A method capable of providing information to an operator for managing at least one cumulative aging process.

Abstract

The invention relates to a method for providing information to an operator, for example a pilot, or to an automated system, for example an autopilot, to help manage, flight after flight, at least one cumulative aging, for example creep, of at least a portion of a gas turbine in a multi-purpose aircraft, for example a helicopter, in order to maximize its long-term performance. Figure to be published with the abstract: [Fig. 3]

Description

Title of the invention: Method capable of providing information to an operator for the management of at least one cumulative aging Technical field of the invention

[0001] The invention relates to a method capable of providing information to an operator, for example a pilot, or to an automated system, for example an Autopilot, making it possible to help manage flight after flight, at least one cumulative aging, for example the finishing, of at least one part of a gas turbine of an aircraft for versatile use, for example a helicopter, in order to get the best out of it in the long term. State of the prior art

[0002] 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.

[0003] Such limits are for example the NI (rotation speed of the gas generator at the high pressure shaft), the T45H shaped temperature of the high pressure turbine, the torque of the power shaft, or an indicator combining this information. These limits constitute for example thresholds not to be crossed in stabilized flight, and for which maximum continuous use times can be defined by regulation.

[0004] These indications do not take into account objectives per mission, such as a quota, or the 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 repair of the turbomachine, for example before its scheduled general overhaul.

[0005] In a context of uses that are not very variable and predictable, for example airliner missions, there are predictive means that fix binary throttle position indexes, in correct correspondence with maintenance costs. These predictive means also most often integrate maintenance costs and fuel consumption costs.

[0006] For versatile uses, for example for the varied missions of helicopters, the correspondence of a binary instruction (whether it is a torque, a gas generator speed or a temperature) with the costs is not reliable. Today, in this context, only ground monitoring of the meters exists, in particular with regard to the finage, carried out manually or with tools.

[0007] However, in this context, concerning these complex cumulative agings, such a posteriori monitoring does not provide any useful prospective indication for the following flights and is not in the nature of helping the pilot to respect a cumulative objective during the flight, for example an objective given by a fleet manager.

[0008] Such monitoring or such indications also do not provide information capable of enabling the pilot to 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.

[0009] Cumulative aging is a form of damage that increases over time. Such aging corresponds perfectly to the phenomenon of turbine blade fining, 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).

[0010] Other types of aging may also occur, such as predominantly “cyclic” aging modes, relating to a number of times stress thresholds are crossed, both upwards and downwards (oligocyclic fatigue (LCF), thermal cycling, number of starts / stops, etc.). However, it is difficult to act on such cyclic aging, so that these are not covered by this document. Presentation of the invention

[0011] This document aims to remedy the aforementioned drawbacks.

[0012] To this end, the present document proposes a method capable of providing information to an operator, for example a pilot, or to an automated system, concerning at least one cumulative aging, for example the finage, 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 defined as follows: SCORE = 0, if A(t) <S1 otherwise, = TERMi + TERM2 + TERM3 +TERM4+TERM 5

[0013] for the calculation of which we define: the mission quota, Q = QFactor*-^

[0014] Or QFactor is a factor between 0.1 and 10, for example, to be made modifiable by the operator if possible, SD is a major maintenance trigger threshold of a CV aging counter, in hours, • DQ is the flight time between two overhauls of said part of the gas turbine or the target life of said part of the gas turbine, in hours.

[0015] - the mission's default quota, QDEF =

[0016] - the cumulative aging counter CV which is a value proportional to the cumulative aging, - the forecast flight duration of the mission entered in hours, M, for example between 0.2 and 3 hours, - the default forecast flight duration of the mission in hours, by example of the order of 1 hour, - Y a parameter to adapt to the application context, chosen between 2 and - the cumulative flight duration of the mission, in hours, at a time t of the mission, T(t) - a first threshold SI, 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 is defined by the instant t= tO of the start of the flight - an instant t = tl at the end of a phase known as the start of the mission is also defined so that: - tl - tO greater than a duration between 1 and 15 minutes, and / or - tl is the first instant t greater than tO for which the flight speed of the aircraft is above a predetermined speed, for example 40 Ktas for a helicopter, and / or - tl is the first instant t greater than tO 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, a / < f _ cv ^1 ~ CVQ-X) - the cumulative total per flight hour since the start of the mission (tO), at a time t of the mission without information on the predicted flight duration of mission M,

[0017] r / rx „ cv (t)-cv(to) ' Q*T(t) - the cumulative flight time per hour since the start of the mission, at a time t of the mission, anticipating a flight duration of “usual short missions” of Y, in hours,

[0018] _ ccü-cm Q*max( Y,T(t) ) the cumulative total per flight hour since the start of the mission, at a time t of the mission anticipating the expected flight duration of the mission provided M,

[0019] CV (t)-CV(tO) Q*M TERM 1 = >S2 [ otherwise, 0 TERM2 = 2. if M = MDEF and Q = QDEF and D(t) >(T(t) f M\ otherwise 1, if and if trend of B( l) over X seconds monotonically increasing otherwise, 0

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028] TERM 3 - TERM 4 = TERM 5 = 2, if Otlet M = MDEF and Q = QDEF and C(t) > 1, otherwise 1, if t> t\ and ( MtMDEF or QïQDEF ) andC[t}> 1, otherwise, 0 L if t>tl and (MïMDEF or Q*QDEF) and D(at >(T(t) / M) otherwise, 0 1, if t>tlet (M* MDEF or Q * QDEF ) and D(t) > 1 otherwise, 0 said method comprising a step of providing information to the operator or to the automated system, dependent on said aging score. The step of providing said information to an operator can be carried out by display. As previously stated, cumulative aging of a gas turbine part is the damage to the affected part that increases over time. Such aging is mainly the fining phenomenon, but can also be oxidation, corrosion, or mechanical wear of the parts of the affected part. 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 CV value, the greater the cumulative aging of the parts of the concerned part 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 varying speeds. The major maintenance trigger threshold is a threshold predetermined by the gas turbine manufacturer, beyond which a large-scale maintenance operation, known as major maintenance, is necessary to ensure proper operation. operation of the gas turbine or prevent premature damage to it. Such an operation generally requires the removal of the gas turbine.

[0029] The flight time between two general overhauls is known by the abbreviation TBO for “Time Between Overhaul”.

[0030] The target lifetime DQ may be a flight duration greater than the duration between two overhauls, for example equal to twice the duration between two overhauls.

[0031] The forecast flight duration of the mission entered M is a value determined before the start of the mission and entered into a computer of the aircraft, for example via an interface. This duration can be entered by an operator, for example a pilot.

[0032] The expected flight duration, by default or not, of the mission entered M or M dEF is for example between 0.2 and 3 hours. MDEF is for example of the order of 1.5 hours.

[0033] M will be filled in with the collection value of MDEF if M is not filled in by the operator.

[0034] The flight duration of the usual short missions Y will either be defined in a fixed manner 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, from MDEF / 2 to

[0035] 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.

[0036] The cumulative flight duration of the mission at a time t, T(t) is the time elapsed between the start of the mission tO and time t.

[0037] 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.

[0038] 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.

[0039] The fact of inhibiting the calculations of terms 2, 3, 4 and 5, that is to say of setting these terms to 0, during the start phase of the mission (T(t) < tl), makes it possible not to bother the operator, for example the pilot, by the appearance of indications during the most delicate flight phases (takeoff, etc.).

[0040] Each term serves a different purpose and therefore allows them to be combined.

[0041] When the level of stress on the engine at time t leads to aging minor (IF to be defined by the engine manufacturer), the score is set to zero regardless of the value of the different terms. There is in fact no point in providing information, for example by display, if the engine load no longer causes significant changes tively the final accumulation, it is not necessary to continue to encourage reducing the solicitation. This is an important element of the invention to avoid unnecessarily limiting solutions operationally since exceeding the quota does not carry any risk and the following missions always offer possibilities of compensation.

[0042] The first term TERM 1 is used to signal to the operator a very high demand, without any obvious relationship with the indications of acceptable speed limits. 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 first moments of the flight. It is also regular information which enriches the operator's intuitive perception of the situation.

[0043] The second term TERM 2 makes it possible to reinforce the score if the level of stress at time t leads to an increase in aging not compensated by the increase in the 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.

[0044] 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 of less than 5 (“option 2”).

[0045] The fourth term TERM 3 makes it possible to increase the score if the quota is exceeded by considering that the mission will last Y hours and to lower the score if, the flight duration Y being exceeded, the cumulative total has converged again below the quota. This term allows a first level of progression of the score in absolute value of the cumulative hourly total, 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).

[0046] Such a method can also provide assistance with piloting and / or training for the operator of critical conditions leading to an aggravation of said cumulative aging.

[0047] Instead of giving 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 can remain at 1, which leads to a maximum score lower than 5 (“option 2”).

[0048] 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 discretion of displays and low use, for example in a context of too much variability of missions).

[0049] The fifth term TERM 4 makes it possible to reinforce the score if the accumulation follows a progression greater than a linear accumulation towards the quota Q entered, for the duration of the mission flight M entered. As the start of the mission is generally more demanding, this makes it possible to reinforce vigilance fairly early and fairly precisely, and to indicate that moderation or action by the pilot is desirable.

[0050] The sixth term TERM 5 makes it possible to reinforce the score by comparing the cumulative total to the quota Q, 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.

[0051] 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 determined duration) 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.

[0052] It is also possible to display a warning light, for example a green warning light, if A(t) < SI (or other value) in the display zone of the aircraft engine speed limits (first limit indicator, NI margin, T45H - defined above), this zone being a priority attention zone for the pilot.

[0053] Three states of vigilance can be permitted 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 case of “option 2”. - high vigilance: invitation to provide information on M Mdef and M Mdef, the maximum score then being equal to 5.

[0054] Conversely, in the “option 1” case, the scale of 5 is preferred and it is the fineness of indication which is degraded with scores which evolve by 2 points at a time for both TERM2 and TERM3.

[0055] It is also possible to manage the case of several cumulative agings (both fining and corrosion for example, which are two different cumulative agings).

[0056] The calculated terms are relatively stable, but instabilities may exist. 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.

[0057] Cumulative aging can be fining, oxidation and / or corrosion.

[0058] 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 provided to the user being dependent on said general score.

[0059] Whether or not t is outside the mission start phase may be determined using a flight time elapsed since the start of the mission, the flight speed of the aircraft, and / or the altitude of the aircraft relative to the ground.

[0060] The level or quantity of information provided to the operator may vary depending on the aging score, the value of A(t) and / or the flight phase concerned.

[0061] The level of information may in particular vary progressively by increment, for example by displaying a value between 0 and 5 or by displaying a progress bar, or even by not displaying such a value.

[0062] The amount of information can also vary by adding or removing information, so as to have more or less detailed information depending on the situation.

[0063] 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) can be provided or displayed depending on the flight phases, the aging, or at the request of the operator.

[0064] Generally speaking, 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).

[0065] These indications are preferably not unnecessarily disturbing, particularly in 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, non-distracting, or even inhibited display (no flashing, etc.) during phases with significant power variation),

[0066] These indications encourage and guide pilots to act on 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, depending on the types and business objectives of the missions, and the operating context.

[0067] These indications must be progressive (several alert levels rather than a binary alert), such progressiveness being particularly useful when the 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 which produce cumulative aging (non-intuitive without indication or with a binary indication).

[0068] Such indications making it possible to identify the phases which cause more or less pronounced cumulative aging can also contribute to more ecological management decisions (CO2 emissions, etc.).

[0069] Unlike existing applications in a non-versatile usage context, this score does not derive from an invariable cost calculation.

[0070] 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, the 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.

[0071] 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 economy score of 0 to 2 depending on the deviation from the most economical stable flight conditions.

[0072] The aircraft may be a rotary wing aircraft, in particular a helicopter. Brief description of the figures

[0073] [Fig.l] is a diagram illustrating the evolution over time of the score during an aircraft mission, without pilot action, this diagram also representing the evolution of the power, of the cumulative damage CV, of the temperature of the hot parts of the gas turbine and of the altitude,

[0074] [Fig.2] is a diagram representing the evolution of the terms A(t), B(t), C(t), D(t), TERM 1, TERM 2, TERM 3, TERM 4, TERM 5, during the mission,

[0075] [Fig.3] is a diagram corresponding to [Fig.l] in which a pilot action allows you to limit the score to 3,

[0076] [Fig.4] is a diagram corresponding to [Fig.l] in which a pilot action allows you to limit the score to 2,

[0077] [Fig.5] is a diagram corresponding to [Fig.l] in which a pilot action allows you to limit the score to 1, Detailed description of the invention

[0078] In the diagrams of Figures 1 to 5, the curves Score, Pw, Cumul, T45H and Z illustrate respectively the evolution over time of the aging progression score, the output shaft power, the cumulative damage, the temperature of the hot parts of the gas turbine and the altitude.

[0079] It is recalled that the aging progression score can be defined as follows: srr>RF-[ a«A(t) <si [otherwise, = TERMÏ + TERM2 + TERM3 +TERM4+TERM 5

[0080] for the calculation of which we define: the mission quota, Q = QFactor*-^

[0081] where • QFactor is a factor between 0.1 and 10, for example, to be made modifiable by the operator if possible, • SD is a major maintenance trigger threshold for a CV aging counter, in hours, • DQ is the flight time between two overhauls of said part of the gas turbine or the target life of said part of the gas turbine, in hours.

[0082] - the mission's default quota, QDEF =

[0083] - the cumulative aging counter CV, which is a value proportional to the cumulative aging the forecast flight duration of the mission entered in hours, M, for example between 0.2 and 3 hours, to be made modifiable by the operator if possible, - the default forecast flight duration of the mission in hours, MDFF, for example of the order of 1 hour, - Y a parameter to adapt to the application context, chosen between MDEF / 2 and - the cumulative flight duration of the mission, in hours, at a time t of the mission, T(t) - a first threshold SI, 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 is defined by the instant t= tO of the start of the flight - an instant t = tl of the end of a phase called the start of the mission is also

[0084]

[0085] defined so that: tl - tO greater than a duration between 1 and 15 minutes, and / or tl is the first instant t greater than tO for which the flight speed of the aircraft is greater than a predetermined speed, for example 40 Ktas for a helicopter, and / or tl is the first instant t greater than tO 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, art \ _ cv U) - CV(tX) the cumulative flight time per hour since the start of the mission (tO), at a time t of the mission without information on the expected flight duration of mission M, R / n _ CV(t)-CV(tO) the cumulative flight time per hour since the start of the mission, at a time t of the mission, anticipating a flight duration of the “usual short missions” of Y, in hours, •' Q*max( Y,T(t) ) the cumulative total per flight hour since the start of the mission, at a time t of the mission anticipating the expected flight duration of the mission provided M,

[0086] D(t) CV (t)-CV(tO) Q *M TERM^^^ [ otherwise, 0 TERM2- 2, if t>llet M-MDEF and Q = QDEF and D(t) >(T(t) / M), otherwise 1 if t>tl and if trend of B ( t ) over X seconds monotonically increasing otherwise, 0

[0087] TE RM 3 = 2, if t > H and M = MDEF and Q = QDEF and C(t)> 1, otherwise 1, if t> tl and ( M^MDEF or Q* QDEF ) and C(t) > 1, otherwise, 0

[0088] TERM 4 = 1, if t>tl and {M^MDEF or Q* QDEF ) and D(t) >(T(t) / M) otherwise, 0

[0089] TERM 5 = ( 1, if t > tl and (M*MDEF or Qt QDEF ) and D(Q > 1 l otherwise, 0

[0090] The mission illustrated in figures 1 to 5 is the case of a helicopter mission: - taking off at point A (time = 0), - moving to point B and landing at point B; - taking off from point B, moving to point C and landing at point C; - taking off from point C, moving back to point A and landing at point A.

[0091] We see on the diagram in [Fig.l] that the score (here the score of the finishing, calculated using the formula described previously summing the terms TERM 1 to TERM 6 whose evolution is presented in [Fig.2]) reaches a maximum of 4. In such a case, the quota Q at the end of the mission reaches twice a desired quota and therefore largely exceeds this desired quota.

[0092] The diagram in [Fig.3] illustrates the case where, during the same mission, the pilot takes actions to limit the score to 3. In the case illustrated in [Fig.3], an action is taken by the pilot each time the score reaches the value 4. Thus, the pilot reduces the horizontal movement speed by 1 ktas a first time, then again a second time later. In such a case, the quota Q at the end of the mission reaches 1.8 times the desired quota. The mission has also been extended by 30 seconds compared to the case illustrated in [Fig.l].

[0093] The diagram in [Fig.4] illustrates the case where, during the same mission, the pilot takes actions to limit the score to 2. In the case illustrated in [Fig.4], an action is taken by the pilot each time the score reaches the value 3. Thus, the pilot reduces the horizontal movement speed by 4 ktas a first time, reduces this speed again by 6 ktas later and then further lowers the vertical movement speed by 100 feet per minute at the end of the climb. In such a case, the quota Q at the end of the mission reaches 1.2 times the desired quota. The mission has also been extended by 2 minutes compared to the case illustrated in [Fig.l].

[0094] The diagram in [Fig. 5] illustrates the case where, during the same mission, the pilot takes actions to limit the score to 1. In the case illustrated in [Fig. 5], an action is taken by the pilot each time the score reaches the value 2. Thus, the pilot first reduces the vertical speed by 100 feet per minute, then reduces the horizontal speed by 4 ktas, reduces this speed again by 2 ktas later and then lowers this speed again by 5 ktas later. In such a case, the quota Q at the end of the mission reaches 0.7 times the desired quota. The mission has also been extended by 4.6 minutes compared to the case illustrated in [Fig. 1]. It can be seen that this extension is relatively small compared to the total flight duration of the mission.

[0095] Depending on the constraints concerning the duration of the mission, and according to the instructions of a fleet manager, the pilot (directly or via an automatic pilot) may choose the score 4, 3 or 2 or 1 that he wishes to aim for, with the assurance of only applying the strict limitations on his flight which allow him to get closer or closer to the quota.

Claims

Claims

1. Method capable of providing information to an operator, for example a pilot, or to an automated system, concerning at least one cumulative aging, for example the finage, 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 defined as follows: SCORE=( 0,«A(tHSl [otherwise, = TERMY + TERM2 + TERM3 + TERM4 + TERM 5 for the calculation of which we define: - the mission quota, Q = QFactor*^^ Or • QFactor is a factor between 0.1 and 10, for example, to be made modifiable by the operator if possible, • SD is a major maintenance trigger threshold for a CV aging counter, in hours, • DQ is the flight time between two overhauls of said part of the gas turbine or the target life of said part of the gas turbine, in hours. - the default quota of the mission, O = - the cumulative aging counter CV which is a value proportional to the cumulative aging, the forecast flight duration of the mission entered in hours, M, for example between 0.2 and 3 hours, - the default forecast flight duration of the mission in hours, EF, for example of the order of 1 hour, - Y a parameter to adapt to the application context, chosen between ^^e>ef / 2 and - the cumulative flight duration of the mission, in hours, at a time t of the mission, T(t) - a first threshold SI, 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 is defined by the time t= tO of the start of the flight an instant t = tl at the end of a phase called the start of the mission is also defined so that: tl - tO greater than a duration between 1 and 15 minutes, and / or tl is the first instant t greater than tO for which the flight speed of the aircraft is greater than a predetermined speed, for example 40 Ktas for a helicopter, and / or tl is the first instant t greater than tO 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, CV ( t) -CV(tX) \ 3600 the cumulative flight time per hour since the start of the mission (tO), at a time t of the mission without information on the forecast flight duration of mission M, B(t) CV' (t)-CV(tO) Q*T(t) the cumulative flight time per hour since the start of the mission, at a time t of the mission, anticipating a flight duration of the “usual short missions” of Y, in hours, CV (t)-CV (tO) Q*max(Y,T(t)) the cumulative total per flight hour since the start of the mission, at a time t of the mission anticipating the forecast mission flight duration entered M, £>(0 = CV (t)-CV (tO) Q *M TERM 1= >52 ' otherwise, 0 2, if t> tl and M = MDEF and Q = QDEF and D(l) >(T(t) / M), TERM2 = otherwise, 1, if t>t\ and if tendency of S(t) over X seconds increasing numotone otherwise, 0 2, if t>tlet M = MDEF and Q-QDEF and C(t)> 1, TERM ?>= otherwise, 1, if t>t\and ( MïMDEF or Q^QDEF ) and C(t)> 1, otherwise, 0 i l1' if t>Aet\M*MDEF or QïQDEF ) and D(t) >(T(t) / M) [ otherwise, 0 _ [1, if t>tlet ( MïMDEF or Q^QDEF ) and D(t) > 1 TERM 5=| [ otherwise, 0 said method comprising a step of providing said information to the operator or to the automated system, dependent on said aging progression score.

2. A method according to any preceding claim, wherein the cumulative aging is fining, oxidation and / or corrosion.

3. Method according to 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 is calculated on the basis of said individual scores, for example in the form of an average or a weighted average, the information provided to the user being dependent on said general score.

4. Method according to 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, the flight speed of the aircraft and / or the altitude of the aircraft relative to the ground.

5. Method according to one of the preceding claims, in which the level or quantity of information provided to the operator varies according to the aging score, the value of A(t) and / or the flight phase concerned.

6. A method according to one of the preceding claims, wherein the aircraft is a rotary wing aircraft.

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