Noncombustible gas distribution methods and systems on aircraft

Patent metadata

Field	Value
Publication number	US-11091273-B2
Application number	US-201916655393-A
Country	US
Kind code	B2
Filing date	Oct 17, 2019
Priority date	Dec 9, 2016
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A noncombustible gas distribution method includes distributing noncombustible gas to a center wing tank throughout a continuous, first flight period and, as a result, reducing flammability exposure time during the first flight period or during a subsequent flight period. The method includes not distributing noncombustible gas to left and right main wing tanks while the noncombustible gas is distributed to the center wing tank throughout the first flight period and while the left and right main wing tanks are non-flammable. A noncombustible gas distribution system includes a noncombustible gas source and distribution tubing from the gas source to left and right main wing tanks and a center wing tank. A distribution mechanism yields a greater proportion of gas flow per tank unit volume distributed to an outboard section of the left and right main wing tanks compared to an inboard section during a climb phase of the aircraft's flight.

First claim

What is claimed is:

1. A noncombustible gas distribution method comprising:
distributing the noncombustible gas to a center wing tank of an aircraft throughout a continuous, first flight period and, as a result, reducing flammability exposure time in which the center wing tank is flammable during the first flight period or during a subsequent flight period compared to the flammability exposure time that will otherwise occur during the first flight period or during the subsequent flight period without the distribution of the noncombustible gas to the center wing tank throughout the first flight period; and
not distributing noncombustible gas to a left main wing tank and a right main wing tank of the aircraft while the noncombustible gas is distributed to the center wing tank throughout the first flight period and while the left and right main wing tanks are non-flammable, wherein the left and right main wing tanks are on opposite sides of the aircraft with the center wing tank being between the left and right main wing tanks.

2. The method of claim 1 further comprising:
opening a first isolation valve throughout the continuous, first flight period;
closing a second isolation valve throughout the continuous, first flight period; and
closing a third isolation valve throughout the continuous, first flight period.

3. The method of claim 2 , wherein opening the first isolation valve permits noncombustible gas to be distributed to the center wing tank and wherein closing the second and third isolation valves prevents noncombustible gas to be distributed to the left and right main wing tanks.

4. The method of claim 1 further comprising not distributing the noncombustible gas to the center wing tank throughout a continuous, second flight period in which the center wing tank is non-flammable, the second flight period not overlapping with the first flight period.

5. The method of claim 4 further comprising closing a first isolation valve throughout the continuous, second flight period, wherein closing the first isolation valve prevents noncombustible gas to be distributed to the center wing tank.

6. The method of claim 5 further comprising distributing the noncombustible gas to the left and right main wing tanks throughout the second flight period and, as a result, reducing flammability exposure time in which the left and right main wing tanks are flammable during the second flight period or during a subsequent flight period compared to the flammability exposure time that will otherwise occur during the second flight period or during the subsequent flight period without the distribution of the noncombustible gas to the left and right main wing tanks throughout the second flight period.

7. The method of claim 6 , further comprising opening a second isolation valve and a third isolation valve throughout the continuous, second flight period, wherein opening the second and third isolation valves permit noncombustible gas to be distributed to the left and right main wing tanks.

8. The method of claim 7 wherein non-flammability occurs because of one or more condition selected from: a) fuel temperature and altitude yielding a fuel-air ratio below a lower flammability limit or above an upper flammability limit and b) oxygen content in an ullage below an inert limit.

9. The method of claim 7 further comprising:
distributing the noncombustible gas to the left and right main wing tanks throughout a continuous, third flight period, the third flight period not overlapping with the first or second flight periods, and, as a result, reducing flammability exposure time in which the left and right main wing tanks are flammable during the third flight period or during a subsequent flight period compared to the flammability exposure time that will otherwise occur during the third flight period or during the subsequent flight period without the distribution of the noncombustible gas to the left and right main wing tanks; and
not distributing noncombustible gas to the center wing tank while the noncombustible gas is distributed to the left and right main wing tanks throughout the third flight period and while the center tank is non-flammable.

10. The method of claim 9 wherein the first flight period occurs during a descent phase, the second flight period occurs during a climb phase, and the third flight period occurs during a cruise phase.

11. The method of claim 7 wherein the first flight period occurs during a descent phase and the second flight period occurs during a climb phase or a cruise phase.

12. The method of claim 11 further comprising:
wherein the left and right main wing tanks each having an inboard section and an outboard section each having baffle ribs and other ribs, the sections being defined by baffle ribs between the sections, the baffle ribs defining the sections having less ullage communication area between the sections compared to the ullage communication area of the other ribs within the sections; and
distributing the noncombustible gas to the left and right main wing tanks throughout the second flight period at a greater proportion of noncombustible gas flow per tank unit volume to the outboard section compared to the inboard section during the climb phase.

13. The method of claim 11 wherein the distribution of the noncombustible gas to the left and right main wing tanks throughout the second flight period occurs through a noncombustible gas distribution system comprising:
a noncombustible gas source on the aircraft;
the left and right main wing tanks each having an inboard section and an outboard section each having baffle ribs and other ribs, the sections being defined by baffle ribs between the sections, the baffle ribs defining the sections having less ullage communication area between the sections compared to the ullage communication area of the other ribs within the sections;
noncombustible gas distribution tubing from the noncombustible gas source to the left and right main wing tanks and the center wing tank, wherein the first, second, and third isolation valves are in the noncombustible gas distribution tubing;
wherein the first, second, and third isolation valves are operable to isolate the left and right main wing tanks and the center wing tank from receiving noncombustible gas; and
a distribution mechanism including first noncombustible gas flow restrictions balancing noncombustible gas flow among the left and right main wing tanks and the center wing tank with the first, second, and third isolation valves fully open to yield a greater proportion of noncombustible gas flow per tank unit volume distributed to the outboard section of the left and right main wing tanks compared to the inboard section during the second flight period occurring during the climb phase.

14. A noncombustible gas distribution method comprising:
opening a first isolation valve to distribute noncombustible gas to a center wing tank of an aircraft during flight each time one or more of the following conditions 1A-1C are met, the center tank being positioned between a left main wing tanks and a right main wing tank of the aircraft and closing the first isolation valve to not distribute the noncombustible gas to the center wing tank during flight when none of the following conditions 1A-1C are met:
1A) the center wing tank contains a usable level of fuel;
1B) the aircraft is cruising in a pre-descent phase; and
1C) the aircraft is in a descent phase; and

opening at least a second isolation valve to distribute noncombustible gas to the left and right main wing tanks during flight each time one or more of the following conditions 2A-2D are met and

Assignees

• Boeing Co

Inventors

• Jojic Ivana
• Grim Alan
• Lin Bill F
• Vaughan Kristopher

Classifications

• Y02T50/40

  Weight reduction · CPC title

• B64D37/00

  Arrangements in connection with fuel supply for power plant (refuelling during flight B64D39/00) · CPC title

• A62C99/0018 Primary

  using gases or vapours that do not support combustion, e.g. steam, carbon dioxide · CPC title

• B64D37/32 Primary

  Safety measures not otherwise provided for, e.g. preventing explosive conditions · CPC title

• A62C3/08

  in aircraft {(A62C3/0207 takes precedence)} · CPC title