Airframe including crossmembers for fixing seats

An airframe having a substantially circular cross section in a lateral direction (Y) and which extends in a longitudinal direction (X), the airframe comprising:

• a plurality of rails for supporting seats, each rail being parallel to the longitudinal direction (X) of the airframe;
• a plurality of beams parallel to the rails;
• and
• a plurality of crossmembers aligned in the lateral direction (Y) of the airframe, wherein each crossmember supports only some of the rails in the lateral direction (Y), wherein each crossmember is supported by only some of the beams in the lateral direction (Y) of the airframe, wherein the plurality of beams form part of a wing box or a main landing gear well of the airframe, wherein each crossmember comprises at least one connection to each of the beams supporting each crossmember, and wherein a portion of each connection is adapted to articulate about at least one axis parallel to the lateral direction of the airframe (Y).