METHOD FOR CONTROLLING AN INTERNAL FOULING LEVEL OF AN AIRCRAFT ENGINE AND SYSTEM CARRYING OUT THE METHOD.

Abstract

The invention relates to a system (10) for controlling a level of soiling of an aircraft engine (1) comprising electronic circuitry configured to obtain first information (EOC), representative of operating conditions of said engine, and to obtain second information (EIP), representative of internal operating parameters of said engine, the system further comprising electronic circuitry configured to perform a determination of expected performances (2) of said engine, from said first information and a pre-established engine performance model; a determination of current performances (S1) of said engine, from said first and second information; a determination of an engine performance index (S3) from said expected performances and said current performances;and a generation of an alert signal (S5) when said performance index is greater than or equal (S4) to 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 AN INTERNAL FOULING LEVEL OF AN AIRCRAFT ENGINE AND SYSTEM CARRYING OUT THE METHOD. Technical field

[0001] The present invention relates to a method for controlling an internal soiling level of an aircraft engine. The invention relates more particularly to a method for determining an internal soiling 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. STATE OF THE PRIOR ART

[0002] Turbojet aircraft engines encounter numerous polluting particles in the air ingested during their operation. These particles can be diverse, such as for example soot, grease, fine particles, and all kinds of pollution.

[0003] Such particles gradually 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 roughness of the surface of the elements present as well as a modification of their aerodynamic profiles, which leads to a degradation of the performance of the turbojet engine by progressive limitation of the air flow and to a reduction in the isentropic efficiency of the compression stage of the turbojet engine.

[0004] Fortunately, this type of engine fouling is reversible and cleaning can be carried out during a maintenance operation to recover performances identical to those achieved in the absence of fouling. Thus, cleanings are planned and scheduled at regular time intervals, which time intervals are determined for example in number of flight cycles or in number of flight hours.

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

[0006] The situation can be improved. Statement 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 controlling an internal soiling level of an aircraft engine is proposed, the system comprising electronic circuitry configured to obtain first information, representative of operating conditions of the engine, and to obtain second information, representative of internal operating parameters of the engine, the control system being such that it further comprises electronic circuitry configured to execute

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

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

[0011] - a determination of an engine performance index from the performances determined expectations and determined current performances,

[0012] - a generation of 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 comprise the optional characteristics considered in isolation or in combination:

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

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

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

[0017] - information on the total temperature of the air flow entering said engine,

[0018] - information on the total pressure of the air flow entering said engine,

[0019] - information on the speed of said aircraft,

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

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

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

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

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

[0025] - information on the temperature of the outlet air flow from a compression stage low pressure of said engine,

[0026] - information on the temperature of the outlet air flow from a compression stage high pressure of said engine,

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

[0028] - information on the temperature of the exhaust gas from said engine,

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

[0030] - The system for controlling an 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 washing of said engine.

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

[0032] - The system for controlling an 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 air flow entering said engine,

[0034] - PT is a total pressure of air flow entering said engine,

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

[0036] - P30 is an output 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 an internal fouling level of an aircraft engine comprises electronic circuitry configured to obtain the first and second information during a takeoff phase of the aircraft.

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

[0040] Another object of the invention is a method for controlling an internal soiling level of an aircraft engine, the method comprising obtaining first information, representative of operating conditions of said engine, and obtaining second information, representative of 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 in- training and a pre-established model of engine performance,

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

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

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

[0045] The method for controlling an internal soiling level of an aircraft engine according to the invention may comprise the additional characteristics 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 from the first information and the second information.

[0047] - The method of controlling an internal fouling level of an aircraft engine is such that the first information includes at least:

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

[0049] - information on the total temperature of the air flow entering said engine,

[0050] - information on the total pressure of the air flow entering said engine,

[0051] - information on the speed of said aircraft,

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

[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 of controlling an internal fouling level of an aircraft engine is such that the second information includes at least:

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

[0057] - information on the temperature of the outlet air flow from a compression stage low pressure of said engine,

[0058] - information on the temperature of the outlet air flow from a compression stage high pressure of said engine,

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

[0060] - information on the temperature of the exhaust gas of said engine,

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

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

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

[0064] - TT is a total temperature of air flow entering said compression stage,

[0065] - PT is a total pressure of air flow entering 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 information used according to the method are obtained during a takeoff phase of the aircraft.

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

[0071] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings:

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

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

[0074] [Fig.3] is a flowchart illustrating a method of controlling an internal fouling level of an aircraft engine executed in the system already shown in [Fig.l], according to one embodiment;

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

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

[0077] DETAILED DESCRIPTION OF EMBODIMENTS

[0078] [Fig.l] schematically represents a system 10 for controlling an internal soiling level of a turbojet type aircraft engine, according to one embodiment. According to a preferred embodiment, the system 10 for controlling an internal soiling level of a turbojet type aircraft engine is arranged on the ground, for example in a ground station receiving information from one or several aircraft and carrying out monitoring and control operations in connection with maintenance (curative or preventive) of this or these aircraft. According to an alternative embodiment, the system 10 is on board an aircraft and operates a control of at least one engine of the aircraft on board.

[0079] The system 10 is connected, via data transmission channels, to an ACMS flight data acquisition module 12 of the aircraft, also commonly called ACMS from the English acronym "Aircraft Condition Monitoring System" and which means "system for monitoring the state of an aircraft". According to one embodiment, the ACMS flight data acquisition module 12 is further connected to a plurality of sensors, receivers and other devices of the aircraft (not shown in the figure), making it possible to know at any time the state of a large number of elements of the aircraft, useful for detailed monitoring of the operational flight and operating conditions of the aircraft. According to one embodiment, the connection between the ACMS module 12 and the various sensors is operated via wired means.Furthermore, when the system 10 is located on the ground, the communication bus(es) which connect the system 10 to the ACMS 12 comprise or are wireless transmission channels, such as telecommunication channels configured to operate data transmissions between the aircraft and the ground station. When the system 10 is located in the aircraft, the bus(es) which connect the system 10 and the ACMS 12 are arranged in the aircraft and may be wired. The connection(s) used to connect the ACMS 12 and the system 10, possibly comprising telecommunication means, are not described here further since the details of their implementation are not useful for understanding the invention.The information measured, calculated or received by the flight data acquisition module ACMS 12 is diverse and includes in particular first EOC (Engine Operating Conditions) information representative of operating conditions of each of the engines and second EIP (Engine Internal Parameters) information representative of internal operating parameters of each of the engines of the aircraft. According to one embodiment, this information is transmitted to an engine performance modeling module EPM 14 (Engine Performance Monitoring) comprising an internal NN neural network previously trained from the first EOC information and the second EIP information, during a learning and validation phase prior to its use in operating 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 having the same technical characteristics and therefore substantially the same performance. According to a first. variant, the learning phase of the EPM 14 engine performance modeling module is carried out using EOC and EIP information obtained in the laboratory or on a maintenance site, from an engine free of dirt. According to a second variant, the learning phase is carried out during a climbing flight phase or a cruising flight phase, for example. According to the exemplary embodiment described in [Fig.l], the NN neural network of the EPM 14 engine performance modeling module is already trained and is then used in a so-called operating 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 this 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 module 12, is carried by communication links which together form a communication bus (or link) 13 between the flight data acquisition module ACMS 12 and the engine performance modeling module EPM 14 on the one hand and a module for determining a performance index (engine performance) HIM 16 on the other hand, and the second EIP information delivered by the engine performance modeling module EPM 14 is carried by communication links which together form a communication bus (or link) 15' between the engine performance modeling module EPM 14 and the module for determining a performance index (engine performance) HIM 16.Furthermore, EIP information not modeled but delivered by the flight data acquisition module ACMS 12 is carried by communication links which jointly form a communication bus (or link) 15 between the flight data acquisition module ACMS 12 and the module for determining a performance index HIM 16.The module for determining a performance index HIM 16 is in fact configured to receive second EIP information generated by the engine performance modeling module EPM 14 used in operating mode on the one hand (via the bus or communication link 15'), and first EOP information and second EIP information generated by the flight data acquisition module ACMS 12 on the other hand (via the buses or links 13 and 15 respectively), for the purpose of generating or not generating an alert signal 17 accessible to other systems of the ground station or of the aircraft, where appropriate, including in particular a module for signaling faults or status indicators of various elements or systems of the ground station or of the aircraft. According to one embodiment, the engine performance modeling modules EPM 14 and deter . mination of a HIM performance index 16 are implemented in entities physically separate from the ground station or the aircraft which comprises the control system 10. According to a preferred embodiment, these modules 14 and 16 are implemented in the same controller device 100 shown in dotted lines in [Fig.l].

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

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

[0082] and,

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

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

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

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

[0087] where: • ^isen is the calculated value of isentropic efficiency of the compression stage of the engine concerned, • TT is a total temperature of air flow entering a compression stage of the engine concerned, • PT is a total pressure of air flow entering the above-mentioned compression stage,

[0088]

[0089]

[0090] • T30 is an outlet temperature of a high pressure compression stage of the engine concerned, • P30 is an outlet pressure of a high pressure compression stage of the engine concerned, and, • Y is an adiabatic coefficient of the incoming air. According to one embodiment, the module for determining a performance index HIM 16 is configured to determine the engine performance indicator HI according to the formula: HI = A p. after a wash - Ap. during the last flights carried out 'tsen * isen OR : A p. -IJ. -p. 'Isen Isen Measure Isen Moaete - ^isen measurement is an isentropic efficiency value calculated from information obtained from the ACMS 12 flight data acquisition module, - ^ism model is an isentropic efficiency value calculated from second EIP information delivered by the EPM 14 engine performance modeling module. [Fig.2] illustrates the EPM 14 engine performance modeling module used in operating mode (as opposed to learning / validation mode). To be used in operating mode, the EPM 14 engine performance modeling module, which comprises a NN neural network, must be previously trained using the first and second information so that it then implements, when operated in so-called “operating mode”, the pre-established engine performance model.In other words, during a learning phase, the EOC information representative of operating conditions of the engine concerned is applied as input to the NN neural network and the EIP information representative of internal parameters of the engine in operation is applied as output to the NN neural network according to the principles of deep learning, then a validation phase is carried out to validate the learning phase as such.Thus, when EOC information representative of engine operating conditions is applied as input to the EPM 14 engine performance modeling module used in operating mode (or more precisely when its internal NN neural network is used in operating mode), the latter delivers EIP information representative of the engine parameters corresponding to nominal operating performance of the engine without fouling, which information can be processed and “compared” to current information from the ACMS 12 flight data acquisition module.

[0091] [Fig. 3] is a flowchart illustrating steps of a method for controlling an internal fouling level of an aircraft engine executed in the system 10 for controlling an internal fouling level of an engine, already illustrated in [Fig. 1].

[0092] A step S0 comprises operations of initialization and configuration of the set of systems present aiming to obtain 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 method.

[0093] Thus, at the end of step S0, it is considered that the neural network NN of the EPM module 14 has been validly trained and that the training phase has been validated, so that the neural network NN is able to be used in operating mode.

[0094] During a step SI, the controller device 100 of the control system 10 obtains the first EOP information and the second EIP information delivered by the flight data acquisition module ACMS 12 making it possible to establish a “measured” engine performance profile since all of the information used comes from the flight data acquisition module ACMS 12.

[0095] 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 an engine performance profile modeled using the neural network NN which implements the pre-established engine performance model.

[0096] It should be noted that steps S1 and S2 can be carried out successively in any order or even in parallel with each other.

[0097] Then, during a step S3, the controller device 100 calculates different isentropic efficiency values ​​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 to then compare, during a step S4, this determined performance index HI with an engine performance index threshold value.

[0098] In the case where the determined value of the index HI is greater than or equal to said threshold value of engine performance index during the comparison in step S4, then the output signal 17 of the controller device 100 is positioned at its active value (assertion of the signal) during a step S5 and a maintenance operation aimed at removing the dirt from the engine concerned will be executed shortly, as soon as the aircraft is available for immobilization in maintenance to do so. In the opposite case, that is to say if the performance index HI is less than the value predefined threshold during the comparison of step S4, then the process loops back to step S1.

[0099] [Fig.4] is a diagram illustrating an example of the internal architecture of the device controller 100 of the system 10 for controlling an internal dirt level of an engine, according to one embodiment.

[0100] According to the example of hardware architecture represented in [Fig. 4], the controller device 100 of an internal soiling level of an engine then comprises, connected by a communication bus 1000: a processor or CPU (“Central Processing Unit” in English) 101; a RAM (“Random Access Memory” in English) 102; a ROM (“Read Only Memory” in English) 103; a storage unit such as a hard disk (or a storage medium reader, such as an SD (“Secure Digital” in English) card reader) 104; at least one interface module 105 allowing the controller device 100 of the internal soiling level of an engine 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 comprises in particular input-output ports, inputs of digital / analog converters and analog / digital converters, outputs controlled by pulse width modulation, and more generally all types of interfaces, including power, in particular useful for capturing or obtaining signals or data from the various systems of the aircraft and in particular from the flight data acquisition module ACMS 12. In particular, the INTER 105 interface module of the controller device 100 is configured to operate in particular functions of obtaining the first EOC information and obtaining the second EIP information, via communication buses or via telecommunication links.

[0101] The processor 101 is capable of executing instructions loaded into the RAM 102 from the ROM 103, from an external memory (not shown), from a storage medium (such as an SD card), or from a communication network. When the controller device 100 of the system 10 for controlling an internal soiling level of an engine is powered up, the processor 101 is capable of reading program code instructions from the 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 this method.

[0102] 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" in English) or a microcontroller, or be implemented in hardware form by a machine or a dedicated component, for example an FPGA ("Field-Programmable Gate Array" in English) or an ASIC ("Application-Specific Integrated Circuit" in English). In general, the controller device 100 of the internal soiling level of an engine comprises electronic circuitry configured to implement the methods described in relation to the system 10 or the controller device 100. Obviously, the controller device 100 of an internal soiling level of an engine further comprises all the elements usually present in a system comprising a control unit and its peripherals, such as, a power supply circuit, a power supply supervision circuit, one or more clock circuits, a reset circuit, related input-output ports, interrupt inputs, bus drivers (or drivers), this list being non-exhaustive.

[0103] Advantageously, the modeling and restitution operations of modeled engine performances can be implemented using techniques based on the use of neural networks trained from information representative of the operation of an engine during a learning and learning validation phase. According to one embodiment, the learning phase is carried out when the level of soiling of the engine concerned is zero or is negligible, for example after a cleaning operation during a maintenance operation.

[0104] According to one embodiment, the NN neural network internal to the controller 100 comprises a software or hardware implementation of a deep artificial neural network or ANN (Artificial Neural Network). Such an ANN module may consist of a set of numerous artificial neurons and organized by successive layers connected to each other. Such an ANN module is classically inspired by a simplistic model of the functioning of a human brain where numerous biological neurons are connected to each other by axons.

[0105] The NN neural network is trained during 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.

[0106] 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 control circuit 10 for the internal soiling level of at least one aircraft engine, which comprises the controller device 100 for the internal soiling level of an engine as previously described.

[0107] The use of the system 10 advantageously makes it possible to provide alert information when the level of internal soiling of an engine exceeds a predetermined threshold level, so that a maintenance operation is carried out in good correlation with the actual level of internal soiling of the engine, or at the very least in better correlation with the actual internal engine soiling level.

Claims

Claims

1. Control system (10) for controlling an internal soiling level of an aircraft engine (1), said control system (10) comprising electronic circuitry configured to obtain first information (EOC), representative of operating conditions of said engine, and to obtain second information (EIP), representative of internal operating parameters of said engine, the control system being characterized in that it further comprises electronic circuitry configured to perform: - a determination of current performances (SI) of said engine, from said first and second information, - a determination of expected performances (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 performances and said current performances,- generation of an alert signal (S5) when said performance index is greater than or equal (S4) to a predefined threshold value.,

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 using a neural network (NN) module trained from said first information and said second information obtained.

3. System for controlling an internal soiling level of an aircraft engine according to one of claims 1 and 2, in which said first information obtained comprises: - information on the shaft speed of a low pressure stage of said engine, - information on the total temperature of the air flow entering said engine, - information on the total pressure of the air flow entering said engine, - information on the speed of said aircraft, - information on the status of an air bleed valve of the aircraft, - information on the status of a wing anti-icing valve of said aircraft, - information on the status of an engine nacelle anti-icing valve of said aircraft.

4. System for controlling an internal fouling level of an aircraft engine according to one of claims 1 to 3, wherein said second information comprises: - information on the shaft speed of a high pressure stage of said engine, - information on the outlet airflow temperature of a low pressure compression stage of said engine, - information on the outlet airflow temperature of a high pressure compression stage of said engine, - information on the outlet airflow pressure of a high pressure compression stage of said engine, - information on the exhaust gas temperature of said engine, - information on the flow rate of fuel supplying said engine.

5. System for controlling an internal soiling level of an aircraft engine according to one of claims 1 to 4, configured to determine said performance index from said expected performances, said current performances and a calculated value of the variation in the isentropic compression efficiency since the last washing of said engine.

6. System for controlling an internal soiling level of an aircraft engine according to one of claims 1 to 5, comprising electronic circuitry configured to calculate said isentropic efficiency value according to the formula [TT / (T30-TT)] x [(P30 / PT) ((Yl) / Y) -l], where: - TT is a total temperature of the air flow entering said compression stage, - PT is a total pressure of incoming air flow 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 incoming air.

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

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

9. Method for controlling an internal soiling level of an aircraft engine, said method comprising obtaining first information, representative of operating conditions of said engine, and obtaining second information, representative of internal operating parameters of said engine, the method being characterized in that it further comprises: - a determination of current performances (SI) of said engine, from said first and second information, - a determination of expected performances (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 performances and said current performances, - a generation of an alert signal (S5) when said performance index is greater than or equal (S4) to a predefined threshold value.

10. A method for controlling an internal fouling level of an aircraft engine according to claim 9, wherein said pre-established engine performance model is implemented using a neural network trained from said first information and said second information.

11. Method for controlling an internal fouling level of an aircraft engine according to one of claims 9 and 10, wherein said first information comprises: - information on the shaft speed of a low pressure stage of said engine, - information on the total temperature of the incoming air flow of said engine, - information on the total pressure of the incoming air flow of said engine, - information on the speed of said aircraft, - information on the status of an air bleed valve of the aircraft, - information on the status of a wing anti-icing valve of said aircraft, - information on the status of an engine nacelle anti-icing valve of said aircraft.

12. Method for controlling an internal fouling level of an aircraft engine according to one of claims 9 to 11, according to which said first information comprises: - information on the shaft speed of a high pressure stage of said engine, - information on the outlet airflow temperature of a low pressure compression stage of said engine, - information on the outlet airflow temperature of a high pressure compression stage of said engine, - information on the outlet airflow pressure of a high pressure compression stage of said engine, - information on the exhaust gas temperature of said engine, - information on the flow rate of fuel supplying said engine.

13. Method for controlling an internal soiling level of an aircraft engine according to one of claims 9 to 12, according to which said performance index is determined from said expected performances, of said current performances and of a calculated value of the variation of the isentropic compression efficiency since the last washing of said engine.

14. A method for controlling an internal fouling level of an aircraft engine according to one of claims 9 to 13, wherein said calculated isentropic efficiency value is calculated according to the formula [TT / (T30-TT)] x [(P30 / PT)«T 9 / o_ 1], where: - TT is a total temperature of airflow entering said compression stage, - PT is a total pressure of airflow entering 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.

15. Method for controlling an internal soiling level of an aircraft engine according to one of claims 9 to 14, according to which said first and second information are obtained during a take-off phase of said aircraft.

16. Computer program product comprising program code instructions for executing the steps of the method according to one of claims 9 to 15, when said program is executed by a processor of a system for controlling an internal soiling level of an engine.

17. A storage medium comprising a computer program product according to claim 16.

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