substantially stabilised with respect to loads acting parallel to the z-axis by the vertical struts  208 ,  209 , while the diagonal struts  210  introduce forces acting in the direction of the x-axis in particular into the two longitudinal supports  204 ,  205 . 
         [0052]    All the components described above can be connected by any type of riveting, screwing, clamping or insertion members or by any combination thereof. Diverging from mechanical connection or attachment means, the mentioned components can also be joined together by welding and/or adhesive bonding processes. 
         [0053]      FIG. 4  illustrates a further variant of the floor system with a bilateral side connection. A further alternative embodiment of a floor system  252  is installed into a fuselage airframe  250  with a fuselage cell skin  251 . Here again, two longitudinal supports  254 ,  255  which run parallel to the x-axis are attached in a lower region  253  of the fuselage airframe  252 . Resting on each of the longitudinal supports  254 ,  255  is a respective support member  256 ,  257  with a plurality of vertical struts, of which only one vertical strut  258  has been given a reference numeral. For the rest, the construction of the support members  256 ,  257  is the same as the construction of the support members  206 ,  207  according to  FIG. 3 . A plurality of crossbars  259  is positioned on the support members  256 ,  257 . A plurality of seat rail profiled parts, one of which has reference numeral  260 , run on the crossbars  259 . In order to form a planar, self-contained and walkable floor surface  261 , a plurality of floor members, of which only one floor member  262  has been referenced, is positioned on the crossbars  259 . Unlike the embodiment according to  FIG. 3 , the floor system  252  has two bilaterally (symmetrically) arranged side connections  263 ,  264  which are formed by way of example with ropes or straps braced diagonally between the floor system  252  and the fuselage airframe  250 . The ropes or straps can be formed, for example, using interlaced carbon fibres or carbon fibre strands. Alternatively, they can have a limited amount of elasticity in order to be able to more effectively intercept and absorb forces parallel to the y-axis in particular, while avoiding load peaks (so-called “lateral impacts”). If necessary, the resilient ropes or straps have to be combined with suitable hydraulic and/or pneumatic damping members to reduce undesirable vibration phenomena. Instead of being formed from carbon fibres, the ropes or straps can be formed, for example, using aramide fibres. Kevlar fibres, natural fibres or any combination thereof. 
         [0054]      FIG. 5  shows a second variant of the substructure according to the invention with a height which, although differing in certain regions, is fixed. A floor system  302  is integrated into a fuselage airframe  300  with a fuselage cell skin  301 . The entire floor system  302  is supported on two continuous longitudinal supports  304 ,  305  attached in a lower region  303  of the fuselage airframe  300 . Unlike the variants according to  FIGS. 3 and 4 , in each case three support members, of which only two front support members  306 ,  307  have been provided with a reference numeral, are arranged on each longitudinal support  304 ,  305 . All the support members  306 ,  307  are connected to a plurality of crossbars, of which likewise only one crossbar  308  has been provided with a reference numeral. Furthermore, parallel to the x-axis of the coordinate system  112 , it is possible for seat rail profiled parts (not shown) to be provided, on which and/or between which three floor members  309  to  311  are attached. As a result of the respectively graduated differing heights of the support members of the floor system  302 , which support members are attached in tandem to the longitudinal supports  304 ,  305 , the three floor members  309  to  311  form, in contrast to the previous variants, a stepped, non-planar floor surface with two steps  312 ,  313  or levels. Since the floor system  302  has been substantially mechanically uncoupled or detached from the primary structure of the fuselage airframe  300 , it is possible for a respective height of the support members and thus a height of the floor members  309  to  311  resting thereon to be broadly selected as desired in relation to the z-axis and in particular independently of possible static restrictions of the fuselage airframe  300 . Consequently, completely new configuration possibilities within aircraft fuselage airframes are presented, compared to previously known embodiments of floor systems. 
         [0055]      FIG. 6  is a greatly schematised view of a progressively vertically adjustable floor system. A floor system  352  is arranged in a fuselage airframe  350  with a fuselage cell skin  351 . Two longitudinal supports  354 ,  355 , inter alia, are attached in a lower region  353  of the fuselage airframe  350 . Two support members  356 ,  357  are arranged on longitudinal support  354  and two support members  358 ,  359  are arranged on longitudinal support  355 . Floor members  360 ,  361  are positioned on the support members  356  to  359  to provide a floor surface  362 . In this embodiment of the floor system  352 , the support members  356  to  359  are respectively configured as (lift) scissors with in each case two crossed struts which allow a continuous vertical adjustment. 
         [0056]    By moving in each case at least one strut (not provided with a reference numeral) in scissors of a support member  356  to  359  along the x-axis of the coordinate system  112  in the direction of arrow  363 , the height of the support members  356  to  359  can preferably be continuously adjusted within a wide range in a vertical direction, i.e. parallel to the z-axis in the direction of arrow  364 . Each support member  356  to  359  has respectively two intersecting struts. At least two struts of each support member  356  to  359  are accommodated such that they can be moved in the longitudinal supports  354 ,  355  or below the floor members  360 ,  361  in the direction of the x-axis. 
         [0057]    As a result of the simultaneous adjustment of the two front support members  356 ,  358  with the same adjustment path, for example the front floor member  360  can be brought to a height  365  which can be varied within wide limits, while as a result of the simultaneous adjustment of the two rear support members  357 ,  359 , it is possible to vary a height  366  of the rear floor member  361 . Consequently, the two floor members  360 ,  361  of the floor surface  362 , in conjunction with the four support members  356  to  359 , form a respective progressively vertically adjustable “scissor lift table”. In order to prevent the floor members from undesirably tilting around the x-axis (slanted position of the floor surface  362  in respect of the xy-plane), the respectively opposing support members  356 ,  358  and  357 ,  359  are moved synchronously parallel to the z-axis. 
         [0058]    In the illustrated embodiment of  FIG. 6 , the heights  365 ,  366  are adjusted identically, thus producing a continuous, planar floor surface  362 . Different heights  365 ,  366  can for example be adjusted, for example if a front hold  368  which is larger than a rear hold  367  is to be provided under the front floor member  360 . The passenger cabin is located inside the fuselage airframe  350  above the floor surface  362 . Although a height adjustment of the floor members  360 ,  361  during flight operation is not provided in this variant, it is possible in principle. 
         [0059]    Reference will be made at the same time to  FIGS. 7 and 8  during the further course of the description. 
         [0060]      FIG. 7  illustrates a further embodiment of the floor system, while  FIG. 8  shows two groups of seats as functional members which can be combined with the floor system. 
         [0061]    A fuselage airframe  400  with a fuselage cell skin  401  is fitted with a further variant of a floor system  402 . Two longitudinal supports  404 ,  405  run parallel to the x-axis of the coordinate system  112  in a lower region  403  of the fuselage airframe  400 . The support members  406 ,  407  are formed by a plurality of vertical struts running parallel to the z-axis and diagonal struts arranged in each case between two vertical struts. Of the vertical struts and the diagonal struts, only two front vertical struts  408 ,  409  and the associated diagonal struts  410 ,  411  have been provided with reference numerals. Attached to the vertical struts  408 ,  409  and to the further undesignated vertical struts are in each case crossbars, of which only a front crossbar  412  has been provided with a reference numeral, said crossbars each running parallel to the y-axis. Arranged on the crossbars in the illustrated embodiment are four seat rail profiled parts as longitudinal profiled parts, of which one seat rail profiled part  413  has a reference numeral in representation of all the others. The seat rail profiled parts are attached to the crossbars by a plurality of attachment means, of which a clamp-like attachment means  414  has been provided with a reference numeral. 
         [0062]    However, the seat rail profiled parts can be freely positioned before attachment parallel to the x-axis (or in the direction of the y-axis) on the crossbars  412 , as indicated by the white double arrow. As a result of such a displacement of two seat rail profiled parts parallel to the y-axis by respectively the same amount, for example an aisle width can be varied between two groups of seats locked in each case on two seat rail profiled parts (a group of two seats or three seats for passengers (cf.  FIG. 8 ); not shown). The attachment means  414  can be any riveting, screwing, clamping or insertion connections or members or any combination thereof. For the locally variable and optionally grid-like attachment of the seat rail profiled parts on the crossbars, grooves, recesses, hollows, clasps, clamps, catches or any combination thereof can also be used. 
         [0063]      FIG. 8  illustrates two optional functional members which can be used as part of the floor system in the region of an interior of an aircraft. Alternatively, the functional members can be configured as galleys, sanitary modules, storage modules, floor members or any combination thereof. 
         [0064]    In the illustrated embodiment of  FIG. 8 , the two functional members  415 ,  416  are configured as groups of seats  417 ,  418 , and—unlike passenger seats of the prior art (cf. FIG.  2 )—in each case three seats for passengers are combined in each group of seats  417 ,  418 . Each group of seats  417 ,  418  has an adapter  419 ,  420  or a connection member which is configured by way of example in  FIG. 8  as a compact prism, although in principle it can have a cuboidal shape or any other geometric shape. Lower connection regions of the adapters  419 ,  420  are connected to the seat rails by suitable attachment means, while the seats themselves are mechanically connected to the adapters in an upper connection region of the adapter. In addition to the functional members  415 ,  416 , the adapters  419 ,  420  are integral components of the floor system  402  and, as such, allow a simple and time-saving connection in terms of assembly of the seats, usually manufactured by external suppliers, to the airbus-specific floor system which is used in the specific individual case. Alternatively, the functional members  415 ,  416  can also be configured as components of floor members. 
         [0065]    Between the two groups (of three) seats  417 ,  418 , there is an indicated aisle width  421  or a spacing (determined along the y-axis between any functional members). The width of the aisle  421  can be varied, if required, by moving at least two seat rail profiled parts  413  parallel to the x-axis on the crossbars which are usually located underneath. 
         [0066]      FIG. 9  shows a further alternative embodiment of the floor system according to the invention. 
         [0067]    The floor system  452  is integrated into a fuselage airframe  450  with a fuselage cell skin  451 . In a lower region  453 , two longitudinal supports  454 ,  455  run in each case in a mutual parallel spacing and in each case parallel to the x-axis of the coordinate system  112 . Arranged on the longitudinal supports  454 ,  455  is a respective lattice-type support member  456 ,  457  which is formed by a plurality of vertical struts configured as Samer rods, as well as diagonal struts positioned between respectively two adjacent vertical struts. On their upper sides, both support members  456 ,  457  have a respective continuous upper longitudinal support  458 ,  459  which preferably have the same longitudinal extent as the (lower) longitudinal supports  454 ,  455 . 
         [0068]    Furthermore, the floor system  452  has a plurality of crossbars, of which only one crossbar  460  has been provided with a reference numeral and which are attached to the upper longitudinal supports  458 ,  459  in any position in the direction of the x-axis, as symbolised by arrow  461 , by attachment means (not shown). The crossbars have a respective recess at each end to prevent an uncontrolled displacement on the upper longitudinal supports  458 ,  459  in the direction of the x-axis and y-axis. The bilateral recesses  462 ,  463  in the front crossbar  460  have been provided with a reference numeral in representation of the others. The curved arrow symbolises a preferred attachment direction of the crossbars on the upper longitudinal supports  458 ,  459  of the support members  456 ,  457  of the floor system  452 . Floor members  464 , of which only one has been provided with a reference numeral in representation of the remaining two, are respectively arranged and attached between and/or on the crossbars  460 , to provide a planar floor surface. 
         [0069]      FIG. 10  shows a further variant of the floor system according to the invention. 
         [0070]    A fuselage airframe  500  with a fuselage cell skin  501  is provided with a floor system  502 . A lower region  503  of the fuselage airframe  500  is in turn provided with longitudinal supports  504 ,  505  which run on both sides parallel to the x-axis of the coordinate system  112  and on which four support members  506 ,  507  and  508 ,  509  are arranged. Attached to the support members  506 ,  507  is a crossbar  510  and positioned on the support members  508 ,  509  is a crossbar  511 . Floor members not shown in  FIG. 10  are arranged on or between the crossbars  510 ,  511  to form the floor surface in a passenger cabin of an aircraft. Each of the four support members  506  to  509  has a vertical strut and a diagonal strut which have not been provided with reference numerals for reasons of clarity. In each case an upper end of a diagonal strut and an upper end of a vertical strut are brought together at one end of a diagonal strut, while the corresponding lower ends of the struts are attached to four straps  512  to  515 . The straps  512  and  514  on the (left-hand side) support members  506 ,  508  are accommodated such that they can be moved and locked inside the longitudinal support  504  in the direction of the x-axis in a rail-like guide means  516  (for example a groove with a reverse T-shaped cross-sectional geometry). The same applies to the straps  513 ,  515  which slide in a guide means  517 . 
         [0071]    This configuration makes it possible for the crossbars  510 ,  511  to move along the x-axis (longitudinal axis of the aircraft) at any point in the direction of arrow  518  and to be fixed there. Consequently, a greater number of crossbars  510 ,  511  can be positioned, for example in those regions of the floor surface in which higher loads arise due to functional members, in particular parallel to the z-axis. 
         [0072]      FIG. 11  illustrates a further variant of the universal floor system. 
         [0073]    A floor system  552  is integrated into a fuselage airframe  550  with a fuselage cell skin  551 . The floor system  552  comprises, inter alia, longitudinal supports  554 ,  555  integrated in a lower region  553  of the fuselage airframe  550 . Both longitudinal supports  554 ,  555  run parallel and with respectively the same spacing from a base line  558 . Arranged on the longitudinal supports  554 ,  555  is a respective support member  556  and  557 , which support members are connected by a crossbar  559 . The crossbar  559  runs substantially parallel to the y-axis of the coordinate system  112 . Unlike the previous variants, the crossbar  559  is configured such that it overhangs with respect to the support members  556 ,  557 , in other words the crossbar  559  has in the region of the two support points (not shown) on the support members  556 ,  557  respectively outwardly directed projecting ends  560 ,  561  (so-called overhanging ends). The two projecting ends  560 ,  561  are braced with approximately triangular struts  562 ,  563  with upper ends (not described in more detail) of the support members  556 ,  557 . Due to the effect of the triangular struts  562 ,  563 , both support members  556 ,  557 , in conjunction with the supported crossbar  559 , are stabilised in respect of loads which act parallel to the y-axis, no that the entire substructure consisting of the two support members  556 ,  557 , the crossbar  559  and the two struts  562 ,  563  can be completely detached and attached to the two longitudinal supports  554 ,  555  independently of the primary structure of the fuselage airframe  550 . This provides completely new and very flexible configuration possibilities in respect of the novel floor system  552 , since it is no longer necessary to take into account possible static peripheral conditions of the fuselage airframe  550  when modifying the floor system  552 . Furthermore, it is also an advantage of this configuration that a side connection of the support members  556 ,  557  to the fuselage airframe  550  or to the annular formers (not shown) is not required. 
         [0074]    In the fuselage airframe  550 , to provide the floor system  552 , a plurality of correspondingly configured support members  556 ,  557  with crossbars  559  respectively resting thereon and attached thereto is arranged and attached offset in tandem in each case in respect of the x-axis to provide a support surface for floor members (not shown) on the longitudinal supports  554 ,  555 . In the simplest case, the floor members resting on and attached to the crossbars  559  form a continuous floor surface on which passengers can walk. 
         [0075]      FIG. 12  shows a “reverse” variant of the floor system. 
         [0076]    Here again, a floor system  602  is integrated into a fuselage airframe  600  with a fuselage cell skin  601 . In contrast to all the variants of the floor system described above, in an upper region  603  two longitudinal supports  604 ,  605  are attached running parallel to the x-axis of the coordinate system. The two longitudinal supports  604 ,  605  run in each case uniformly spaced from a crown line  606  in the upper region  603  of the fuselage airframe  600 . The crown line  606  runs through the highest point (apex) of the cross-sectional geometry of the fuselage airframe  600 . Attached to (suspended from) the two longitudinal supports  604 ,  605  in the illustrated embodiment of  FIG. 12  are again two support members  607 ,  608  which, by way of example, are formed from a total of six vertical struts, of which only the two front vertical struts  609 ,  610  have been provided with a reference numeral. Attached to the vertical struts  609 ,  610  are a plurality of floor members to provide a continuous and walkable floor surface  612 , of which only the foremost floor member  611  has been provided with a reference numeral. Subject to a suitable static inherent stability and loadability, the floor members  611  can at the same time take over the function of the otherwise present crossbars and can be directly connected to the vertical struts. Alternatively, in each case two opposing vertical struts can be connected by a respective crossbar. Longitudinal profiled parts, for example seat rail profiled parts or the like, which run parallel to the x-axis can then optionally be attached to the crossbars and the floor members are then arranged and attached between or on said longitudinal profiled parts to provide the floor surface  612 . The floor members  611  or the crossbars preferably have in each case a projecting end  613 ,  614  on both sides. To further strengthen the floor system  602  in respect of loads which engage parallel to the y-axis, a bracing is preferably also effected by diagonal struts which run from the respective projecting ends  613 ,  614  to the respective connection points (not designated) of the vertical struts  609 ,  610  in the region of the longitudinal supports  604 ,  605 . In representation of all the other diagonal struts, the front diagonal struts  615  and  616  are provided with a reference numeral. The diagonal struts  615 ,  616  can be formed by profiled parts which can be loaded in compression and tension and/or by components which can optionally be loaded exclusively with tensile forces, for example ropes or straps. Reference is made to the information provided above regarding the choice of material for the diagonal struts. 
         [0077]    The variant according to  FIG. 12  has the particular advantage that the support members  607 ,  608  and the vertical struts  609 ,  610  forming these in each case are substantially only loaded in tension parallel to the z-axis, thereby providing the potential to save weight compared to other constructive solutions which require assemblies which can be loaded equally in tension and compression. Furthermore, due to the diagonal struts  615 ,  616 , an additional side connection of the support members  607 ,  608  to the fuselage airframe  600  and to the annular formers integrated therein is usually superfluous. Thus, with this variant of the floor system  602  which is statically uncoupled from the fuselage airframe  600 , it is also possible to make necessary modifications to the floor system  602  substantially independently of the static restrictions of the fuselage airframe  600  at low expense. 
         [0078]      FIG. 13  shows the floor system with two floor members. A floor system  650  in a fuselage airframe  651  comprises, inter alia, two longitudinal supports, only one longitudinal support  652  being visible in the illustration of  FIG. 13 . Arranged on the longitudinal support  652  is a support member  653  which extends parallel to the x-axis substantially over the entire length of the aircraft. The same applies to the longitudinal support which is not shown. In the illustrated embodiment, the support member  653  comprises vertical struts  654 ,  655  which can also be configured as (vertically adjustable) Samer rods. A plurality of crossbars  656  to  658  are positioned on the support member  653  and the further support member (not shown), parallel to the y-axis. Positioned on the crossbars  656  to  658  are three longitudinal profiled parts  659  to  661  which, in the illustrated embodiment, are each braced in the manner of a lattice. The longitudinal profiled parts  659  to  661  can be formed, for example, by longitudinal profiled parts having a double-T-shaped cross-sectional geometry (so-called double-T supports), triangular and/or rectangular recesses being milled in a vertical web connecting the two sides of the double-T support to provide the overall lattice-type structure. 
         [0079]    A floor member  662  has an adapter  663  which is used to attach a group of three seats (not shown) for passengers (cf. in particular  FIG. 8 ). Both the adapter  663  and the group of seats (not shown) form a functional member  664  which is an integral component of the floor member  662 . The adapter  663  allows a straightforward attachment of different assemblies or components, for example groups of seats from different suppliers, on the standardised floor member  662 . A further floor member does not have a functional member, but is configured as an equalising floor member  665  which is used in particular for filling (seat spacings) and for equalising empty spaces between floor members with functional members. To achieve this purpose, a width  666  and a length  667  of the equalising floor member  665  are configured in a standardised grid. For example, whole-number multiples of 2.54 cm can be selected for the width  666  (along the y-axis) and for the length (along the x-axis). 
         [0080]    The floor member  662  and the equalising floor member  665  are preferably formed using high-strength sandwich boards consisting of fibre-reinforced plastics materials. Subject to an adequate mechanical strength of the floor members  662 ,  665 , it is optionally possible to partly or completely dispense with the longitudinal profiled parts  659  to  661  and/or the crossbars  656  to  658  inside the floor system  650 . The floor members  662 ,  665  are attached to the longitudinal profiled parts  659  to  661  by attachment members (not shown). A surface (not designated) of the floor member  662  or of the equalising floor member  665 , but in particular the surfaces of the floor members with functional members arranged thereon, are selected such that each floor member  662 ,  665  preferably covers at least one grid (not designated) which is defined by at least two crossbars  656 ,  658  and at least two longitudinal profiled parts  659 ,  660 . Consequently, forces emanating from the functional members of the respective floor members, for example in the form of an arrangement of three passenger seats, are introduced into the floor system  650  over a large area so that the individual components, in particular the crossbars  656  to  658  and the longitudinal profiled parts  659  to  661  can be configured in a statically lighter manner, thus reducing weight, compared to conventional embodiments of floor frames. Furthermore, the floor members with integrated functional members allow a faster and easier assembly because the various functional members are already attached to the floor members and the respective floor portion including, for example, a group of seats is completed by lowering onto the floor member  662  to the longitudinal profiled parts  659 ,  660  in the direction of the two white arrows and attaching it thereto. 
         [0081]      FIG. 14  shows a floor member  700  with an adapter  701  located thereon for attaching further functional members, for example groups of seats (not shown) with in each case two or three seats for passengers. 
         [0082]    In order to produce a flexible length equalisation for adjusting specific seat spacings in the direction of the x-axis of the coordinate system  112 , the floor member  700  is available in respectively different lengths. In the illustration, the floor member has, for example, alternatively the fixed length  702  or  703 . A difference in length  704  (ΔL) between the lengths  702 ,  703  preferably follows a graduated standard modular dimension, as indicated by the white double arrow, in order to limit a total number of floor members to be stored with respectively different dimensions (length/width). For example, for the difference in length  704  a value can be selected which corresponds to a whole-number multiple of a crossbar spacing of the floor system, which crossbar system, in many cases, will also be identical to a former spacing in the fuselage airframe. For example, if the former spacing in the fuselage airframe is 50 cm, the difference in length  704  can be, for example, a multiple of 50 cm in order to achieve at least a complete peripheral support of the floor members on a grid (not shown) defined by the crossbars and/or the longitudinal profiled parts. 
         [0083]    Varying the lengths  702 ,  703  makes it possible to change a spacing  705  from a previous or subsequent floor member with a group of seats (for example a group of three seats or a group of two seats) mounted thereon as a functional member. 
         [0084]    If, in addition, the crossbar spacings (parallel to the y-axis; cf. in this respect in particular  FIGS. 9 and 10 ) and/or the longitudinal profiled part spacings (parallel to the x-axis, cf. in this respect in particular  FIG. 7 ) are varied independently of an existing annular former spacing dimension of the fuselage airframe, the gradation of the difference in length  704  and at the same time a variation of a width  706  of the floor member  700  can be performed in almost any small steps, for example in steps of 10 cm, to achieve a maximum flexibility. 
         [0085]    As a result of the tandem arrangement of a plurality of floor members with respectively different fixed lengths  702 ,  703  graduated in this manner and/or a different width  706  on the support members and the crossbars and/or the longitudinal profiled parts of the floor system, it is possible to adapt a seating arrangement in a passenger aircraft at least in the direction of the x-axis in a simple, rapid and flexible manner to a wide range of customer-specific special requests (for example seat spacings in the direction of flight). 
         [0086]    By varying the width  706  of the floor member  700  in likewise preferably standardised gradations, it is also possible to flexibly adapt in particular an aisle width in the direction of the y-axis (cf. in particular  FIG. 7 ) between rows of seating groups within the seating arrangement. 
         [0087]      FIG. 15  schematically shows a further alternative variant of a floor member to be used with the floor system. 
         [0088]    A floor member  750  is fitted with an adapter  751  in the form of three undesignated platforms as a first functional member  752  which serves as a universal interface to a group of three seats (not shown) for passengers. The floor member  750  is attached to the two longitudinal profiled parts  753 ,  754  at four attachment points  755  to  758  by suitable attachment members (not shown), as basically indicated by the four opposing arrows. The floor member  750  also has an equalising portion  759  which can be moved inwards and outwards like a drawer along the x-axis of the coordinate system  112  (parallel to the y-axis), as a result of which a length  760  of the floor member  750  can be varied within wide limits. Due to the equalising portion  759  which can be moved inwards and outwards preferably continuously or in stages and can be locked, a length  760  of the floor member  750  can be widely adapted. As a result, it is possible, for example for the first time to flexibly adapt a schematically indicated (seat) spacing  761  of the floor system to different customer requests. The floor member  750  according to  FIG. 15  at the same time takes over the function of a floor member with an integrated functional member  752  and that of a universal equalising floor member for a universal equalisation of length along the x-axis of the coordinate system  112 . 
         [0089]    Due to the fact that the floor member  750  has a large support surface on the longitudinal profiled parts  753 ,  754 , which is defined by the currently adjusted length  760  and a generally fixed width  762 , the forces emanating from the adapter  751  and from the functional member  752  arranged thereon are introduced into the floor system, being distributed over a large surface, such that the individual components of the floor system, in particular the longitudinal profiled parts and/or the crossbars, can be configured in a statically lighter manner. Alternatively, the width  762  of the floor member  750  can also be provided with an equalising mechanism which corresponds in construction to the equalising portion  759 , in order to be able to vary the width  762  along the y-axis. 
         [0090]      FIG. 16  shows a further variant of a floor member with an integrated functional member. 
         [0091]    A floor member  800  is equipped by way of example with a complete kitchen module  801  (so-called “galley”) as an optional functional member. The floor member  800  is preferably attached to the longitudinal profiled parts or the crossbars of the floor system in the corner regions, indicated by opposing arrows, of the floor member  800 . Instead of the galley  801 , the floor member  800  can alternatively be equipped with any other functional members, for example with a complete sanitary module, a storage module, a locker module, a module with at least one sleeping compartment and/or recreation room for passengers and/or staff as well as a housing module for technical devices or any combination thereof. 
         [0092]    All the connections for linking the functional member to the necessary on-board systems of the aircraft are preferably integrated into the floor member  800  in the form of a universal interface, so that a rapid and preferably insertable and re-detachable connection of the functional member is possible. 
         [0093]    The on-board systems are, for example, electrical systems, optical systems, hydraulic systems, pneumatic systems, fresh water systems, waste water systems or air-conditioning systems of the aircraft. 
         [0094]      FIGS. 17 and 18 , to which reference will be jointly made, show a further variant of a floor member. A floor member  850  comprises a planar floor plate  851 , an elevation (platform) being formed with three supports  852  to  854  which are arranged next to one another and evenly spaced on the floor plate  851 . Three adapters  855  to  857  can be attached to the supports  852  to  854 , for example by an insertion connection or mortise joint, a screw connection, a plug-in connection or the like. The adapters  855  to  857  are each divided into two with in each case an upper part and a lower part (not provided with a reference numeral). Provided in the upper and lower parts is a respective recess (not designated) which, when the upper and lower parts are assembled, respectively complement each other approximately to form a cross-sectional geometry which corresponds to that of a seat support  858  (cf.  FIG. 18 ), a light press locking preferably occurring between the crossbar and the upper and lower parts of the adapters when assembled in order to ensure a secure fit. In the illustrated embodiment, the seat support  858  has an elliptical cross-sectional geometry. In principle, the seat support  858  can have any other suitable cross-sectional geometry (for example rectangular, square, triangular, oval or the like) which makes it difficult for the seat support  858  to twist around its longitudinal axis in the adapters  855  to  857 , or which prevents this from happening. Mounted on the seat support  858  in the illustrated embodiment of FIG.  18  are two (single) seats  859  and  860  with arm rests and head supports, which form a group of seats. When assembled, the floor member  850  comprises the floor plate  851 , the three supports  852  to  854 , the adapters  855  to  857 , the seat support  858  as well as the group of seats located thereon with the two seats  859 ,  860 . Thus, the floor member  850  can be easily integrated into the modular and flexible floor system according to the invention. 
         [0095]    The seats  859 ,  860  attached to the seat supports  858  can be obtained from external suppliers as a result of using the three adapters  855  to  857 , while the floor member  850  which is independent of this system is produced by the aircraft manufacturer itself in a standardised state. Thus, a large number of different seat supports  858  with seats  859 ,  860  can be arranged on and attached to always the same standardised floor member  850 , thereby significantly increasing the production efficiency. Furthermore, the adapters  855  to  857  make it easier to remove the passenger seats for rearrangement purposes and/or for cleaning or maintenance operations. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           100  fuselage airframe (aircraft) 
           101  fuselage cell skin 
           102  annular former 
           103  floor system (prior art) 
           104  crossbar 
           105  Samer rod 
           106  Samer rod 
           107  seat rail profiled part 
           108  floor plate 
           109  floor 
           110  passenger compartment (passenger cabin) 
           111  hold 
           112  coordinate system 
           150  seat (passenger seat) 
           151  leg 
           152  leg 
           153  attachment point (seat) 
           154  attachment point (seat) 
           155  seat rail profiled part 
           156  spacing (parallel to the x-axis) 
           200  fuselage airframe 
           201  fuselage cell skin 
           202  floor system 
           203  lower region (fuselage airframe) 
           204  longitudinal support 
           205  longitudinal support 
           206  support member 
           207  support member 
           208  vertical strut 
           209  vertical strut 
           210  diagonal strut 
           211  longitudinal strut 
           212  crossbar 
           213  side connection (Samer rod) 
           214  Samer rod 
           215  Samer rod 
           216  crossbar 
           250  fuselage airframe 
           251  fuselage cell skin 
           252  floor system 
           253  lower region 
           254  longitudinal support 
           255  longitudinal support 
           256  support member 
           257  support member 
           258  vertical strut 
           259  crossbar 
           260  seat rail profiled part 
           261  floor surface 
           262  floor member 
           263  side connection 
           264  side connection 
           300  fuselage airframe 
           301  fuselage cell skin 
           302  floor system 
           303  lower region 
           304  longitudinal support 
           305  longitudinal support 
           306  support member 
           307  support member 
           308  crossbar 
           309  floor member 
           310  floor member 
           311  floor member 
           312  step 
           313  step 
           350  fuselage airframe 
           351  fuselage cell skin 
           352  floor system 
           353  lower region 
           354  longitudinal support 
           355  longitudinal support 
           356  support member 
           357  support member 
           358  support member 
           359  support member 
           360  floor member 
           361  floor member 
           362  floor surface 
           363  arrow 
           364  arrow 
           365  height 
           366  height 
           367  rear hold 
           368  front hold 
           369  passenger cabin 
           400  fuselage airframe 
           401  fuselage cell skin 
           402  floor system 
           403  lower region 
           404  longitudinal support 
           405  longitudinal support 
           406  support member 
           407  support member 
           408  vertical strut 
           409  vertical strut 
           410  diagonal strut 
           411  diagonal strut 
           412  crossbar 
           413  seat rail profiled part 
           414  attachment means 
           415  functional member 
           416  functional member 
           417  group of seats (group of three seats) 
           418  group of seats (group of three seats) 
           419  adapter 
           420  adapter 
           421  aisle width 
           450  fuselage airframe 
           451  fuselage cell skin 
           452  floor system 
           453  lower region 
           454  longitudinal support 
           455  longitudinal support 
           456  support member 
           457  support member 
           458  upper longitudinal support 
           459  upper longitudinal support 
           460  crossbar 
           461  arrow 
           462  recess 
           463  recess 
           464  floor member 
           500  fuselage airframe 
           501  fuselage cell skin 
           502  floor system 
           503  lower region 
           504  longitudinal support 
           505  longitudinal support 
           506  support member 
           507  support member 
           508  support member 
           509  support member 
           510  crossbar 
           511  crossbar 
           512  strap 
           513  strap 
           514  strap 
           515  strap 
           516  guide means 
           517  guide means 
           518  arrow 
           550  fuselage airframe 
           551  fuselage cell skin 
           552  floor system 
           553  lower region 
           554  longitudinal support 
           555  longitudinal support 
           556  support member 
           557  support member 
           558  base line (fuselage airframe) 
           559  crossbar 
           560  projecting end (overhanging end) 
           561  projecting end (overhanging end) 
           562  triangular strut 
           563  triangular strut 
           600  fuselage airframe 
           601  fuselage cell skin 
           602  floor system 
           603  upper region 
           604  longitudinal support 
           605  longitudinal support 
           606  crown line 
           607  support member 
           608  support member 
           609  vertical strut 
           610  vertical strut 
           611  floor member 
           612  floor surface 
           613  projecting end (floor member/crossbar) 
           614  projecting end (floor member/crossbar) 
           615  diagonal strut 
           616  diagonal strut 
           650  floor system 
           651  fuselage airframe 
           652  longitudinal support 
           653  support member 
           654  vertical strut 
           655  vertical strut 
           656  crossbar 
           657  crossbar 
           658  crossbar 
           659  longitudinal profiled part 
           660  longitudinal profiled part 
           661  longitudinal profiled part 
           662  floor member 
           663  adapter (for example for group of seats) 
           664  functional member 
           665  equalising floor member 
           666  width (equalising floor member) 
           667  length (equalising floor member) 
           700  floor member 
           701  adapter (for example for a group of seats) 
           702  length (first floor member) 
           703  length (second floor member) 
           704  difference in length 
           705  spacing (seat spacing) 
           706  width 
           750  floor member 
           751  adapter 
           752  functional member 
           753  longitudinal profiled part 
           754  longitudinal profiled part 
           755  attachment point 
           756  attachment point 
           757  attachment point 
           758  attachment point 
           759  equalising portion (telescopic) 
           760  length (floor member) 
           761  spacing (seat spacing) 
           762  width (floor member) 
           800  floor member 
           801  functional member (galley) 
           850  floor member 
           851  floor plate 
           852  support 
           853  support 
           854  support 
           855  adapter 
           856  adapter 
           857  adapter 
           858  seat support 
           859  seat 
           860  seat