Method for selecting activation logic of inerting system of aircraft fuel tank

Abstract

One aspect of the invention relates to a method (100) for selecting activation logic of an inerting system (3122) of at least one fuel tank of an aircraft (31) for at least one flight mission of the aircraft (31), the method (100) comprising the steps of:-sending (101) data relating to a preparation flight mission to a computer (32); -estimating (102), by the calculator (32), N flammability risks of the fuel comprised in the fuel tank, N being a non-zero natural number, each flammability risk being estimated as a function of:-a single activation logic of an inerting system selected from the N activation logics of the inerting system (3122); and-data relating to the preparation of a flight mission; -selecting (103) an activation logic from among the N activation logics as a function of the estimated N flammability risks and as a function of conditions relating to the inerting system (3122).

Description

Technical Field

[0001] The technical field of the present invention is the technical field to which the fuel tank inerting system of an aircraft belongs.

[0002] The present invention relates to a method for selecting the activation logic of an inerting system for an aircraft fuel tank. Background Art

[0003] The purpose of an inerting system is to ensure a volume containing vapors, the mixture of which with the active products (e.g., air) has a risk of flammability, by replacing the active products with a neutral gas, such as nitrogen or carbon dioxide.

[0004] In particular, an aircraft fuel tank inerting system (Fuel Tank Inerting System, called FTIS) is an automated system without pilot control, the purpose of which is to prevent the formation of a mixture of flammable fuel and vapors in these fuel tanks by preparing engine bleed air, then generating a neutral gas and introducing it into one or more fuel tanks.

[0005] Document EP3176093A1 relates to an aircraft fuel tank inerting system, which includes an inerting gas generator supplied with exhaust gas and means for distributing the inerting gas into one or more fuel tanks, the means being connected to the inerting gas generator and including a device for measuring the amount of oxygen present in the inerting gas. The prior art inerting gas generator includes at least one air separation module (Air Separation Module, ASM) for generating nitrogen from the supplied air.

[0006] However, the engine bleed air supplied to the inerting system is diverted from at least one turbofan engine of the aircraft, which thus results in a loss of compressed air, which can be used, for example, to drive the aircraft and to pressurize and condition the passenger cabin. In addition, the compressed air supplied to the inerting system is one of the causes of wear of the parts of the inerting system. The wear of some parts of the inerting system makes it impossible for the components to have a longer life than the life of the aircraft, which means / requires multiple maintenance operations during the life of the aircraft.

[0007] Therefore, it is necessary to reduce the consumption of air supplied to the inerting system and limit the wear on the parts of the inerting system. Summary of the Invention

[0008] The present invention provides a solution to the above problems by adjusting the operation and activation of the inerting system without compromising flight safety, while reducing air consumption and limiting the wear of the parts of the inerting system.

[0009] A first aspect of the present invention relates to a method for selecting an activation logic of an inerting system of at least one fuel tank of an aircraft for a flight mission of the aircraft, the method comprising the steps of:

[0010] - Sending data related to preparing for a flight mission to a calculator;

[0011] - Estimating N flammability risks of the fuel comprised in the fuel tank by the calculator, N being a non-zero natural number, each flammability risk being estimated based on:

[0012] o A single activation logic of the inerting system selected from N activation logics of the inerting system; and

[0013] o Data related to preparing for a flight mission;

[0014] - Selecting an activation logic from the N activation logics based on the estimated N flammability risks and based on conditions related to the inerting system.

[0015] "The activation logic of the inerting system" refers to a time graph representing the process of the operating state of the inerting system changing over time, wherein the inerting system can be in a so-called activated operating state for at least a part of the time, and / or can be in a so-called deactivated operating state for at least another part of the time. Therefore, the horizontal axis of the time graph represents time, while the vertical axis of the time graph represents two logical states of the operating state of the inerting system: a first state (so-called "activated" state), and a second state (so-called "deactivated" state). The part of the time during which the inerting system is in the activated operating state includes a plurality of non-necessarily continuous time periods, which are, for example, separated from the time periods during which the inerting system is in the deactivated state.

[0016] When the inerting system is in the so-called "activated" operating state, the electrical system transmits electrical power to the inerting system, and the inerting system can be supplied with air taken from the engine.

[0017] When the inerting system is in the so-called "deactivated" operating state, the electrical system is in an electrical standby state and does not transmit electrical power to the inerting system, and the inerting system is not supplied with air taken from the engine.

[0018] The time defining the activation logic is the flight mission time defined by the certification rules defined in the document AC25.981-2A, titled "FUEL TANK FLAMMABILITY REDUCTION MEANS", and its addenda, issued by the Federal Aviation Administration (FAA) of the United States on September 19, 2008. That is, the time elapsed from when the aircraft starts preparing for flight, then during the flight until all the aircraft payloads are unloaded and all passengers and crew members have disembarked after the flight lands. Thus, the flight mission includes: a first phase, where before the flight, the aircraft is on the ground and starts when the aircraft is ready for flight; a second phase, where the aircraft is in flight; and a third phase, where after the flight, the aircraft is on the ground again, and the third phase ends when all the payloads of the aircraft are unloaded and all passengers and crew members have disembarked. The first phase, the second phase, and the third phase are consecutive.

[0019] Figure 1 is an example of the activation logic.

[0020] "Flammability risk" refers to the ratio or percentage of the cumulative time during which the fuel in the fuel tank is flammable to the flight mission time, with the time expressed in minutes.

[0021] Advantageously, the selected activation logic enables the fuel tank inerting system to be fully or partially deactivated without compromising flight safety, as the flammability risk is taken into account during the selection. The selected activation logic also takes into account the conditions related to the inerting system.

[0022] In addition to the characteristics just discussed in the previous paragraphs, the method according to one aspect of the present invention may also have one or more of the following additional characteristics (these additional characteristics are considered individually or in any technically possible combination):

[0023] - The flammability risk estimated according to the selected activation logic is less than or equal to the reference flammability risk estimated according to the reference activation logic. Advantageously, if the reference activation logic is, for example, the activation logic where the inerting system is activated throughout the flight mission time, the protection against fuel flammability achieved by the selected activation logic is equivalent to the protection achieved when the inerting system is activated throughout the flight mission time. Thus, the present invention can avoid generating inert gas when there is no flammability risk for the fuel.

[0024] - The flight mission includes a phase where the aircraft is in flight, and the data related to the flight mission of preparing the aircraft includes at least one of the following data:

[0025] ​o Type of aircraft;

[0026] o Mass of fuel included in the fuel tank of the aircraft before flight;

[0027] o Temperature of the fuel included in the fuel tank of the aircraft before flight;

[0028] o Flight destination;

[0029] o Flight profile, which includes at least one of the following data:

[0030] · Geographical location of the aircraft during flight;

[0031] · Altitude of the aircraft during flight;

[0032] · Airspeed or Mach number during flight;

[0033] - Each of the N flammability risks is also estimated based on meteorological data. Advantageously, the data related to the preparation of the flight mission is combined with the meteorological data, in particular by means of the meteorological data, to accurately estimate each flammability risk. The meteorological data enables the temperature throughout the flight mission to be known, especially the temperature in the flight profile, rather than just the temperature at a single moment t, so as to plan the activation logic in advance. Thus, for example, it is possible to activate the inerting system at some geographical locations with very low temperatures without causing a flammability risk of the fuel.

[0034] - Each flammability risk of the fuel included in the fuel tank is also estimated based on the flash point of the fuel included in the fuel tank. The flash point of the fuel is the temperature at which the fuel included in the fuel tank emits enough flammable gas to form a gas mixture that can be ignited by a flame with the ambient air.

[0035] - Advantageously, knowing the flash point enables a more accurate flammability risk to be obtained.

[0036] - N is between 2 and 10. As a reminder, N is the number of activation logics included in the N activation logics, and one logic is selected from the N activation logics according to several conditions.

[0037] - Each activation logic is a time graph representing the operating state of the inerting system over time during the flight mission, where the inerting system can be in a so-called activated operating state during at least a part of the flight mission and / or can be in a so-called deactivated operating state during at least another part of the flight mission.

[0038] - The conditions related to the inerting system at least involve:

[0039] o Energy consumption of the inerting system;

[0040] o Wear of at least one part of the inerting system;

[0041] o Supply air pressure of the inerting system.

[0042] Advantageously, the conditions associated with the inerting system enable the acquisition of activation logic according to a criterion desired by the operator. When the conditions associated with the inerting system relate to the energy consumption of the inerting system, the selected activation logic enables, for example, reducing the air consumption / energy consumption and reusing the hot air saved when deactivating the inerting system to generate propulsion.

[0043] A second aspect of the invention relates to a method for activating an inerting system of a fuel tank of an aircraft, the method comprising the following steps:

[0044] - Sending to the aircraft the activation logic selected by the selection method according to the first aspect of the invention;

[0045] - Activating the inerting system according to the selected activation logic.

[0046] Advantageously, the method according to the second aspect of the invention enables the activation of the inerting system according to the selected activation logic.

[0047] Another aspect of the invention relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to implement the method according to the first aspect of the invention.

[0048] Another aspect of the invention relates to a computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to implement the method according to the first aspect of the invention.

[0049] The invention and its different applications will be better understood on reading the following description and on consulting the drawings. Description of the Drawings

[0050] The drawings are illustrated by way of indication and in no way limit the invention.

[0051] Figure 1 shows an example of the activation logic of an aircraft fuel tank inerting system.

[0052] Figure 2 shows a schematic diagram of a system configured to implement the method for selecting activation logic according to the first aspect of the invention and the method for activating an inerting system according to the second aspect of the invention.

[0053] ​​​Figure 3 Block diagram of a method for selecting an activation logic of an inerting system according to a first aspect of the present invention.

[0054] Figure 4 Example of an activation logic of an aircraft fuel tank inerting system when selecting an activation logic according to a condition related to the supply pressure of the inerting system.

[0055] Figure 5 Block diagram of a method for activating an inerting system according to a second aspect of the present invention.

[0056] Figure 6 Example of an embodiment of a method for selecting an activation logic and a method for activating an inerting system. Detailed Description of the Invention

[0057] The accompanying drawings are illustrative by way of indication and in no way limit the present invention.

[0058] Figure 2 Shows system 30, which includes aircraft 31 and calculator 32.

[0059] For example, aircraft 31 is an airplane or a helicopter.

[0060] Aircraft 31 includes at least one avionics system 311.

[0061] According to one embodiment, avionics system 311 is configured to allow a pilot to prepare a flight mission of aircraft 31 and generate data related to preparing the flight mission. In this embodiment, avionics system 311 is further configured to establish a two-way exchange channel with the calculator and send data related to preparing the flight mission to calculator 32.

[0062] The two-way exchange channel between avionics system 311 and calculator 32 is preferably secure and capable of using one or more communication technologies in the prior art, especially at least one of the following communication technologies:

[0063] - Radio communication network, such as a radio beam.

[0064] - Communication standard.

[0065] - Internet network via different mobile phone standards, such as the 3rd generation mobile communication technology (3G), the 4th generation mobile communication technology (4G), and / or the 5th generation mobile communication technology (5G).

[0066] - Wired communication network.

[0067] - Satellite antenna.​​​​

[0068] According to another embodiment, the aircraft 31 includes a portable electronic device (not shown) that can communicate with the avionics system 311 of the aircraft 31 and is configured to allow a pilot to prepare a flight mission. The portable electronic device is also referred to as a portable electronic flight mission preparation device.

[0069] The portable electronic device preferably includes a network interface (which includes an antenna), a memory, and a processor, such as a microprocessor. The portable electronic device also includes one or more means for acquiring and displaying data, such as a touch screen.

[0070] For example, the portable electronic device is a tablet computer.

[0071] The portable electronic device can be included in the avionics system 311 or located outside the avionics system 311.

[0072] When the portable electronic device is located outside the avionics system 311, the portable electronic device is configured to send data related to preparing a flight mission to the avionics system 311, and then the avionics system can transmit this data to the calculator 32; alternatively, the portable electronic device is also configured to directly send data related to preparing a flight mission to the calculator 32 via a two-way exchange channel. In this case, similar to that described for the avionics system, the two-way exchange channel between the portable electronic device and the calculator 32 is preferably secure and can use one or more communication technologies in the prior art, especially at least one of the following communication technologies:

[0073] - A radio communication network, such as a radio beam.

[0074] - Communication standards.

[0075] - An Internet network via different mobile phone standards, such as 3G, 4G, and / or 5G.

[0076] - A wired communication network.

[0077] - A satellite antenna.

[0078] The aircraft also includes an electrical system 312 and a fuel system 313.

[0079] The fuel system 313 includes at least one fuel tank ( Figure 1 (not shown in the figure) and a fuel tank inerting system 3131.

[0080] The electrical system 312 is configured to receive data sent by the avionics system 311 and send electrical power to the inerting system.

[0081] The calculator 32 includes a network interface (which includes an antenna, not shown), a memory, and a processor, which is a microprocessor for example.

[0082] The calculator 32 is preferably a computer.

[0083] According to one embodiment, the system includes a plurality of calculators, and the plurality of calculators form a computing center. Hereinafter, the calculator 32 and the computing center are the same.

[0084] One aspect of the present invention relates to a method for selecting an activation logic of an inerting system 3131 of a fuel tank of an aircraft 31 for at least one flight mission of the aircraft 31.

[0085] Figure 3 is a block diagram showing the steps in this method 100.

[0086] The method 100 includes a first step 101: sending data related to preparing for a flight mission to the calculator 32.

[0087] The flight mission includes a phase during which the aircraft is in flight (previously defined as the second phase). The data related to preparing the flight mission of the aircraft 31 preferably includes at least one of the following data: the type of the aircraft 31 that will perform the flight; the mass of the fuel included in the fuel tank of the aircraft 31 before the flight; the temperature of the fuel included in the fuel tank of the aircraft 31 before the flight; the profile of the flight.

[0088] For example, the data related to preparing for a flight mission may also include the geographical location of the aircraft throughout the flight mission.

[0089] The flight profile may include at least one of the following data: the geographical location of the aircraft 31 during the flight; the altitude of the aircraft 31 during the flight; the airspeed and Mach number during the flight.

[0090] In addition, the calculator 32 downloads meteorological data from an external database that can be queried by the calculator 32. The meteorological data is preferably averaged or accumulated using two time scales (per minute and per hour).

[0091] The downloaded meteorological data preferably includes at least one of the following data: air temperature; wind speed; total solar radiation.

[0092] ​The meteorological data relates to the 12 hours to 24 hours after the start of the flight mission. For example, for each position of the aircraft during the flight mission, the meteorological data includes the temperature change process from 12 hours to 24 hours at each position of the aircraft.

[0093] Method 100 further includes step 102: estimating N flammability risks of the fuel included in the fuel tank by calculator 32.

[0094] Each flammability risk is estimated based on: a single activation logic of the inerting system selected from the N activation logics of the inerting system; data related to preparing for the flight mission; and meteorological data.

[0095] The flammability of the fuel is evaluated every minute during the flight mission.

[0096] Fuel is considered flammable when it releases vapor within a temperature range (e.g., there is a risk of ignition when the vapor contacts air).

[0097] Fuel is flammable when its temperature is between the Lower Flammability Limit (LFL) temperature and the Upper Flammability Limit (UFL) temperature. The LFL temperature ensures that the mixture of fuel vapor and air has extremely low flammability, while the UFL temperature ensures that the mixture of fuel vapor and air has extremely high flammability.

[0098] N is a non - zero natural number. For example, N can be between 2 and 10. Preferably, N is between 5 and 10.

[0099] The N activation logics are preferably stored in the memory of calculator 32.

[0100] According to one embodiment, each flammability risk is also estimated based on the flash point of the fuel loaded in the fuel tank. The flash point of the fuel is the temperature at which the fuel in the fuel tank emits enough flammable gas to form a gas mixture that can be ignited by a flame with the ambient air.

[0101] For example, for fuel of the AVGAS type, the flash point can be: - 40 ± 10 °C; for fuel of the JET A - 1 type, the flash point can be: + 38 ± 12 °C.

[0102] Preferably, each flammability risk is estimated by means of certified software that is stored in the memory of calculator 32 or accessed by calculator 32 via a network and executed by the processor of calculator 32.

[0103] It is advantageous to use certification software to estimate each flammability risk, as the certification software ensures that each flammability risk is evaluated according to certified safety methods and aircraft-specific criteria.

[0104] The method further includes a fourth step 103: selecting activation logic from the N activation logics according to the estimated N flammability risks and according to conditions related to the inerting system.

[0105] The step 103 of selecting activation logic is preferably performed by so-called optimization software, which is stored in the memory of the calculator 32 or accessed by the calculator 32 via a network and executed by the processor of the calculator 32.

[0106] Preferably, the optimization software receives each activation logic among the N activation logics, each flammability risk among the N flammability risks, and conditions related to the inerting system as inputs, and selects the following activation logic: the activation logic such that the estimated flammability risk is less than or equal to a reference flammability risk estimated according to a reference activation logic.

[0107] Preferably, the reference flammability risk is estimated according to the reference activation logic and data related to the preparation of the flight mission.

[0108] Preferably, the reference activation logic is the activation logic for aircraft certification from a certification organization (such as the Federal Aviation Administration (FAA) of the United States or the European Union Aviation Safety Agency (EASA)).

[0109] Preferably, the reference activation logic is the following activation logic: during this activation logic, the inerting system is in an activated operating state throughout the flight mission time, that is, it is activated regardless of flight mission conditions, such as meteorological conditions and flight mission preparation. In this embodiment, it is possible to estimate a flammability risk less than or equal to the reference flammability risk, because according to data related to the preparation of the flight mission, the fuel in the fuel tank is non-flammable throughout the flight mission time. In fact, when the inerting system is activated during a period when the fuel is non-flammable, reducing the oxygen concentration by increasing the concentration of inert gas with the help of the inerting system does not bring an additional reduction in flammability risk, and the inerting system does not provide additional protection for the fuel tank.

[0110] The conditions related to the inerting system can at least involve: the energy consumption of the inerting system; the wear of at least one part of the inerting system; the supply pressure of the inerting system; or a combination of at least two of the mentioned elements.

[0111] The energy consumption refers, for example, to the amount of air supplied to the inerting system.

[0112] For example, if the inerting system condition relates to the energy consumption of the inerting system, then the condition can be to minimize the energy consumption of the inerting system. The determination software can determine the activation logic of the inerting system from N activation logics, the flammability risk estimated according to this activation logic is less than or equal to the reference flammability risk, and the minimum energy consumption of the inerting system can be obtained. Preferably, minimizing the energy consumption of the inerting system corresponds to minimizing the activation time of the inerting system, that is, the time during which the inerting system is in the so-called activation operation state during the flight mission time. Therefore, the determination software estimates the activation time of the inerting system 3122 for each of the N activation logics and determines the following activation logic among the N activation logics: the flammability risk estimated according to this activation logic is less than or equal to the reference flammability risk, and the activation time of the inerting system is the minimum.

[0113] For example, if the condition related to the inerting system involves the wear of at least one part of the inerting system, then the condition can be to minimize the wear of this part. This part is, for example, a filter or a membrane included in the inerting system.

[0114] The wear of the part can be estimated according to the duration of exposure of the part to ozone at high altitude; for example, the condition related to the inerting system can be to minimize the activation time of the inerting system at high altitude in order to reduce the time the inerting system is exposed to ozone.

[0115] When the aircraft is on the ground or close to the ground, the wear of the part can be estimated according to the duration of exposure of the part to pollution; for example, the condition related to the inerting system can be to minimize the activation time of the inerting system on the ground in order to reduce the duration of exposure of the part to pollution.

[0116] According to an embodiment where the condition related to the inerting system involves the supply pressure of the parts of the inerting system, the condition can be to minimize the supply pressure of the inerting system. In this embodiment, each activation logic is a schematic diagram representing the process of the supply pressure of the inerting system changing with time, where the inerting system can be in a first (so-called) activation operation state or a second (so-called) activation operation state during at least a part of the time, and / or can be in a so-called deactivation operation state during at least another part of the time. The first activation state is the state where the supply pressure is equal to the engine pressure; the second activation state is the state where the supply pressure is equal to a part of the engine pressure. Figure 4 is an example of the activation logic of the inerting system according to this embodiment. Therefore, the horizontal axis of the activation logic represents time, and the vertical axis of the activation logic represents the supply pressure of the inerting system. For example, the unit of the supply pressure is bar or Pascal. The supply pressure of the inerting system can take three values, for example: Pengine, k*Pengine (at Figure 3Denoted as kPengine) and 0, where k is a real factor between 0 and 1. When the supply pressure is equal to Pengine, the inerting system is in the first activation state; when the supply pressure is equal to kPengine, the inerting system is in the second activation state; when the supply pressure is equal to 0, the inerting system is in the deactivation state.

[0117] Let P be the supply pressure of the inerting system and t be the time defined by the activation logic.

[0118] In this embodiment, the selected activation logic is as follows: for this activation logic, the estimated flammability risk is less than or equal to the reference flammability risk, and the activation time of the inerting system is minimized and the integral value is minimized.

[0119] Another aspect of the present invention relates to a method for activating an inerting system 3131 of a fuel tank of an aircraft 31.

[0120] Figure 5 is a block diagram showing the steps of the activation method 200.

[0121] The method 200 for activating the inerting system includes a first step 201: sending, by a calculator 32, the activation logic determined by the method 100 for determining the activation logic of the inerting system 3122 to the aircraft 31 (in particular, the avionics system of the aircraft 31).

[0122] The activation method 200 may include a step 202: sending the determined activation logic from the avionics system 311 to the electrical system 3121.

[0123] The activation method 200 further includes a step 203: activating the inerting system 3122 according to the determined activation logic. The step 203 of activating the inerting system 3122 is performed by means of the electrical system 3121, which is configured to transmit electric power to the inerting system according to the determined activation logic.

[0124] Figure 6 is Figure 4 the embodiment of the activation logic selection method 100 and Figure 5 the activation method 200 shown for a planned aircraft flight.

[0125] Referring to Figure 6 , the reference numeral 10 corresponds to the preparation work of the flight mission performed by the pilot on / in the avionics system or via a portable electronic device communicating with the avionics system.

[0126] Referring to Figure 6 , the reference numeral 11 corresponds to the destination to be reached, and the reference numeral 12 corresponds to the type of the aircraft.​​

[0127] Refer to Figure 6 , reference numeral 13 corresponds to data corresponding to the planned flight: the planned flight, in particular the time of the flight, the position of the aircraft during the flight, and waypoints (waypoints correspond to points of flight or turning points and are points on the route specified to be reached in navigation, at which the course should be changed).

[0128] Refer to Figure 6 , reference numeral 14 corresponds to the amount of fuel on the aircraft.

[0129] Refer to Figure 6 , reference numeral 15 corresponds to flight mission preparation.

[0130] Refer to Figure 6 , reference numeral 311 corresponds to the avionics system.

[0131] Refer to Figure 6 , reference numeral (1) corresponds to an embodiment of the transmission of flight mission preparation from a portable electronic device to the avionics system 311.

[0132] Refer to Figure 6 , reference numeral (2) corresponds to an embodiment of the transmission of flight mission preparation from a portable electronic device to both the avionics system 311 and the calculator 32.

[0133] Refer to Figure 6 , reference numeral 16 corresponds to the transmission of flight mission preparation to the calculator 32.

[0134] Refer to Figure 6 , reference numeral 32 corresponds to the calculator.

[0135] Refer to Figure 6 , reference numeral 32-(1) corresponds to the world weather forecast for less than 24 hours.

[0136] Refer to Figure 6 , reference numeral 32-(2) corresponds to the weather forecast for the flight.

[0137] Refer to Figure 6 , reference numeral 32-(3) corresponds to the simulation run.

[0138] Refer to Figure 6 , reference numeral 32-(4) corresponds to the estimation of the flammability risk of the fuel vapor of the aircraft by the authentication software according to the first activation logic among N activation logics.

[0139] Refer to Figure 6, reference numeral 32-(5) corresponds to the estimate of the flammability risk of the fuel vapor of the aircraft by the certification software according to the second activation logic among the N activation logics.

[0140] Refer to Figure 6 , reference numeral 32-(6) corresponds to the estimate of the flammability risk of the fuel vapor of the aircraft by the certification software according to the Nth activation logic among the N activation logics. (In Figure 6 , for clarity, only the estimates of the flammability risks calculated according to the first activation logic, the second activation logic, and the Nth activation logic are shown respectively in Figure 6 , however, in this embodiment, N flammability risks are estimated according to the N activation logics, but not shown).

[0141] Refer to Figure 6 , reference numeral 32-(7) corresponds to the optimization software selecting an activation logic among the N activation logics, and this activation logic is selected according to the certification: for example, the selected activation logic is calculated according to the following flammability risk: this flammability risk is less than or equal to enabling the calculation of the reference activation logic and also enabling the reduction of the flammability risk of using the inerting system.

[0142] Refer to Figure 6 , reference numeral 32-(8) corresponds to sending the selected activation logic to the aircraft.

[0143] Refer to Figure 6 , reference numeral 311 corresponds to the avionics system of the aircraft that receives the selected activation logic.

[0144] Simulations were carried out using known flash point values and unknown flash point values estimated by the certification software. For a given aircraft, these simulations show that:

[0145] - When the accuracy of the known flash point is 1 °C, the inerting system can be deactivated during 56% of the flights performed by the aircraft. Thus, the activation logic determined for 56% of the flights only includes the deactivation operating state of the inerting system during the flight mission time.

[0146] - When the accuracy of the known flash point is 4 °C, the inerting system can be deactivated during 45% of the flights performed by the aircraft. Thus, the activation logic determined for 45% of the flights only includes the deactivation operating state of the inerting system during the flight mission time.

[0147] - When the flash point is unknown (taking into account typical production dispersion), the inerting system can be deactivated during 16% of the flights performed by the aircraft. Therefore, the activation logic determined for 16% of the flights only includes the deactivation operating state of the inerting system during the flight mission time.

Claims

1. A method (100) for selecting activation logic of an inerting system (3122) of at least one fuel tank of an aircraft (31) for a flight mission of the aircraft (31), the method (100) comprises the following steps: - Sending (101) data related to preparing the flight mission to a calculator (32); - Estimating (102) N flammability risks of the fuel comprised in the fuel tank by the calculator (32), N being a non-zero natural number, each flammability risk being estimated based on: o A single activation logic of the inerting system selected from N activation logics of the inerting system; and o Data related to preparing the flight mission; - Selecting (103) activation logic from the N activation logics according to the estimated N flammability risks and according to conditions related to the inerting system (3122).

2. The method (100) according to the preceding claim, characterized in that The flammability risk estimated according to the selected activation logic is less than or equal to a reference flammability risk estimated according to a reference activation logic.

3. The method (100) according to the preceding claim, characterized in that The flight mission includes a phase during which the aircraft is in flight, and the data related to preparing the flight mission of the aircraft (31) includes at least one of the following data: - The type of the aircraft (31); - The mass of the fuel comprised in the fuel tank of the aircraft (31) before flight; - The temperature of the fuel comprised in the fuel tank of the aircraft (31) before flight; - The flight destination; - The flight profile, the flight profile including at least one of the following data: o The geographical location of the aircraft (31) during flight; o The altitude of the aircraft (31) during flight; o The airspeed or Mach number during flight.

4. The method (100) according to any one of the preceding claims, characterized in that Each of the N flammability risks is further estimated based on meteorological data.

5. The method (100) according to the preceding claim, characterized in that Each flammability risk of the fuel comprised in the fuel tank is further estimated based on the flash point of the fuel comprised in the fuel tank, the flash point of the fuel being the temperature at which the fuel comprised in the fuel tank emits sufficient flammable gas to form a gas mixture ignitable by a flame with ambient air.

6. The method (100) according to any one of the preceding claims, characterized in that Each activation logic is a time graph representing the operating state of the inerting system varying with time during the flight mission, wherein the inerting system can be in a so-called activated operating state during at least a part of the flight mission, and / or can be in a so-called deactivated operating state during at least another part of the flight mission.

7. The method (100) according to any one of the preceding claims, characterized in that The conditions related to the inerting system (3122) at least relate to: - the energy consumption of the inerting system (3122); - the wear of at least one part of the inerting system (3122); - the supply air pressure of the inerting system (3122).

8. A method (200) for activating an inerting system of a fuel tank of an aircraft (31), the method (200) comprises the following steps: - sending (201) the activation logic selected by the selection method (100) according to any one of claims 1 to 8 to the aircraft (31); - activating (203) the inerting system (3122) according to the selected activation logic.

9. A computer program product, the computer program product comprising instructions which, when executed by a computer, cause the computer to implement the method according to any one of claims 1 to 8.

10. A computer-readable recording medium, the computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to implement the method according to any one of claims 1 to 8.

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