Method of operating an aircraft fuel management system

A method, comprising:

• operating an aircraft during a first temporal period, the aircraft including an aircraft fuel management system, the aircraft having at least one fuel tank and at least one engine;
• during operation of the aircraft during the first temporal period, automatically indicating with respective fuel quantity indicators respective amounts of fuel in respective fuel tanks of the aircraft;
• during a second temporal period subsequent to the first temporal period, during which at least one of the fuel quantity indicators has failed, automatically operating the aircraft fuel management system by:
• calculating, by a processor, a value for the amount of fuel on board (FOB_FailedFQI) the aircraft to be utilised by the fuel management system, the amount of fuel on board being calculated as a value for the initial amount of fuel on board (FOBinit) minus the amount of fuel used, wherein the value for the initial amount of fuel on board (FOBinit) is automatically determined at the time when all the aircraft engines are running as the sum of an assigned value of fuel for each fuel tank having an associated failed fuel quantity indicator plus the sum of fuel in each of the remaining fuel tanks provided by each associated fuel quantity indicator, wherein the assigned value is automatically set to zero.

A method, comprising;

• operating an air vehicle, wherein the air vehicle includes at least one engine, the action of operating the air vehicle including running all engines of the aircraft;
• and
• executing the following method while operating the air vehicle with all engines running:
• automatically operating an air vehicle fuel management system of the air vehicle, wherein the air vehicle has at least one fuel tank, each fuel tank having an associated fuel quantity indicator arranged to provide an indication of the amount of fuel in the associated fuel tank, the method comprising calculating, by a processor, a value for the amount of fuel on board (FOB_FailedFQI) the air vehicle to be utilised by the fuel management system in the event of a failure of at least one of the fuel quantity indicators, the amount of fuel on board being calculated as a value for the initial amount of fuel on board (FOBinit) minus the amount of fuel used, wherein the value for the initial amount of fuel on board (FOBinit) is determined at the time when all the air vehicle engines are running as the sum of an assigned value of fuel for each fuel tank having an associated failed fuel quantity indicator plus the sum of fuel in each of the remaining fuel tanks provided by each associated fuel quantity indicator, wherein the assigned value is automatically set equal to the amount of fuel in another fuel tank in the system that has a working fuel quantity indicator.

A method, comprising;

• operating an air vehicle, wherein the air vehicle includes at least one engine, the action of operating the air vehicle including running all engines of the aircraft;
• and
• executing the following method while operating the air vehicle with all engines running:
• operating an air vehicle fuel management system of the air vehicle, wherein the air vehicle has at least one fuel tank, each fuel tank having an associated fuel quantity indicator arranged to provide an indication of the amount of fuel in the associated fuel tank, the method comprising calculating, by a processor, a value for the gross weight centre of gravity of the air vehicle to be utilised by the fuel management system in the event of a failure of at least one of the fuel quantity indicators, the calculation using an assigned value of fuel in each fuel tank having an associated failed fuel quantity indicator, wherein the assigned value is automatically set equal to the amount of fuel in another fuel tank in the system that has a working fuel quantity indicator.

A method of automatically operating an aircraft fuel management system for an aircraft having at least one fuel tank, each fuel tank having an associated fuel quantity indicator arranged to provide an indication of the amount of fuel in the associated fuel tank, the method comprising calculating, by a processor, a value for the amount of fuel on board (FOB_FailedFQI) the aircraft to be utilised by the fuel management system in the event of a failure of at least one of the fuel quantity indicators, the amount of fuel on board being calculated as a value for the initial amount of fuel on board (FOBinit) minus the amount of fuel used, wherein the value for the initial amount of fuel on board (FOBinit) is determined at the time when all the aircraft engines are running as the sum of an assigned value of fuel for each fuel tank having an associated failed fuel quantity indicator plus the sum of fuel in each of the remaining fuel tanks provided by each associated fuel quantity indicator, wherein the assigned value is automatically set equal to the amount of fuel in another fuel tank in the system that has a working fuel quantity indicator, wherein the method further comprises:

• operating the aircraft during a first temporal period in which the respective amounts of fuel in respective fuel tanks are indicated by respective fuel quantity indicators;
• and
• operating the aircraft during a second temporal period subsequent to the first temporal period, during which at least one of the fuel quantity indicators has failed, wherein
• the action of calculating a value for the amount of fuel on board and the action of determining the value for the initial amount of fuel on board occur during the second temporal period during which at least one of the fuel quantity indicators has failed.

A method of automatically operating an aircraft fuel management system for an aircraft having at least one fuel tank, each fuel tank having an associated fuel quantity indicator arranged to provide an indication of the amount of fuel in the associated fuel tank, the method comprising calculating, by a processor, a value for the gross weight centre of gravity of the aircraft to be utilised by the fuel management system in the event of a failure of at least one of the fuel quantity indicators, the calculation using an assigned value of fuel in each fuel tank having an associated failed fuel quantity indicator, wherein the assigned value is automatically set equal to the amount of fuel in another fuel tank in the system that has a working fuel quantity indicator, wherein the method further comprises:

• operating the aircraft during a first temporal period in which the respective amounts of fuel in respective fuel tanks are indicated by respective fuel quantity indicators;
• and
• operating the aircraft during a second temporal period subsequent to the first temporal period, during which at least one of the fuel quantity indicators has failed, wherein
• the action of calculating a value for the amount of fuel on board and the action of determining the value for the initial amount of fuel on board occur during the second temporal period during which at least one of the fuel quantity indicators has failed.