Piloting assist method for managing at least one cumulative ageing process

Abstract

The invention relates to a piloting assist method for an operator, for example a pilot, or for an automated system, for example an autopilot, the assist relating to at least one cumulative ageing process (CV), for example creep, in at least one portion of a gas turbine of an aircraft during a mission of the aircraft, wherein the method comprises a step of determining an ageing progression score that is a function of a plurality of terms comprising TERM 1, TERM 2, TERM 3, TERM 4 and TERM 5, and wherein the method comprises a step of supplying information on the at least one cumulative ageing process to the operator or to the automated system for the piloting assist, on the basis of the ageing progression score.

Description

[0001]DESCRIPTION TITLE: Pilot assistance method for managing at least one cumulative aging Technical field of the invention The invention relates to a pilot assistance method for an operator, for example a pilot, or for an automated system, for example an autopilot, making it possible to help manage flight after flight at least one cumulative aging, for example creep, of at least one part of a gas turbine of an aircraft, for example a helicopter, in order to get the best out of it in the long term. STATE OF THE PRIOR ART An aircraft pilot generally has access to piloting indications relating to the propulsion systems, displayed in the cockpit. These indications refer in particular to certified limits (maximum limits not to be exceeded, limits required in the flight manual), these limits being managed by the pilot or managed by the computer.Such limits are, for example, N1 (gas generator rotation speed at the high-pressure shaft), the T45H conformal temperature of the high-pressure turbine, the power shaft torque, or an indicator combining this information. These limits constitute, for example, thresholds not to be exceeded in stabilized flight, and for which maximum continuous use times may be defined by regulation. These indications do not take into account objectives per mission, such as a quota, or a notion of acceptable cumulative aging. They are purely instantaneous and are not intended to prevent cumulative aging modes from leading to a need for premature overhaul of the turbomachine, for example before its scheduled general overhaul.In a context of uses that are not very variable and predictable, for example airliner missions, there are predictive means that set binary throttle position indexes, in correct correspondence with maintenance costs. These predictive means also most often integrate maintenance costs and fuel consumption costs. For versatile uses, for example for the varied missions of helicopters, the correspondence of a binary setpoint (whether it is a torque, a gas generator speed or a temperature) with costs is however not reliable. Today, in this context, only ground monitoring of the meters exists, in particular with regard to creep, carried out manually or with tools.However, in this context, concerning these complex cumulative aging processes, such a posteriori monitoring does not provide any useful prospective indication for subsequent flights and is not in the current state of being likely to help the pilot to respect a cumulative objective during the flight, for example an objective given by a fleet manager. Such monitoring or such indications also do not provide information capable of helping the pilot understand and develop an intuition of the actions to be taken to manage aging modes. Indeed, these aging phenomena are multi-factorial and non-linear. Consequently, a pilot cannot develop a reliable intuition of the conditions in which these aging modes accelerate or slow down, without additional indication. Cumulative aging is a form of damage that increases over time.Such aging corresponds perfectly to the phenomenon of turbine blade creep, in the context of the intended application, but can also be oxidation, corrosion, or mechanical wear of the parts (friction wear or bearing wear, for example). Other types of aging can also occur, such as predominantly "cyclic" aging modes, relating to a number of passages of stress thresholds, both upwards and downwards (oligocyclic fatigue (LCF), thermal cycling, number of starts / stops, etc.). However, it is difficult to act on such cyclic aging. Presentation of the invention The present document aims to remedy the aforementioned drawbacks.For this purpose, the present document proposes a method of piloting assistance for an operator, for example a pilot, or for an automated system, for example an autopilot, said assistance relating to at least one cumulative aging, for example creep, of at least one part of a gas turbine of an aircraft during a mission of said aircraft, said method comprising a step of determining an aging progression score which is a function of a plurality of terms comprising TERM1, TERM2, TERM3, TERM4 and TERM5, and the following are defined for the calculation of the aging progression score: - the quota of the mission, ,. where - QFactor is a factor between 0.1 and 10, for example, to be made modifiable by the operator if possible, - QFactor ageing is a factor, , - ^^ is a threshold of major of a cumulative aging counter CV, in hours, - ^^ ^^^^^is the target life of said part of the gas turbine, in hours, over an engine life before deep maintenance or minimum power margin reached, - ^^ is the life between two overhauls of said part of the gas turbine, in flight hours, preferably a life targeted for current flight, assuming that all flights are made with the same power margin, , - the default quota of the mission, , - a measure of the margin of engine, EPCT4, for example between 0 and 10, - a verification margin of the estimated power of a new engine, EPCT4New, for example equal to 10, - an average verification margin of the power of a new engine, EPCT4Moy = λ* EPCT4New, - a coefficient λ, λ preferably being equal to 1 / 3, - a duration, DQmin, minimum threshold for triggering major maintenance for the engine, for example if it had to operate for its entire life without power margin, such that EPCT4 = 0, - a duration, DQ max, maximum major maintenance trigger threshold for the engine, for example if it were to operate for a lifetime with the maximum power margin, such as EPCT4Moy = EPCT4New, for example DQmax= DQcible *3, - the cumulative aging counter CV which is a value proportional to the cumulative aging, the forecast flight duration of the mission entered in hours, ^, for example between 0.2 and 3h, - the default forecast flight duration of the mission in hours, M ^^^, for example of the order of 1 hour, - the cumulative flight duration of the mission, in hours, at a time t of the mission, T(t) - a first threshold S1, for example between 0.3 and 0.8, for example equal to 0.5, - a second threshold S2, for example between 3 and 10, for example equal to 5, - the start of the mission defined by the time t= t0 of start of flight, - a time t= t1 of end of a phase called start of mission, also defined so that: -- t1 – t0 is greater than a duration of between 1 and 15 minutes, and / or -- t1 is the first time t greater than t0 for which the flight speed of the aircraft is greater than a predetermined speed, for example 40 Ktas for a helicopter, and / or -- t1 is the first time t greater than t0 for which the altitude of the aircraft relative to the ground, also called ground clearance, is greater than a determined value, for example 500 feet, - a sliding duration X in seconds, for example between 10 and 30 seconds,for example of the order of 20 seconds, - the average gradient sliding over X seconds, , - the cumulative total per flight hour since the start, instant t of the mission without information on the forecast flight duration of mission M, - the cumulative total per flight hour since the start of the mission, at anticipating a flight duration of the “usual short missions” of Y, in hours, Y being a parameter to be adapted to the application context, chosen between M ^^^ / 2 and M ^^^ , , - of flight since the start of the mission, at a time t of the mission anticipating the forecast mission flight duration entered M, , - , - , at least one cumulative aging to the operator or automated system for said piloting aid, according to said aging progress score. The aging progress score can be defined as follows: . The step of providing said information to an operator can be carried out by display. As previously indicated, the cumulative aging of a part of a gas turbine is the damage to the part concerned which increases with time. Such aging is mainly the phenomenon of creep, but can also be oxidation, corrosion, or mechanical wear of the parts of the part concerned. The cumulative aging counter CV is a value generally provided by the gas turbine computer, and proportional to the cumulative aging, measured or determined by calculation, from values ​​from sensors (gas generator rotation speed, temperature within the gas turbine, torque, outside temperature, deformations, etc.). The higher the value of CV, the greater the cumulative aging of the parts of the part concerned or module of the gas turbine.An aircraft mission is defined by a succession of flight phases between a start and an end of the mission. Typically, such a mission may include one or more takeoff and landing phases, and flight phases at more or less significant speeds. The major maintenance trigger threshold is a threshold predetermined by the gas turbine manufacturer, beyond which a large-scale maintenance operation, called major maintenance, is necessary to ensure the proper functioning of the gas turbine or prevent premature damage to it. Such an operation generally requires the removal of the gas turbine. DQ is defined as a second-degree function of the engine's current power verification margin, EPCT4.In this way, one can choose between: - aircraft performance that takes advantage of the best engine performance, on each flight, in which case it is the attainable performance (beyond what is guaranteed) that varies significantly according to the engine margins. In the limiting case, DQmin = DQmax = DQtarget, and - more constant aircraft performance over the engine life, always maintaining an identical overall life target. This can for example be achieved by choosing DQmin = DQtarget / 5 and DQmax = DQtarget *3.DQ therefore takes into account the engine's lifetime and produces a compensation, called engine margin compensation: - at the beginning of the engine's life, the compensation leads to targeting a quota lower than the target average quota, - in the middle of the engine's life, i.e. when the engine has reached an intermediate margin value corresponding to the average potential (for example, an output shaft power Pw such that it is equal to 2 / 3 of the certified limits and a constant high pressure turbine T45H conformed temperature value), the compensation is zero, - At the end of the engine's life (i.e. in the last period of engine potential), i.e. for lower margin values, the compensation leads to targeting a quota higher than the target average quota to enable the continued achievement of higher aircraft performance.The magnitude of this compensation with respect to the engine's lifetime (the difference between the compensation at the beginning of the engine's life and the compensation at the end of the engine's life) is adjusted according to: - on the one hand, the acceptability of an operational constraint at the beginning of the engine's life while the visible damage will be less than a linear progression, and - on the other hand, the desired proportion of engine operation. For linear operation, there will be no compensation and for non-linear operation, there will be a strong compensation leading to more constant aircraft performance. The flight time between two general overhauls is known by the abbreviation TBO for "Time Between Overhauls", in English. The forecast flight time of the mission entered M is a value determined before the start of the mission and entered into an aircraft computer, for example via an interface.This duration can be entered by an operator, for example a pilot. The expected flight duration, by default or not, of the mission entered M or MDEF is for example between 0.2 and 3 hours. MDEF is for example of the order of 1.5 hours. M will be entered at the collection value of MDEF if M is not entered by the operator. The flight duration of the usual short missions Y will either be defined in a fixed way for a given application, for example of the order of 0.8 hours if MDEF = 1.5h, or determined by the application and calculated as an average of the flight durations of the previous missions of the aircraft less than MDEF in the interval, of M. ^^^ / 2 to M ^^^The parameter Y can be adapted for example in this interval depending on whether there are more or less mission frequencies much shorter than MDEF. The cumulative flight duration of the mission at a time t, T(t) is the time elapsed between the start of the mission t0 and time t. The sliding CV value over X seconds at a time t is equal to the difference between the CV values ​​at time t and CV at time tX. The calculation of all or part of said terms can be carried out in real time, at time periods of less than 1 second for example, of the order of 500ms for example. By inhibiting the calculations of TERM2, TERM3, TERM4 and TERM5, i.e. by setting these terms to 0, during the start phase of the mission (T(t) < t1), the operator, for example the pilot, is not bothered by the appearance of indications during the most delicate flight phases (takeoff, etc.). Each term serves a different purpose and therefore allows them to be combined.When the engine load level at time t leads to minor aging (S1 to be defined by the engine manufacturer), the score is set to zero, regardless of the value of the various terms. There is in fact no point in providing information, for example by display, if the engine load no longer significantly changes the final total, and there is no need to continue to encourage a reduction in the load. This avoids unnecessarily limiting solutions operationally since exceeding the quota does not involve any risk and the following missions always offer compensation possibilities.The current engine power verification margin, EPCT4, the estimated new engine power verification margin, EPCT4New, and the average power verification margin for an engine with mid-life hot parts, EPCT4Moy, are an image of the additional power margin that an engine can give over its T45H conforming temperature limit, compared to the certified guaranteed minimum. The first term, TERM 1, is used to signal to the operator a very high demand, without any obvious relationship to the acceptable speed limit indications. This is a first sign for the operator that the current flight conditions may lead to significant cumulative aging, and it can be displayed from the very first moments of the flight. It is also regular information that enriches the operator's intuitive perception of the situation.The second term TERM 2 allows the score to be reinforced if the level of stress at time t leads to an increase in aging not compensated by the increase in mission flight duration, versus the quota Q, or greater than a linear progression (if the values ​​M and Q are not defined by the operator). This indication reinforces the score when, at the start of the mission in particular, the stress is carried out at a high rate. It is an intermediate variant between the gradient and the cumulative aging which integrates any previous debits and credits and allows a signal in the first part of the mission. It gradually loses relevance with the lengthening of the mission and then no longer contributes to the score, unless the stress remains truly excessive.Instead of giving a weight of 2 to TERM 2 ("option 1") in the case where no effort to customize the objective of future missions is provided (i.e. when neither the quota Q nor the mission flight duration M have been defined, for example by the operator), the weight can remain at 1, which leads to a maximum score lower than 5 ("option 2"). The third term TERM 3 makes it possible to reinforce the score if the quota is exceeded by considering that the mission will last Y hours and to lower the score if, flight duration Y being exceeded, the cumulative score has converged again below the quota. This term allows a first level of progression of the score in absolute value of the cumulative hourly score, avoiding an untimely increase in the score at the start of the mission if the minimum duration of Y hours was not used (reason why B(t) is not used in absolute value).Such a method may also allow piloting assistance and / or training for the operator of the critical conditions leading to an aggravation of said cumulative aging. Instead of granting a weight of 2 to TERM 3 (“option 1”), in the case where no effort to customize the objective of future missions is provided, (i.e. when neither the quota Q nor the mission flight duration M have been defined, for example by the operator), the weight may remain at 1, which leads to a maximum score lower than 5 (“option 2”). The terms TERM 4 and TERM 5 are inhibited (equal to 0) when no effort to customize the objective of future missions is provided (i.e. when neither the quota Q nor the mission flight duration M have been defined, for example by the operator).These terms can also be inhibited for other reasons (desire for discreet displays and low use, for example in a context of too much mission variability). The fourth term TERM 4 allows the score to be reinforced if the cumulative value follows a progression greater than a linear cumulative value towards the Q quota entered, for the mission flight duration M entered. As the start of the mission is generally more demanding, this allows vigilance to be reinforced early enough and precisely enough, and indicates that moderation or pilot action is desirable. The fifth term TERM 5 allows the score to be reinforced by comparing the cumulative value to the Q quota, in particular in a case where it is not possible to remain within the quota during the mission, but it is still possible to limit the excess. It is also possible to freeze the display of the score during transient flight phases for which the pilot is otherwise occupied.Such a phase can in particular be determined by a strong variation in the sliding average (for example over a given period) of the engine torque, outside a reduced range (for example +-5%) around the sliding average. This makes it possible to freeze the display during such maneuvers. It is also possible to display a warning light, for example a green warning light, if A(t) < S1 (or other value) in the aircraft engine speed limits display zone (first limit indicator, margin N1, T45H – defined above), this zone being a priority attention zone for the pilot. Three states of vigilance can be allowed in the “option 2” case: - no vigilance: no indication of the score - moderate vigilance: M = Mdef , Q = Qdef , the maximum score then being equal to 3, in the “option 2” case. - high vigilance: invitation to enter M ≠ Mdef and M ≠ Mdef, the maximum score then being equal to 5.Conversely, in the "option 1" case, the scale of 5 is preferred and it is the fineness of indication that is degraded with scores that evolve by 2 points at a time for both TERM2 and TERM3. It is also possible to manage the case of several cumulative agings (both creep and corrosion for example, which are two different cumulative agings). We can also define for the calculation of the aging progression score: - a first component, _Comp_FB. time , for example equal to -0.1 per flight hour (or per “Flight Hours” in English), - a second component, _Comp_FBageing, for example equal to -0.1 / (EPCT4 / EPCT4New*100), , The aging progression score can then be defined as follows: . The sixth term TERM 6 allows to add a compensation to the score to take into account the aircraft's weight reduction, called weight reduction compensation. TERM 6 produces an average compensation of the score progression so as to correct the decrease in damage progression, under given flight conditions, of aircraft weight reduction with an associated standard average consumption, itself dependent on the engine power margin. The value of a slope of this weight reduction compensation is adjusted to avoid any overcompensation. TERM 6 is the product of a first compensation slope parameter [YT(t)] and a second compensation slope parameter [_Comp_FBtime + _Comp_FBageing * (EPC T4 / EPC T4New)]. The first compensation slope parameter [YT(t)] is mission time dependent and zero for T(t) = Y. It is calculated to produce the average compensation of the score progression. In this way, it compensates for the decrease in damage progression at the desired standard average speed, due to the aircraft's weight reduction and its guaranteed reference average fuel consumption. The second compensation slope parameter [_Comp_FB time + _Comp_FB ageing * (EPC T4 / EPC T4New )] has a component proportional to EPC T4. It is calculated to adjust on average the compensation slope for engines from new to aged condition. The compensation for the weight reduction makes it possible to avoid a part of conservatism at the start of the mission which is avoidable. Operators can thus carry out missions with less variation in speeds achievable over the course of the mission. For example, this is particularly suitable for missions whose speed requirement is located at the start of the mission. The calculated terms are relatively stable, but there may be instabilities. In order to overcome such instabilities, it is possible to put hysteresis on the display of the scores. Some terms may have an adapted hysteresis, for example greater than other terms. The aging progression score can be defined as follows: . The method may further comprise a step of determining an inverse aging progression score defined as follows: , said method further comprising a step of providing reverse information of said at least one cumulative aging to the operator or to the automated system for said piloting assistance, according to said reverse aging progression score. The aging progression score may in certain cases be too demanding for the operator, because he must adjust the piloting to a median value. The reverse progression score allows the operator to adjust the piloting to 100%, and to consider that if he does not have the opportunity to check later, the objective will still be globally achieved. Conversely, this may limit the visibility on possibilities of increasing the flight conditions in particular cases (significant payload deposition mid-mission for example). The cumulative aging may be creep, and / or oxidation, and / or corrosion.Said method may be capable of providing information concerning at least two different cumulative agings, the individual score of each aging being determined and a general score is calculated on the basis of said individual scores, for example in the form of an average or a weighted average, the information of said at least one cumulative aging to be provided to the user being dependent on said general score. It may be determined whether or not t is outside the start phase of the mission using a flight duration elapsed since the start of the mission, and / or the flight speed of the aircraft, and / or the altitude of the aircraft relative to the ground. The level or quantity of information of said at least one cumulative aging to be provided to the operator may vary depending on the aging progression score, and / or the value of A(t), and / or the flight phase concerned.The level of information may in particular vary progressively by increments, for example by displaying a value between 0 and 5 or by displaying a progress bar, or by not displaying such a value. The quantity of information may also vary by adding or removing information, so as to have more or less detailed information depending on the situations. In particular, it is possible that no information is provided (for example no display), in certain critical flight phases, for example during the mission start phase, or if the aging is low (low score or A(t)). Increasingly complex information (different levels of information) may be provided or displayed depending on the flight phases, the aging, or at the operator's request.In general, the invention proposes to determine or calculate laws in real time and real-time tests on these laws, leading to indications (displayable or not in the cockpit, at different degrees of detail or according to the flight phases), whatever the aircraft and the installation (single or multi-engine). These indications are preferably not unnecessarily disturbing, in particular in the flight phases which require particular attention from the pilot. (For example, they will be displayed so as to be visible during long phases – cruising or climbing flight (discreet flashing for example) – and in constant display, not annoying, or even inhibited (no flashing, etc.) during phases with strong power variation.) These indications encourage and guide the pilots, to act on the long and stable phases of flight, for the management, flight after flight, of cumulative aging of major components of the propulsion system.As previously indicated, these indications can be adjusted according to the score or previous cumulative aging, according to the types and business objectives of the missions, and the operating context. These indications must be progressive (several alert levels rather than a binary alert), such progressiveness being particularly useful when aging is difficult to predict, the short-term consequences are minor, the use of the aircraft is versatile, and to provide the pilot with a perception of the flight conditions that produce cumulative aging (non-intuitive without indication or with a binary indication). Such indications, making it possible to identify the phases that cause more or less pronounced cumulative aging, can also contribute to more ecological piloting decisions (CO2 emissions, etc.).Unlike existing applications in a non-versatile usage context, this score does not derive from an invariable cost calculation. Here, the fleet manager, keen to get the most out of his gas turbines, will be able, by following the trend a posteriori, to modify the quota and the score instructions to be respected by the pilot to enable the pilot to manage a globally controlled cumulative aging trajectory. He will be able to do this by considering all the versatility of his priorities, the geographical context of operation, seasonality, the age of the engines, the needs for protection of the air intakes, and all the other influential factors, by a pragmatic method of learning and instructions using the graduation of the invention.On the other hand, a combination with fuel-efficient condition indicators is a logical association with this indicator, for example the addition of a fuel-saving score from 0 to 2 depending on the deviation from the most economical stable flight conditions. This document may also relate to an aircraft comprising a display unit configured to provide information on at least one cumulative aging, said information being derived from a piloting assistance method of the aforementioned type. The display unit may be an information bar. The aircraft may be a rotary-wing aircraft, in particular a helicopter. Brief description of the figures [Fig. 1] is a trend diagram illustrating an evolution of the engine damage during the engine's lifetime, this diagram representing the aircraft speed and the cumulative aging counter CV without engine margin compensation, [Fig.2] is a trend diagram illustrating a change in engine damage over the engine lifetime, this diagram representing the aircraft speed and the cumulative aging counter CV with engine margin compensation according to one embodiment, [Fig. 3] is a trend diagram illustrating a change in engine creep accumulation, this diagram representing the aircraft speed and the cumulative aging counter CV with engine margin compensation according to one embodiment, [Fig. 4] is a trend diagram illustrating a change over time of a mission, this diagram representing the aircraft speed and the aging progress score without weight reduction compensation, in the case of a substantially constant aging progress score, [Fig.5] is a trend diagram illustrating a change over time of a mission, this diagram representing the speed of the aircraft and the aging progression score without weight reduction compensation, in the case of a substantially constant aircraft speed, and [Fig.6] is a trend diagram illustrating a change over time of a mission, this diagram representing the aging progression score with weight reduction compensation according to one embodiment. Detailed description of the invention The diagram in Figure 1 represents the case for which DQ=DQ. cible and therefore Q =QFactor * SD / DQ cible. In other words, DQ is a constant and corresponds to the target lifetime of said part of the gas turbine, the engine margin compensation not being taken into account. The aircraft speed in this example is V_aeronef_def and the cumulative aging counter is CV_def. By aging counter, we mean the cumulative damage. The diagram in Figure 2 represents an embodiment for which DQ is a second-degree function of the verification margin of the current engine power, EPCT4. The aircraft speed in this embodiment is V_aeronef and the cumulative aging counter is CV. In other words, this embodiment corresponds to the case where the engine margin compensation is taken into account. Unlike CV_def in Figure 1, the cumulative aging counter CV does not follow a linear progression.It can be seen that taking into account the evolution of the engine margin (in the form of the engine margin compensation illustrated in Figure 2) allows maintaining more constant aircraft performance (i.e. a more constant speed) over the engine's life. The aircraft speed is higher at the end of the engine's life compared to the case without engine margin compensation in Figure 1. The diagram in Figure 3 represents a particular example of the embodiment in Figure 2 in which the engine life is linked to the creep accumulation. In other words, it is the creep that produces the achievement of the revision criterion of the major parts concerned. The aircraft speed in this particular example is V_aeronef_creep and the cumulative aging counter is CV_creep. Point P represents a limit situation for which CV_creep reaches a maximum value corresponding to a creep accumulation equal to 100%.At point P, the major parts concerned must therefore be overhauled. In other examples, the engine may have to be shut down according to other wear characteristics. The diagram in Figure 4 represents the case of a substantially constant aging progression score (for example, under the action of a pilot who makes speed corrections for this purpose). The aging progression score, here SCORE_def_1, is substantially constant from point P1. It can be seen that for a substantially constant aging progression score, the aircraft speed, here V_aeronef_def_1, is not constant, but increasing throughout the mission. The diagram in Figure 5 represents the case of a substantially constant aircraft speed. The aircraft speed, here V_aeronef_def_2, is substantially constant from point P2.We note that for a substantially constant aircraft speed, the aging progression score, here SCORE_def_2, is not constant, but increasing from point P2' (equivalent to point P1). To have a substantially constant aging progression score (i.e. corresponding to SCORE_def_1), we note that a compensation at the level of the aging progression score must be applied: - between P2' and P2'', the compensation (noted Δ1) must be positive (to "raise the curve"); - at point P2'', the compensation must be zero; - from P2'', the compensation (noted Δ2) must be negative (to "lower the curve"). The compensation to be applied must therefore be increasing during the mission and respect the three conditions listed above. Point P2'' defines an engine life corresponding to a cumulative flight duration T(t) = Y.In order to have both a substantially constant aircraft speed and a substantially constant aging progress score, it is necessary to apply the weight reduction compensation. The diagram in Figure 6 represents an embodiment for which the weight reduction compensation is applied. It is recalled that, in this embodiment, the following are defined: - a first component, _Comp_FBtime, for example equal to - 0.1 per flight hour (or per "Flight Hours" in English), - a second component, _Comp_FBageing, for example equal to -0.1 / (EPCT4 / EPCT4New*100), ,. this embodiment is equal to: . TERM 6 adds the weight reduction compensation, TERM 6 being an increasing function, and zero for T(t) = Y. We see that the weight reduction compensation makes it possible to obtain a substantially constant aircraft speed, V_aeronef', from point P3 (equivalent to points P1 and P2') and a substantially constant aging progression score, SCORE, from point P3' (equivalent to point P2).

Claims

CLAIMS 1. Piloting assistance method for an operator, for example a pilot, or for an automated system, for example an autopilot, said assistance relating to at least one cumulative aging (CV), for example creep, of at least one part of a gas turbine of an aircraft during a mission of said aircraft, said method comprising a step of determining an aging progression score (SCORE) which is a function of a plurality of terms comprising TERM 1, TERM 2, TERM 3, TERM 4 and TERM 5, and for the calculation of the aging progression score (SCORE) it is defined: 0,1 and 10, to be made if possible modifiable by the operator, - QFactorageing is a factor, , - ^^ is a threshold of major of a cumulative aging counter CV, in hours, - ^^ ^^^^^is the target life of said part of the gas turbine, in hours, over a life of the engine before deep maintenance or minimum power margin reached, - ^^ is the life between two overhauls of said part of the gas turbine, in flight hours, preferably a life targeted for the current flight, assuming that all flights are made with the same power margin, , - the - a measurement of the current power margin of the engine, EPCT4, for example between 0 and 10, - a verification margin of the estimated power of a new engine, EPCT4New, for example equal to 10, - an average verification margin of the power of a new engine, EPCT4Moy = λ* EPCT4New, - a coefficient λ, λ preferably being equal to 1 / 3, - a duration, DQ min, minimum major maintenance trigger threshold for the engine, for example if it were to operate for its entire life without power margin, such as EPCT4 = 0, - a duration, DQmax, maximum major maintenance trigger threshold for the engine, for example if it were to operate for its entire life with the maximum power margin, such as EPCT4Moy = EPCT4New, for example DQmax= DQcible *3, - the cumulative aging counter CV which is a value proportional to the cumulative aging, the forecast flight duration of the mission entered in hours, ^, for example between 0.2 and 3h, - the default forecast flight duration of the mission in hours, M ^^^, for example of the order of 1 hour, - the cumulative flight duration of the mission, in hours, at a time t of the mission, T(t) - a first threshold S1, for example between 0.3 and 0.8, for example equal to 0.5, - a second threshold S2, for example between 3 and 10, for example equal to 5, - the start of the mission defined by the time t= t0 of start of flight, - a time t= t1 of end of a phase called start of mission, also defined so that: -- t1 – t0 is greater than a duration of between 1 and 15 minutes, and / or -- t1 is the first time t greater than t0 for which the flight speed of the aircraft is greater than a predetermined speed, for example 40 Ktas for a helicopter, and / or -- t1 is the first time t greater than t0 for which the altitude of the aircraft relative to the ground, also called ground clearance, is greater than a determined value, for example 500 feet, - a sliding duration X in seconds, for example between 10 and 30 seconds,for example of the order of 20 seconds, - the average gradient sliding over X seconds, , - the cumulative total per flight hour since the start of the mission at a time t without information on the forecast flight duration of mission M, - the cumulative total per flight hour since the start of the mission, at anticipating a flight duration of the “usual short missions” of Y, in hours, Y being a parameter to be adapted to the application context, chosen between M ^^^ / 2 and M ^^^ , , - of flight since the start of the mission, at a time t of the mission anticipating the forecast mission flight duration entered M, , - , - , at least one cumulative aging to the operator or automated system for said piloting assistance, according to said aging progression score (SCORE).

2. Method according to the preceding claim, in which the aging progression score (SCORE) is defined as follows: .

3. Method according to claim 1, in which the following are further defined for the calculation of the aging progression score (SCORE): - a first component, _Comp_FBtime, for example equal to -0.1 per flight hour, - a second component, _Comp_FBageing, for example equal to -0.1 / (EPCT4 / EPCT4New*100), , 4. Method according to the preceding claim, in which the aging progression score (SCORE) is defined as follows: .

5. The method of claim 3, wherein the aging progression score (SCORE) is defined as follows: , said method further comprising a step of determining an inverse aging progression score defined as follows: , and said method further comprising a step of providing reverse information of said at least one cumulative aging to the operator or to the automated system for said piloting assistance, according to said reverse aging progression score.

6. Method according to any one of the preceding claims, in which the cumulative aging is creep, and / or oxidation, and / or corrosion.

7. Method according to any one of the preceding claims in which said method is capable of providing information concerning at least two different cumulative agings, the individual score of each aging being determined and a general score being calculated on the basis of said individual scores, for example in the form of an average or a weighted average, the information of said at least one cumulative aging to be provided to the user being dependent on said general score. 8.Method according to any one of the preceding claims, in which it is determined whether or not t is outside the start phase of the mission using a flight time elapsed since the start of the mission, and / or the flight speed of the aircraft, and / or the altitude of the aircraft relative to the ground.

9. Method according to any one of the preceding claims, in which the level or quantity of information of said at least one cumulative aging provided to the operator varies according to the aging progress score, and / or the value of A(t), and / or the flight phase concerned.

10. Aircraft comprising a display unit configured to provide information of at least one cumulative aging, said information being derived from a pilot assistance method according to any one of the preceding claims.

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