method for determining the fuel consumption margin of an engine relative to a theoretical consumption

Abstract

The present invention relates to a method for determining a current fuel consumption margin of a functional engine (10) of an aircraft (1) relative to a theoretical fuel consumption of a reference engine (99). This method comprises: a) performing at least one engine health check in flight, including at least one measurement of a current value of a monitoring temperature and a control value of a power parameter of said functional engine (10); b) determining, based on at least the control value, with a consumption model applied by a controller (42), said current fuel consumption margin relative to the theoretical fuel consumption; c) transmitting said current fuel consumption margin to a receiver (43). Abstract figure: Figure 1

Description

Title of the invention: method for determining a fuel consumption margin of an engine compared to a theoretical consumption

[0001] The present invention relates to a method for determining a fuel consumption margin of an engine compared to a theoretical consumption.

[0002] The term “consumption” subsequently designates a fuel flow rate, such as a volume flow rate expressed for example in liters per second or a mass flow rate expressed for example in kilograms per second.

[0003] The invention is therefore in the technical field of vehicle power plants, in particular of an aircraft and more particularly of a rotorcraft.

[0004] Indeed, an aircraft is usually equipped with a power plant. For example, a rotary wing aircraft has a power plant provided with at least one engine in order to rotate a rotary wing. A helicopter is often equipped with at least one turboshaft engine, sometimes called a "gas turbine".

[0005] Furthermore, each engine is sized to be able to be used according to at least one operating regime, each operating regime associating a power developed with a duration of use. Among the known regimes, we can cite in particular:

[0006] - the take-off regime associating a maximum take-off power PMD with a duration of use of the order of five to ten minutes,

[0007] - the maximum continuous regime associating a maximum continuous power PMC with unlimited duration of use.

[0008] On a multi-engine aircraft, there are also emergency overpower regimes, these regimes being used when one of the engines fails. These overpower regimes may include:

[0009] - a first emergency regime associating a super emergency power OEI30' ' with a duration of use of around thirty seconds, usable two or three times,

[0010] - a second emergency regime associating a maximum emergency power OEI2' to a cumulative usage time of around two minutes,

[0011] - a third emergency regime associating an emergency intermediate power OEIcontinues to a duration of use covering the end of a flight for example.

[0012] At the same time, it is common to determine the number of flight hours that an aircraft engine can withstand before it needs to be overhauled. This number of flight hours is known by the acronym TBO or the expression "time between overhaul" in English.

[0013] Under these conditions, for each regime, a guaranteed minimum power is established. This guaranteed minimum power corresponds to the minimum power that the engine will be able to provide when it has reached the said number of flight hours TBO, such an engine being referred to as an “aged engine” for convenience in the remainder of the text.

[0014] The performance of an aircraft actually depends on the power that can be developed by each engine. However, the power developed by an engine tends to decrease over time. Therefore, to guarantee the required performance regardless of the age of the engines of an aircraft, the performance of an aircraft can be calculated on the basis of the guaranteed minimum powers while the performance of the aircraft could be evaluated upwards in the presence of new engines.

[0015] Among these performances, the theoretical fuel consumption of an engine is determined in particular on the basis of the consumption of a generic reference engine, with a given level of aging. For example, such a reference engine may correspond to a new engine capable of providing a guaranteed minimum power called "minimum new" or to an aged engine capable of providing a guaranteed minimum power called "minimum aged". The flight manual of an aircraft may thus provide a model giving the theoretical fuel consumption of the engine(s) as a function of the applied speed, this theoretical fuel consumption being equal to the consumption of the reference engine. Using this theoretical consumption, a pilot can then evaluate the quantity of fuel to be taken on board to carry out a mission, or can evaluate the distance that can be covered in the presence of a certain quantity of fuel and the on-board mass.

[0016] As this method is advantageously conservative, the theoretical fuel consumption is generally higher than the actual fuel consumption for a given engine. Indeed, a new engine tends to consume less fuel than an aged engine. Therefore, taking into account not actual but theoretical fuel consumption, when developing a flight plan, may tend, for example, to overestimate the volume of fuel to be carried. The excess fuel may limit the mass of the payload that can be carried.

[0017] Furthermore, certain certification regulations may require means to verify that each engine is capable of providing the guaranteed minimum powers allowing the aircraft to achieve the certified performances.

[0018] In order to verify that an engine is operating correctly, an engine health check is carried out to ensure that the engine is developing power greater than or equal to the minimum guaranteed power for a given speed. If so, the engine remains capable of providing the power required to achieve the certified performance. Conversely, unscheduled maintenance action must be undertaken.

[0019] For example, the health check may consist of measuring the current value of a monitoring parameter, then verifying that the value of the current power developed by the engine is greater than or equal to the value of the guaranteed minimum power that an aged engine would have in the presence of the same conditions, namely at the isovalue of the monitoring parameter.

[0020] The monitoring parameter may be an engine temperature, this temperature being able to be the temperature TET of the gases at the inlet of a high pressure turbine of a gas generator or the temperature T45 of the gases at the inlet of a free turbine of a turbo-engine.

[0021] The guaranteed minimum powers are usually established by testing an engine on a test bench. To compare the results of measurements made in flight with measurements made on a test bench, the in-flight measurement conditions can be optimized to be close to the measurement conditions on a test bench. The measurements made on a test bench are carried out under thermally stable conditions. Therefore, to carry out an engine health check in flight, the aircraft can be placed in a particular flight phase such as level flight at a stabilized altitude and speed for several minutes. The pilot can then initiate a manual action requiring the performance of an engine health check or such an engine health check can be carried out automatically when the required conditions are present.

[0022] Furthermore, to evaluate the current power developed by an engine, aircraft effects can be taken into consideration. Aircraft effects cause an increase in fuel consumption and power losses due, for example, to pressure losses in the engine air intakes or to pressure distortions. In addition, aircraft effects include power losses due to power taken from the engine by accessories and / or to the altitude of the aircraft and / or to the outside temperature in particular.

[0023] These aircraft effects tend to reduce the power developed by an output shaft of an engine once installed on an aircraft. The aircraft effects are then also called "aircraft losses" in reference to the loss of power encountered. Thus, a loss of power corresponding to the aircraft losses can be evaluated to determine the current power of the engine as such. The current power of the engine can thus be equal to the sum of the power loss and the power measured in flight developed by an output shaft of the engine installed on an aircraft.

[0024] Documents EP 262374 B1, EP 2623748 B1 and EP 3730410 B1 refer to engine health checks.

[0025] Document EP3123254 Bl is known, but far removed from the problem of deter- mination of the actual fuel consumption of an engine.

[0026] The present invention therefore aims to propose a method for determining a fuel consumption margin of an engine in relation to a theoretical fuel consumption, in particular in order to optimize a range or the payload that can be carried in the aircraft.

[0027] Thus, the invention aims at a method for determining a current fuel consumption margin of a functional engine of an aircraft compared to a theoretical fuel consumption of a reference engine.

[0028] This method comprises an evaluation phase comprising the following steps:

[0029] - carrying out in flight, during at least one aircraft parameterization flight, at least an engine health check comprising at least: i) measuring with a temperature sensor a current value of a monitoring temperature of the functional engine, and ii) determining with a power sensor a control value of a power parameter of said functional engine,

[0030] - determination based at least on the control value for the same value current operational engine monitoring temperature, with a consumption model applied by a controller, of said current fuel consumption margin compared to the theoretical fuel consumption, the theoretical fuel consumption being a reference engine fuel consumption determined according to said control value,

[0031] - transmission to a receiver of said fuel consumption margin current.

[0032] The term "functional engine" means an engine of the aircraft. The term "functional" is used to identify this engine, and not to confuse it with other engines.

[0033] The expression "reference engine" designates an engine of the same model as the functional engine, namely an engine identical to the functional engine. However, the reference model may have a service life substantially, or even strictly, equal to the service life that should lead to an overhaul, usually called TBO.

[0034] The controller designates a device on board the aircraft or remote from the aircraft to determine the current fuel consumption margin of an aircraft, compared to the theoretical fuel consumption of the reference engine.

[0035] According to this method, the controller receives the current value of a temperature of the functional engine at a predetermined location of this engine, this temperature being called "monitoring temperature". The controller also receives the control value of a power parameter of the functional engine. This power parameter can be a mechanical power, this mechanical power being able to be equal to the power developed by the engine possibly corrected by the addition of a predetermined power completed or calculated corresponding to aircraft effects. The controller deduces the fuel consumption margin of the functional engine compared to the reference engine for operation at iso-power margin at the monitoring temperature.

[0036] Indeed, the monitoring temperature has a direct impact on the fuel consumption of the engine, particularly for a turboshaft engine. To compare the operation of the functional engine and the reference engine, the controller compares the operation of this functional engine and this reference engine in the presence of the same monitoring temperature.

[0037] Furthermore, the fuel consumption of an engine and the power developed by this engine vary in a similar manner, particularly for a turboshaft engine. Therefore, a consumption model can be established. This consumption model makes it possible to obtain the fuel consumption margin of the functional engine compared to the reference engine. For example, a new engine may have a fuel consumption margin of the order of 2 to 6% of the theoretical fuel consumption measured on the reference engine.

[0038] Thus, a controller may, for example, use one or more previously performed engine health checks to assess the current fuel consumption margin of the functional engine. This controller then transmits a control signal carrying this current fuel consumption margin to a receiver. For example, such a receiver comprises a display showing the consumption margin following reception of the control signal. A pilot may then take this consumption margin into consideration in order to optimize the onboard fuel and / or the mass of the onboard payload.

[0039] In the presence of several functional engines within an aircraft, the method can be applied, for example, for each functional engine. The total fuel consumption of the installation then corresponds to the sum of the individual fuel consumptions of the functional engines. The method can further comprise one or more of the following characteristics.

[0040] According to one possibility, the functional engine and the reference engine may be identical turbine engines, namely identical models, each comprising a gas generator and at least one free turbine. The monitoring temperature may then be a gas temperature at the inlet of a high-pressure turbine of the gas generator of the associated engine or a gas temperature at the inlet of the free turbine of the associated engine.

[0041] According to a possibility compatible with the previous ones, the power parameter can be a mechanical power, said determination depending at least on the control value of a current fuel consumption margin comprising a de termination of an intermediate power margin between the control value and a guaranteed minimum power obtained with the reference engine having said monitoring temperature equal to the current value.

[0042] The power margin of an engine at iso-temperature monitoring is in fact correlated with fuel consumption. The use of the power margin at iso-temperature monitoring makes it possible to obtain a precise method for evaluating a fuel consumption margin. Indeed, the power developed by an engine can be determined precisely, or even more precisely than the measurement of a fuel flow rate with the flow meters on board aircraft for example.

[0043] Furthermore, such a guaranteed minimum power can advantageously take into account aircraft effects reducing the power developed by an output shaft of an engine once installed on an aircraft.

[0044] Optionally, said determination as a function at least of the control value of a current fuel consumption margin may then comprise: i) determination of a reference power margin equal to the intermediate power margin or to an average of several intermediate power margins evaluated during several engine health checks, ii) conversion of the reference power margin into the current fuel consumption margin by the controller with said consumption model.

[0045] Said average may, for example, be an arithmetic average taking into consideration the n previous engine health checks, n being a predetermined positive integer.

[0046] Depending on the desired accuracy, only the last engine health check or several health checks are used to evaluate the current power margin compared to the reference engine, and consequently the current fuel consumption margin.

[0047] Optionally, said consumption model can provide said current fuel consumption margin as a function of said reference power margin.

[0048] According to a possibility compatible with the previous ones, the method can comprise an initialization phase comprising a determination of said consumption model.

[0049] The initialization phase makes it possible to determine the consumption model used by the controller to convert a power margin into a fuel consumption margin.

[0050] According to a first alternative, the determination of said consumption model may comprise:

[0051] - a plurality of tests carried out on at least one test engine arranged on a bench of tests, each test including a determination of a power developed by the test engine at a test point as well as a fuel flow rate consumed by the test engine at the test point and a test value of the monitoring temperature at the test point,

[0052] - for each test, determination of a parameterization power margin and a parameter fuel consumption margin respectively in relation to a guaranteed minimum power at the test value of the monitoring temperature and a theoretical fuel consumption obtained with the reference engine in the presence of the power developed by the test engine, and

[0053] - determination of the consumption model as a function of the power margin of setting and fuel consumption margin of setting each test.

[0054] According to the first alternative, each test point makes it possible to determine the fuel consumption margin of the test engine, called the “parameterization power margin”, as a function of the power margin of the test engine, called the “parameterization power margin”. The measurement of a fuel flow rate on the bench is indeed reliable. Using the point cloud obtained, a computer, and for example the controller, can determine by a known method a law giving a fuel consumption margin as a function of the power margin. For example, a linear regression method makes it possible to determine an affine function giving a fuel consumption margin as a function of a power margin. The consumption model then takes the form of this affine function.

[0055] According to a second alternative, the determination of the consumption model can comprise:

[0056] - a plurality of tests performed on at least one flight test engine, each test including a determination of a power developed by the test engine at a test point as well as a fuel flow rate consumed by the test engine at the test point and a test value of the monitoring temperature at the test point,

[0057] - for each test, determination of a fuel flow rate corrected as a function of the flow rate of fuel consumed by the test engine at the test point and a correction model,

[0058] - for each test, determination of a parameterization power margin and a parameter fuel consumption margin respectively in relation to a guaranteed minimum power at the test value of the monitoring temperature and a theoretical fuel consumption obtained with the reference engine in the presence of the test value for the power developed by the test engine,

[0059] - determination of the consumption model as a function of the power margin of setting and fuel consumption margin of setting each test.

[0060] According to the second alternative, the tests are carried out in flight, and not on the test bench. The fuel flow measured in flight is then corrected using a correction model. This correction model can be established, for example, using a linear or polynomial regression method obtained from the precise fuel consumptions measured on the test bench with dedicated flow meters and simultaneously with a management system on board the aircraft generally designated by the expression in English “Full Authority Digital Engine Control” or by its acronym “FADEC”. Such a correction model thus makes it possible to characterize the estimation error of the FADEC compared to the calibrated flow meters of the test bench and can then be used in flight in order to improve the accuracy of the fuel flow measurements provided by the FADEC.

[0061] According to another aspect, the invention also relates to a method for refueling an aircraft to reach a destination, said method comprising developing a route comprising at least one flight segment.

[0062] This method of refueling an aircraft to reach a destination comprises the following steps:

[0063] - for at least said segment of the flight plan, determination of a margin of current fuel consumption by applying the method for determining a fuel consumption margin of an engine compared to a theoretical fuel consumption previously described, said at least one engine health check being carried out during a flight preceding said development of a route comprising at least one flight segment,

[0064] - determination of a theoretical fuel consumption during said segment of flight from the theoretical model established with said reference engine,

[0065] - determining a predicted fuel consumption comprising an ap application of the current fuel consumption margin to the theoretical fuel consumption,

[0066] - determination of a necessary quantity of fuel, namely a volume of fuel required or a mass of fuel required based on predicted fuel consumption,

[0067] - transmission of the necessary quantity of fuel.

[0068] The method may then comprise a step of filling the aircraft with fuel, said necessary quantity of fuel being placed in the aircraft before the start of the mission.

[0069] The expression "necessary quantity of fuel" means a quantity of fuel sufficient to ensure the planned flight.

[0070] Thus, this method makes it possible to determine the quantity of fuel sufficient to follow a route, for example to optimize the payload of the aircraft.

[0071] The invention also relates to an aircraft equipped with at least one functional engine. This aircraft comprises a planning system configured to apply the method for determining a current fuel consumption margin mentioned above, said planning system comprising said controller as well as said power sensor and said temperature sensor, said planning system having a receiver receiving said current fuel consumption margin determined by said controller.

[0072] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent:

[0073] [Fig.l], a view of an aircraft configured to apply the method for determining a current fuel consumption margin,

[0074] [Fig.2], a diagram illustrating the method of determining a current fuel consumption margin,

[0075] [Fig.3], a diagram illustrating a consumption model, and

[0076] [Fig.4], a diagram illustrating a method of refueling an aircraft according to the invention.

[0077] Elements present in several distinct figures are assigned a single reference.

[0078] [Fig.l] shows an aircraft 1 according to the invention. Such an aircraft 1 is provided with a power plant 2 comprising at least one functional engine 10. The functional engine(s) 10 each comprise a working shaft 11 connected to a mechanical chain 20. For example, this mechanical chain 20 comprises a rotor 22 participating at least in the lift and / or propulsion or traction of the aircraft 1. According to the example illustrated, at least one functional engine 10 comprises a shaft connected by a mechanical connection to a power transmission box 21, this power transmission box 21 being connected by another mechanical connection to a rotor 22.

[0079] According to another aspect, the functional engine(s) 10 may be turbo-engines. Such a turbo-engine then comprises a gas generator 12 provided with a compressor 13 comprising one or more compression stages, a combustion chamber 15 and at least one high-pressure turbine 14. The high-pressure turbine(s) 14 are connected by an internal shaft to the compressor 13. Following the gas generator 12 in the direction of circulation of the gases in the functional engine 10, the functional engine 10 comprises a free assembly provided with at least one free turbine 16 secured to the working shaft 11.

[0080] Furthermore, the performance of the aircraft is established on the basis of the performance of a reference engine 99 which is not installed on the aircraft 1. The engine functional engine 10 and the reference engine 99 have different performances, and in particular have different fuel flow rates due to their respective durations of use. At the same power level and under the same conditions, the fuel flow rate supplying the reference engine 99 is greater than or equal to the fuel flow rate supplying the potentially less used functional engine 10.

[0081] This aircraft 1 cooperates with a planning system 40 configured in particular to determine the actual fuel consumption of the functional engine 10 before a flight, this fuel consumption being called “current fuel consumption DQ” for convenience and representing a fuel flow rate supplied to the functional engine 10.

[0082] This planning system 40 comprises a temperature sensor 25 configured to measure a temperature in the functional engine 10, a power sensor configured to evaluate a power developed by the functional engine 10, and a controller 42 configured to determine the current fuel consumption by taking into consideration the measured temperature and the measured power.

[0083] The term “sensor” designates a sensor capable of directly measuring the parameter in question but also a system which may comprise one or more sensors as well as signal processing means making it possible to provide an estimate of the parameter in question from the measurements provided by this or these physical sensors.

[0084] [Fig.l] illustrates an example of aircraft architecture in order to illustrate the invention. Other known aircraft architectures can of course be used without departing from the scope of the invention.

[0085] Thus, the temperature sensor 25 can be a usual sensor arranged within the functional engine 10. The temperature sensor 25 emits a signal carrying a monitoring temperature TS within the functional engine 10.

[0086] The term “signal” designates in the description a digital or analog signal, optical or electrical for example.

[0087] The temperature sensor 25 can be positioned so as to measure a monitoring temperature of the “TET turbine inlet temperature” type, by being arranged at the inlet of the free assembly, or of the “T45 temperature” type, by being arranged at the inlet of a high pressure turbine 14.

[0088] Furthermore, the power sensor 30 may be a conventional sensor configured to measure a power image of a power developed by the functional engine 10. For example, the power sensor 30 comprises a speed sensor 31 and a torque meter 32 arranged on a measuring shaft set in motion by the low-pressure turbine(s) 16. For example, the measuring shaft may be the working shaft 11. The speed sensor 31 emits a speed signal carrying a rotation speed of the measuring shaft, and the torque meter 32 emits a torque signal carrying the torque exerted on the measuring shaft. A standard calculator can then determine the power developed by taking the product of the rotation speed and the measured torque, or even a proportionality coefficient, and possibly correcting this product with calculated or fixed aircraft losses.

[0089] Optionally, the planning system 40 may include a memory storing the signals emitted by the power sensor 30 and the temperature sensor 25, or the values ​​of the temperatures and powers measured or even decoded by a standard computer.

[0090] The controller 42 may be arranged in the aircraft 1 according to the example illustrated, or may be remote outside the aircraft 1. The controller 42 may receive the signal emitted by the temperature sensor 25 as well as the signal(s) emitted by the power sensor 30 in order to receive and decode them and deduce therefrom the measured monitoring temperature and power. Alternatively, the controller 42 may be connected to the memory 41, this memory 41 storing the measured monitoring temperature and power.

[0091] The controller 42 may have one or more processing units comprising, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression “processing unit”. The term processor may also designate a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc.

[0092] The controller 42 may be connected by a wired or wireless connection to a receiver 43. This receiver 43 may, for example, take the form of a display. The receiver 43 may be arranged inside or outside the aircraft 1.

[0093] The controller 42 may be connected by a wired or wireless link to a planner 45. The planner 45 may be arranged inside or outside the aircraft 1. This planner 45 may, for example, comprise a display and a human-machine interface making it possible to configure data in order to establish a route 46. Such a route 46 may comprise at least one flight segment 47 between two waypoints. For example, the configurable data comprise an arrival point to be joined with the aircraft 1, a departure point of the flight, one or more intermediate waypoints, etc.

[0094] Furthermore, the aircraft 1 and the planning system 40 are configured to apply the method PROC1 for determining a current fuel consumption margin DQ of the aircraft 1 illustrated in [Fig.2].

[0095] This method PROC1 for determining a current fuel consumption margin DQ may include an initialization phase PHASINI. This phase PHASINI initialization includes a STPINI determination of a consumption model.

[0096] According to a first alternative, the STPINI determination of a consumption model comprises a plurality of STPINI 1.1 tests carried out on at least one test engine 95 arranged on a test bench 96. Each test includes an STPINI 1.1a determination:

[0097] - of a PINI power developed by the test engine 95 at a test point, at know at a measurement time, by requesting a power sensor of the type described previously,

[0098] - of a fuel flow rate QINI consumed by the test engine 95 at the test point, in using a standard flow meter, and

[0099] - and a test value TINI of the monitoring temperature TS at the test point, by requesting a temperature sensor of the type described above.

[0100] For each test carried out, the determination STPINI of said consumption model comprises a determination STPINIl.lb, with a processing unit called “modeling calculator” for convenience, of a parameterization power margin DPINI and a parameterization fuel consumption margin DQINI respectively with respect to a guaranteed minimum power PMINI for the same test value TINI and a theoretical fuel consumption Qref obtained with the reference engine 99 in the presence of the test value TINI for the power measured at the monitoring temperature TS.

[0101] For illustration purposes, the test value relates to the temperature T45 and is equal to 900 degrees Celsius, the fuel flow rate QINI consumed is equal to 200 liters per hour and the power PINI is equal to 600 Kilowatts. The modeling computer can store a table or equivalent providing the guaranteed minimum power PMINI and the theoretical fuel consumption Qref as a function respectively of the monitoring temperature TS and the measured power, these data being established during tests on a reference engine 99. For example, for a temperature T45 of 900 degrees Celsius, the power Pmini is equal to 500 Kilowatts, and for a power PINI of 600 kW, the fuel flow rate Qref is equal to 210 liters per hour.Therefore, the DPINI setting power margin is equal to 600-500 or 100 Kilowatts and the DQINI setting fuel consumption margin is then 10 liters per hour or can be expressed as a percentage of the Qref fuel flow rate or 4.76%.

[0102] Therefore, the STPINI determination of said consumption model comprises a STPINI 1.1c determination of the consumption model as a function of the DPINI parameter power margin and the DQINI parameter fuel consumption margin of each test.

[0103] According to [Fig.3], each test point can be plotted in a diagram comprising a power margin DP on the abscissa and a fuel consumption margin DQ on the ordinate. According to the illustrated example, four tests are carried out. Therefore, four points Ptl-Pt4 are arranged in the diagram, each point having as coordinates the parameter power margin DPINI and the parameter fuel consumption margin DQINI determined during a test. The modeling computer can then, for example, establish the equation of a straight line 200 in the usual manner, typically by linear regression, this equation forming the consumption model.

[0104] According to a second alternative, the STPINI determination of the consumption model comprises a plurality of STPINI 1.2 tests carried out in flight on at least one test engine 95 arranged on an aircraft. Each test includes an STPINI 1.2a determination:

[0105] - of a PINI power developed by the test engine 95 at a test point, at know at a measurement time, by requesting a power sensor of the type described previously,

[0106] - of a fuel flow rate QINI consumed by the test engine 95 at the test point, in using a standard flow meter.

[0107] - and a test value TINI of the monitoring temperature TS at the test point, by requesting a temperature sensor of the type described above.

[0108] In addition, a processing unit called a "modeling calculator" for convenience performs a STP1.2b determination of a corrected fuel flow QCOR as a function of the fuel flow QINI consumed by the test engine 95 at the test point and a correction model. The correction model can be established by testing or simulation to adjust the fuel flow measured by the aircraft flow meter relative to a more accurate flow meter.

[0109] For each test carried out, the STPINI determination of said consumption model includes a STPINI1.2c determination, with a modeling calculator for example, of a DPINI parameter power margin compared to a guaranteed minimum power PMINI, and of a DQINI parameter fuel consumption margin between the corrected fuel flow QCOR and the theoretical fuel consumption Qref.

[0110] Therefore, the STPINI determination of said consumption model comprises a STPINI1.2d determination of the consumption model as a function of the DPINI parameter power margin and the DQINI parameter fuel consumption margin of each test. This step may be identical to the corresponding step of the first alternative.

[0111] Regardless of how the consumption model is established, the method PR0C1 for determining a current fuel consumption margin DQ includes a PHAS1 evaluation phase.

[0112] The evaluation phase PHAS1 comprises an STPCSM performance, in flight, namely when the aircraft 1 is not resting on a landing area, of at least one engine health check. This engine health check is carried out, for example in the usual manner, at monitoring iso-temperature TS. The engine health check can be carried out automatically or on command via the operation of a human-machine interface.

[0113] The engine health check(s) then comprise at least: i) the measurement with the temperature sensor 25 of a current value TCUR of the monitoring temperature TS of the functional engine 10, and the determination with the power sensor 30 of a control value PCUR of a power parameter P of the functional engine 10.

[0114] Before a flight, the evaluation phase includes the determination STPEVAL as a function at least of the control value PCUR, with the consumption model applied by the controller 42, of the current fuel consumption margin DQ of the functional engine 10 compared to its theoretical fuel consumption Qref, namely compared to the fuel consumption of the reference engine 99 at isopower at the monitoring temperature TS.

[0115] For example, the controller 42 determines during a step STPINT an intermediate power margin DPINT between the control value PCUR and the guaranteed minimum power PMINI obtained with the reference engine 99 at monitoring iso-temperature TS.

[0116] The controller 42 can determine during a step STPPW a reference power margin DPREF, equal depending on the variant to the intermediate power margin DPINT or to an average of several intermediate power margins DPINT evaluated during several previous CSM engine health checks. The controller 42 then converts, during a step STPCONV, the reference power margin DPREF into a current fuel consumption margin DQ with said consumption model. According to the example of [Fig.3], the reference power margin DPREF is injected for this purpose into the equation of the straight line determined during the initialization phase.

[0117] Finally, during a transmission step STPT, the controller 42 transmits a signal carrying the current fuel consumption margin DQ to the receiver 43. This receiver 43 can then, for example, display the current fuel consumption margin. A pilot can then adapt the fuel to be loaded into the aircraft 1 according to this margin.

[0118] [Fig.4] thus illustrates a PROC2 process for refueling the aircraft. 1 to reach a destination.

[0119] This method comprises an STPROUTE development of a route 46 comprising at least one flight segment 47, for example with the planner 45.

[0120] For at least one segment 47 of the flight plan, the controller 42 then determines the current fuel consumption margin DQ of the functional engine(s) 10 of the aircraft 1 by applying the method PROC1 for determining a current fuel consumption margin, using the data estimated during at least one engine health check CSM carried out during a previous flight.

[0121] The controller 42 or the planner 45 determines, during a step STPQTHEO, a theoretical fuel consumption Qref for this same flight segment 47 from a stored theoretical model of the reference engine 99.

[0122] The controller 42 or the planner 45 determines, during a step STPQPRED, a predicted fuel consumption QPRED by applying the current fuel consumption margin DQ to the theoretical fuel consumption Qref. For illustration purposes, the theoretical fuel consumption Qref is 150 liters per hour and the current fuel consumption margin determined is 3% of this theoretical fuel consumption Qref. Therefore, the predicted fuel consumption QPRED is 150 divided by 1.03, or 146.7 liters per hour.

[0123] Subsequently, the controller 42 or the planner 45 determines, during a step STPCARBU, a volume of fuel required or a mass of fuel required as a function of the predicted fuel consumption to reach the destination.

[0124] The controller 42 or the planner 45 transmits, for example to the receiver 43 or to another display, the volume of fuel required or the mass of fuel required.

[0125] Thus, the method may comprise a transmission STPINFO of the necessary quantity of receiver fuel 43 then a filling STPFUEL of the aircraft 1, namely of at least one tank, by storing in the aircraft 1 the necessary volume of fuel or the necessary mass of fuel.

[0126] Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims

Claims

1. Method (PROC1) for determining a current fuel consumption margin (DQ) of a functional engine (10) of an aircraft (1) relative to a theoretical fuel consumption (Qref) of a reference engine (99), characterized in that the method comprises an evaluation phase (PHAS1) comprising the following steps: - carrying out (STPCSM) in flight, during at least one parameterization flight of the aircraft, at least one engine health check comprising at least: i) measuring with a temperature sensor (25) a current value (TCUR) of a monitoring temperature (TS) of the functional engine (10), and ii) determining with a power sensor (30) a control value (PCUR) of a power parameter (P) of said functional engine (10), - determining (STPEVAL) as a function at least of the control value (PCUR) for the same current value (TCUR) of the monitoring temperature (TS) of the functional engine (10),with a consumption model applied by a controller (42), of said current fuel consumption margin (DQ) compared to the theoretical fuel consumption (Qref), the theoretical fuel consumption (Qref) being a fuel consumption of the reference engine (99) determined as a function of said control value (PCUR), - transmission (STPT) to a receiver (43) of said current fuel consumption margin (DQ).,

2. Method according to claim 1, characterized in that said functional engine (10) and said reference engine (99) being identical turboshaft engines each comprising a gas generator (12) and at least one free turbine (16), said monitoring temperature (TS) is a gas temperature at the inlet of a high pressure turbine (14) of the gas generator (12) of the associated engine or a gas temperature at the inlet of the free turbine (16) of the associated engine.

3. Method according to any one of claims 1 to 2, characterized in that the power parameter is a mechanical power, said determination (STPEVAL) as a function at least of the control value (PCUR) of a fuel consumption margin current (DQ) comprising a determination (STPINT) of an intermediate power margin (DPINT) between the control value (PCUR) and a guaranteed minimum power (PMINI) obtained with the reference engine (99) having said monitoring temperature (TS) equal to the current value (TCUR).

4. Method according to claim 3, characterized in that said determination (STPEVAL) as a function at least of the control value (PCUR) of a current fuel consumption margin (DQ) comprises: i) determination (STPPW) of a reference power margin (DPREF) equal to the intermediate power margin (DPINT) or to an average of several intermediate power margins (DPINT) evaluated during several engine health checks (CSM), ii) conversion (STPCONV) of the reference power margin (DPREF) into the current fuel consumption margin (DQ) by the controller (42) with said consumption model.

5. Method according to claim 4, characterized in that said consumption model provides said current fuel consumption margin (DQ) as a function of said reference power margin (DPREF).

6. Method according to any one of claims 1 to 5, characterized in that said method comprises an initialization phase (PHASINI) comprising a determination (STPINI) of said consumption model.

7. Method according to claim 6, characterized in that said determination (STPINI) of said consumption model comprises: - a plurality of tests (STPINI1.1) carried out on at least one test engine (95) arranged on a test bench (96), each test including a determination (STPINI 1.1a) of a power (PINI) developed by the test engine (95) at a test point as well as a fuel flow rate (QINI) consumed by the test engine (95) at the test point and a test value (TINI) of the monitoring temperature (TS) at the test point, - for each test, determination (STPINIl.lb) of a parameter power margin (DPINI) and a parameter fuel consumption margin (DQINI) respectively with respect to a guaranteed minimum power (PMINI) at said test value (TINI) of the monitoring temperature (TS) and a theoretical fuel consumption (Qref) obtained with the reference engine (99) in the presence of said power (PINI) developed by said test engine (95), - determination (STPINIl.lc) of the consumption model as a function of the parameter power margin (DPINI) and the parameter fuel consumption margin (DQINI) of each test.

8. Method according to claim 6, characterized in that said determination (STPINI1.2) of said consumption model comprises: - a plurality of tests (STPINI1.2.a) carried out on at least one test engine (95) in flight, each test including a determination (STP1.2.a) of a power (PINI) developed by the test engine (95) at a test point as well as a fuel flow rate (QINI) consumed by the test engine (95) at the test point and a test value (TINI) of the monitoring temperature (TS) at the test point, - for each test, determination (STP1.2.d) of a corrected fuel flow rate (QCOR) as a function of the fuel flow rate (QINI) consumed by the test engine (95) at the test point and a correction model, - for each test, determination (STPINI1.2.b) a parameter power margin (DPINI) and a parameter fuel consumption margin (DQINI) respectively with respect to a guaranteed minimum power (PMINI) at said test value (TINI) of the monitoring temperature (TS) and a theoretical fuel consumption (Qref) obtained with the reference engine (99) in the presence of said power (PINI) developed by said test engine (95), - determination (STP1.2.c) of the consumption model as a function of the parameter power margin (DPINI) and the parameter fuel consumption margin (DQINI) of each test.

9. Method (PROC2) for refueling an aircraft (1) to reach a destination, said method comprising a development (STPROUTE) of a route (46) comprising at least one flight segment (47), characterized in that the method for refueling an aircraft (1) to reach a destination comprises the following steps: - for at least said segment (47) of the flight plan, determination of a current fuel consumption margin (DQ) by applying the method (PROC1) according to any one of claims 1 to 8, said at least one engine health check being carried out during a flight preceding said development of a route comprising at least one flight segment, - determination (STPQTHEO) of a theoretical fuel consumption (Qref) during said flight segment (47) from a theoretical model established with said reference engine (99), - determination (STPQPRED) of a predicted fuel consumption (QPRED) comprising an application of the current fuel consumption margin (DQ) to the theoretical fuel consumption (Qref), - determination (STPCARBU) of a necessary quantity of fuel based on the predicted fuel consumption, - transmission (STPINFO) of the required quantity of fuel.

10. Aircraft (1) provided with at least one functional engine (10), characterized in that said aircraft (1) comprises a planning system (40) configured to apply the method for determining a current fuel consumption margin according to any one of claims 1 to 8, said planning system (40) comprising said controller (42) as well as said power sensor (30) and said temperature sensor (25), said planning system (40) having a receiver (43) receiving said current fuel consumption margin (DQ) determined by said controller (42).

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