METHOD FOR CONTROLLING THE LEVEL OF INTERNAL SOILING IN AN AIRCRAFT ENGINE AND SYSTEM EXECUTING THE METHOD.

Abstract

The invention relates to a system for controlling the level of soiling of an aircraft engine (1) comprising electronic circuitry configured for obtaining first information (EOC), representative of the operating conditions of said engine, and for obtaining second information (EIP), representative of internal operating parameters of said engine, the system further comprising electronic circuitry configured to perform a determination of expected performance (2) of said engine, from said first information and a pre-established engine performance model; a determination of current performance (S1) of said engine, from said first and second information; a determination of an engine performance index (S3) from said expected performance and said current performance;and the generation of a warning signal (S5) when said performance index is greater than or equal to (S4) a predefined threshold value. Thus, it is advantageously possible to reduce the operating and maintenance costs of the aircraft. Fig. 1;

Description

Title of the invention: METHOD FOR CONTROLLING THE LEVEL OF INTERNAL SOILING IN AN AIRCRAFT ENGINE AND SYSTEM EXECUTING THE METHOD. technical field

[0001] The present invention relates to a method for monitoring the internal fouling level of an aircraft engine. More particularly, the invention relates to a method for determining the internal fouling level of an aircraft engine by comparing current engine performance with normally expected engine performance defined according to a pre-established engine performance model. The invention further relates to a control system configured for implementing the method. PRIOR TECHNOLOGY

[0002] Turbojet aircraft engines encounter numerous polluting particles in the air they ingest during operation. These particles can be diverse, such as soot, grease, fine particles, and all kinds of pollutants.

[0003] Such particles progressively foul the inlet elements of a turbojet engine, such as the fan and all the compression elements (compression stage). The fouling then leads to increasing surface roughness of the elements present as well as a modification of their aerodynamic profiles, which results in a degradation of the turbojet engine's performance by progressively limiting the airflow and reducing the isentropic efficiency of the turbojet's compression stage.

[0004] Fortunately, this type of engine fouling is reversible, and cleaning can be carried out during maintenance to restore performance identical to that achieved in the absence of fouling. Therefore, cleanings are planned and scheduled at regular intervals, which are determined, for example, by the number of flight cycles or flight hours.

[0005] However, fouling is not regular and it may happen that the level of soiling is relatively reduced during a planned cleaning operation, or conversely that the level of soiling is significant, so that this substantially affects the performance of the engine which then operates with overconsumption of fuel and an abnormally high operating temperature, which is likely to increase operating costs and maintenance costs.

[0006] The situation can be improved. Description of the invention

[0007] An object of the present invention is to provide a method for generating an alert when the level of internal soiling (or fouling) of an engine reaches a predetermined threshold level, so that the cleaning operation can then be carried out, in good correlation with the level of soiling, which makes it possible to improve the operating and maintenance costs of the aircraft.

[0008] To this end, a system for monitoring the internal soiling level of an aircraft engine is proposed, the system comprising electronic circuitry configured to obtain first information, representative of engine operating conditions, and second information, representative of internal engine operating parameters, the control system being such that it further comprises electronic circuitry configured to perform:

[0009] - a determination of expected engine performance, based on the first information and a pre-established engine performance model,

[0010] - a determination of current engine performance, from the first and second piece of information,

[0011] - a determination of an engine performance index from the performance expected values ​​determined and current performance determined,

[0012] - generating an alert signal when the determined performance index is greater than or equal to a predefined threshold value.

[0013] The system according to the invention may further include the optional features considered in isolation or in combination:

[0014] - The system for controlling the internal fouling level of an aircraft engine It also includes electronic circuitry configured to implement the pre-established engine performance model using a neural network module previously trained on the first and second pieces of information obtained.

[0015] - The system for controlling the internal fouling level of an aircraft engine is configured so that the first information obtained includes at least:

[0016] - shaft speed information from a low-pressure stage of said motor,

[0017] - information on the total temperature of the incoming airflow of said engine,

[0018] - information on the total pressure of the incoming airflow of said engine,

[0019] - speed information for said aircraft,

[0020] - status information for an aircraft air bleed valve,

[0021] - status information of an aircraft wing anti-icing valve,

[0022] - status information of an aircraft engine nacelle anti-icing valve.

[0023] - The system for controlling the internal fouling level of an aircraft engine is configured so that the second set of information includes at least:

[0024] - shaft speed information of a high-pressure stage of said motor,

[0025] - outlet airflow temperature information from a compression stage low pressure of said engine,

[0026] - outlet airflow temperature information from a compression stage high pressure of said engine,

[0027] - outlet airflow pressure information from a high compression stage pressure of said engine,

[0028] - exhaust gas temperature information for said engine,

[0029] - information on the fuel flow rate supplying said engine.

[0030] - The system for controlling the internal fouling level of an aircraft engine is configured to determine the performance index from said expected performance, said current performance, and a calculated value of a variation in isentropic compression efficiency since the last wash of said engine.

[0031] - The performance index determined by the system uses calculated values ​​of isentropic efficiency of the compression stage of the aircraft engine from said expected performance and said actual performance.

[0032] - The system for controlling the internal fouling level of an aircraft engine includes electronic circuitry configured to calculate the isentropic efficiency value according to the formula [TT / (T30-TT)] x [(P30 / PT) ((Yl) / Y) — 1], where:

[0033] - TT is a total temperature of the incoming airflow of said engine,

[0034] - PT is a total incoming airflow pressure of said engine,

[0035] - T30 is an outlet temperature of a high-pressure compression stage of said engine,

[0036] - P30 is an outlet pressure of the high-pressure compression stage of the engine,

[0037] - Y is an adiabatic coefficient of the incoming air.

[0038] - The system for controlling the internal fouling level of an aircraft engine includes electronic circuitry configured to obtain first and second information during an aircraft takeoff phase.

[0039] The invention also relates to a ground station or an aircraft comprising at least one system for controlling the internal soiling level of an engine as previously described.

[0040] Another object of the invention is a method for monitoring the level of internal soiling of an aircraft engine, the method comprising obtaining first information, representative of the operating conditions of said engine, and obtaining second information, representative of the internal operating parameters of said engine, the method being such that it further comprises:

[0041] - a determination of expected engine performance, based on the first information and a pre-established engine performance model,

[0042] - a determination of current engine performance, from the first and second piece of information,

[0043] - a determination of an engine performance index from the performance expected and current performance

[0044] - generating an alert signal when the determined performance index is greater than or equal to a predefined threshold value.

[0045] The method for controlling the internal fouling level of an aircraft engine according to the invention may include the following additional features, considered alone or in combination:

[0046] - The pre-established engine performance model used by the system is implemented thanks to a neural network module previously trained on the first and second pieces of information.

[0047] - The method for controlling the level of internal soiling of an aircraft engine is such as the initial information includes at least:

[0048] - shaft speed information from a low-pressure stage of said motor,

[0049] - total temperature information of the incoming airflow of said engine,

[0050] - information on the total pressure of the incoming airflow of said engine,

[0051] - speed information for said aircraft,

[0052] - status information from an aircraft air bleed valve,

[0053] - status information of a wing anti-icing valve of said aircraft,

[0054] - status information of an anti-icing valve of the engine nacelle of said aircraft.

[0055] - The method for controlling the level of internal soiling of an aircraft engine is such that the second set of information includes at least:

[0056] - shaft speed information from a high-pressure stage of said motor,

[0057] - outlet airflow temperature information from a compression stage low pressure of said engine,

[0058] - outlet airflow temperature information from a compression stage high pressure of said engine,

[0059] - outlet airflow pressure information from a high compression stage pressure of said engine,

[0060] - exhaust gas temperature information for said engine,

[0061] - information on the fuel flow rate supplying said engine.

[0062] - The performance index used according to the process is determined from said expected performance, said current performance, and a calculated value of a variation in isentropic compression efficiency since the last washing of said engine.

[0063] - The calculated value of isentropic yield used according to the process is calculated according to the formula [TT / (T30-TT)] x [(P30 / PT) ((Yl) / Y) - 1], where:

[0064] - TT is a total temperature of the incoming airflow of said compression stage,

[0065] - PT is a total pressure of the incoming airflow to said compression stage,

[0066] - T30 is an outlet temperature of a high-pressure compression stage of said engine,

[0067] - P30 is an outlet pressure of said high-pressure compression stage of said engine,

[0068] - Y is an adiabatic coefficient of the incoming air.

[0069] - The first and second pieces of information used according to the method are obtained during the aircraft's takeoff phase.

[0070] The invention further relates to a computer program product comprising program code instructions to execute the steps of the process as described, when this program is executed by a processor of an internal engine fouling level control system of an aircraft engine, as well as a storage medium comprising such a computer program product. Brief description of the drawings

[0071] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings:

[0072] [Fig-1] illustrates a system for controlling the internal soiling level of an engine aircraft arranged in a ground station, according to an embodiment;

[0073] [Fig.2] illustrates input and output signals of a module comprising a neural network used in operating mode of the system already represented on [Fig.1];

[0074] [Fig.3] is a flowchart illustrating a method for controlling the level of internal soiling of an aircraft engine carried out in the system already shown in [Fig.1], according to one embodiment;

[0075] [Fig.4] schematically illustrates an example of the internal architecture of a device controlling the internal soiling level of an aircraft engine of the system shown in [Fig.1], according to one embodiment; and,

[0076] [Fig.5] illustrates an aircraft comprising a system for controlling the internal soiling level of an aircraft engine according to one embodiment.

[0077] DETAILED STATEMENT OF IMPROVEMENTS

[0078] Figure 1 schematically represents a system 10 for controlling the internal fouling level of a turbojet aircraft engine, according to one embodiment. According to a preferred embodiment, the system 10 for controlling the internal fouling level of a turbojet aircraft engine is arranged in ground, for example in a ground station receiving information from one or more aircraft and performing monitoring and control operations related to maintenance (corrective or preventive) of that aircraft or those aircraft. According to one embodiment, the system 10 is installed on board an aircraft and controls at least one engine of the aircraft on which it is installed.

[0079] The system 10 is connected, via data transmission channels, to an aircraft flight data acquisition module (ACMS) 12, also commonly referred to as ACMS, from the English acronym "Aircraft Condition Monitoring System." In one embodiment, the ACMS 12 flight data acquisition module is further connected to a plurality of sensors, receivers, and other aircraft devices (not shown in the figure), making it possible to know the status of a large number of aircraft components at any given time, useful for detailed monitoring of the aircraft's operational flight and functioning conditions. In one embodiment, the connection between the ACMS 12 module and the various sensors is made via wired means.Furthermore, when the system 10 is located on the ground, the communication bus(es) connecting the system 10 to the ACMS 12 include or are wireless transmission channels, such as telecommunication channels configured to carry out data transmissions between the aircraft and the ground station. When the system 10 is located in the aircraft, the bus(es) connecting the system 10 and the ACMS 12 are arranged within the aircraft and may be wired. The connection(s) used to link the ACMS 12 and the system 10, including any telecommunication means, are not described herein further, as the details of their implementation are not necessary for understanding the invention.The information measured, calculated, or received by the ACMS 12 flight data acquisition module is diverse and includes, in particular, primary EOC (Engine Operating Conditions) data representing the operating conditions of each engine and secondary EIP (Engine Internal Parameters) data representing the internal operating parameters of each aircraft engine. In one embodiment, this information is transmitted to an EPM 14 (Engine Performance Monitoring) engine performance modeling module comprising an internal neural network (NN) pre-trained using the primary EOC and secondary EIP data during a learning and validation phase prior to its use in operational mode.According to one embodiment, the learning phase of the EPM 14 engine performance modeling module is carried out using EOC and EIP information obtained during takeoff phases of the aircraft concerned or of an aircraft of the same type exhibiting the . The two engines share the same technical characteristics and therefore essentially the same performance. In one variant, the learning phase of the EPM 14 engine performance modeling module is performed using EOC and EIP data obtained in the laboratory or at a maintenance site, from a clean engine. In a second variant, the learning phase is performed during a climb or cruise flight, for example. According to the implementation described in [Fig. 1], the NN neural network of the EPM 14 engine performance modeling module is already trained and is then used in a so-called operational mode. Thus, the engine performance model used, implemented using the NN neural network, is a pre-established model.The EPM 14 engine performance modeling module operating in operating mode is therefore capable of providing EIP information from the EPM 14 module, representative of internal operating parameters of an aircraft engine, from EOC information representative of operating conditions of that same aircraft engine using a pre-established engine performance model prepared and implemented during a learning phase.The first EOC information, delivered by the ACMS 12 module, is carried by communication links which together form a communication bus (or link) 13 between the ACMS 12 flight data acquisition module and the EPM 14 engine performance modeling module on the one hand and a HIM 16 engine performance index determination module on the other hand, and the second EIP information delivered by the EPM 14 engine performance modeling module is carried by communication links which together form a communication bus (or link) 15' between the EPM 14 engine performance modeling module and the HIM 16 engine performance index determination module.In addition, EIP information not modeled but delivered by the ACMS flight data acquisition module 12 is carried by communication links which together form a communication bus (or link) 15 between the ACMS flight data acquisition module 12 and the HIM performance index determination module 16.The HIM 16 performance index determination module is indeed configured to receive second EIP information generated by the EPM 14 engine performance modeling module used in operating mode on the one hand (via the communication bus or link 15'), and first EOP information and second EIP information generated by the ACMS 12 flight data acquisition module on the other hand (via buses or links 13 and 15 respectively), for the purpose of generating or not an alert signal 17 accessible to other systems of the ground station or aircraft, as appropriate, including in particular a fault signaling module or status indicators of various elements or systems of the ground station. or aircraft. According to one embodiment, the engine performance modeling modules EPM 14 and HIM 16 are implemented in entities physically separate from the ground station or aircraft which includes the control system 10. According to a preferred embodiment, these modules 14 and 16 are implemented in the same controller device 100 represented by dashed lines in [Fig. 1].

[0080] The described arrangement advantageously allows the HIM performance index determination module 16 to be able to establish or not an assertion of the warning signal 17 from representative information of modeled engine performance on the one hand, from the engine performance modeling module (implemented by the NN neural network) EPM 14 and from the first EOP information and second EIP information available delivered by the ACMS flight data acquisition module 12.In other words, the engine performance modeling module EPM 14 is configured to perform a determination of expected engine performance from the first EOP information delivered by the flight data acquisition module ACMS 12 and a pre-established engine performance model, the pre-established model being established from the first EOC information and the second EIP information, while the flight data acquisition module ACMS 12 is configured to deliver representative current performance information of the engine in question from its input information, and to transmit it to the performance index determination module HIM 16 in the form of the first EOC information and the second EIP information.Thus, the HIM 16 performance index determination module is able to determine an engine performance index based on expected engine performance according to the pre-established engine performance model and actual (observed / measured) performance, and to generate, if necessary, a warning signal when this engine performance index is greater than or equal to a predefined threshold value. In one embodiment, the predefined threshold value of the engine performance index is fixed and stored in a non-volatile memory of the control system 10. In another variant, the predefined threshold value of the engine performance index is variable and can be updated in memory according to current maintenance procedures.

[0081] According to one embodiment, the first EOP information (representative of engine operating conditions) delivered by the ACMS 12 flight data acquisition module includes at least: - EOC1 shaft speed information for a low-pressure stage of the engine in question, - EOC2 information regarding the total temperature of the incoming airflow from the engine in question, - EOC3 information regarding the total incoming airflow pressure of the engine in question, - EOC4 aircraft speed information, - EOC 5 status information from an air bleed valve the aircraft, - EOC6 status information for an aircraft wing anti-icing valve, - EOC7 status information for an engine nacelle anti-icing valve of the aircraft,

[0082] and,

[0083] the second EIP information (representing internal engine operating parameters) delivered by the ACMS 12 flight data acquisition module includes at least: - EIP1 information regarding the shaft speed of a high-pressure stage of the motor in question, - EIP2 information regarding the outlet airflow temperature of a low-pressure compression stage of said engine, - EIP3 information regarding the outlet airflow temperature of a high-pressure compression stage of said engine, - EIP4 information regarding the outlet airflow pressure of a high-pressure compression stage of said engine, - EIP5 information regarding the exhaust gas temperature of said engine, - EIP6 information on fuel flow supplying said engine.

[0084] According to one embodiment, the HIM 16 performance index determination module is configured to determine the performance index from said expected performance, said current performance and a calculated value of the variation in isentropic compression efficiency since the last wash of said engine.

[0085] According to one embodiment, the module for determining a performance index

[0086] HIM 16 is configured to determine said isentropic yield value according to the formula qisen = [TT / (T30-TT)] x [(P30 / PT) ((Yl) / Y) - 1]

[0087] where: • Hisen is the calculated value of the isentropic efficiency of the compression stage of the engine in question, • TT is the total temperature of the incoming airflow to a compression stage of the engine in question,

[0088]

[0089]

[0090]

[0091]

[0092] • PT is the total pressure of the incoming airflow from the aforementioned compression stage, • T30 is an outlet temperature of a high-pressure compression stage of the engine in question, • P30 is an outlet pressure of a high-pressure compression stage of the engine in question, and • Y is an adiabatic coefficient of the incoming air. According to one embodiment, the HIM 16 performance index determination module is configured to determine the HI engine performance indicator according to the formula: HI = A. after a wash - A. during the last flights carried out 'isen ° 'isen Or : An. = n. -n. isen 'isen measure * tseri model - ^isen measurement is an isentropic yield value calculated from information obtained from the ACMS 12 flight data acquisition module, - The isen model is an isentropic yield value calculated from second EIP information delivered by the EPM 14 engine performance modeling module. Figure 2 illustrates the EPM 14 motor performance modeling module used in operational mode (as opposed to training / validation mode). To be used in operational mode, the EPM 14 motor performance modeling module, which includes an NN neural network, must be pre-trained using first and second inputs so that it then implements the pre-established motor performance model during its operation in operational mode.In other words, during a learning phase, EOC information representing the operating conditions of the motor in question is applied as input to the NN neural network, and EIP information representing the internal parameters of the operating motor is applied as output to the NN neural network, according to the principles of deep learning. A validation phase is then performed to validate the learning phase itself. Thus, when EOC information representing the motor's operating conditions is applied as input to the EPM 14 motor performance modeling module used in operational mode (or more precisely, when its internal NN neural network is used in operational mode), the module delivers EIP information representing the corresponding motor parameters. to nominal engine operating performance without fouling, which information can be processed and "compared" to current information from the ACMS 12 flight data acquisition module.

[0093] Fig. 3 is a flowchart illustrating steps of a process for controlling the internal fouling level of an aircraft engine carried out in the system 10 for controlling the internal fouling level of an engine, already illustrated in Fig. 1.

[0094] A step S0 includes initialization and configuration operations of the set of systems present aimed at obtaining a nominal state defined as a normally operational configuration of the system 10 for controlling an internal soiling level of an engine, and more generally of all the elements involved in carrying out the process.

[0095] Thus, at the end of step S0, it is considered that the NN neural network of the EPM 14 module has been validly trained and that the training phase has been validated, so that the NN neural network is ready to be used in operational mode.

[0096] During an SI step, the controller device 100 of the control system 10 obtains the first EOP information and the second EIP information delivered by the ACMS flight data acquisition module 12, enabling the establishment of a "measured" engine performance profile, since all the information used comes from the ACMS flight data acquisition module 12.

[0097] During a step S2, the controller device 100 of the control system 10 obtains first information delivered by the flight data acquisition module ACMS 12 and processes second information EIP delivered by the engine performance modeling module EPM 14, thus making it possible to determine a modeled engine performance profile using the neural network NN which implements the pre-established engine performance model.

[0098] It should be noted that steps SI and S2 can be carried out successively in any order or in parallel with each other.

[0099] Then, during a step S3, the controller device 100 calculates different values ​​of isentropic efficiency from the first EOC information and the second EIP information, namely the current isentropic efficiency, the modeled isentropic efficiency, so as to be able to determine the performance index HI during the step S3 and then to compare, during a step S4, this determined performance index HI with a threshold value of engine performance index.

[0100] In the event that the determined value of the HI index is greater than or equal to said engine performance index threshold value during the comparison in step S4, then the output signal 17 of the controller device 100 is set to its active value (signal assertion) during a step S5 and a maintenance operation aimed at The engine fouling removal process will be carried out as soon as the aircraft is available for maintenance. Otherwise, if the performance index HI is below the predefined threshold value during the comparison in step S4, the process loops back to step SI.

[0101] The [Fig.4] is a diagram illustrating an example of the internal architecture of the controller device 100 of the system 10 for controlling an internal soiling level of an engine, according to one embodiment.

[0102] According to the hardware architecture example shown in [Fig.4], the controller device 100 of an internal engine soiling level then comprises, connected by a communication bus 1000: a processor or CPU (Central Processing Unit) 101; a RAM (Random Access Memory) 102; a ROM (Read Only Memory) 103; a storage unit such as a hard disk drive (or a storage media reader, such as an SD card reader (Secure Digital) 104); at least one interface module 105 allowing the controller device 100 of the internal engine soiling level to interact with devices present in a control circuit 10, such as, for example, the ACMS flight data acquisition module 12.Advantageously, the INTER 105 interface module includes, in particular, input / output ports, digital-to-analog converter inputs and analog-to-digital converter inputs, pulse-width modulation controlled outputs, and more generally all types of interfaces, including power interfaces, particularly useful for capturing or obtaining signals or data from the various aircraft systems and in particular from the ACMS 12 flight data acquisition module. In particular, the INTER 105 interface module of the controller device 100 is configured to operate, in particular, functions for obtaining first EOC information and obtaining second EIP information, via communication buses or via telecommunication links.

[0103] The processor 101 is capable of executing instructions loaded into RAM 102 from ROM 103, external memory (not shown), storage media (such as an SD card), or a communication network. When the controller device 100 of the control system 10 for an internal engine soiling level is powered on, the processor 101 is capable of reading program code instructions from RAM 102 and executing them. These instructions form a computer program causing the processor 101 to implement all or part of a method described in relation to [Fig. 3], or all or part of the described variants of that method.

[0104] All or part of the method described in relation to [Fig. 3], or its described variants, can be implemented in software form by executing a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor) or a microcontroller, or implemented in hardware form by a dedicated machine or component, for example a FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). In general, the internal soiling level control device 100 of an engine comprises electronic circuitry configured to implement the methods described in relation to the system 10 or the control device 100.Obviously, the controller device 100 of an internal engine soiling level also includes all the elements usually present in a system comprising a control unit and its peripherals, such as, a power supply circuit, a power supply monitoring circuit, one or more clock circuits, a reset circuit, related input / output ports, interrupt inputs, bus drivers, this list being non-exhaustive.

[0105] Advantageously, the modeling and rendering of modeled engine performance can be implemented using techniques based on neural networks trained on information representative of an engine's operation during a learning and validation phase. In one embodiment, the learning phase is carried out when the engine's level of soiling is zero or negligible, for example, after a cleaning operation during maintenance.

[0106] According to one embodiment, the internal neural network NN of the controller 100 comprises a software or hardware implementation of a deep artificial neural network or an ANN (Artificial Neural Network). Such an ANN module can consist of a set of numerous artificial neurons organized in successive layers connected to each other. Such an ANN module is classically inspired by a simplified model of the functioning of a human brain where numerous biological neurons are connected to each other by axons.

[0107] The NN neural network is trained in a learning mode, which is followed by a validation phase, before it can be used in an operating mode as is the case according to a preferred embodiment.

[0108] According to a preferred embodiment, the control system 10 is arranged on the ground, for example in a ground station. However, [Fig. 5] illustrates an aircraft 1 configured according to an alternative embodiment and advantageously comprising the internal fouling level control circuit 10 of at least one aircraft engine, which includes the internal fouling level controller device 100 of an engine as previously described.

[0109] The use of system 10 advantageously provides an alert when the internal soiling level of an engine exceeds a predetermined threshold level, so that a maintenance operation is carried out in good correlation with the actual internal soiling level of the engine, or at least in better correlation with the actual internal soiling level of the engine.

Claims

Demands

1. A control system (10) for the internal fouling level of an aircraft engine (1), said control system (10) comprising electronic circuitry configured for obtaining first information (EOC), representative of the operating conditions of said engine, and for obtaining second information (EIP), representative of the internal operating parameters of said engine, the control system being such that it further comprises electronic circuitry configured to perform: - a determination of the current performance (SI) of said engine, from said first and second information, - a determination of the expected performance (S2) of said engine, from said first information and a pre-established engine performance model, - a determination of an engine performance index (S3) from said expected performance and said current performance,- the generation of a warning signal (S5) when said performance index is greater than or equal to (S4) a predefined threshold value, characterized in that the control system (10) of an internal soiling level of an aircraft engine is configured to determine said performance index from said expected performance, said current performance and a calculated value of the variation in isentropic compression efficiency since the last washing of said engine.

2. Control system (10) of an internal soiling level of an aircraft engine (1) according to claim 1, further comprising electronic circuitry (14) configured to implement said pre-established engine performance model by means of a neural network (NN) module trained from said first information and said second information obtained.

3. A system for monitoring the internal fouling level of an aircraft engine according to any one of claims 1 and 2, wherein said first information obtained comprises:

4.

5. - shaft speed information from a low-pressure stage of said motor, - information on the total temperature of the incoming airflow of said engine, - information on the total pressure of the incoming airflow of said engine, - information regarding the speed of said aircraft, - status information from an aircraft air bleed valve, - status information from a wing anti-icing valve of said aircraft, - status information of an anti-icing valve of the engine nacelle of said aircraft. A system for monitoring the internal fouling level of an aircraft engine according to any one of claims 1 to 3, wherein said second information comprises: - shaft speed information from a high-pressure stage of said engine, - temperature information for the outlet airflow of a low-pressure compression stage of said engine, - temperature information for the outlet airflow of a high-pressure compression stage of said engine, - information on the outlet airflow pressure of a high-pressure compression stage of said engine, - exhaust gas temperature information for said engine, - information on the fuel flow rate supplying said engine. System for controlling the internal fouling level of an aircraft engine according to any one of claims 1 to 4, comprising electronic circuitry configured to calculate said isentropic efficiency value according to the formula [TT / (T30-TT)] x [(P30 / PT) ((Yl) / Y) - 1], where: - TT is the total temperature of the incoming airflow of said compression stage, - PT is the total pressure of the incoming airflow of said compression stage, - T30 is an outlet temperature of a high-pressure compression stage of said engine, - P30 is an outlet pressure of said high-pressure compression stage of said engine, - Y is an adiabatic coefficient of the incoming air.

6. System for controlling the internal fouling level of an aircraft engine according to any one of claims 1 to 5, comprising electronic circuitry configured to obtain said first and second information during a takeoff phase of said aircraft.

7. Aircraft (1) comprising at least one system for controlling an internal engine fouling level according to any one of claims 1 to 6.

8. A method for controlling the internal fouling level of an aircraft engine, said method comprising obtaining first information, representative of the operating conditions of said engine, and obtaining second information, representative of the internal operating parameters of said engine, the method being such that it further comprises: - a determination of the current performance (SI) of said engine, from said first and second information, - a determination of the expected performance (S2) of said engine, from said first information and a pre-established engine performance model, - a determination of an engine performance index (S3) from said expected performance and said current performance,- the generation of a warning signal (S5) when said performance index is greater than or equal to (S4) a predefined threshold value, characterized in that said performance index is determined from said expected performance, said current performance and a calculated value of the variation in isentropic compression efficiency since the last washing of said engine.

9. A method for controlling the internal fouling level of an aircraft engine according to claim 8, wherein said pre-established engine performance model is implemented by means of a network of neurons trained from the aforementioned first pieces of information and the aforementioned second pieces of information.

10. A method for controlling the internal fouling level of an aircraft engine according to any one of claims 8 and 9, wherein said first information comprises: - shaft speed information of a low-pressure stage of said engine, - total inlet airflow temperature information of said engine, - total inlet airflow pressure information of said engine, - speed information of said aircraft, - status information of an air bleed valve of the aircraft, - status information of a wing anti-icing valve of said aircraft, - status information of an engine nacelle anti-icing valve of said aircraft.

11. A method for controlling the internal fouling level of an aircraft engine according to any one of claims 8 to 10, wherein said first information comprises: - shaft speed information of a high-pressure stage of said engine, - outlet airflow temperature information of a low-pressure compression stage of said engine, - outlet airflow temperature information of a high-pressure compression stage of said engine, - outlet airflow pressure information of a high-pressure compression stage of said engine, - exhaust gas temperature information of said engine, - fuel flow information supplying said engine.

12. A method for controlling the internal fouling level of an aircraft engine according to any one of claims 8 to 11, wherein said calculated value of isentropic efficiency is calculated according to the formula [TT / (T30-TT)] x [(P30 / PT)0 l, / n- 1], where:

13.

14.

15. - TT is the total temperature of the incoming airflow of said compression stage, - PT is the total pressure of the incoming airflow of said compression stage, - T30 is an outlet temperature of a stage of high-pressure compression of said engine - P30 is an outlet pressure of said compression stage high pressure of said engine, - Y is an adiabatic coefficient of the incoming air. Method of checking the internal fouling level of an aircraft engine according to any one of claims 8 to 12, wherein said first and second information is obtained during a takeoff phase of said aircraft. Product computer program comprising program code instructions to execute the steps of the process according to any one of claims 8 to 13, when said program is executed by a processor of a control system of an internal engine soiling level. Storage medium comprising a computer program product according to claim 14.

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