Device and method for monitoring the life of hydraulic equipment of an aircraft

The invention relates to a device and a method for monitoring the life of at least one hydraulic equipment item of an aircraft subjected to variations in hydraulic pressure in flight.

One field of application of the invention is the maintenance of aircraft, in particular those equipped with turbojets.

In particular, the hydraulic equipment can be a heat exchanger, positioned in the secondary flow as an additional source of cooling for this equipment, in an aircraft turbojet. Such a heat exchanger is known, for example, from document EP-A1 916 399.

The aim of the invention is to obtain a device and a method for monitoring the life of at least one piece of equipment, making it possible to monitor the fatigue of the hydraulic equipment, in order to be able to carry out preventive maintenance on this equipment. Indeed, such preventive maintenance, consisting in monitoring the state of health of the equipment to change or repair it sufficiently early, makes it possible to reduce in-flight failures (in English: In-Flight Shut Down), the rate of forced stopping of the aircraft on the ground (in English: Aircraft On Ground) and the cancellation and delay rate of flights (in English: Delays & Cancellations), this reduction being crucial for the profitability of a turbojet.

To this end, a first object of the invention is a device for monitoring the life of at least one hydraulic equipment item of an aircraft subjected to variations in hydraulic pressure in flight, the device comprising a data reception interface. of measurements representative of the hydraulic pressure of the equipment as a function of the time in flight,

characterized in that the device comprises a processing device, comprising a means for detecting, from the measurement data, a pressure stress of a damaging nature, defined by the fact that the pressure includes an increase in pressure, greater than a threshold determined

damage greater than zero, followed by a decrease in pressure greater than the determined damage threshold,

a means of calculating an amplitude of pressure variation, equal to the maximum of the absolute value of the increase in pressure of the pressure stress of a damaging nature and of the absolute value of the pressure decrease of the pressure stress at damaging character,

a means for projecting the amplitude of pressure variation on a decreasing prescribed damage model curve or decreasing prescribed line of damage model, giving an allowable number of damaging pressure stresses as a function of the variation amplitude of pressure, to determine the admissible number of pressure stresses of a damaging nature corresponding to the amplitude of the pressure variation having been calculated,

a calculation means for calculating a damage potential ratio, equal to a number of reference stresses, determined, divided by the admissible number of pressure stresses of a damaging nature having been calculated, a means for incrementing a cumulative counter of damage potential ratios by the damage potential ratio that has been calculated.

The fatigue wear of the hydraulic equipment of aircraft engines over the hours of operation of the engine is directly linked not only to the number of stresses to which they are subjected but also to the amplitude of the pressure variations during each cycle. The invention thus makes it possible to individually quantify the severity of the stresses of a damaging nature for each flight.

The invention makes it possible to develop aging predictors, allowing the introduction of means dedicated to predictive maintenance.

The cumulative damage ratio, calculated by the meter, makes it possible to estimate the remaining service life of an equipment in operation.

The invention thus enables a statistical verification of the service life observed in service for the hydraulic equipment of the aircraft, a categorization of the aircraft engines fitted with the hydraulic equipment for

know which aircraft fleets and operating conditions generate the most equipment fatigue, and consequently generate the fastest aging of the equipment. The data from the pressure stresses of a damaging nature detected produced by the invention, coupled with information relating to the conditions in which the fleets operate, make it possible to provide estimates as to the aging and the remaining life of the hydraulic equipment, thus allowing the implementation of predictive maintenance.

In the event of quality problems, improper repairs or alterations or use of parts not guaranteed or provided by unofficial sources, the statistical knowledge of the rate of aging of the equipment provided by the use in service of the invention will also facilitate the identification of the fatigue behavior deviation from the reference parts and the detection of anomalies concerning the service life of a piece of equipment.

The invention allows the collection and storage of a very large mass of data relating to the pressure levels actually observed at the level of the hydraulic equipment, which makes it possible to specify as accurately as possible the need for the equipment to be held in future programs.

According to one embodiment of the invention, the monitoring device comprises an estimator for determining the hydraulic pressure of the equipment from values ​​of another hydraulic pressure of another equipment item of the aircraft as a function of time, which are included in the measurement data and which have been measured by a measurement sensor provided on this other equipment.

According to one embodiment of the invention, the processing device comprises an alert means for sending an alert message to the outside, when the accumulation of damage potential ratios of the meter is greater than or equal to one. predefined alert threshold.

A second object of the invention is a method for monitoring the life of at least one hydraulic equipment item of an aircraft subjected to variations in hydraulic pressure in flight, a method in which one receives, during a step of reception on a reception interface of measurement data representative of the hydraulic pressure of the equipment as a function of time in flight,

characterized in that

during a detection step, a processing device, from the measurement data, detects a pressure load of a damaging nature, defined by the fact that the pressure includes an increase in pressure, greater than one determined damage threshold greater than zero, followed by a pressure reduction greater than the determined damage threshold, during a calculation step, the processing device calculates a pressure variation amplitude, equal to the maximum the absolute value of the pressure increase of the damaging pressure load and the absolute value of the pressure decrease of the damaging pressure load,

during a projection step, the pressure variation amplitude is projected by the processing device onto a decreasing prescribed curve of the damage model or decreasing prescribed straight line of the damage model, giving an admissible number of stresses in damaging pressure as a function of the pressure variation amplitude, to determine the admissible number of damaging pressure stresses, corresponding to the pressure variation amplitude having been calculated,

during another calculation step, the processing device calculates a damage potential ratio, equal to a determined number of reference stresses, divided by the admissible number of damaging pressure stresses that have been calculated ,

during a counting step, a cumulative damage potential ratio counter is incremented by the damage potential ratio that has been calculated.

According to one embodiment of the invention, in the event of missing pressure values ​​between present pressure values, which are temporally spaced apart, replacement pressure values ​​varying in a linear fashion between these pressure values ​​are inserted. present.

According to one embodiment of the invention, the measurement data comprise values ​​of another hydraulic pressure of another item of equipment of the aircraft as a function of time, having been measured by a measurement sensor provided on this other item of equipment. before the reception stage,

the method comprising an estimation step, which is subsequent to the receiving step and prior to the detection step and during which the hydraulic pressure of the equipment is estimated by an estimator of the treatment device from values ​​of the other hydraulic pressure of the other equipment of the aircraft.

According to one embodiment of the invention, during an alert step subsequent to the counting step, an alert message is sent to the outside by the processing device, when the accumulation meter damage potential ratios is greater than or equal to a predefined alert threshold.

According to one embodiment, which may be provided for the monitoring device and / or for the monitoring method, the hydraulic equipment comprises a heat exchanger, forming part of a hydraulic circuit for circulating a hydraulic fluid of a turbomachine, the hydraulic circuit being positioned in the secondary gas flow of the turbomachine located between a nacelle and a casing of the turbomachine to cool the hydraulic fluid.

According to one embodiment, which can be provided for the monitoring device and / or for the monitoring method, the determined damage threshold is greater than or equal to 15% of a hydraulic pressure, maximum and nominal of the hydraulic equipment. and is less than or equal to 35% of the hydraulic pressure, maximum and nominal.

According to one embodiment, which can be provided for the monitoring device and / or for the monitoring method, the decreasing prescribed curve of the damage model comprises an exponential or decreasing linear curve, giving the admissible number of pressure stresses of a character. damaging as a function of the pressure variation amplitude.

According to one embodiment, which can be provided for the monitoring device and / or for the monitoring method, the decreasing prescribed curve of the damage model comprises a portion of the decreasing curve, depending on the inverse of the amplitude of variation pressure to give the admissible number of damaging pressure stresses.

The invention will be better understood on reading the description which follows, given solely by way of non-limiting example with reference to the appended drawings, in which:

- Figure 1 schematically shows a longitudinal sectional view of an example of a turbojet, on which is located the equipment that can be subjected to the device and the monitoring method according to the invention,

FIG. 2 diagrammatically represents an example of a hydraulic circuit for lubricating the turbojet engine of FIG. 1, comprising the equipment which can be subjected to the device and to the monitoring method according to the invention,

- Figure 3 schematically shows a perspective view of an example of the equipment that can be subjected to the device and the monitoring method according to the invention according to Figure 1,

FIG. 4 is a diagram schematically showing an example of pressure stresses of a damaging nature, which can be detected by the device and the monitoring method according to the invention,

- Figure 5 is a diagram schematically showing an example of a damage model, giving an admissible number of pressure stress cycles of damaging nature on the abscissa as a function of the amplitude of pressure variation on the ordinate, which can be used by the device and the monitoring method according to the invention,

FIG. 6 represents an example of a flowchart of the monitoring method according to the invention,

- Figure 7 schematically shows an example of the monitoring device according to the invention,

FIG. 8 diagrammatically represents another piece of equipment on which pressure measurements are carried out for the device and the monitoring method according to the invention,

- figure 9 is a diagram schematically showing an example of a pressure cycle, in which data is missing, which can be detected by the device and the monitoring method according to the invention, and - figure 10 is a diagram schematically showing an example of a pressure cycle, which can be detected by the device and the monitoring method according to the invention and in which missing data has been replaced according to an embodiment of the invention.

In FIGS. 1, 2 and 3, hydraulic equipment of an aircraft subjected to variations in hydraulic pressure in flight and to which the invention can be applied can comprise for example a heat exchanger 130, forming part of a hydraulic circuit 100 for circulating a hydraulic fluid used for the in-flight operation of a turbomachine 10 or gas turbine engine assembly 10 of an aircraft such as for example an airplane. The hydraulic circuit 100 is for example positioned in the bypass duct 40 of the secondary gas flow 52 of the turbomachine 10, located between a nacelle 42 and an external part 44 or casing 44 of the central engine 13 of the turbomachine 10, to cool the fluid. hydraulic, and is for example of annular shape.

This example of hydraulic equipment 130 is first described below in more detail with reference to FIGS. 1, 2 and 3.

In Figure 1, the gas turbine engine assembly 10 has a longitudinal axis 11. The gas turbine engine assembly 10 includes a fan assembly 12 and a central gas turbine engine 13. The gas turbine engine assembly 10 includes a fan assembly 12 and a central gas turbine engine 13. The gas turbine engine assembly 10 includes a fan assembly 12 and a central gas turbine engine 13. Central gas 13 comprises a high pressure compressor 14, a combustion chamber 16 and a high pressure turbine 18. The gas turbine engine assembly 10 may also include a low pressure turbine 20. The blower assembly 12 comprises a network of Fan blades 24 extending radially outward from a rotor disc 26. The motor assembly 10 has an intake side 28 and an exhaust side 30.The gas turbine engine assembly 10 also includes a plurality of bearing assemblies (not shown in the figures) used to provide rotary and axial support to the fan assembly 12, to the high pressure compressor 14, to the turbine. high pressure 18 and the low pressure turbine 20, for example.

In operation, air flows through the blower assembly 12 and a first portion 50 (primary flow 50) of the air flow is routed through the high pressure compressor 14, in which the air flow is. compressed and sent to the combustion chamber 16. The hot combustion products (not shown in the figures) from the combustion chamber 16 are used to drive the turbines 18 and 20 and thereby produce the thrust of the turbine engine assembly. gas turbine 10. The gas turbine engine assembly 10 also includes a bypass duct 40 which is used to pass a second portion 52 (secondary flow 52) of the air flow discharged from the blower assembly 12 around the gas turbine. central gas turbine engine 13. More precisely, the bypass duct 40 s'extends between an inner wall 201 of a fan fairing 42 or nacelle 42 and an outer wall 203 of the separator 44 surrounding the central gas turbine engine 13.

FIG. 2 is a simplified schematic illustration of an exemplary hydraulic circuit 100 for supplying lubricating hydraulic fluid, such as, for example, oil, which may be used in the gas turbine engine assembly 10 of FIG. 1. In the exemplary embodiment, the system 100 comprises an oil supply source 120, one or more pumps 110 and 112 which circulate the oil in bearings 104, 106, 108 of the turbine engine. central gas 13 and in its gears 60 and return the hot oil via the heat exchanger 130 which cools the oil to a lower temperature. Optionally, the heat exchanger 130 includes an inlet valve 132 and an outlet valve 134 and a bypass valve 136 which can be operated manually or electrically.

In the example shown in Figure 1, the heat exchanger 130 is an air-cooled heat exchanger which is positioned in the bypass duct 40. The heat exchanger 130 is coupled to the inner wall 201 of the fairing. fan 42 between the fan assembly 12 and a fan spacer 150. In other embodiments not shown, the heat exchanger 130 may be coupled to the internal wall 201, upstream of the fan assembly. 12 and downstream of the intake side 28. As such, the heat exchanger 130 can be positioned anywhere along the axial length of the bypass duct 40 or on the inner side of the fan shroud 42. , or on the outer wall 203 of the separator 44. In Figure 3, during assembly,the heat exchanger 130 is curved such that the heat exchanger assembly 130 has a circumferential and axial profile substantially similar to the circumferential and axial profile of at least a part of the bypass duct 40, for example conforming to the circumferential and axial profile of the inner surface 201 of the fan fairing 42 as shown in Figure 1 or the outer surface 203 of the separator 44 in other embodiments not shown.for example conforms to the circumferential and axial profile of the inner surface 201 of the fan fairing 42 as shown in Figure 1 or the outer surface 203 of the separator 44 in other embodiments not shown.for example conforms to the circumferential and axial profile of the inner surface 201 of the fan fairing 42 as shown in Figure 1 or the outer surface 203 of the separator 44 in other embodiments not shown.

As shown in Figure 3, the heat exchanger 130 covers substantially the entire (approximately 320 °) circumference. Alternatively, the heat exchanger can be formed of several segments, which are fitted end to end to cover the same circumferential length.

In Figure 3, the heat exchanger 130 includes a manifold portion 202 extending between a first end 210 and an opposing second end 212. The manifold portion 202 also includes a radially inner surface 220, a radially outer surface 222. , such that the manifold portion 202 has a profile of substantially rectangular axial cross section. The manifold portion 202 also includes a plurality of cooling fins 230 extending radially inward from the inner surface 220 in the case of Figure 1, to face the bypass 52. Of course, the fins 230 may be located on the outer surface 222,

The manifold portion 202 also contains at least one hydraulic fluid passage channel extending into the manifold portion 202 between its ends 210 and 212. This hydraulic fluid passage channel is connected to at least one inlet connection 240. hydraulic fluid, which is located at end 210 and which is coupled downstream of valve 132 (shown in Figure 2) and at least one hydraulic fluid outlet connection 242, which is located at end 212 and which is coupled upstream of valve 134 (shown in Figure 2), so that valves 132 and 134 can be actuated to circulate system 100 lubricating fluid through the channel of heat exchanger 130.The hydraulic fluid circulating in the heat exchanger 130 transfers part of its heat to the part 202 of the collector surrounding the channel, this part 202 of the collector transferring, via the fins 230, part of the heat received to the secondary air flow. passing into the bypass duct 40 or to the air passing outside the fairing 42.

Embodiments of the device 400 for monitoring the life of the hydraulic equipment according to the invention and of the method for monitoring the life of the equipment are first described below with reference to FIGS. 4 to 10. hydraulic according to the invention, having the steps mentioned below. Of course, the device 400 for monitoring the life of the hydraulic equipment according to the invention and the method for monitoring the life of the hydraulic equipment according to the invention can be applied to any hydraulic equipment of a aircraft subjected in flight to variations in hydraulic pressure, this equipment possibly being different from the heat exchanger 130 described above and being generally referred to below as hydraulic equipment 130.

As illustrated in FIGS. 6 and 7, the device 400 for monitoring the life of the hydraulic equipment according to the invention and the method for monitoring the life of the hydraulic equipment according to the invention are intended to treat measurement data 403, which were acquired during a flight on the aircraft and which are representative of the hydraulic pressure P (for example in the example described above in FIGS. 1 to 3, the pressure P d (internal oil of the hydraulic equipment 130) of the hydraulic equipment 130 as a function of time t during this flight, to process these data 403 on the ground after the flight. The device 400 thus comprises a reception interface 401 for receiving the measurement data 403 (or input data), during a first reception step E1.

The device 400 comprises a processing device 402 connected to the reception interface 401. The device 400 and the lifetime monitoring method are implemented by automatic means. The processing device 402 and the means described can be implemented by a processor or a

computer or a computer or a server, which are provided with computer processing programs for carrying out the processing described below and with permanent memories for recording therein the measurement data 403 and the processing operations carried out, the interface 401 possibly being a port of 'access to these.

The processing device 402 comprises a detector 404 for detecting, from the measurement data 403 during a second detection step E2 subsequent to the first reception step E1, a SOLL END stress in pressure P of a damaging nature, called hereinafter SOLL END stress in damaging pressure.

As illustrated in FIG. 4 showing on the ordinate a curve of pressure P as a function of time t on the abscissa, the solicitation SOLL END in pressure P of damaging nature is detected by the fact that the pressure P includes an increase AP AUG of pressure, greater than a determined threshold S AP of damage, this increase AP AUG of pressure being followed by a decrease AP D of pressure greater than the determined threshold S AP of damage. The determined damage threshold S AP is a fatigue threshold of the hydraulic equipment 130 and has been determined beforehand. The threshold S APdetermined of damage is positive and not zero. The pressure increase AP AUG and the pressure decrease AP D are each taken as an absolute value.

A pressure cycle CYC P of the hydraulic equipment 130 in flight begins at a certain start time T1 with a first prescribed pressure value P1 and ends at a certain end time T2 with a second prescribed pressure value P2. The CYC pressure cycle P may include none, one or more SOLL END pressure P stresses of a damaging nature, after having taken the first prescribed value Pl for the start of cycle pressure and before taking the second prescribed value P2 for the end pressure. cycle after the first prescribed pressure value Pl. For example, in FIG. 4, two SOLL END stresses in pressure P of a damaging nature are detected. In figure 4, the maximum of the pressure P separating the increase APAUG of the decrease AP D is represented by a star.

The processing device 402 comprises a calculation means 414 for calculating, during a calculation step E30 subsequent to the detection step E2, a pressure variation amplitude DeltaP N , equal to the maximum of the absolute value of l 'increase DR A uo in pressure of the solicitation SOLL END in pressure P with damaging character having been detected and of the absolute value of the decrease AP D in pressure of the solicitation SOLL END in pressure P with damaging nature, which follows this increase DR A uo pressure.

The treatment device 402 comprises a projection means 415 comprising a damage model in the form of a function DeltaP N = ÎCNSOLL) giving an admissible number NSOLL of pressure stresses P of a damaging nature as a function of the amplitude DeltaP N of pressure variation.

An example of such a damage model MOD is illustrated in FIG. 5, comprising a decreasing prescribed line MOD of the damage model, giving the admissible number NSOLL of pressure stresses P of a damaging nature as a function of the amplitude DeltaP N of pressure variation. For example, the decreasing prescribed line MOD of the damage model is in the form of the following affine function:

DeltaP = A. NSOLL + B,

where A is a negative real number, not zero and prescribed,

and B is a positive, non-zero, prescribed real number.

The model may be other than the example of FIG. 5, for example in the form of a decreasing prescribed curve MOD of the damage model, giving the admissible number NSOLL of pressure stresses P of a damaging nature as a function of the DeltaP N amplitude of pressure variation.

In another example, the damage model decreasing prescribed curve MOD is in the form of the following function:

DeltaP N = C. exp (-D x NSOLL + E) + F,

where C is a positive real number, not zero and prescribed,

D is a positive real number, not zero and prescribed,

E and F are prescribed real numbers.

In another example, the prescribed decreasing curve MOD of the damage model comprises a part of a decreasing curve, depending on the inverse of the DeltaP N pressure variation amplitude to give the admissible number NSOLL of pressure stresses P with character damaging. The MOD curve can be in the form of the following function:

DeltaP N = G / NSOLL + H,

where G is a positive real number, not zero and prescribed,

H is a prescribed real number.

The projection means 415 is provided to project, during a projection step E40 subsequent to the calculation step E30, the DeltaP N pressure variation amplitude having been calculated during step E30, onto the curve decreasing prescribed MOD of damage model or decreasing prescribed straight line MOD of damage model, to determine the admissible number NSOLLN of pressure stresses P of a damaging nature corresponding to this amplitude DeltaP N of pressure variation having been calculated.

In general, whatever the form of the function, the damage model DeltaP N = f (N S o LL ) is characterized by the following specific pressures:

• DeltaP Max : DeltaP N amplitude of pressure variation from which the equipment presents a plastic deformation from the first SOLL END stress ; at DeltaP Max it is assumed that the service life of the equipment 130 is entirely consumed.

• DeltaP Ref : DeltaP N amplitude of the reference pressure variation; for DeltaP Ref , it is assumed that the service life of the equipment is equal to an admissible number N SOLL of pressure stresses P of a damaging nature, which is prescribed and which is called the number NRef of reference stresses.

• DeltaP Min : DeltaP N pressure variation amplitude below which the DeltaP N pressure variation amplitudes are not taken into account because they are not considered damaging for the equipment 130 considered. This is the determined threshold S Ap of damage

allowing the detection of a SOLLEND stress in pressure P of a damaging nature. We therefore have DeltaP Min = S AP .

The processing device 402 comprises a calculation means 416 for calculating, during another calculation step E50, a damage potential ratio R N , equal to the number NRef of reference stresses, divided by the admissible number NSOLLN of stress loads P of a damaging nature, having been calculated, namely:

RN = NRef / NSOLLN

The method and the monitoring device according to the invention thus make it possible to estimate the severity of the SOLLEND stresses encountered on the flight.

The SOLLEND pressure load P of damaging nature, the DeltaP N amplitude of pressure variation and the admissible number NSOLLN of pressure loads P of a damaging nature and the damage ratio RN are associated with the flight of the aircraft during which the measurement data 403 and / or 408 have been acquired.

The processing device 402 comprises means 417 for incrementing, during a counting step E60, a counter 405 of the cumulative RNCUM of damage potential ratios R N. The counter 405 of the cumulative RNCUM is incremented by the damage potential ratio R N , which was calculated during step E50 for the flight corresponding to the data 405 and / or 408. The ratio R N thus makes it possible to monitor the flight by making it possible to quantify the severity of the SOLLEND pressure stresses undergone by the equipment during flight. The counter 405 thus makes it possible to monitor the flight taking into account previous flights. The counter 405 thus provides a cumulative RNCUM of damage potential ratios R N for this flight and the previous flights.

The cumulative damage ratio counter 405 is thus a pressure-weighted SOLLEND stress counter, which calculates and accumulates over the life of the equipment 130 a number of stresses equivalent to pressure reference conditions for each SOLLEND stress. in pressure detected during flights. Each SOLLEND request is weighted in relation to its

DeltaP N pressure variation amplitude , so as to bring the SOLLEND stress back to reference conditions.

These reference conditions correspond to the DeltaP Ref amplitude of the reference pressure variation associated with the number NRef of SOLLEND stresses in pressure P of a damaging nature that the equipment can withstand at this amplitude before its failure (which can be manifested by the appearance cracks, ruptures ...). The chosen reference conditions DeltaP Refcorrespond to a pressure for which the number of admissible stresses NRef = NSOLLN that the equipment can withstand before its failure is known; NRef will for example have been demonstrated during the certification or qualification tests of the equipment 130. It is however possible to define another reference (pressure, number of stresses) provided that it is the same for all the SOLLEND stresses counted. The weighting of each SOLLEND request with respect to these reference pressure conditions thus makes it possible to establish the cumulative counter 405 which it is possible to compare with the number NRef of reference requests. The cumulative RNCUM of R N ratiosof damage potential calculated by the counter 405 represents a damage potential brought back to the conditions of the DeltaP Ref amplitude of the reference pressure variation.

Thus, in the case where DeltaP Min DeltaP Max , the admissible number NSOLLN of pressure stresses P of a damaging nature is equal to 0, as represented by the line MOD 0 illustrated in FIG. 5. In this case , the counter 405 is incremented by an “infinite” damage potential ratio R N (because NSOLLN = 0) or equal to a prescribed value REND of damage reached, chosen arbitrarily to be very large, by the incrementing means 417 during step E60, the service life of the equipment 130 is considered to be entirely consumed. This prescribed value REND of damage reached is for example chosen at a finite value, greater than or equal to a threshold S AL preset alert.

According to one embodiment of the invention, the processing device 402 comprises alert means 418 for transmitting to the outside, during a warning step E8 after step E60, a message AL d 'alert, when the cumulative RNCUM of damage potential ratios R N is greater than or equal to the predefined alert threshold S AL , as shown in FIG. 7. Thus, for example, the case where DeltaP N ³ DeltaP Max will trigger by the alert means 418 the transmission of the alert message AL.

This counter 405 thus accounts for the various transient increases / drops in the pressure P in the equipment 130 during its life, brought back to conditions equivalent to the reference conditions. It is a fine counter making it possible to decide on the state of mechanical damage of the equipment 130, since it makes it possible to compare the admissible number NSOLLN of pressure stresses P of a damaging nature with the number of theoretically admissible cycles NRef, associated to the DeltaP Ref amplitude of the reference pressure variation.

The cumulative RNCUM of damage potential ratios R N , calculated by this counter 405 is not necessarily an integer; the cumulative RNCUM is to be interpreted as the number of SOLL END stresses in pressure P of a damaging nature to which the equipment 130 would have been subjected by carrying out only SOLL END stresses at the DeltaP Ref amplitude of the reference pressure variation.

According to one embodiment of the invention, the determined damage threshold S Ap is greater than or equal to 15% of a maximum and nominal hydraulic pressure PMAX of the hydraulic equipment and is less than or equal to 35% of the maximum and nominal hydraulic pressure PMAX- The determined threshold S Ap of damage may in particular be greater than or equal to 20% of PMAX and less than or equal to 30% of PMAX- For example, the determined threshold S AP of damage may be equal to approximately 25% of PMAX - The determined threshold S AP of damage, the MOD model, DeltaP Ref , NRef, DeltaP Min , DeltaP Max , S AL, the first prescribed pressure value P1 and the second prescribed pressure value P2 form part of the configuration parameters of the method and of the device 400 and are prerecorded in a memory of the processing device 402. The amplitude DeltaP N and / or the number NSOLLN and / or the ratio RN and / or the cumulative RNCUM, having been calculated, are recorded in a memory of the processing device 402, which is updated on each execution. The processing device 402 may include an output interface 406 (which may be a display screen or the like) to supply the outside, during a step E7 with output subsequent to step E8 or E60, as data of output the DeltaP N amplitude and / or the NSOLLN number and / or the R N ratioand / or the cumulative RNCUM, having been calculated and / or the alarm AL message, and possibly other indicators, such as the determined threshold S AP of damage, the MOD model, DeltaP Ref , NRef, DeltaP Min , DeltaP Max , S AL , the first prescribed value Pl of pressure and the second prescribed value P2 of pressure.

According to one embodiment of the invention, these configuration parameters are predefined as a function of the materials of the hydraulic equipment 130 and of its structure. These configuration parameters can be set for the same type of hydraulic equipment 130 and / or for the same type of aircraft. According to one embodiment of the invention, the determined damage threshold S AP can be variable during the life of the equipment 130.

According to one embodiment of the invention, the first prescribed pressure value P1 and the second prescribed pressure value P2 are substantially zero. The first prescribed pressure value Pl may correspond to a value of

pressure of the hydraulic equipment 130 when the turbojet engine is stopped at the start of the flight or when the turbojet engine is idling shortly after the start of the flight, in which case the first prescribed pressure value P1 is not zero. The second prescribed pressure value P2 may correspond to a pressure value of the hydraulic equipment 130 when the turbojet engine is stopped at the end of the flight or at idle speed of the turbojet engine shortly before the end of the flight, in which case the second prescribed value P2 of pressure is not zero.

According to one embodiment of the invention, shown in Figures 7 and 8, the hydraulic equipment 130 may not be provided with a pressure sensor to measure its hydraulic pressure P. In this case, the treatment device 402 comprises an estimator 407 for determining, during an estimation step E4 subsequent to the reception step E1 and prior to the detection step E2, the hydraulic pressure P of the equipment 130 from the values ​​408 of another hydraulic pressure of other equipment 131 of the aircraft as a function of time t, which are included in the measurement data 403 and which were measured by a measurement sensor 133 provided on this other equipment. This other equipment 131 can for example form part of the same hydraulic circuit 100 as the hydraulic equipment 100 of FIG. 2,

In another embodiment of the invention not shown, a hydraulic equipment 130 is provided with a measurement sensor making it possible to directly measure the hydraulic pressure P of the hydraulic equipment 130.

Pressure values ​​P3 may be missing between present pressure values ​​which are temporally spaced. For example, as shown in Figure 9 during a pressure cycle CYC, pressure values ​​P3 may be missing between the start time T1 corresponding to the first prescribed pressure value Pl and a pressure P present after Pl (or in another case not shown between a pressure P present prior to the second prescribed pressure value P2 and the end instant T2 corresponding to the second prescribed pressure value P2).

According to one embodiment of the invention, during a step

E5 for verifying the data using the detector 404 of the processing device 402, the replacement pressure values ​​P4, varying in a linear fashion, for example in the form of a single straight line, between these present pressure values P, Pl or P2, for example between the start time Tl corresponding to the first prescribed pressure value Pl and the pressure P present, as illustrated in FIG. 10 (or in the other aforementioned case, we insert by the device 402 for processing the replacement pressure values ​​P4, varying in a linear fashion, for example in the form of a single straight line, between the pressure P present and the end instant corresponding to the second prescribed value of pressure).

According to one embodiment of the invention, the method comprises, between the receiving step E1 and the step E2 or E4, the step E5 of verifying the data 403 or 408, for example to detect invalid data, to detect data. missing data and apply methods to replace missing data, as described above with reference to Figures 9 and 10. Data 403, 408 may include in addition to pressure P measurements and time t measurements, the number engine serial number, the number of flights counted by another turbojet counter, a serial number of the monitored hydraulic equipment, a history of pressure measurements P.

According to one embodiment of the invention, the method comprises a step of calculating a confidence indicator of the DeltaP N amplitude and / or of the number NSOLLN and / or of the ratio R N and / or of the cumulative RNCUM having been calculated. This confidence indicator can be calculated as being a numerical value weighted by the quality of the data 403 and / or 408, estimated during step E2 and by the number of missing data.

Of course, the above embodiments, characteristics, possibilities and examples can be combined with each other or be selected independently of each other.

CLAIMS

1. Device (400) for monitoring the life of at least one hydraulic item of equipment (130) of an aircraft subjected to variations in hydraulic pressure (P) in flight, the device (400) comprising an interface (401) receiving measurement data (403, 408) representative of the hydraulic pressure (P) of the equipment (130) as a function of time (t) in flight,

characterized in that the device (400) comprises:

a processing device (402), comprising means (404) for detecting, from the measurement data (403, 408), a stress (SOLLEND) in pressure (P) of a damaging nature, defined by the fact that the pressure (P) comprises an increase (AP AUG ) in pressure, greater than a determined threshold (S AP ) of damage greater than zero, followed by a decrease (AP D ) in pressure greater than the determined threshold (S AP ) of damage,

a means (414) for calculating an amplitude (DeltaP N ) of pressure variation, equal to the maximum of the absolute value of the increase (AP AUG ) in pressure of the stress (SOLL END ) in pressure (P) at damaging nature and the absolute value of the pressure reduction (AP D ) of the stress (SOLL END ) in pressure (P) with damaging nature,

means (415) for projecting the magnitude (DeltaP N ) of pressure variation onto a decreasing prescribed curve (MOD) of damage model or decreasing prescribed line (MOD) of damage model, yielding an allowable number (NSOLL ) of pressure stresses (P) of a damaging nature as a function of the amplitude (DeltaP N ) of pressure variation, to determine the admissible number (NSOLLN) of pressure stresses (P) of a damaging nature corresponding to the amplitude ( DeltaP N ) of pressure variation having been calculated,

a calculation means (416) for calculating a damage potential ratio (R N ), equal to a number (NRef) of reference stresses, determined, divided by the admissible number (NSOLLN) of pressure stresses (P) of a damaging nature having been calculated,

means (417) for incrementing a counter (405) of accumulation (RNCUM) of damage potential ratios (RN) by the damage potential ratio (RN) having been calculated.

2. Device according to claim 1, characterized in that it comprises an estimator (407) for determining the hydraulic pressure (P) of the equipment from values ​​of another hydraulic pressure of another equipment (131) of the aircraft as a function of time (t), which are included in the measurement data (408) and which have been measured by a measurement sensor (133) provided on this other equipment (131).

3. Device according to any one of claims 1 and 2, characterized in that the hydraulic equipment comprises a heat exchanger (130), forming part of a hydraulic circuit (100) for circulating a hydraulic fluid from a turbomachine (10), the hydraulic circuit (100) being positioned in the secondary gas flow (52) of the turbomachine located between a nacelle (42) and a casing (44) of the turbomachine (10) for cooling the hydraulic fluid.

4. Device according to any one of claims 1 to 3, characterized in that the determined threshold (S Ap ) of damage is greater than or equal to 15% of a hydraulic pressure, maximum and nominal (PMAX) of the hydraulic equipment and is less than or equal to 35% of the hydraulic pressure, maximum and nominal (PMAX).

5. Device according to any one of claims 1 to 4, characterized in that the decreasing prescribed curve (MOD) of the damage model comprises an exponential or linear decreasing curve, giving the admissible number (NSOLL) of pressure stresses ( P) of damaging nature as a function of the amplitude (DeltaP N ) of pressure variation.

6. Device according to any one of claims 1 to 4, characterized in that the decreasing prescribed curve (MOD) of the damage model comprises a part of a decreasing curve, depending on the inverse of the amplitude (DeltaP N ). of pressure variation to give the admissible number (NSOLL) of pressure stresses (P) of a damaging nature.

7. Device according to any one of claims 1 to 6, characterized in that the processing device (402) comprises warning means (418) for transmitting an alert message (AL) to the outside, when the accumulation (RNCUM) of damage potential ratios (RN) of the meter (405) is greater than or equal to a predefined alert threshold (S A L).

8. A method of monitoring the life of at least one hydraulic item of equipment (130) of an aircraft subjected to variations in hydraulic pressure (P) in flight, a method in which one receives, during a step (El ) receiving on a reception interface (401), measurement data (403, 408) representative of the hydraulic pressure (P) of the equipment (130) as a function of time (t) in flight, characterized in that

during a detection step (E2), a processing device (402), on the basis of the measurement data (403, 408), is detected by a pressure ( SOLL END ) demand (P) of damaging, defined by the fact that the pressure (P) includes an increase (AP A UG) in pressure, greater than a determined threshold (S AP ) of damage greater than zero, followed by a decrease (AP D ) in pressure greater than the determined threshold (S AP ) of damage,

during a calculation step (E30), the processing device (402) calculates an amplitude (DeltaP N ) of pressure variation, equal to the maximum of the absolute value of the increase (AP A UG) of stress pressure (SOLLEND) in pressure (P) with damaging nature and the absolute value of the decrease (APDIM) in pressure of the stress (SOLLEND) in pressure (P) with damaging nature,

during a projection step (E40), the amplitude (DeltaP N ) of the pressure variation is projected by the processing device (402) on a decreasing prescribed curve (MOD) of the damage model or decreasing prescribed straight line (MOD) of damage model, giving an admissible number (NSOLL) of pressure stresses (P) of a damaging nature as a function of the amplitude (DeltaP N ) of pressure variation, to determine the admissible number (NSOLLN) of pressure loads (P) of a damaging nature, corresponding to the amplitude (DeltaP N ) of pressure variation having been calculated,

during another calculation step (E50), the processing device (402) calculates a damage potential ratio (R N ), equal to a determined number (NRef) of reference stresses, divided by admissible number (NSOLLN) of stress loads (P) of a damaging nature having been calculated,

during a counting step (E60), a counter (405) for the accumulation (R NCUM ) of damage potential ratios (R N ) is incremented by the damage potential ratio (R N ) having been calculated.

9. Method according to claim 8, characterized in that in the event of missing pressure values ​​(P3) between present pressure values ​​(Pl, P2, P) which are spaced apart in time, pressure values ​​are inserted. (P4) replacement varying in a linear fashion between these present pressure values ​​(P1, P2, P).

10. The method of claim 8 or 9, characterized in that the measurement data (408) comprise values ​​of another hydraulic pressure of another equipment (131) of the aircraft as a function of time (t), having been measured by a measurement sensor (133) provided on this other equipment (131) before the reception step (El),

the method comprising an estimation step (E4), which is subsequent to the reception step (El) and prior to the detection step (E2) and during which an estimator (407) of the device is estimated (402), the hydraulic pressure (P) of the equipment from the values ​​of the other hydraulic pressure of the other equipment (131) of the aircraft.

11. A method according to any one of claims 8 to 10, characterized in that the hydraulic equipment comprises a heat exchanger (130), forming part of a hydraulic circuit (100) for circulating a hydraulic fluid of a turbomachine (10), the hydraulic circuit (100) being positioned in the secondary gas flow (52) of the turbomachine located between a nacelle (42) and a casing (44) of the turbomachine (10) for cooling the hydraulic fluid.

12. Method according to any one of claims 8 to 11, characterized in that the determined threshold (S Ap ) of damage is greater than or equal to 15% of a hydraulic pressure, maximum and nominal (P MAX ) of l 'equipment

hydraulic and is less than or equal to 35% of the hydraulic pressure, maximum and nominal (PMAX).

13. Method according to any one of claims 8 to 12, characterized in that the decreasing prescribed curve (MOD) of the damage model comprises an exponential or linear decreasing curve, giving the admissible number (NSOLL) of pressure stresses ( P) of damaging nature as a function of the amplitude (DeltaP N ) of pressure variation.

14. Method according to any one of claims 8 to 12, characterized in that the decreasing prescribed curve (MOD) of the damage model comprises a part of the decreasing curve, depending on the inverse of the amplitude (DeltaP N ). of pressure variation to give the admissible number (NSOLL) of pressure stresses (P) of a damaging nature.

15. A method according to any one of claims 8 to 14, characterized in that, during a step (E8) of warning subsequent to the counting step (E60), it transmits to the outside. by the processing device (402), an alert message (AL), when the accumulation (RNCUM) of damage potential ratios (R N ) of the counter (405) is greater than or equal to a threshold (S AL ) preset alert.