METHOD FOR DETECTING MALFUNCTIONS OF A FUEL RETURN VALVE IN AN AIRCRAFT

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of monitoring and detecting malfunction of a fuel return valve (FRV) in an aircraft. STATE OF PRIOR ART

[0002] In an aircraft, an Integrated Drive Generator (IDG) is a system associated with each propulsion engine (turbomachine) to convert the kinetic energy of said propulsion engine into electrical energy to provide electricity to the aircraft. The IDG potentially provides electrical power to all electrical loads of the aircraft.

[0003] The IDG consists of an alternator and a constant speed drive (CSD) mounted in a single housing. The CSD is a mechanical device that provides a constant rotation frequency at the alternator input despite variations in the propulsion engine's rotation speed. Thus, the IDG can deliver a fixed frequency (e.g., 400 Hz) to the aircraft's electrical network.

[0004] Oil is a vital component of the IDG, and keeping the temperature of this oil within specifications is a key parameter for the longevity and efficiency of the IDG. The oil used to cool the IDG circulates in a closed circuit and is cooled, via an oil cooler, by the fuel supplying the propulsion engine to which the IDG is associated. Similarly, a heat exchanger is used to cool the oil used to lubricate the propulsion engine itself. The heat exchanges required to cool these oils therefore depend on the flow of fuel supplying the propulsion engine in question.

[0005] However, as during certain phases of flight, and more particularly during the descent phase, the propulsion engine's fuel requirement is lower, the fuel supplying the propulsion engine may not be sufficient to cool these oils, which reduces the longevity and performance of the IDG.

[0006] To address this, a Fuel Return Valve (FRV) is used to increase fuel flow to maintain cooling of the oil used for IDG cooling and the oil used for propulsion engine lubrication. The FRV controls fuel flow from a propulsion engine fuel delivery system to a recirculation system returning the hot fuel to the aircraft fuel tank. When the FRV is in the closed position, the recirculation system is inhibited.

[0007] It is clear from the above that when the FRV malfunctions, whether due to a failure of the FRV itself or a failure of another component with which the FRV interacts, directly or indirectly, such as a sensor or a fuel level sensing control unit (FLSCU), the longevity and performance of the IDG may be reduced. For example, a sensor failure may result in an unwanted closure of the FRV which will cause an undesirable rise in temperature of the oil used to cool the IDG.

[0008] Document US 2022 / 090515 A1 describes a method and system for detecting high oil consumption in an aircraft engine according to the prior art.

[0009] Document US 2021 / 388736 A1 relates to monitoring the life of oil in a gearbox of an air turbine starter according to the prior art.

[0010] It is therefore desirable to overcome these disadvantages of the state of the art. In particular, it is desirable to provide a solution that can detect a malfunction suffered by the FRV that could impact the cooling of the IDG. It is also desirable to provide a solution that is simple and inexpensive. STATEMENT OF THE INVENTION

[0011] For this purpose, a method is proposed for monitoring a fuel return valve, called FRV, controlling a fuel flow, used for cooling an oil supplying a propulsion engine of an aircraft and an oil of an integrated drive generator, called IDG, from a fuel distribution system to the propulsion engine to a recirculation system returning hot fuel to a fuel tank of the aircraft in order to allow cooler fuel to be injected into the fuel distribution system from said fuel tank of the aircraft, a first oil temperature sensor providing oil temperature measurements at the outlet port of the IDG, a second oil temperature sensor providing propulsion engine supply oil temperature measurements, the method being implemented by an FRV operation monitoring system in the form of electronic circuitry,the method being characterized in that it comprises the following steps: determining, per flight of the aircraft, a maximum oil temperature at the outlet port of the IDG based on the measurements of said first oil temperature sensor and / or a maximum oil temperature of the propulsion engine based on the measurements of said second oil temperature sensor; evaluating a change in one and / or the other of the oil temperature maximums over several flights; and generating an alarm when the change in one and / or the other of the oil temperature maximums shows an exceeding of a predetermined oil temperature threshold T.,

[0012] Thus, a malfunction suffered by the FRV that could impact the cooling of the IDG is easily detected. Maintenance related to the FRV is facilitated.

[0013] In a particular embodiment, the alarm is generated when the evolution of one and / or the other of the oil temperature maximums shows an exceeding of said predetermined threshold T during Y flights of a sliding window of Z consecutive flights, with Y and Z predetermined values ​​such that Y < Z.

[0014] In a particular embodiment, only the measurements taken during the cruise flight phases of the aircraft are taken into account.

[0015] In a particular embodiment, only measurements taken during flights of the aircraft lasting longer than a predefined duration threshold D are taken into account.

[0016] In a particular embodiment, to monitor several FRVs respectively associated with several propulsion engines of the aircraft, the FRV operation monitoring system is distributed in control units respectively associated with the propulsion engines of the aircraft.

[0017] In a particular embodiment, the FRV operation monitoring system is centralized in the avionics of the aircraft.

[0018] Also provided is a computer program product, which may be stored on a medium and / or downloaded from a communications network, for reading by a processor. This computer program comprises instructions for implementing the above-mentioned method in any of its embodiments, when said program is executed by the processor. Also provided is a non-transitory information storage medium on which such a computer program is stored.

[0019] There is also provided a system for monitoring the operation of a fuel return valve, called FRV, the FRV controlling a flow of fuel, used for cooling an oil supplying a propulsion engine of an aircraft and an oil of an integrated drive generator, called IDG, from a fuel distribution system to the propulsion engine to a recirculation system returning hot fuel to a fuel tank of the aircraft in order to allow the injection into the fuel distribution system of cooler fuel from said fuel tank of the aircraft, a first oil temperature sensor providing oil temperature measurements at the outlet port of the IDG, a second oil temperature sensor providing propulsion engine supply oil temperature measurements,the FRV operation monitoring system being in the form of electronic circuitry characterized in that it is configured to implement the following steps: determining, per flight of the aircraft, a maximum oil temperature at the output port of the IDG based on the measurements of said first oil temperature sensor and / or a maximum oil temperature of the propulsion engine based on the measurements of said second oil temperature sensor; evaluating a change in one and / or the other of the oil temperature maximums over several flights; and generating an alarm when the change in one and / or the other of the oil temperature maximums shows an exceeding of a predetermined oil temperature threshold T.,

[0020] An aircraft is also proposed comprising at least one system for monitoring the operation of a fuel return valve, known as FRV, as mentioned above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above-mentioned and other features of the invention will become more clearly apparent from the following description of at least one exemplary embodiment, said description being given in relation to the attached drawings, among which: [ Fig. 1 ] schematically illustrates, in top view, an aircraft equipped with propulsion engines respectively provided with integrated drive generators IDG; [ Fig. 2 ] schematically illustrates a monitoring algorithm; and [ Fig. 3 ] schematically illustrates an example of a hardware platform configured to carry out an implementation of the algorithm of the Fig. 2 . DETAILED PRESENTATION OF IMPLEMENTATION METHODS

[0022] There Fig. 1 thus schematically illustrates, in a top view, an aircraft 10. The aircraft 10 comprises at least one propulsion engine 102, preferably of the turbomachine type. Each propulsion engine 102 is equipped with an integrated drive generator IDG 103. Each propulsion engine 102 is also preferably equipped with a generator control unit GCU (Generator Control Unit) whose main functions are to regulate and monitor the frequency and voltage of the alternator of the IDG 103 of the propulsion engine 102 in question, to monitor feeder faults, overloads and phase reversals, and to protect the electrical network of the aircraft 10 by controlling an associated generator line contactor GLC (Generator Line Contactor).Each GCU is connected to the avionics 101 of the aircraft 10, more particularly to a centralized electronic aircraft monitoring system ECAM (“Electronic Centralized Aircraft Monitoring” in English), so as to provide alert signals as needed, in particular in the cockpit of the aircraft 10.

[0023] Each IDG 103 is typically equipped with two oil temperature sensors: one oil temperature sensor at the inlet port and another oil temperature sensor at the outlet port. These sensors are typically thermistors. Using these sensors, the GCU associated with the IDG 103 in question monitors the oil temperature of the IDG 103 and provides an alert signal if a predefined temperature threshold is exceeded on one and / or the other of these two oil temperature sensors.

[0024] Each IDG 103 is associated with a fuel return valve FRV 104 which controls the flow of fuel, used in particular for cooling the oil of the IDG 103, from a fuel distribution system to the propulsion engine 102, to which the IDG 103 is associated, to a recirculation system returning hot fuel to a fuel tank of the aircraft. An opening of the FRV makes it possible to increase the flow of fuel circulating in the fuel distribution system, this fuel being colder fuel coming from said fuel tank of the aircraft. The FRV 104 also controls said flow of fuel for cooling the oil of said propulsion engine 102. Thus, the oil of the IDG 103 in question and the oil of said propulsion engine 102 are better cooled.

[0025] The aircraft 10 is equipped with an FRV operation monitoring system 104. The FRV operation monitoring system 104 may monitor the operation of all the FRVs 104 centrally, for example within the avionics 101. Alternatively, the FRV operation monitoring system 104 may be distributed in control units (in the form of electronic circuitry) associated respectively with the propulsion engines 102.

[0026] There Fig. 2 schematically illustrates an FRV 104 operation monitoring algorithm implemented by the FRV 104 operation monitoring system. The algorithm of the Fig. 2 is implemented in parallel for each FRV 104 of aircraft 10.

[0027] In a step 201, the FRV operation monitoring system 104 obtains temperature measurements from the oil temperature sensor at the output port of the IDG 103 with which the FRV 104 in question is associated and / or temperature measurements from the oil temperature sensor supplying the propulsion engine 102 with which the IDG 103 is associated.

[0028] In a step 202, the FRV operation monitoring system 104 determines a maximum oil temperature at the output port of the IDG 103 based on the measurements of the oil temperature sensor at the output port of the IDG 103 in question and / or a maximum oil temperature of the propulsion engine 102 concerned based on the measurements of the second oil temperature sensor of said propulsion engine 102. Each maximum is determined per flight of the aircraft 10. The IDG oil level monitoring system 103 makes a recording in non-volatile memory of the maximum(s) determined, in order to be able to follow its or their evolution over several consecutive flights. For example, the evolution is considered over a sliding window of Z consecutive flights, where Z is equal to 5. Beyond Z flights, the IDG oil level monitoring system 103 can erase any previous recording.

[0029] Preferably, the FRV operation monitoring system 104 takes into account only the measurements made during the cruise flight phases of the aircraft 10. An altitude level marked by the altimeter can for example be used to detect a cruise phase. Thus, the oil level monitoring algorithm operates on oil at a generally stabilized temperature. Preferably again, for the same reasons, the FRV operation monitoring system 104 takes into account only the measurements made during flights of duration greater than a predefined duration threshold D, for example 30 minutes. An internal clock of the avionics 101 can for example be used to determine the flight times.

[0030] In a step 203, the FRV operating monitoring system 104 evaluates a change in the oil temperature maximum(s) over several flights, for example over Z consecutive flights (sliding window).

[0031] In a step 204, the FRV operating monitoring system 104 checks whether the evolution of the oil temperature maximum(s) shows an exceeding, by the temperature maximum, of a predetermined temperature threshold T on the sliding window. For example, T is equal to 110°C.

[0032] In a particular embodiment, the FRV operating monitoring system 104 checks whether the evolution of the oil temperature maximum(s) shows an exceeding of said threshold T during Y flights of the sliding window of Z consecutive flights, with Y a predetermined value such that Y < Z. For example, Y is equal to 3.

[0033] Thus, if the FRV 104 operating monitoring system notes that said threshold T has been exceeded, a step 205 is performed. Otherwise, the algorithm loops back to step 201 for a next flight of the aircraft 10.

[0034] In step 205, the FRV operation monitoring system 104 generates an alarm. In the aircraft 10, the alarm is preferably generated in the cockpit, for the pilot, and more particularly, via the ECAM. Thus, thanks to this automatically generated alarm, maintenance of the aircraft 10 is facilitated.

[0035] The alarm can be reset, for example by a dedicated procedure with the avionics 101, when a maintenance intervention is carried out on the FRV 104 in question or on a component with which the FRV 104 interacts, directly or indirectly, such as a sensor or a fuel level detection control unit FLSCU.

[0036] There Fig. 3 schematically illustrates an example of a hardware platform 300 of the FRV 104 operation monitoring system, in the form of electronic circuitry, which is adapted and configured to implement the algorithm of the Fig. 2. As already indicated, the FRV 104 operation monitoring system can be centralized in the avionics 101, or distributed in control units associated respectively with the propulsion engines 102.

[0037] The hardware platform 300 then comprises, connected by a communication bus 310: a processor or CPU (Central Processing Unit) 301; a RAM (Read-Only Memory) 302; a read-only memory 303, for example of the ROM (Read Only Memory) or EEPROM (Electrically-Erasable Programmable ROM) type; a storage unit 304, such as a hard disk drive (HDD) or a storage media reader, such as an SD (Secure Digital) card reader; and an I / f interface manager 305.

[0038] The I / f interface manager 305 makes it possible to interact with one or more equipment of the aircraft 10, such as the aforementioned temperature sensors, and possibly with a communication network. For example, the I / f interface manager 305 is adapted and configured to make it possible to interact with the avionics 101.

[0039] The processor 301 is capable of executing instructions loaded into the RAM 302 from the ROM 303, an external memory, a storage medium (such as an SD card), or a communications network. When the hardware platform 300 is powered on, the processor 301 is capable of reading instructions from the RAM 302 and executing them. These instructions form a computer program causing the processor 301 to implement some or all of the steps and operations described herein.

[0040] All or part of the steps and operations described herein may thus be implemented in software form by executing a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor) type processor or a microcontroller, or be implemented in hardware form by a machine or a dedicated electronic component (chip) or a dedicated set of electronic components (chipset), for example an FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit) component. Generally speaking, the hardware platform comprises electronic circuitry adapted and configured to implement the operations and steps described herein.

Claims

1. Method for monitoring a fuel return valve, called FRV (104), the FRV valve controlling a flow of fuel, used to cool an oil feeding a propulsion engine (102) of an aircraft (10) and an oil of an integrated drive generator, called IDG (103), from a system for distributing fuel to the propulsion engine (102) to a recirculation system returning hot fuel to a fuel tank of the aircraft (10), an aperture of the FRV making it possible to increase the flow of fuel circulating in the fuel distribution system, this fuel being colder fuel originating from said fuel tank of the aircraft (10), a first oil temperature sensor supplying measurements of the temperature of oil at an outlet port of the IDG (103), a second oil temperature sensor supplying measurements of the temperature of oil feeding the propulsion engine (102), the method being implemented by an FRV (104) operation monitoring system in the form of electronic circuitry, the method being characterized in that it comprises the following steps: - receiving measurements from the first oil temperature sensor and from the second oil temperature sensor; - determining (202), for each flight of the aircraft (10), an oil temperature maximum at the outlet port of the IDG (103) according to the measurements of said first oil temperature sensor and / or an oil temperature maximum of the propulsion engine (102) according to the measurements of said second oil temperature sensor; - assessing (203) a trend of one and / or the other of the oil temperature maxima over several flights; and - generating (205) an alarm flagging a malfunction experienced by the FRV, this malfunction leading to an undesirable closure of the FRV leading to an undesirable temperature rise of the oil used to cool the IDG, when the trend of one and / or the other of the oil temperature maxima shows that a predetermined oil temperature threshold T has been exceeded.

2. Method according to Claim 1, wherein the alarm is generated when the trend of one and / or the other of the oil temperature maxima shows that said predetermined threshold T has been exceeded during Y flights of a sliding window of Z consecutive flights, with Y and Z predetermined values such that Y < Z.

3. Method according to Claim 1 or 2, wherein only the measurements performed during the cruising flight phases of the aircraft (10) are taken into account.

4. Method according to any one of Claims 1 to 3, wherein only the measurements performed during flights of the aircraft (10) of a duration greater than a predefined duration threshold D are taken into account.

5. Method according to any one of Claims 1 to 4, wherein, to monitor several FRVs (104) respectively associated with several propulsion engines of the aircraft (10), the FRV (104) operation monitoring system is distributed in control units respectively associated with the propulsion engines of the aircraft (10).

6. Method according to any one of Claims 1 to 4, wherein the FRV (104) operation monitoring system is centralized in the avionics (101) of the aircraft (10).

7. Computer program product, comprising instructions driving the execution, by a processor (301), of the method according to any one of Claims 1 to 6, when said instructions are executed by the processor (301).

8. Storage medium, storing a computer program comprising instructions driving the execution, by a processor (301), of the method according to any one of Claims 1 to 6, when said instructions are read and executed by the processor (301).

9. System for monitoring operation of a fuel return valve, called FRV (104), the FRV valve controlling a flow of fuel, used to cool an oil feeding a propulsion engine (102) of an aircraft (10) and an oil of an integrated drive generator, called IDG (103), from a system for distributing fuel to the propulsion engine (102) to a recirculation system returning hot fuel to a fuel tank of the aircraft (10), an aperture of the FRV making it possible to increase the flow of fuel circulating in the fuel distribution system, this fuel being colder fuel originating from said fuel tank of the aircraft (10), the monitoring system being characterized in that it comprises: a first oil temperature sensor supplying measurements of the temperature of oil at an outlet port of the IDG (103), a second oil temperature sensor supplying measurements of the temperature of oil feeding the propulsion engine (102), and electronic circuitry configured to implement the following steps: - receiving measurements from the first sensor oil temperature sensor and from the second oil temperature sensor; - determining (202), for each flight of the aircraft (10), an oil temperature maximum at the outlet port of the IDG (103) according to the measurements of said first oil temperature sensor and / or an oil temperature maximum of the propulsion engine (102) according to the measurements of said second oil temperature sensor; - assessing (203) a trend of one and / or the other of the oil temperature maxima over several flights; and - generating (205) an alarm flagging a malfunction experienced by the FRV, this malfunction leading to an undesirable closure of the FRV leading to an undesirable temperature rise of the oil used to cool the IDG, when the trend of one and / or the other of the oil temperature maxima shows that a predetermined oil temperature threshold T has been exceeded.

10. Aircraft (10) comprising at least one FRV (104) operation monitoring system according to Claim 9.