Systems and methods to provide compliance with structural load requirements for aircraft with additional fuel tankage
Methods and systems are provided to comply with structural load requirements applicable to aircraft additional fuel tank systems. A plurality of aircraft fuel tanks may be positioned adjacent to one another, preferably within the fuselage (e.g., a cargo compartment) of the aircraft so as to be disposed generally along a longitudinal axis of the aircraft. The tank body defining an interior space for holding aircraft fuel, an intercommunication conduit assembly between the fuel tank modules configured to refuel and transfer fuel from the tank modules by a cascade mode and an intentional air-filled ullage space are operatively associated with the tank body to prevent an overpressure condition within the interior space of the fuel tank body. The intentional air-filled ullage is obtained through the predetermined positioning of the terminal open end of the intercommunication tube inside the respective fuel tank module. The intentional air-filled ullage can be configured in all or in only some of the fuel tank modules according to the design of the auxiliary fuel tanks or aircraft structural loads requirements.
1. An aircraft fuel tank system comprising:
a series of multiple fuel tanks; and
intercommunication conduit assemblies fluid-connecting pairs of adjacent fuel tanks in the series to establish a cascade mode of fuel flow serially from one tank to another tank in the series of multiple fuel tanks, wherein the intercommunication conduit assemblies comprise:
(i) an external manifold conduit spanning a distance between an adjacent pair of the fuel tanks,
(ii) an inlet conduit connected to one end of the manifold conduit and extending within an interior of a first tank of the adjacent pair, and
(iii) a discharge conduit connected to an opposite end of the manifold conduit and extending within an interior of a second tank of the adjacent pair, and wherein
the inlet conduit has an open end which is separated from a top wall of the first tank by a predetermined distance to establish ullage volume within the first tank.
2. An aircraft fuel tank system as in claim 1 , wherein the predetermined distance in one of the fuel tanks in the series is equal to the predetermined distance in other fuel tanks in the series.
3. An aircraft fuel tank system as in claim 1 , wherein the predetermined distance in one of the fuel tanks in the series is different than the predetermined distance in other fuel tanks in the series.
4. An aircraft fuel tank system as in claim 1 , further comprising a vent conduit connected to a last tank in the series of fuel tanks for venting the fuel tanks.
5. An aircraft fuel system as in claim 1 , further comprising a transfer line fluid-connected to a first tank in the series of fuel tanks for transferring fuel from the fuel tanks.
6. An aircraft fuel system as in claim 1 , further comprising a refuel conduit fluid-connected to a first tank in the series of fuel tanks for refueling the fuel tanks.
7. An aircraft fuel system comprising:
a series of adjacent multiple fuel tanks each having an internal volume for holding fuel for the aircraft;
intercommunication conduit assemblies fluid-connecting pairs of adjacent fuel tanks in the series to establish a cascade mode of fuel flow serially from one tank to another tank in the series of multiple fuel tanks, wherein
the intercommunication conduit assemblies establish an air-filled ullage within the internal volume of at least one of the fuel tanks in the series to damp fuel column pressure within the fuel tank in response to a deceleration force and thereby prevent a fuel overpressure condition within the fuel tank,
wherein the intercommunication conduit assemblies comprise:
(i) an external manifold conduit spanning a distance between an adjacent pair of the fuel tanks,
(ii) an inlet conduit connected to one end of the manifold conduit and extending within an interior of a first tank of the adjacent pair, and
(iii) a discharge conduit connected to an opposite end of the manifold conduit and extending within an interior of a second tank of the adjacent pair, and wherein
the inlet conduit has an open end which is separated from a top wall of the first tank by a predetermined distance to establish ullage volume within the first tank.
8. An aircraft fuel tank system as in claim 7 , wherein the predetermined distance in one of the fuel tanks in the series is equal to the predetermined distance in other fuel tanks in the series.
9. An aircraft fuel tank system as in claim 7 , wherein the predetermined distance in one of the fuel tanks in the series is different than the predetermined distance in other fuel tanks in the series.
10. An aircraft fuel tank system as in claim 7 , further comprising a vent conduit connected to a last tank in the series of fuel tanks for venting the fuel tanks.
11. An aircraft fuel system as in claim 7 , further comprising a transfer line fluid-connected to a first tank in the series of fuel tanks for transferring fuel from the fuel tanks.
12. An aircraft fuel system as in claim 7 , further comprising a refuel conduit fluid-connected to a first tank in the series of fuel tanks for refueling the fuel tanks.
13. An aircraft which comprises an aircraft tank fuel system as in claim 1 or 7 .