METHOD AND SYSTEM FOR MONITORING THE PERFORMANCE OF AN AIRCRAFT OIL FILTER

Abstract

A method is proposed for monitoring the performance of an aircraft oil filter, comprising: at at least one predetermined measurement time, acquiring (301) a measured temperature value and a measured differential pressure value of the oil passing through the oil filter; estimating (302), for the measurement time(s), a reference differential pressure value, using a predictive model and the measured temperature value; calculating (303), for the measurement time(s), a comparison value between the measured differential pressure value and the reference differential pressure value; and triggering (307) an alert if a triggering condition, based on the calculated comparison value(s) for the measurement time(s), is met. Thus, the filter performance is monitored using a reliable and simple-to-calculate indicator. Figure to be published with the abstract: Fig. 3

Description

Title of the invention: METHOD AND SYSTEM MONITORING THE PERFORMANCE OF AN AIRCRAFT OIL FILTER technical field

[0001] The field of the invention is that of health monitoring and aircraft maintenance.

[0002] More specifically, the present invention relates to a method for monitoring the performance of an aircraft oil filter.

[0003] The present invention also relates to a monitoring system adapted to the implementation of such a process, as well as a computer program product and a storage medium enabling the implementation of such a process. STATE OF PRIOR ART

[0004] Aircraft are subjected to extreme conditions when they are in the air, particularly in terms of variations in temperature, pressure and speed. The performance of their components must be regularly checked to ensure their proper functioning.

[0005] Preventive or predictive maintenance consists of carrying out checks and repairs before a breakdown occurs.

[0006] In the field of aeronautics, maintenance makes it possible in particular to improve the availability and performance of an aircraft by avoiding its immobilization on the ground (AOG, for "Aircraft On Ground" in English), and to reduce maintenance costs by making it possible to identify in advance maintenance operations based on the actual performance of the aircraft.

[0007] Monitoring the aircraft's health status for maintenance purposes includes collecting technical data from the moment the aircraft is powered on, then during flight and until it is shut down. The data thus collected is used in particular to calculate the various indicators on which maintenance is based, and therefore the scheduling of maintenance operations.

[0008] The use of data can take place during the flight (this is referred to as in-flight health monitoring) and / or after the flight (for example, if the volume of data to be processed requires higher computing resources).

[0009] Furthermore, calculations using the collected data can be performed in the aircraft and / or in one or more ground-based devices. In the latter case, the Ground-based equipment (computers) receive, in real time or with a delay, the data collected in the aircraft.

[0010] Observing the condition of an aircraft over several flights allows ground personnel to make decisions and plan maintenance operations in advance, thus saving valuable execution time. Ground personnel can then make appropriate decisions based on criticality, logistics, and upcoming maintenance checks, and prepare repairs and replacements in advance.

[0011] As part of this maintenance, there is a particular need to monitor the performance of aircraft oil filters. For this, a reliable and easy-to-calculate performance indicator for an aircraft oil filter is required. Description of the invention

[0012] A method for monitoring the performance of an aircraft oil filter is proposed herein, the aircraft being equipped with a temperature sensor and a differential pressure sensor providing respectively measured values ​​of temperature and measured values ​​of differential pressure of the oil passing through the oil filter, the method being implemented by an oil filter performance monitoring system in the form of electronic circuitry, the method comprising:

[0013] - at at least one predetermined measurement instant, acquire a measured value of temperature and a measured value of differential pressure of the oil passing through the oil filter;

[0014] - to estimate, for the measurement instant or instant, a reference pressure value differential, thanks to a prediction model and the measured temperature value;

[0015] - calculate, for the or each measurement instant, a comparison value between the measured value of differential pressure and the reference value of differential pressure; and

[0016] - trigger an alert if a triggering condition, depending on the one or more The calculated comparison value(s) for the measurement time(s) is verified.

[0017] Thus, it is possible to monitor the performance of an aircraft oil filter, using an oil filter performance indicator that is reliable and simple to calculate.

[0018] According to a particular embodiment, the prediction model is a polynomial law aimed at approximating pairs of values, comprising a measured temperature value and a measured differential pressure value, measured at predefined measurement times during flights preceding a current flight, and expressing a reference value of differential oil pressure as a function of oil temperature.

[0019] According to a particular embodiment, at least two comparison values ​​are calculated for at least two measurement times. The method further comprises: determining an indicator value based on the at least two calculated comparison values. The triggering condition is a function of the indicator value.

[0020] According to a particular embodiment, the method includes a normalization of the indicator forming value, in order to obtain a normalized indicator forming value, and the triggering condition is a function of the normalized indicator forming value.

[0021] According to a particular embodiment, the operations preceding the triggering of an alert and resulting in the determination of an indicator value are iterated N times, for N successive flights, with N > 2, in order to obtain N indicator values. Furthermore, the triggering condition is that an average of the N indicator values ​​be greater than a threshold value.

[0022] According to a particular embodiment, at least one predetermined measurement instant belongs to a time zone under study comprising one or more time sub-zones under study defined according to at least one criterion belonging to the group comprising: - a criterion based on a flight phase parameter of the aircraft; - a criterion based on an aircraft altitude parameter; and - a criterion based on a speed parameter N2 of rotation of a high-speed rotor aircraft engine pressure.

[0023] In a first particular implementation, the calculation of a comparison value includes, for each measurement instant, calculating a difference between the measured differential pressure value and the reference differential pressure value. Furthermore, the indicator value is the differential pressure value measured at the measurement instant for which the calculated difference is minimal.

[0024] In a second particular implementation, the aircraft is further equipped with a speed sensor N2 providing N2 rotational speed values ​​for a high-pressure rotor of an aircraft engine. A measured speed value N2 is also acquired at each measurement instant. The estimation, for each measurement instant, of a reference differential pressure value using the prediction model and the measured temperature value, is also performed using the measured speed value N2. The calculation of a comparison value includes, for each measurement instant, calculating a ratio between the measured differential pressure value and the value of differential pressure reference. The indicator value is the median value of the ratios calculated for at least two measurement times.

[0025] Also proposed is a computer program product, comprising instructions leading to the execution, by a processor, of the process mentioned above according to any one of its embodiments, when said instructions are executed by the processor.

[0026] A storage medium is also proposed, storing such instructions.

[0027] A system for monitoring the performance of an oil filter is also proposed. of an aircraft, the aircraft being equipped with a temperature sensor and a differential pressure sensor providing respectively measured values ​​of temperature and measured values ​​of differential pressure of the oil passing through the oil filter, the monitoring system comprising electronic circuitry configured to implement:

[0028] - at at least one predetermined measurement instant, acquire a measured value of temperature and a measured value of differential pressure of the oil passing through the oil filter;

[0029] - to estimate, for the measurement instant or instant, a reference pressure value differential, thanks to a prediction model and the measured temperature value;

[0030] - calculate, for the or each measurement instant, a comparison value between the measured value of differential pressure and the reference value of differential pressure; and

[0031] - trigger an alert if a triggering condition, depending on the one or more The calculated comparison value(s) for the measurement time(s) is verified.

[0032] An aircraft is also proposed comprising at least one oil filter and the aforementioned system for monitoring the performance of an oil filter (in any of its various embodiments). Brief description of the drawings

[0033] 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:

[0034] [Fig-1] schematically illustrates, in side view, an aircraft equipped with a system of monitoring the performance of one (or more) oil filter(s) of an aircraft;

[0035] [Fig.2] schematically illustrates an example of the hardware architecture of the system of monitoring the performance of one (or more) oil filter(s) of an aircraft;

[0036] [Fig.3] schematically illustrates an example of a monitoring algorithm for a performance of an aircraft oil filter; and

[0037] [Fig.4] schematically illustrates an example of a polynomial law expressing a reference value of differential oil pressure as a function of oil temperature.

[0038] DETAILED DESCRIPTION OF IMPROVEMENTS

[0039] Fig. 1 schematically illustrates, in side view, an aircraft 100 equipped with one or more oil filters (not shown) and a system 101 for monitoring the performance of this or these oil filters.

[0040] An oil filter is a consumable cartridge that collects particles released into the oil circuit of an engine. For example, an aircraft includes a main filter and a backup filter to ensure oil filtration if the main filter becomes clogged. Oil filters are regularly replaced to ensure optimal filtration.

[0041] For each oil filter, the aircraft 100 is for example equipped with a temperature sensor and a differential pressure sensor (not shown) providing respectively temperature values ​​(denoted "V_OIL") and differential pressure values ​​(denoted "V_OFDP", with OFDP being the acronym for "Oil Filter Delta Pressure" in English) of the oil passing through the oil filter.

[0042] The aircraft 100 is further equipped with an N2 speed sensor, providing N2 speed values ​​of rotation of a high-pressure rotor of the aircraft engine (denoted "V_N2").

[0043] The oil filter performance monitoring system 101 is an embedded electronic device. For example, it is part of the electronic circuitry of the aircraft avionics 100. Preferably, it is integrated into a computer of the aircraft 100.

[0044] In one variant, the aircraft 100 includes several systems 101 each enabling the monitoring of the performance of an oil filter.

[0045] In another variant, the system 101 for monitoring the performance of one or more oil filters is not carried on board the aircraft 100 but is present on the ground.

[0046] In another embodiment, the system 101 for monitoring the performance of one or more oil filters comprises a first part that is installed in the aircraft 100 and a second part that is located on the ground. Thus, the calculations of the performance indicator and the triggering of alerts can be distributed between the two parts of the system 101. For example, the first part calculates the value of the performance indicator and the second part triggers the alerts.

[0047] In another variant, at least one 101 system for monitoring the performance of one or more oil filters is carried on board the aircraft and at least one 101 system for monitoring the performance of one or more oil filters is installed on the ground.

[0048] Fig. 2 schematically illustrates an example of the hardware architecture of the system 101 for monitoring the performance of one or more oil filters, which then comprises, connected by a communication bus 210: a processor or CPU (Central Processing Unit) 201; a RAM (Random Access Memory) 202; a ROM (Read Only Memory) 203, 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 204; at least one communication interface 205 allowing the system 101 for monitoring the performance of one or more oil filters to interact in the avionics of the aircraft 100.

[0049] The processor 201 is capable of executing instructions loaded into RAM 202 from ROM 203, external memory (not shown), a storage medium such as an SD card, or a communication network (not shown). When the performance monitoring system 101 for one or more oil filters is powered on, the processor 201 is capable of reading instructions from RAM 202 and executing them. These instructions form a computer program causing the processor 201 to implement the behaviors, steps, and algorithm described herein.

[0050] 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 dedicated machine or component (chip) or a dedicated set of components (chipset), such as an FPGA (Field-Programmable Gated Array) or an ASIC (Application-Specific Integrated Circuit). Generally speaking, the 101 system for monitoring the performance of one or more oil filters comprises electronic circuitry arranged and configured to implement the behaviors, steps, and algorithms described herein.

[0051] Figure 3 schematically illustrates an example of an algorithm for monitoring the performance of an aircraft oil filter. It is executed by the performance monitoring system for one (or more) oil filter(s), which is referenced as 101 in Figure 1. In the following description, the performance monitoring of a single oil filter is considered.

[0052] In a step 301, the system 101 acquires (301), at one or more predetermined measurement instant(s), a measured temperature value V_TOIL and a measured differential pressure value V_OFDP of the oil passing through the oil filter, which are measured by the sensors (temperature sensor and pressure sensor) differential) and form a pair of measured values ​​(V_TOIL, V_OFDP). The measurement instant(s) (also called "time stamp value(s)") belong(s) to a time zone of study (also called "stabilized zone").

[0053] In one embodiment, the time zone under study comprises one or more time sub-zones under study defined according to one or more of the following criteria: - a criterion based on a flight phase parameter of the aircraft (the value taken by this parameter, at a measurement instant, is noted "V_FLIGHT_PHASE"); - a criterion based on an aircraft altitude parameter (the value taken by this parameter at a given measurement time is denoted "V_ALTITUDE"); and - a criterion based on a speed parameter N2 of rotation of a high pressure rotor of an aircraft engine (as already discussed above, the value taken by this parameter, at a measurement instant, is noted "V_N2").

[0054] In a particular implementation, the time zone under study includes the measurement times for which the following three criteria are met: - V_FLIGHT_PHASE = 6, this value of 6 indicates that the aircraft is in a cruise phase; Rolling_Max (V_ALTITUDE) - Rolling_Min (V_ALTITUDE) <= 50ft; and Rolling_Max (V_N2) - Rolling_Min (V_N2) <= 5%;

[0055] with the Rolling_Max(X) function and the Rolling_Min(X) function returning respectively the maximum value and the minimum value of a parameter X over a sliding window (for example of 120s).

[0056] In a step 302, the system 101 estimates, for the measurement instant or instant, a reference value of differential pressure V_OFDP_REF, using a prediction model and the measured value of temperature V_TOIL.

[0057] In one embodiment, the prediction model is a polynomial law aimed at approximating pairs of values, comprising a measured temperature value V_TOIL and a measured differential pressure value V_OFDP, measured at predefined measurement times during flights preceding a current flight, and expressing a reference value of oil differential pressure V_OFDP_REF as a function of the oil temperature.

[0058] The polynomial law is written for example: V_OFDP_REF = f (V_TOIL).

[0059] It is determined in a preliminary phase of developing the prediction model, by processing a large amount of flight data from one or more aircraft. It can then be used in step 302 of the present algorithm (illustrated in [Fig. 3]) for monitoring the performance of an aircraft oil filter.

[0060] In a step 303, the system 101 calculates, for each measurement instant at which a given pair of measured values ​​(V_TOIL, V_OFDP) is measured, a comparison value V_COMP between the measured value of differential pressure V_OFDP and the reference value of differential pressure V_OFDP_REF (provided by the polynomial law for the temperature value V_TOIL of the given pair of measured values).

[0061] In a step 304, the system 101 determines an indicator forming value V_INDIC, based on the comparison values ​​V_COMP calculated for the different measurement times.

[0062] In a step 305, the system 101 performs a normalization of the indicator forming value V_COMP, in order to obtain a normalized indicator forming value V_INDIC_NORM.

[0063] In a step 306, the system 101 detects whether an alert triggering condition, based on the normalized indicator value V_INDIC_NORM, is verified, and if so proceeds to step 307 in which it triggers an alert, otherwise returns to step 301. The alert is associated with a preventive maintenance operation relating to the oil filter, and indicates, for example, a state of filter clogging and, if applicable, whether the filter is in an advanced state of clogging.

[0064] In one embodiment, the system 101 acquires values ​​at a single measurement instant, and thus acquires a single pair of measured values ​​(V_TOIL, V_OFDP). Then, for this single measurement instant, the system 101 estimates (in step 302) a single differential pressure reference value V_OFDP_REF and then calculates (in step 303) a single comparison value V_COMP. In this embodiment, steps 304 and 305 are omitted, and in step 306 the system 101 detects whether an alert triggering condition, based on the single comparison value V_COMP (possibly normalized), is met.

[0065] The alert triggering condition is, for example, the fact that an average of the last N normalized indicator values ​​is greater than a threshold value, with N > 2. In this case, the normalized indicator value V_INDIC_NORM resulting from the execution of steps 301 to 305 is used, with the "average" operator, jointly with the Nl previous values ​​resulting from the Nl previous iterations of the same steps 301 to 305 (i.e. for the Nl previous time zones of study).

[0066] In one variant, the 101 system manages two alert levels (for example, alerts sent to an Electronic Centralized Aircraft Monitor (ECAM) system to inform the crew and / or the airline), each with a different alert threshold. In other words, if the (first) alert triggering condition of the stage 306 is not checked, system 101 does not return to step 301 but goes to a step (not shown) in which it detects if a second alert triggering condition (also a function of the normalized indicator forming value V_INDIC_NORM, but with a different threshold value) is checked, and if so goes to a step (not shown) in which it triggers a second alert, otherwise returns to step 301.

[0067] Thus, it is possible to trigger different types of alerts (two in the embodiment presented above, but in variations there can be more than two) depending on the value of the indicator V_INDIC_NORM and therefore on the severity level (risk level). Each type of alert can be associated with preventive maintenance operations that are adapted to the risk level of the alert in question. For example, the interval within which the oil filter should be replaced is shorter the higher the risk level.

[0068] In one variant, the normalization step 305 is omitted and therefore the triggering condition (checked in step 306) is a function of the value forming indicator V_COMP. First specific implementation

[0069] We now present a first particular implementation of the algorithm of [Fig.3],

[0070] In a preliminary phase, not shown and carried out before the algorithm in [Fig. 3], the prediction model is developed by processing a large amount of data relating to past flights by one or more aircraft. As illustrated in [Fig. 4], for pairs of values ​​(V_TOIL, V_OFDP) measured at times within the time periods of the study, which fall within the time periods of past flights by one or more aircraft, the differential pressure values ​​V_OFDP are sorted according to their associated temperature values ​​V_TOIL (i.e., of the same pair). Next, for each range of oil temperature values ​​with a width of 2°C (see for example the range referenced 402), an average value of the differential pressure values ​​V_OFDP is calculated (see for example the average differential pressure value V_OFDP, referenced 401, for the temperature range referenced 402).Finally, the polynomial distribution (referenced as 403) is defined by a polynomial regression.

[0071] In an execution phase of the algorithm in [Fig.3] (algorithm for monitoring the performance of an aircraft oil filter), the prediction model (previously developed as detailed above) is used in step 302 by the system 101 in order to estimate, for each measurement instant, a reference value of differential pressure V_OFDP_REF.

[0072] Then, in step 303, the calculation of a comparison value V_COMP includes, for each measurement instant at which a given pair of measured values ​​(V_TOIL, V_OFDP) is measured, a calculation of a difference DELTA between the measured value of differential pressure V_OFDP and the reference value of differential pressure V_OFDP_REF (provided by the polynomial law for the measured temperature value V_TOIL):

[0073] DELTA = V_OFDP_REF - V_OFDP.

[0074] In step 304, the indicator value V_INDIC is the differential pressure value V_OFDP of the couple whose values ​​(V_TOIL, V_OFDP) were measured at the measurement instant for which the calculated deviation DELTA is minimal. Second particular implementation

[0075] A second particular implementation of the algorithm in [Fig.3] is now presented. This differs from the first particular implementation presented above in that the N2 velocity values ​​are also used to calculate the polynomial distribution.

[0076] It is recalled that at each measurement instant, included in the time zone of study, a temperature value V_TOIL, a differential pressure value V_PFDP and a velocity value N2 V_N2 are measured, forming a triplet of measured values.

[0077] Again, in a preliminary phase, not shown and executed before the algorithm in [Fig. 3], the prediction model is developed by processing a large amount of data relating to past flights by one or more aircraft. In this second particular implementation, the polynomial distribution aims to approximate triplets of values ​​(V_TOIL, V_PFDP, V_N2) measured at times within the time periods of the study, which are included in the time periods of past flights by one or more aircraft. It expresses a reference value of the oil differential pressure V_OFDP_REF as a function of the oil temperature (V_TOIL) and the velocity N2 (V_N2).

[0078] In an execution phase of the algorithm of [Fig.3] (algorithm for monitoring the performance of an aircraft oil filter), the prediction model (previously developed as detailed above) is used in step 302 by the system 101 in order to estimate, for each measurement instant, a reference value of differential pressure V_OFDP_REF.

[0079] Then, in step 303, the calculation of a comparison value V_COMP includes, for each measurement instant at which a given triplet of measured values ​​(V_TOIL, V_OFDP, V_N2) is measured, a calculation of a ratio RATIO between the measured value of differential pressure V_OFDP and the reference value of differential pressure V_OFDP_REF (provided by the polynomial law for the measured value of temperature V_TOIL and the measured value of velocity N2 V_N2):

[0080] RATIO = V_OFDP / V_OFDP_REF

[0081] In step 304, the indicator forming value V_INDIC is the median value RATIO_MEDIAN of the RATIO ratios calculated for the different measurement times.

[0082] In step 305, the normalization of the indicator forming value V_INDIC includes, in order to obtain the normalized indicator forming value V_INDIC_NORM, a multiplication:

[0083] - of the value forming the indicator V_INDIC,

[0084] - by the differential pressure reference value V_OFDP_REF provided by law polynomial for an oil temperature V_TOIL_MEDIAN (equal to a median value of temperature values ​​V_TOIL measured during flights made in the past by one or more aircraft) and for a speed N2 V_N2_MEDIAN (equal to a median value of speed values ​​N2 V_N2 measured during flights made in the past by one or more aircraft).

[0085] Thus, with such normalization, the metric returned (V_INDIC_NORM) by the algorithm relates to differential pressure values ​​observable on an oil filter. This metric is therefore more understandable to maintenance personnel who read it and receive alerts.

Claims

Demands

1. A method for monitoring the performance of an oil filter of an aircraft (100), the aircraft being equipped with a temperature sensor and a differential pressure sensor providing respectively measured values ​​of temperature and measured values ​​of differential pressure of the oil passing through the oil filter, the method being implemented by an oil filter performance monitoring system (101) in the form of electronic circuitry, the method comprising: - at at least one predetermined measurement instant, acquiring (301) a measured value of temperature and a measured value of differential pressure of the oil passing through the oil filter; - estimating (302), for the measurement instant(s), a reference value of differential pressure, using a prediction model and the measured temperature value;- calculate (303), for the measurement instant(s), a comparison value between the measured differential pressure value and the reference differential pressure value; and - trigger (307) an alert if a triggering condition (306), based on the comparison value(s) calculated for the measurement instant(s), is met.

2. A method according to claim 1, wherein the prediction model is a polynomial law aimed at approximating pairs of values, comprising a measured value of temperature and a measured value of differential pressure, measured at predefined measurement times during flights preceding a current flight, and expressing a reference value of differential oil pressure as a function of oil temperature.

3. A method according to any one of claims 1 and 2, wherein at least two comparison values ​​are calculated, for at least two measurement times, wherein the method further comprises: determining (304) an indicator form value, as a function of the at least two calculated comparison values, and wherein the triggering condition is a function of the indicator form value.

4. A method according to claim 3, comprising a normalization (305) of the indicator forming value, in order to obtain a normalized indicator forming value, and wherein the triggering condition (307) is a function of the normalized indicator forming value.

5. A method according to any one of claims 3 and 4, wherein the operations (301 to 305) prior to triggering an alert and resulting in the determination of an indicator value are iterated N times, for N successive flights, with N > 2, in order to obtain N indicator values, and wherein the triggering condition (306) is that an average of the N indicator values ​​is greater than a threshold value.

6. A method according to any one of claims 3 to 5, wherein the calculation (303) of a comparison value comprises, for each measurement instant, a calculation of a difference between the measured value of differential pressure and the reference value of differential pressure, and wherein the indicator value is the differential pressure value measured at the measurement instant for which the calculated difference is minimal.

7. A method according to any one of claims 3 to 5, wherein the aircraft (100) is further equipped with a speed sensor N2 providing N2 speed values ​​of rotation of a high-pressure rotor of an aircraft engine, wherein a measured speed value N2 is also acquired at each measurement instant, wherein the estimation (302), for each measurement instant, of a differential pressure reference value using the prediction model and the measured temperature value, is also performed using the measured speed value N2, wherein the calculation (303) of a comparison value comprises, for each measurement instant, a calculation of a ratio between the measured differential pressure value and the differential pressure reference value, and wherein the indicator value (304) is the median value of the ratios calculated for the at least two instants of measure.

8. Product computer program, comprising instructions causing a processor (201) to execute the method according to any one of claims 1 to 7, when said instructions are executed by the processor.

9. System (101) for monitoring the performance of an oil filter of an aircraft (100), the aircraft being equipped with a temperature sensor and a differential pressure sensor providing respectively measured values ​​of temperature and measured values ​​of differential pressure of the oil passing through the oil filter, the monitoring system comprising electronic circuitry configured to implement: - at at least one predetermined measurement instant, acquire (301) a measured value of temperature and a measured value of differential pressure of the oil passing through the oil filter; - estimate (302), for the or each measurement instant, a reference value of differential pressure, by means of a prediction model and the measured value of temperature;- calculate (303), for the measurement instant(s), a comparison value between the measured differential pressure value and the reference differential pressure value; and - trigger (307) an alert if a triggering condition (306), based on the comparison value(s) calculated for the measurement instant(s), is met.

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