METHOD AND DEVICE FOR MONITORING EQUIPMENT IN A FUEL SUPPLY CIRCUIT OF AN AUXILIARY POWER UNIT OF AN AIRCRAFT.

Abstract

This disclosure relates to a method and system for monitoring equipment (103) of a fuel supply circuit (100) of an auxiliary power unit (107) of an aircraft (500).The method includes: determining whether the fuel supply circuit has been, during a predetermined period, in a configuration such that the following conditions have been met: (i) the auxiliary power unit was in an operational state "on", and, (ii) the fuel supply circuit was in a mode "refueling a compensation tank", and (iii) the compensation tank (106) had a fuel-filling status "empty", then determining a duration for which said configuration was maintained and, when the duration is greater than a first predetermined threshold, then recording an event, and if a number of recorded events is greater than a second predetermined threshold, then generating an alert message.It is possible to indirectly monitor equipment in an APU fuel supply circuit and issue an alert message when that equipment requires action and / or maintenance scheduling. Figure to be published with the abbreviation: Fig. 3.

Description

Title of the invention: METHOD AND DEVICE FOR MONITORING EQUIPMENT IN A FUEL SUPPLY CIRCUIT OF AN AUXILIARY POWER UNIT OF AN AIRCRAFT. technical field

[0001] The scope of this disclosure relates to the monitoring of equipment belonging to a fuel supply circuit of an aircraft auxiliary power unit. In particular, the invention relates to the monitoring of a pressure switch on a refueling line belonging to the fuel supply circuit of the auxiliary power unit. STATE OF PRIOR ART

[0002] In the field of aeronautics, an auxiliary power unit (APU) is an electrical generator that provides power for functions other than propulsion. In particular, it is designed to start the main propulsion systems and to produce power on board aircraft to supply electrical power to various onboard systems on the ground (e.g., cabin lighting, air conditioning, ventilation, etc.) when these main propulsion systems are shut down.

[0003] An APU is generally fueled via a fuel supply system that delivers fuel from tanks on the aircraft. Such tanks are, for example, a left internal main tank located in the left wing of the aircraft, or a trim tank located in the tail of the aircraft. Without departing from the scope of the invention, the main tank could also be a right internal main tank located in the right wing of the aircraft. The trim tank's role is to maintain the aircraft's center of gravity at its center of lift, according to flight parameters and the loads carried, by refueling from the main tanks (e.g., left or right internal tanks) or by draining fuel from them.

[0004] The APU fuel supply is governed by different operating modes depending on the aircraft's operational status. Figures [Fig. 1A] and [Fig. 1B] schematically illustrate examples of APU fuel supply according to different operating modes.

[0005] Conventionally, the fuel supply circuit 100 of an APU 107 includes a first pump 101 positioned at a fuel line 110 of the APU 107. The first pump 101 is capable of delivering fuel from a portion of a refueling line 104 supplying fuel to a compensation tank 106 to the APU 107. The fuel supply circuit 100 further includes a second pump 102 capable of delivering fuel from a left internal main tank 105 of the aircraft to a portion of the refueling line 104 to the APU 107. The fuel supply circuit 100 further includes a pressure switch 103 positioned at the refueling line 104.This pressure switch 103 is capable of measuring fuel pressure in the supply line 104 and transmitting an electrical signal when a certain fuel pressure threshold in the supply line 104 has been reached.

[0006] In a first operating mode referred to as "ground operation" (see [Fig. 1A]), the APU 107 is supplied with fuel from a left internal main tank 105 by means of the aircraft's second pump 102. The fuel then flows from this left internal main tank 105 to the refueling line 104 supplying the compensation tank 106, then to the fuel line 110 and the APU 107. This operating mode is generally used during conventional aircraft ground operations (e.g., during passenger boarding).

[0007] In a second operating mode called "refueling the compensation tank" ([Fig.1B]), when the aircraft is on the ground, the APU 107 is supplied with fuel via the fuel supply line 104 while the compensation tank 106 is being refueled. More specifically, when the compensation tank 106 is being refueled, an inlet valve 109 of the compensation tank 106 is opened to allow fuel into this compensation tank 106. A portion of this fuel intended for the compensation tank 106 is then pumped by the first pump 101 into the refueling line 104 and / or directly into the compensation tank 106 to supply fuel to the APU 107.

[0008] When the pressure switch 103 detects a pressure below a predetermined threshold in the refueling line 104, it transmits an electrical signal to switch the fuel supply circuit 100 from a "refueling the compensation tank" operating mode to a "ground operation" operating mode. Indeed, during the refueling operation of the compensation tank 106, a pressure that is too low in the refueling line 104 means that the first pump 101 pumps more fuel than is present in the refueling line 104 from the compensation tank 106. Consequently, Not only is the refueling operation of the compensation tank 106 compromised, but the APU 107 risks running out of fuel and therefore shutting down during the refueling operation. Switching to the "ground operation" mode prevents the first pump 101 from emptying the refueling line 104 from the compensation tank 106, as it could otherwise potentially pump air if the compensation tank 106 no longer contained sufficient fuel, which would cause the APU 107 to shut down.

[0009] In order to avoid a shutdown of the APU 107 in the "refueling of the compensation tank" operating mode, it is desirable to monitor the proper operation of the pressure switch 103 so as not to leave the fuel supply circuit 100 in the operating mode known as "refueling of the compensation tank" when there is no longer enough fuel in the supply line 104 and / or in the compensation tank 106.

[0010] The pressure switch 103 is not a natively monitored device (i.e., no direct data from sensors to monitor this device is received and analyzed).

[0011] It is therefore desirable to overcome this drawback of the prior art.

[0012] It is particularly desirable to provide a solution that allows monitoring of equipment, such as a pressure switch, of a fuel supply circuit of an APU, particularly during refueling operations of an aircraft's compensation tank. Description of the invention

[0013] A method for monitoring equipment in a fuel supply circuit of an aircraft auxiliary power unit is proposed herein. This method is implemented by a monitoring device in the form of electronic circuitry. This method comprises: - determine if the fuel supply circuit has been, over a predetermined period, in a configuration such that the following conditions have been met: (i) the auxiliary power unit was in an "on" operational state, and, (ii) the fuel supply circuit was in a so-called "refueling a compensating tank" operating mode, and (iii) the compensation tank had a fuel fill status described as “empty”, - and each time the fuel supply circuit was in said configuration, determine a duration for which said configuration was maintained and, when said specified duration exceeds a first predetermined threshold, then record an event indicating that said specified duration exceeded the first predetermined threshold, - determine, for the said predetermined period, a number of recorded events, and if the said number of determined events is greater than a second predetermined threshold, then generate an alert message.

[0014] Thus, it is possible to indirectly monitor equipment in an APU fuel supply circuit, such as a pressure switch, which is not natively monitored. It is therefore possible to issue an alert message when this equipment requires action and / or maintenance scheduling by monitoring a parameter such as the duration of a particular configuration of the APU fuel supply circuit.

[0015] According to one embodiment, the alert message includes a request for maintenance of said equipment to be carried out and / or scheduled.

[0016] According to one embodiment, the method further comprises: - collect initial data, representative of the said operational state of said auxiliary power unit during said predetermined period, said initial data being measurements of the rotational speed of the auxiliary power unit, and determine that said auxiliary power unit is in the operational state known as "on" when a rotational speed measurement is greater than 0, - collect second data, representative of said operating mode of said fuel supply circuit during said predetermined period, said second data being a status of an inlet valve of the compensation tank, and determine that the operating mode is "refueling of the compensation tank", when the status of the inlet valve is "open", - collect third data, representative of said fuel filling status of the compensation tank during said predetermined period, said third data being measurements of quantity of fuel in the compensation tank, and determine that the status of the tank is "empty" when the quantity of fuel is less than a predetermined threshold of quantity of fuel.

[0017] In one embodiment, the step of recording an event indicating that said determined duration was greater than the first predetermined threshold is implemented so as to record at most one event for the same use of the aircraft.

[0018] A method for maintaining equipment in a fuel supply circuit of an auxiliary power unit of an aircraft is also proposed here, comprising: - monitor said equipment according to the monitoring procedure as described above, - to perform and / or plan maintenance on said equipment when an alert message is generated by execution of the monitoring process as described above.

[0019] Also proposed here is a monitoring device for equipment in a fuel supply circuit of an aircraft auxiliary power unit. This monitoring device comprises electronic circuitry configured to: - determine whether the fuel supply circuit has been, over a predetermined period, in a configuration such that the following conditions have been met: (i) the auxiliary power unit was in an "on" operational state, and, (ii) the fuel supply circuit was in a so-called "refueling a compensating tank" operating mode, and (iii) the compensation tank had a fuel fill status described as “empty”, - and each time the fuel supply circuit has been in said configuration, determine a duration for which said configuration was maintained and, when said determined duration exceeds a first predetermined threshold, then record an event indicating that said determined duration exceeded the first predetermined threshold, - determine, for the said predetermined period, a number of recorded events, and if the said number of determined events is greater than a second predetermined threshold, then generate an alert message.

[0020] In particular, the monitoring device is installed in an operational center or in a maintenance center located on the ground, receiving operational data from the aircraft.

[0021] A computer program product is also proposed, comprising instructions that cause a processor to execute the process described above in any of its embodiments when said instructions are executed by the processor. A storage medium for storing such instructions is also proposed. Brief description of the drawings

[0022] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of at least one exemplary embodiment, said description being made in relation to the accompanying drawings, among which:

[0023] [Fig.1A] and [Fig.1B] schematically illustrate examples of APU fuel supply according to different operating modes;

[0024] [Fig.2] illustrates in graphical form the duration of a circuit configuration fuel supply to an APU that may precede a sudden shutdown of the APU, before and after replacement of the fuel supply circuit pressure switch;

[0025] [Fig.3] illustrates in diagram form the steps of a method for monitoring equipment in a fuel supply circuit of an APU, according to one embodiment; [Fig.4] schematically illustrates an example of the hardware architecture of a surveillance device according to one embodiment.

[0026] DETAILED DESCRIPTION OF IMPROVEMENTS

[0027] The general principle of this disclosure is to indirectly monitor equipment in the fuel supply circuit of an aircraft APU, such as a pressure switch. This makes it possible to provide, if necessary, an alert message when maintenance of this equipment (e.g., pressure switch) is required.

[0028] It has been previously observed that most of the APU 107 ground stops during the refueling operations of the compensation tank 106 are preceded by a configuration of the fuel supply circuit 100 whose conditions are as follows: the APU 107 is maintained in an operational state called "on" while the fuel supply circuit 100 is in "refueling compensation tank" operating mode (i.e., the compensation tank 106 is being refueled) and that a status of the compensation tank 106 is "empty", i.e. that the quantity of fuel is below a predetermined threshold of fuel quantity, noted Q, of the compensation tank 106.

[0029] Subsequently, this configuration of the fuel supply circuit 100 is referred to as the "APU pre-shutdown configuration".

[0030] Fig. 2 illustrates in graphic form the duration of the APU fuel supply circuit configuration prior to a sudden APU shutdown, before and after replacement of the fuel supply circuit pressure switch.

[0031] According to [Fig. 2], before replacement of the pressure switch 103, the number of sudden shutdowns of the APU 107 preceded by the "APU pre-shutdown" configuration, the duration of which exceeds a first predetermined threshold SI, is greater than the number of shutdowns after replacement of the pressure switch 103. In other words, the longer the duration of this "APU pre-shutdown" configuration of the fuel supply circuit 100, the greater the risk of shutdown of the APU 107. Conversely, during the refueling operation of the compensation tank 106, after replacement of the pressure switch 103, the duration of the "APU pre-shutdown" configuration is below the first threshold SI. The predetermined threshold SI and the number of sudden shutdowns of the APU 107 decrease. Thus, by monitoring the duration of this so-called "APU pre-shutdown" configuration, it is possible to indirectly monitor the status of the pressure switch 103 and, if necessary, alert the system to a maintenance need for this equipment.

[0032] Fig. 3 illustrates in diagram form the steps of a method for monitoring equipment, such as a pressure switch, in the fuel supply circuit of an APU, according to one embodiment.

[0033] The monitoring method described below is implemented by a DISP monitoring device shown below in connection with [Fig.4].

[0034] First, during step 300, the DISP monitoring device collects data from at least one avionics system of the aircraft, for example, an ACMS (Aircraft Condition Monitoring System), a FOMAX (Flight Operations & Maintenance Exchanger), or an RMAX (Retrofit Maintenance Exchanger). This data corresponds, for example, to data transmitted by the aircraft after each flight to an operations center or a ground-based maintenance center, where it is recorded in a database. This data is then collected from the database by the DISP monitoring device. The operations center is, for example, an operations center of the aircraft manufacturer, providing maintenance support services for aircraft belonging to airlines.The maintenance center is, for example, the maintenance center of the airline operating the aircraft. Data collection, in step 300, corresponds to data acquired by the aircraft's avionics system over a predetermined data acquisition period P and at a predetermined data acquisition frequency F (e.g., 1 Hz or 2 Hz). In one example, this predetermined period P corresponds to the number of aircraft flights. In another example, this predetermined period P corresponds to a number of days.

[0035] Thus, for each acquisition instant (i.e., instant defined by the predetermined frequency F) of the predetermined period P, the DISP monitoring device obtains representative data: - a measurement of the rotation speed of the APU 107. The DISP monitoring device can thus determine the operational state of the APU 107. Indeed, if the rotation speed of the APU 107 is greater than 0 RPM, then the DISP monitoring device determines that the operational state of the APU 107 is: "on", otherwise the operational state is said to be "off" (e.g., when the APU 107 suddenly stops because it runs out of fuel during the refueling operation of the compensation tank 106 or when the APU 107 is intentionally switched off because the main propulsion systems are on); - of an "open" or "closed" status of the inlet valve 109 of the compensation tank 106. The DISP monitoring device then determines that when the status of the inlet valve of the compensation tank 106 is "open", then the compensation tank 106 is being refueled and the operating mode of the fuel supply circuit 100 is "refueling the compensation tank". If the status of the inlet valve 109 is "closed" (e.g., when the refueling operation of the compensation tank 106 is completed or when the pressure switch 103 detects a fuel pressure in the refueling line 104 below a predetermined threshold and switches the fuel supply circuit 100 to the "ground operation" mode), then the fuel supply circuit 100 is in another operating mode (e.g., "ground operation" mode), and; - a measurement of the quantity of fuel in the compensation tank 106. The DISP monitoring device then determines a status of "empty" or "not empty" of the compensation tank 106. When the quantity of fuel is less than a predetermined threshold of quantity of fuel Q (for example 50 liters, or about 110 Ibs), then the DISP monitoring device determines that the status of the compensation tank 106 is "empty", otherwise the DISP monitoring device determines that the compensation tank is "not empty".

[0036] The DISP monitoring device then records the collected data corresponding to the predetermined period P in a memory, for example in the form of a table where each row corresponds to a set of collected data corresponding to a particular acquisition instant of the predetermined period P (e.g., one row per second if the predetermined frequency F is 1 Hz), the data being representative, for that instant: - a measurement of the rotational speed of the APU 107, - the status of the inlet valve 109 of the compensation tank 106, and - a measurement of the quantity of fuel contained in the compensation tank 106.

[0037] Each line is also to be timestamped. Thus, each piece of data collected is associated, for example, with a date and time of acquisition.

[0038] Next, the collected data is processed by the DISP monitoring device. In particular, the DISP monitoring device determines, during a step 301, whether, during the predetermined data acquisition period P, the fuel supply circuit 100 was in an "APU pre-shutdown" configuration as described previously. In particular, the DISP monitoring device determines that the fuel supply circuit 100 was in an "APU pre-shutdown" configuration when the APU 107 was in the "on" operational state. that the operating mode of the fuel supply circuit 100 of the APU 107 was in "refueling of the compensation tank" mode (i.e., compensation tank 106 being refueled) and that furthermore the status of the compensation tank 106 was "empty".

[0039] It should be noted that during the predetermined period P, the fuel supply circuit 100 may have been several times in the "APU pre-shutdown" configuration.

[0040] Then, during a step 302, the DISP monitoring device determines a duration, denoted D, during which this "APU pre-shutdown" configuration was maintained. Optionally, when, during the predetermined period P, the fuel supply circuit 100 has been in the "APU pre-shutdown" configuration several times, then the DISP monitoring device determines, for each occurrence, the duration D of the detected "APU pre-shutdown" configuration.

[0041] In one example, when the collected data is recorded in the form of a table as described above, the DISP monitoring device then identifies the lines for which the fuel supply circuit 100 is in an "APU pre-shutdown" configuration and then performs a filtering operation to retain only the lines corresponding to a fuel supply circuit 100 in the "APU pre-shutdown" configuration. The DISP monitoring device then determines a ratio between a number of successive lines corresponding to the fuel supply circuit 100 in the desired "APU pre-shutdown" configuration, and the predetermined data acquisition frequency.For example, if the predetermined data acquisition frequency is 2HZ, and 20 successive lines correspond to a 100 fuel supply circuit in the "APU pre-shutdown" configuration, then the duration D of the "APU pre-shutdown" configuration is 10s.

[0042] In the case where the fuel supply circuit 100 has been several times in the "APU pre-shutdown" configuration, the DISP monitoring device determines for each set of successive lines the ratio between the number of successive lines in the set of lines and the predetermined data acquisition frequency.

[0043] Alternatively, with the collected data time-stamped, the DISP monitoring device determines the duration D of the "APU pre-shutdown" configuration by comparing the timestamp of the data at the beginning (i.e., when the "APU pre-shutdown" configuration is detected by the DISP monitoring device) and at the end of the "APU pre-shutdown" configuration (i.e., when the "APU pre-shutdown" configuration is no longer detected by the DISP monitoring device).

[0044] Once the duration D of the "APU pre-shutdown" configuration is determined, the monitoring device compares this duration D to a first predetermined threshold SI. In one example, the first predetermined threshold SI is approximately 75 seconds. If the duration D is greater than the first predetermined threshold SI (resulting in "yes" at the end of step 302), then, during step 303, the DISP monitoring device records a value, denoted E, in memory indicating that a duration D of the "APU pre-shutdown" configuration is greater than the first predetermined threshold SI. Conversely, if the duration D of the "APU pre-shutdown" configuration is less than the first predetermined threshold SI (resulting in "no" at the end of step 302), then step 300 is repeated.

[0045] In one embodiment, if the duration D exceeds the first predetermined threshold SI, the DISP monitoring device compares, on the one hand, the timestamp of the collected data on the basis of which the duration D was determined with, on the other hand, the timestamp of the collected data on the basis of which a duration D' of the last event recorded in memory was determined. If these timestamps correspond to the same aircraft usage, then the DISP monitoring device compares the durations D and D'. If the duration D' is greater than or equal to the duration D, then the DISP monitoring device does not record the event E in memory. If the duration D is greater than the duration D', then the DISP monitoring device records the event E in memory in place of the last recorded event.This embodiment advantageously allows for the recording of at most one event per aircraft use, namely the event with the longest duration. Aircraft use refers to a flight of the aircraft, specifically a portion of the flight extending from the start of flight preparation at a gate of a departure airport to the aircraft's takeoff from the departure airport.

[0046] According to one embodiment, during step 304, the DISP monitoring device determines, over the predetermined data acquisition period P, a number of events, denoted NE (where NE is an integer greater than or equal to 1), corresponding to the number of recorded events indicating that the duration D exceeds the first predetermined threshold SL. When the number of NE events over the predetermined period P exceeds a second predetermined threshold S2 (resulting in "yes" at the end of step 303), then the DISP monitoring device determines that the pressure switch 103 requires action and / or maintenance scheduling. An alert message is then generated during step 305, described below. Otherwise (resulting in "no" at the end of step 304), steps 300 and subsequent steps are repeated. In a particular example, the predetermined period P is 50 days and the second predetermined threshold S2 is 10.

[0047] According to one embodiment, during step 305, the DISP monitoring device generates an alert message including a request for maintenance to be performed and / or scheduled. In another variant, the alert message further includes a information representative of the duration D of maintenance of the "APU pre-shutdown" configuration and / or a number of NE events, for example.

[0048] In one embodiment, this alert message is a text message indicating that the pressure switch 103 requires action and / or maintenance planning.

[0049] In one embodiment, this alert message is for example transmitted by the operational center or the ground maintenance center to a human-machine interface for the attention of ground personnel (e.g., technician / operator).

[0050] The monitoring method as described above in the various embodiments allows for the indirect monitoring of equipment in the fuel supply circuit 100 of the APU 107, such as the pressure switch 103. In other words, the monitoring method as described above allows for the implementation of a maintenance method for equipment in the fuel supply circuit 100 of the APU 107, such as the pressure switch 103. In particular, by generating an alert message including a request for maintenance to be carried out and / or scheduled, a technician / operator, for example, can carry out and / or schedule this maintenance of this equipment (e.g., pressure switch 103).

[0051] Figure 4 schematically illustrates an example of hardware architecture of the DISP monitoring device, which then includes, connected by a communication bus 410: a processor or CPU (Central Processing Unit) 401; a RAM (Random Access Memory) 402; a ROM (Read Only Memory) 403, for example a Flash memory; a data storage device, such as a HDD (Hard Disk Drive), or a storage media reader, such as an SD (Secure Digital) card reader 404; at least one communication interface 405 I / f enabling the DISP monitoring device to collect the data received from an aircraft, and to display an alert message in the operations center or the ground maintenance center.

[0052] The processor 401 is capable of executing instructions loaded into RAM 402 from ROM 403, external memory (not shown), a storage medium such as an SD card, or a communication network (not shown). When the monitoring device DISP is powered on, the processor 401 is capable of reading instructions from RAM 402 and executing them. These instructions form a computer program causing the processor 401 to implement the behaviors, steps, and algorithm described herein.

[0053] All or part of the behaviors, steps, and algorithm described herein can thus be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller, or be implemented in hardware form by a machine or a A dedicated component (or "chip") or a dedicated set of components (or "chipset"), such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). Generally, the DISP monitoring device comprises electronic circuitry arranged and configured to implement the behaviors, steps, and algorithm described herein.

Claims

Demands

1. A method for monitoring equipment (103) in a fuel supply circuit (100) of an auxiliary power unit (107) of an aircraft (500), said method being implemented by a monitoring device (501) in the form of electronic circuitry, said method comprising: - determining whether said fuel supply circuit (100) has been, during a predetermined period P, in a configuration such that the following conditions have been met: (i) said auxiliary power unit (107) was in an "on" operating state, and (ii) said fuel supply circuit (100) was in an operating mode known as "refueling a compensation tank", and (iii) said compensation tank (106) had a fuel-filling status known as "empty", - and each time the fuel supply circuit (100) has been in said configuration,determine a duration D during which said configuration has been maintained and, when said determined duration D is greater than a first predetermined threshold (SI), then record an event indicating that said determined duration D has been greater than the first predetermined threshold (SI), - determine, for said predetermined period P, a number (NE) of recorded events, and if said number (NE) of determined events is greater than a second predetermined threshold (S2), then generate an alert message.

2. A monitoring method according to claim 1, wherein the alert message includes a request for maintenance of said equipment (103) to be performed and / or scheduled.

3. A method according to claim 1 or 2, further comprising: - collecting initial data, representative of said operational state of said auxiliary power unit (107) during said predetermined period P, said initial data being rotational speed measurements of the auxiliary power unit (107), and determining that said auxiliary power unit (107) is in the operational state known as "on" when a rotational speed measurement is greater than 0, - collect second data, representative of said operating mode of said fuel supply circuit (100) during said predetermined period P, said second data being a status of an inlet valve (109) of the compensation tank (106), and determine that the operating mode is "refueling of the compensation tank", when the status of the inlet valve (109) is "open", - collect third data, representative of said fuel filling status of the compensation tank (106) during said predetermined period P, said third data being measurements of quantity of fuel in the compensation tank (106), and determine that the status of the tank is "empty" when the quantity of fuel is less than a predetermined threshold of quantity of fuel Q.

4. A monitoring method according to any one of claims 1 to 3, wherein the step of recording an event indicating that said determined duration D was greater than the first predetermined threshold is implemented so as to record at most one event for the same use of the aircraft.

5. A method for maintaining equipment (103) of a fuel supply circuit (100) of an auxiliary power unit (107) of an aircraft (500) comprising: - monitoring said equipment (103) according to the monitoring method according to any one of claims 1 to 4, - performing and / or scheduling maintenance on said equipment (103) when an alert message is generated by executing the monitoring method according to any one of claims 1 to 4.

6. A monitoring device (501) for equipment (103) of a fuel supply circuit (100) of an auxiliary power unit (107) of an aircraft (500), said monitoring device (501) comprising electronic circuitry configured to: - determine whether said fuel supply circuit (100) has been, during a predetermined period P, in a configuration such that the following conditions have been met: (i) said auxiliary power unit (107) was in an "on" operational state, and, (ii) said fuel supply circuit (100) was in an operating mode called "refueling a compensation tank", and (iii) said compensation tank (106) had a fuel filling status called "empty", - and each time the fuel supply circuit (100) was in said configuration, determine a duration D during which said configuration was maintained and, when said determined duration D is greater than a first predetermined threshold (SI), then record an event indicating that said determined duration D was greater than the first predetermined threshold (SI), - determine, for said predetermined period P, a number (NE) of events recorded, and if said number (NE) of determined events is greater than a second predetermined threshold (S2), then generate an alert message.

7. Product computer program, comprising instructions causing a processor to execute the method according to any one of claims 1 to 4, when said instructions are executed by the processor.

8. Storage medium, storing a computer program comprising instructions causing a processor to execute the method according to any one of claims 1 to 4, when said instructions are read and executed by the processor.

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