Aircraft cargo floor architecture and method of modifying the aircraft cargo floor architecture

1. An aircraft cargo floor architecture, comprising:

a plurality of aircraft keel frames; and

three or more longitudinal rails disposed above, and attached directly to, the aircraft keel frames, the three or more longitudinal rails designed to provide structural support for an aircraft cargo floor, the three or more longitudinal rails including at least one inner longitudinal rail, a first outer longitudinal rail positioned on a first side of the at least one inner longitudinal rail and a second outer longitudinal rail positioned on a second side of the at least one inner longitudinal rail, a top of the at least one inner longitudinal rail being spaced farther from the aircraft keel frames than tops of the first and second outer longitudinal rails, and there being no intervening support beam or keel frame extension between the keel frames and the three or more longitudinal rails.

2. The cargo floor architecture of claim 1 , wherein the keel frames are variable depth frames.

3. The cargo floor architecture of claim 1 , further comprising a thermal isolator positioned between the three or more longitudinal rails and the aircraft keel frames.

4. The cargo floor architecture of claim 3 , wherein the thermal isolator provides thermal protection by providing separation between the longitudinal rails and the aircraft keel frames.

5. The cargo floor architecture of claim 1 , further comprising a plurality of roller trays attached directly to the longitudinal rails.

6. The cargo floor architecture of claim 5 , further comprising side guides attached to the keel frames.

7. The cargo floor architecture of claim 1 , further comprising bulk cargo floor panels attached to the longitudinal rails.

8. The cargo floor architecture of claim 7 , further comprising bulk cargo tie-down receptacles attached to the keel frames.

9. The cargo floor architecture of claim 1 , wherein the longitudinal rails are designed and sized to bear cargo loads ranging from about 30 pounds/inch to about 120 pounds/inch.

10. The cargo floor architecture of claim 1 , wherein the top of the at least one inner longitudinal rail is spaced apart from a top edge of the aircraft keel frames.

11. The cargo floor architecture of claim 1 , wherein the aircraft keel frames are curved with an inner portion of each aircraft keel frame being positioned below outer portions of each aircraft keel frame, wherein the at least one inner longitudinal rail extends upward from the aircraft keel frames a greater distance than the first and second outer longitudinal rails, and wherein the top of the at least one inner longitudinal rail is substantially level with the tops of the first and second outer longitudinal rails.

12. An aircraft cargo floor architecture system, comprising:

a plurality of aircraft keel frames; and

three or more longitudinal rails disposed above, and attached directly to, the aircraft keel frames, the three or more longitudinal rails including at least one inner longitudinal rail, a first outer longitudinal rail positioned on a first side of the at least one inner longitudinal rail and a second outer longitudinal rail positioned on a second side of the at least one inner longitudinal rail, a top of the at least one inner longitudinal rail being spaced farther from the aircraft keel frames than tops of the first and second outer longitudinal rails, and there being no intervening support beam or keel frame extension between the keel frames and the three or more longitudinal rails,

wherein the three or more longitudinal rails are designed to provide structural support for both a bulk cargo floor and a containerized cargo floor.

13. The cargo floor architecture system of claim 12 , further comprising at least one component chosen from bulk cargo floor panels and roller trays.

14. The cargo floor architecture system of claim 12 , wherein the keel frames are variable depth frames.

15. A method of modifying an aircraft cargo floor architecture, the aircraft cargo floor architecture comprising a plurality of aircraft keel frames and three or more longitudinal rails disposed above, and attached directly to, the aircraft keel frames, the three or more longitudinal rails providing structural support for an aircraft cargo floor, the three or more longitudinal rails including at least one inner longitudinal rail, a first outer longitudinal rail positioned on a first side of the at least one inner longitudinal rail and a second outer longitudinal rail positioned on a second side of the at least one inner longitudinal rail, a top of the at least one inner longitudinal rail being spaced farther from the aircraft keel frames than tops of the first and second outer longitudinal rails, and there being no intervening support beam or keel frame extension between the keel frames and the three or more longitudinal rails, the method comprising:

removing parts of a first cargo floor configuration from the aircraft cargo floor architecture; and

attaching parts of a second cargo floor configuration to the aircraft cargo floor architecture.

16. The method of claim 15 , wherein the first cargo floor configuration is a bulk cargo floor and the second cargo floor configuration is a containerized cargo floor, the method further comprising positioning roller trays directly on the longitudinal rails.

17. The method of claim 15 , wherein the first cargo floor configuration is a containerized cargo floor and the second cargo floor configuration is a bulk cargo floor, the method further comprising removing roller trays that are positioned directly on the longitudinal rails.

18. The method of claim 15 , wherein the modifying of the aircraft cargo floor architecture is carried out without modifying structural floor supports.

19. An aircraft cargo floor architecture, comprising:

a plurality of aircraft keel frames; and

a plurality of longitudinal rails disposed above, and attached directly to, the aircraft keel frames, a top of an inner one of the longitudinal rails being spaced farther from the aircraft keel frames than a top of an outer one of the longitudinal rails, the longitudinal rails designed to provide structural support for an aircraft cargo floor, wherein the longitudinal rails comprise an assembly of a plurality of rail subsections connected together at rail joints, the rail joints configured to allow for flexing of the longitudinal rails at the rail joints.

20. An aircraft cargo floor architecture, comprising:

a plurality of aircraft keel frames; and

a plurality of longitudinal rails disposed above, and attached directly to, the aircraft keel frames, the longitudinal rails designed to provide structural support for an aircraft cargo floor, a top of an inner one of the longitudinal rails being spaced farther from the aircraft keel frames than a top of an outer one of the longitudinal rails, the plurality of aircraft keel frames comprising first adjacent keel frames and second adjacent keel frames, the longitudinal rails comprising first portions that span a distance between the first adjacent keel frames and second portions that span a distance between the second adjacent keel frames, an intercostal being disposed under each of the first portions of the longitudinal rails and an intercostal not being positioned under the second portions of the longitudinal rails.