AIRCRAFT FUEL SYSTEM

• US 20160009406A1
• Filed: 07/09/2015
• Published: 01/14/2016
• Est. Priority Date: 07/10/2014
• Status: Active Grant

• Current Assignee: Airbus Operations Limited (Airbus SE)
• Original Assignee: Airbus Operations Limited (Airbus SE)
• Inventors: BURNELL, Stephen, LEIGH, Tim
• Granted Patent: US 9,809,319 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B64D 37/10 to facilitate fuel pressurisation
• CPC Class Codes: B64D 37/14 Filling or emptying transferring fuels to adjust aircraft trim B64C
• CPC Class Codes: B64D 37/24 using gas pressure
• CPC Class Codes: B64D 37/32 Safety measures not otherwise provided for, e.g. preventing explosive conditions extinguishing or preventing fires in aircraft A62C

Abstract

The invention provides an aircraft fuel system comprising a fuel storage facility for storing fuel and ullage, a separate ullage storage facility for storing ullage, and a transfer arrangement for transferring ullage between the fuel storage facility and the ullage storage facility, wherein the transfer arrangement is capable of controlling the transfer of ullage based on a pressure input to the transfer arrangement. The invention also provides an aircraft with such a fuel system and a method of operating an aircraft.

Claims

1. An aircraft fuel system comprising;

a fuel storage facility for storing fuel and ullage,

a separate ullage storage facility for storing ullage, and

a transfer arrangement for transferring ullage between the fuel storage facility and the ullage storage facility,

wherein the transfer arrangement is capable of controlling the transfer of ullage based on a pressure input to the transfer arrangement.

2. An aircraft fuel system as claimed in claim 1, wherein a pressure-controlled valve arrangement of the transfer arrangement is capable of controlling the transfer of ullage based on a pressure input to the valve arrangement.

3. An aircraft fuel system as claimed in claim 2, wherein the pressure-controlled valve arrangement is designed to control the transfer of ullage based on a continually changing pressure input.

4. An aircraft fuel system as claimed in claim 2, wherein the pressure input is an indication of the pressure in the fuel storage facility.

5. An aircraft fuel system as claimed in claim 4, wherein the pressure input is a pressure measured in the fuel storage facility.

6. An aircraft fuel system as claimed in claim 4, wherein the pressure input is based on an ambient pressure and an amount of fuel usage.

7. An aircraft fuel system as claimed in claim 3, wherein the pressure-controlled valve arrangement is designed to transfer ullage from the fuel storage facility to the ullage storage facility when the pressure input is relatively high and to transfer ullage from the ullage storage facility to the fuel storage facility when the pressure input is relatively low.

8. An aircraft fuel system as claimed in claim 1, wherein the transfer arrangement is capable of only allowing the transfer of ullage to the ullage storage facility and not to allowing the transfer of fuel to the ullage storage facility.

9. An aircraft fuel system as claimed in claim 8, wherein the transfer arrangement comprises a valve, such as a float valve, for allowing transfer of ullage, but not transfer of fuel, from the fuel storage facility to the ullage storage facility.

10. An aircraft fuel system as claimed in claim 1, further comprising a pump for effecting transfer of the ullage between the fuel storage facility and the ullage storage facility.

11. An aircraft fuel system as claimed in claim 1, wherein the ullage storage facility comprises a variable volume ullage container.

12. An aircraft fuel system as claimed in claim 1, wherein the aircraft fuel system further comprises a compressor for compressing the ullage and wherein the ullage storage facility comprises a pressurisable container for storing the compressed ullage.

13. An aircraft fuel system as claimed in claim 12, wherein the ullage storage facility further comprises an intermediate container connected between the pressurisable container and the pressure-controlled valve arrangement.

14. An aircraft fuel system as claimed in claim 1, wherein the fuel storage facility comprises a surge container for accommodating excess fuel.

15. An aircraft fuel system as claimed in claim 1, further comprising a climb-dive valve for ensuring a limited pressure difference between a pressure in the fuel storage facility and an atmospheric pressure.

16. An aircraft fuel system as claimed in claim 1, further comprising an inerting system for reducing the oxygen content of the ullage.

17. An aircraft fuel system as claimed in claim 16, wherein the inerting system is connected to the ullage storage facility so as to act upon the ullage in the ullage storage facility to reduce its oxygen content.

18. An aircraft comprising the aircraft fuel system of claim 1.

19. A method of operating an aircraft, the method comprising the following steps;

supplying fuel to a fuel storage facility of an aircraft fuel system of the aircraft,

transferring at least some ullage from the fuel storage facility, through a transfer arrangement, to a separate ullage storage facility, based on a pressure input to the transfer arrangement,

storing at least some of the transferred ullage in the ullage storage facility, and

transferring at least some of the stored ullage from the ullage storage facility, through the transfer arrangement, to the fuel storage facility, based on the pressure input to the transfer arrangement.

20. A method of operating an aircraft as claimed in claim 19, wherein the transfer of ullage between the fuel storage facility and the ullage storage facility is controlled by a pressure-controlled valve arrangement, based on a pressure input to the pressure-controlled valve arrangement.

21. A method of operating an aircraft as claimed in claim 19, wherein the pressure input is an indication of the pressure in the fuel storage facility.

22. A method of operating an aircraft as claimed in claim 19, wherein the method comprises the step of flying the aircraft, thereby using up some of the fuel in the fuel storage facility and thereby reducing the pressure in the fuel storage facility, and then transferring at least some of the stored ullage from the ullage storage facility, through the transfer arrangement, to the fuel storage facility, based on the pressure input to the transfer arrangement.

23. A method of operating an aircraft as claimed in claim 19, wherein the method comprises the step of climbing the aircraft to an increased altitude level, thereby increasing the pressure in the fuel storage facility relative to atmospheric pressure, and, at the increased altitude level, transferring at least some ullage from the fuel storage facility, through the transfer arrangement, to the ullage storage facility, based on a pressure input to the transfer arrangement.

24. A method of operating an aircraft as claimed in claim 19, wherein the method comprises the step of descending the aircraft to a reduced altitude level, thereby decreasing the pressure in the fuel storage facility relative to atmospheric pressure, and, at the reduced altitude level, transferring at least some ullage from the ullage storage facility, through the transfer arrangement, to the fuel storage facility, based on a pressure input to the transfer arrangement.

25. A method of operating an aircraft as claimed in claim 24, wherein the method comprises the step of in-taking atmospheric air from outside the aircraft into the fuel storage facility at a first altitude and then allowing transfer of the at least some of the stored ullage from the ullage storage facility, through the transfer arrangement, to the fuel storage facility at a second, lower altitude.