Device for monitoring vibrations of mechanical powertrain of aircraft engine

Abstract

One aspect of the invention relates to a device 100 for monitoring vibrations of a mechanical powertrain in an aircraft engine, the device comprising a first accelerometer 101 adapted to continuously measure a first vibration signal when the first accelerometer 101 is in operation; the housing 106 comprises a processing unit 103 configured to: acquire a first vibration signal for a predetermined time period and store the measured first vibration signal; calculating a speed N2 according to the collected and stored first vibration signal; identifying a first event based on the speed N2; after the first event is identified, a storage of the speed N2, the stored first vibration signal, and the timestamp associated with the speed N2 is indicated, where the storage occurs in the memory 107, and after the second event is identified, the first accelerometer 101 is activated.

Description

Technical Field

[0001] The technical field of this invention is vibration monitoring, especially vibration monitoring of aircraft engines.

[0002] This invention relates to a vibration monitoring device, and more particularly to a vibration monitoring device for a mechanical power transmission system of an aircraft engine. The invention also relates to a vibration monitoring method implemented by this vibration monitoring device. Background Technology

[0003] Health monitoring of aircraft engines is crucial for ensuring passenger safety during flight. For example, excessive vibration excitation in an engine can cause damage, such as cracking or breakage of engine components due to vibration fatigue. Therefore, monitoring the operating condition of engine bearings is a common practice. Patent EP1367226B1, entitled "Method and system for detecting damage to an aircraft engine rotor," is an example of such a monitoring method. Indeed, experience shows that these components are particularly susceptible to degradation during the engine's service life. Bearings, consisting of ball or roller bearings, support shafts that connect the compressor to the turbine, which are mounted on the fixed structure of a turbojet engine.

[0004] Therefore, aircraft engine health monitoring is performed using a vibration monitoring system, which includes a health monitoring box and vibration sensors specifically designed for this task. This system is permanently located on the engine; that is, its position on the engine is permanent. Typically, two vibration sensors are used to monitor the engine bearings. The locations of the vibration sensors are defined during the engine design phase. The health monitoring box records and analyzes the vibration characteristics from the sensors to assess the aircraft engine's health condition. Given the critical nature of the task performed by the vibration monitoring system, the health monitoring box is developed with a high level of safety, namely DAL (Design Assurance Level) C, and sometimes even DAL A.

[0005] Sometimes, additional vibration measurements can be expected after engine commissioning. For example, when an incident occurring during flight indicates a risk related to the health of the aircraft engine, adding sensors to obtain these additional vibration measurements would be useful. Currently, there are many drawbacks to adding new vibration sensors after engine commissioning because their installation is not planned during the design phase. For example, adding a new vibration sensor would require modifying the health monitoring box interface to connect the new sensor. Adding a new vibration sensor would also require updating the health monitoring box software to process this data. Therefore, adding new sensors would necessitate modifying the operation of critical components such as the health monitoring box after the design phase. This could have a significant impact on the engine and reduce its overall reliability. Finally, it would also increase the development time of the health monitoring box software and increase aircraft downtime. Therefore, in practice, due to too many drawbacks, additional sensors are generally not installed on engines already in service.

[0006] Therefore, there is a need for a vibration monitoring device that does not have the above-mentioned disadvantages or at least limits the above-mentioned disadvantages. Summary of the Invention

[0007] This invention provides a solution to the problems previously discussed by offering a device for monitoring aircraft engines. The device monitors the aircraft engine by additionally measuring vibration signals from the engine's mechanical power transmission system. These measurements are further processed by the device's processing unit to automatically control data storage. This data can then be used, for example, by ground personnel to identify potential faults affecting the aircraft engine, thereby repairing the engine components associated with the fault.

[0008] One aspect of the present invention relates to a vibration monitoring device for a mechanical power transmission system of an aircraft engine, comprising:

[0009] - A first accelerometer adapted to continuously measure a first vibration signal while performing the first accelerometer;

[0010] - A housing, which includes a processing unit configured to:

[0011] - Acquire and store the measured first vibration signal during a predetermined time period;

[0012] - Calculate the set value N2 based on the first vibration signal that has been collected and stored;

[0013] - Identify the first event based on the set value N2;

[0014] - When the first event is identified, the control setpoint N2, the stored first vibration signal, and the timestamp associated with the setpoint N2 are stored in the memory.

[0015] - When the second event is identified, the first accelerometer is activated.

[0016] According to the present invention, aircraft engines can be monitored by obtaining additional vibration measurements, namely, additional vibration measurements of the mechanical power transmission system of the aircraft engine in addition to the measurements provided by vibration sensors permanently installed on the aircraft engine. Furthermore, the device is modular, meaning it can be considered an add-on module that can be added to or removed from the engine after it has been commissioned, without degrading engine operation or overall reliability. In fact, the components of the device according to the invention can be mounted on and removed from the aircraft engine. Therefore, the housing and accelerometer of the device are modules that can be mounted on and removed from the aircraft engine. Moreover, the presence and operation of the components of the device according to the invention do not affect the operation of the aircraft engine, as the device operates autonomously and independently relative to other engine components. The device is particularly autonomous and independent in terms of vibration measurement and calculations based on these vibration measurements. Specifically, it does not require connection to a health monitoring box. Finally, the device can be used both on the ground, for example when the aircraft is parked on the ground or the engine is on a test bench, and in flight, i.e., when the engine is running.

[0017] In addition to the features just discussed in the preceding paragraphs, the apparatus according to one aspect of the invention may also have one or more of the following additional features, which can be considered individually or in all possible combinations:

[0018] - The first accelerometer has the first power consumption;

[0019] The housing also includes a second accelerometer adapted to measure a second vibration signal and having a second power consumption lower than that of the first accelerometer.

[0020] - The processing unit is also configured to identify a second event based on the second vibration signal;

[0021] The housing also includes a battery adapted to power the first accelerometer, the second accelerometer, the processing unit, and the memory.

[0022] The device also includes a noise-reducing cable that connects the housing to the first accelerometer and is adapted to transmit vibration signals measured by the first accelerometer to the housing.

[0023] - Measure the second vibration signal at fixed intervals between 1 and 20 seconds;

[0024] - The predetermined time period for the processing unit to collect and store the first vibration signal is between 30 and 120 seconds.

[0025] - The second event is the aircraft engine start-up phase, while the first event is the aircraft engine operating mode from the following:

[0026] -Aircraft engine start-up phase

[0027] -End of the aircraft engine start-up phase

[0028] - Gliding phase

[0029] -Takeoff phase

[0030] - The peak of the ascent phase

[0031] - Cruise setting phase

[0032] - The peak of the descent phase, and

[0033] - Aircraft engine shutdown phase.

[0034] A second aspect of the invention relates to an aircraft engine comprising a vibration monitoring device and a mechanical power transmission system according to the invention. In one example, a first accelerometer of the device according to the invention is positioned in the middle portion of the mechanical power transmission system, and the housing of the device according to the invention is located at the fan casing of the aircraft engine.

[0035] A third aspect of the invention relates to an aircraft comprising an engine according to the invention.

[0036] A fourth aspect of the present invention relates to a vibration monitoring method for a mechanical power transmission system of an aircraft engine, implemented by an apparatus according to the invention, the method comprising the following steps:

[0037] - When the processing unit identifies the second event, the processing unit implements the first accelerometer reading;

[0038] -The first vibration signal is measured by the first accelerometer;

[0039] - The processing unit acquires and stores the first vibration signal over a predetermined duration; and

[0040] - Calculate the set value N2 based on the first vibration signal collected and stored by the processing unit;

[0041] - When the processing unit identifies the first event based on the calculated setpoint N2, it controls the storage of the calculated setpoint N2, the first vibration signal acquired and stored, and the timestamp associated with the setpoint N2 in the memory.

[0042] In addition to the features just discussed in the preceding paragraphs, the vibration monitoring method according to one aspect of the invention may also have one or more of the following additional features, which may be considered individually or in all possible combinations:

[0043] - This method is implemented by a device, wherein:

[0044] - The first accelerometer has the first power consumption;

[0045] The housing also includes a second accelerometer adapted to measure a second vibration signal and having a second power consumption lower than that of the first accelerometer; and

[0046] The processing unit is also configured to identify a second event based on the second vibration signal.

[0047] The method also includes an initial step of measuring a second vibration signal by a second accelerometer.

[0048] A better understanding of the invention and its various applications will be gained after reading the following description and interpreting the accompanying drawings. Attached Figure Description

[0049] The accompanying drawings are for illustrative purposes and not for limiting the scope of the invention.

[0050] - Figure 1 A schematic representation of an example of a vibration monitoring device according to the present invention is shown.

[0051] - Figure 2 A block diagram illustrating an example of a vibration monitoring method according to the present invention is shown.

[0052] - Figure 3 A schematic representation of an example of placing an accelerometer included in a vibration monitoring device according to the invention on the mechanical power transmission system of an aircraft engine is shown. Detailed Implementation

[0053] Unless otherwise stated, the same element appearing in different figures has the same reference numeral.

[0054] Figure 1 A schematic representation of an example of a vibration monitoring device 100 according to the present invention is shown.

[0055] Device 100 enables vibration monitoring of the mechanical power transmission system of an aircraft engine. For example, device 100 can be used to monitor the vibration behavior of an aircraft engine's accessory gearbox (commonly referred to as AGB) or reduction gearbox (commonly referred to as RGB). Therefore, when the device monitors AGB or RGB, it allows monitoring of the gears and bearings (such as...) of these systems. Figure 3 As illustrated in the diagram (where AGB is designated as 300), these gears and bearings may generate high levels of vibration. Furthermore, by monitoring the vibration behavior of the aircraft engine's mechanical power transmission system, device 100 can detect anomalies in the system's vibration behavior before system failure occurs. For example, using this invention, device 100 can detect anomalies in the vibration behavior of the mechanical power transmission system at least 60 flights before system failure occurs.

[0056] Device 100 includes a housing 106. Housing 106 is, for example, a machined aluminum housing that withstands the environmental conditions of an aircraft engine. The housing contains two compartments. The first compartment contains electronic components, while the second compartment contains only the battery. The existence of these two separate compartments fulfills the need for physical separation between the battery and electronic equipment for flight safety reasons. For example, the compartment containing the battery can be physically separated from the compartment containing the electronic components. Therefore, in the event of electrochemical leakage from the battery, the electronic components will not deteriorate. The housing is adapted to house a processing unit 103 and a memory 107. In an exemplary embodiment, housing 106 may also contain the battery. The housing is enclosed. Therefore, all components within the housing are protected from the external environment, such as from ambient temperature. The surface of the housing may have ports for cables to pass through. The surface of the housing may also have a USB port (Universal Serial Bus). In one example, the housing is shaped like a cuboid, 137 mm long, 99 mm wide, and 35.5 mm thick.

[0057] The device 100 includes a first accelerometer 101. The first accelerometer 101 is located outside a housing 106. The first accelerometer 101 can be attached to the aircraft engine assembly to be monitored by adhesive or using one or more screws. The first accelerometer 101 continuously (i.e., uninterruptedly) measures a first vibration signal. This continuous measurement is performed only when the first accelerometer 101 is in operation. The term "in operation" in this application means that the first accelerometer is in operation, or in other words, activated. Therefore, when the first accelerometer is not in operation, it is in standby or even off, i.e., not powered. In this case, the first accelerometer does not perform measurements of the first vibration signal. In one example, the first accelerometer measures a first vibration signal at a high frequency (i.e., a frequency between 1 and 50,000 Hz, for example, 32,768 Hz). In an example compatible with the foregoing example, the first accelerometer 101 is a piezoelectric accelerometer. The first accelerometer 101 can be connected to the housing 106, for example via cable 109 or any other means, enabling it to transmit the data of the first measured vibration signal to the housing 106, or more precisely, to the various components included in the housing.

[0058] In a preferred embodiment compatible with the foregoing example, the first accelerometer 101 is connected to the housing 106 via a noise-reducing cable 109. The noise-reducing cable 109 allows the vibration signal measured by the first accelerometer 101 to be transmitted to the housing 106, and more precisely, to the various components contained within the housing. The noise-reducing cable 109 may be, for example, heat-resistant, capable of withstanding temperatures up to 150°C or even 300°C. To avoid interference from parasitic signals, the cable comprises two conductors. Furthermore, the conductors are twisted together and then covered with a shielding braid and a sheath covering the shielding braid. Using the noise-reducing cable 109 limits the interference effects on the signal transmitted through it.

[0059] The housing 106 of the device 100 also includes a processing unit 103. The processing unit 103, placed within the housing 106, is configured to acquire a first vibration signal during a predetermined time period and store the first vibration signal acquired during the predetermined time period. In other words, the processing unit 103 is configured to acquire a first vibration signal during a predetermined time period, and the processing unit 103 is also configured to store the acquired first vibration signal. In this application, the term "configured as" means that the processing unit has been "programmed as". In other words, the term "configured as" means that the processing unit is adapted to perform one or more operations to carry out a task, possibly in a fully automatic or semi-automatic manner. The processing unit may include one or more processors, preferably two processors. The processing unit may also include one or more memory units, preferably four memory units.

[0060] In one example, the predetermined time period for acquiring and storing the first vibration signal is between 30 and 120 seconds, preferably 60 seconds. Then, the processing unit 103 uses this first vibration signal to calculate a setpoint N2. The setpoint N2 corresponds to the rotational speed of the high-pressure shaft of the aircraft engine. French patent application FR2300770, entitled "Determination of a mean carrier frequency of a pseudo-periodic signal," discloses an example of a method for obtaining the setpoint N2 of an aircraft engine based on a first vibration signal. This invention relates to a method for determining a pseudo-periodic signal within a period T. A method for averaging carrier frequency, implemented by a calculator, includes:

[0061] - Receive the signal sampled within period T The sample, the signal is related to the physical quantity associated with the system;

[0062] - Using an iterative search mechanism, by adjusting the resampling frequency For signal Perform resampling to construct the stretch signal The resampling frequency It varies within a period T and depends on the signal. The change in carrier frequency during period T stretches the signal. Relative to signal Oversampling was performed;

[0063] - By stretching the signal The average carrier frequency is determined by comparing it with one or more reference signals.

[0064] Processing unit 103 is also configured to identify a first event based on a setpoint N2. "Identifying an event based on a setpoint N2" means "identifying an event from a set of predefined events based on a setpoint N2." For example, the event might correspond to a rising or falling peak in the setpoint N2, which can be detected by observing whether the rising or falling edge of the setpoint N2 reaches a predefined threshold. When the first event is identified, processing unit 103 sends a control signal to store the data in memory 107. Memory 107 is also located in housing 106. For example, memory 107 can store up to 32 gigabits of data. Limiting the size of memory 107 allows for limiting its power consumption.

[0065] The data stored in memory 107 after the processing unit 103 sends a signal includes the calculated setpoint N2. The stored data also includes a first vibration signal used to perform the calculation of the setpoint N2, i.e., a first vibration signal collected and stored by the processing unit 103 during a predetermined time period. The term "stored" means that the data (here, the first vibration signal) is put into memory by the processing unit 103. Finally, the data stored in memory 107 includes a timestamp associated with the setpoint N2, such as the time when the calculation of the setpoint N2 was performed. Furthermore, the collected data can be partially stored depending on the nature of the first event and / or the second event. For example, storage can be performed for 20% to 80% of the collected dataset. In other words, for 120 seconds of collected data, only 30 to 120 seconds of data can be stored. In an example compatible with the foregoing example, the processing unit 103 includes two processors. When the processing unit includes two processors, the first and second processors operate in parallel using a sliding window. In fact, when the first processor acquires and stores the first vibration signal within time period T, the second processor calculates the setpoint N2 based on the first vibration signal acquired and stored within the previous time period T-1, where time period T-1 is the time period preceding time period T, for example, time period T-1 immediately preceding time period T. For time period T+1, which is the time period following time period T, the first processor acquires and stores the first vibration signal within time period T+1, while the second processor calculates the setpoint N2 based on the first vibration signal acquired and stored within time period T. Therefore, the calculated setpoint N2 allows the first vibration signal to be correlated with the degree of engagement of various parts of the monitored mechanical transmission system, thereby detecting abnormal vibration behavior. Furthermore, the presence of these two processors allows for uninterrupted acquisition and storage of the first vibration signal while simultaneously performing the calculation of the setpoint N2 based on that first vibration signal. If the first event is not identified based on the setpoint N2, the second processor does not send a control signal, and therefore no data is stored in memory 107.

[0066] In an example compatible with the foregoing example, the first event identified corresponds to an aircraft engine operating mode. For example, the first event identified is an aircraft engine operating mode from one of the following:

[0067] -Aircraft engine start-up phase;

[0068] - The end of the aircraft engine start-up phase;

[0069] - Taxiing phase, which corresponds to the time when the aircraft is taxiing on the ground;

[0070] -take off;

[0071] - The peak of the climb phase, which corresponds to the transition between the ascent phase and the cruise setting phase of flight, that is, the moment when the planned climb to cruise altitude is completed;

[0072] - Cruise setting phase;

[0073] - The peak of the descent phase, corresponding to the transition between the flight's cruise setting phase and the descent phase, or the moment when the planned descent begins at the final approach altitude; and

[0074] - Aircraft engines shut down.

[0075] This identification of the first event can be performed using the method disclosed in French patent application FR2210673 entitled "Method for detecting the operating mode of a rotating machine, especially for an aircraft in flight". Therefore, for a 10-hour flight, in this example, the time spent measuring the first vibration signal and calculating the setpoint N2 can be limited to a few minutes, for example, 5 minutes.

[0076] Processing unit 103 is configured to activate the first accelerometer 101 when a second event is identified. Therefore, processing unit 103 controls the activation and standby mode of the first accelerometer 101, or even disables it. This activation is performed when the second event is identified. The second event can be of different types. For example, the second event can be a user interaction, such as pressing a button on a user interface to control the recording of a first vibration signal.

[0077] In an example compatible with the foregoing example, device 100 may further include a second accelerometer 102. The second accelerometer 102 may be placed inside or outside housing 106. The second accelerometer 102 is configured to measure a second vibration signal. This second vibration signal can be used to identify a second event. It should be noted that the identification of the second event is a condition for processing unit 103 to perform the identification of the first accelerometer 101. Processing unit 103 performs the identification of the second event based on the second vibration signal. In an example compatible with the foregoing example, the second event is the aircraft engine start-up phase. The identification of this second event may include identifying a time period within a predetermined duration during which the second vibration signal is greater than a predetermined vibration level threshold.

[0078] In the foregoing example, the second accelerometer 102 may have a lower power consumption than the first accelerometer 101. Various characteristics affect the power consumption of an accelerometer, such as the sampling frequency and the accelerometer's lifespan. For example, the second accelerometer has a power consumption of less than or equal to 45 microamps (denoted as μA) in "measurement" mode and less than or equal to 0.1 μA in "standby" mode. Therefore, since the first accelerometer 101 is only activated when a second event is identified based on the measurement of the second vibration signal performed by the second accelerometer 102, the power consumption of the device 100 is optimized. In an example compatible with the foregoing example, the measurement of the second vibration signal is performed at fixed intervals between 1 and 20 seconds. Preferably, the second vibration signal is measured every 5 seconds.

[0079] In an example compatible with the foregoing example, housing 106 also includes an attachment member for placing housing 106 onto an aircraft engine assembly. In one example, this attachment member allows housing 106 to be placed onto an aircraft engine assembly while maintaining a distance between the surface closest to the housing and the surface of the engine assembly to which the housing is attached, for example, between 10 and 100 mm, preferably 30 mm. This distance also allows for maintaining an air gap to insulate housing 106 from temperature variations in the aircraft engine assembly. This attachment member, like those used for attaching the first accelerometer 101, is adapted to the environmental constraints of the aircraft engine, particularly temperature and vibration constraints. For example, the attachment member for housing 106 may include screws that allow housing 106 to be placed quickly (i.e., within a maximum of 20 minutes) onto the aircraft engine assembly. For example, housing 106 may be attached to a bracket permanently attached to the aircraft engine. As for the attachment member for the first accelerometer 101, similar members to those used for attaching housing 106 may be used. Therefore, device 100 can be plug-and-play.

[0080] In an example compatible with the foregoing example, housing 106 also includes a battery 108. This battery 108 provides the power necessary for the operation of the various components of device 100. Thus, battery 108 provides the power necessary for the operation of the first accelerometer 101, processing unit 103, and memory 107. When a second accelerometer 102 is included in device 100, battery 108 can also power it. Therefore, device 100 achieves energy self-sufficiency sufficient to ensure its operation. For example, battery 108 is adapted to operate in a temperature range of -55°C to 90°C. Furthermore, to meet fire safety requirements, for example, a battery pack containing lithium batteries can be used. The lithium batteries are insulated between them by a special coating to contain fluids. This battery pack can also be encapsulated in a stainless steel case and placed within a compartment in housing 106, physically isolated from the compartments of housing 106 containing other components.

[0081] In an alternative to the aforementioned example, the energy required for operating device 100 and all its components can be supplied by a piezoelectric or thermoelectric energy recovery device.

[0082] In an example compatible with the foregoing example, housing 106 also includes components for transmitting data stored in memory 107 to a ground maintenance station. The transmitted data may include all or part of the data stored in memory 107. Preferably, the transmission component (such as a USB connector) allows all data to be transmitted within a timeframe of no more than 15 minutes (preferably no more than 10 minutes). For this purpose, the transmission component has a data rate suitable for transmitting the dataset within the allocated time. For example, the transmission may be performed via a wired connection and / or via a wireless connection. Furthermore, this transmission can be performed independently of other communication systems on the aircraft.

[0083] In an example compatible with the foregoing example, the mass of housing 106 and the assembly of components included in housing 106 is less than 1% of the mass of the aircraft engine fan casing monitored by device 100. For example, the mass of housing 106 is less than or equal to 800 grams, preferably less than or equal to 700 grams. Therefore, device 100 does not affect the overall dynamic performance of the aircraft engine when the aircraft engine is in operation.

[0084] A second aspect of the invention relates to an aircraft engine comprising:

[0085] -The device 100 according to the invention, and

[0086] -Mechanical power transmission system.

[0087] For example, the housing 106 of the device 100 can be placed on the casing of the fan of the aircraft engine, and the first accelerometer 101 of the device 100 can be placed in the middle part of the mechanical power transmission system of the engine. Figure 3 The illustration shows an example of placing the first accelerometer 101 of the device 100 in the middle part of the AGB 300.

[0088] Figure 2 This is a block diagram illustrating the steps of an example vibration monitoring method 200 according to the present invention. Necessary steps of the example method 200 are indicated by solid rectangles, while optional steps are indicated by dashed rectangles.

[0089] Vibration monitoring method 200 for mechanical power transmission system of aircraft engine is implemented by vibration monitoring device 100.

[0090] In one example where the device 100 includes a second accelerometer 102, an optional first step 201 of method 200 may include measuring a second vibration signal by the second accelerometer 102.

[0091] When processing unit 103 identifies the second event, it executes the second step 202 of method 200. This second step 202 includes the processing unit 103 implementing the first accelerometer 101. In one example, while step 201 has been executed, the identification of the second event can be based on a second vibration signal.

[0092] The third step 203 of method 200 includes measuring a first vibration signal by the first accelerometer 101. This step 203 is performed when the processing unit 103 performs the first accelerometer reading and therefore when the second event has been identified.

[0093] The fourth step 204 of method 200 includes acquiring a first vibration signal over a predetermined duration. The fourth step 204 also includes storing the acquired first vibration signal.

[0094] The fifth step 205 of method 200 includes calculating a set value N2 based on the first vibration signal acquired and stored by the processing unit 1031.

[0095] When the processing unit 103 identifies the first event, the sixth step 206 of method 200 is executed. The first event is identified based on a calculated setpoint N2. The sixth step 206 includes sending a control signal to store the calculated setpoint N2, the first vibration signal acquired and stored by the processing unit 103, and a timestamp associated with the setpoint N2. This storage is performed in memory 107.

Claims

1. A vibration monitoring device (100) for a mechanical power transmission system of an aircraft engine, comprising: - A first accelerometer (101), the first accelerometer having a first power consumption and adapted to continuously measure a first vibration signal when the first accelerometer (101) is implemented; - Enclosure (106), the enclosure comprising: o Second accelerometer (102), the second accelerometer is adapted to measure a second vibration signal and has a second power consumption lower than the first power consumption of the first accelerometer; o Processing unit (103), the processing unit is configured to: - Collect and store the measured first vibration signal within a predetermined time period; - Calculate the set value N2 based on the first vibration signal collected and stored. The set value N2 corresponds to the set value of the rotation of the high-pressure shaft of the aircraft engine. - Identify the first event based on the set value N2; - When the first event is identified, the storage of the control setpoint N2, the stored first vibration signal, and the timestamp associated with the setpoint N2 is performed in the memory (107); - Identify the second event based on the second vibration signal; and - When the second event is identified, the first accelerometer (101) is activated.

2. The apparatus (100) according to claim 1, wherein: - The first accelerometer (101) has the first power consumption; The housing (106) also includes a second accelerometer (102), the second accelerometer being adapted to measure a second vibration signal and having a second power consumption lower than the first power consumption of the first accelerometer; and The processing unit (103) is also configured to identify a second event based on a set value N2.

3. The device (100) according to claim 2, wherein the housing (106) further comprises a battery (108) adapted to supply power to: - First accelerometer (101) and second accelerometer (102); - Processing unit (103); and -Memory (107).

4. The apparatus (100) according to claims 2 to 3, wherein: - Measurements of the second vibration signal were performed at fixed intervals between 1 and 20 seconds, and / or The processing unit (103) collects and stores the first vibration signal for a predetermined period of 30 to 120 seconds.

5. The apparatus (100) according to any one of claims 2 to 4, wherein the second event is the aircraft engine start-up phase, and the first event is from an aircraft engine operating mode of: -Aircraft engine start-up phase; - The end of the aircraft engine start-up phase; - Gliding phase; - Takeoff phase; - The peak of the ascent phase; - Cruise setting phase; - The peak of the descent phase; as well as -Aircraft engine shutdown phase.

6. The device (100) according to any one of the preceding claims further includes a noise reduction cable (109) that connects the housing (106) to the first accelerometer (101) and is adapted to transmit vibration signals measured by the first accelerometer (101) to the housing (106).

7. An aircraft engine comprising a vibration monitoring device (100) according to any one of the preceding claims and a mechanical power transmission system.

8. An aircraft comprising the engine according to the preceding claims.

9. A vibration monitoring method (200) for a mechanical power transmission system of an aircraft engine, implemented by the apparatus (100) according to any one of claims 1 to 7, the method comprising the following steps: - The second vibration signal is measured (201) by the second accelerometer (102); - When the processing unit (103) identifies the second event based on the second vibration signal, the processing unit (103) implements (202) the first accelerometer (101); - The first vibration signal is measured (203) by the first accelerometer (101); - The processing unit (103) acquires and stores (204) the first vibration signal within a predetermined duration; and -Calculate (205) the set value N2 based on the first vibration signal collected and stored by the processing unit (103); When the processing unit (103) identifies the first event based on the calculated set value N2, the set value N2 calculated by the control (206), the first vibration signal collected and stored, and the timestamp associated with the set value N2 are stored in the memory (107) and executed.

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