Pilot assistance method for managing at least one cumulative aging

Abstract

The invention relates to a method for 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 (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 which is a function of a plurality of terms comprising TERM 1, TERM 2, TERM 3, TERM 4 and TERM 5, said method comprising a step of providing information on said at least one cumulative aging to the operator or to the automated system for said piloting assistance, according to said aging progression score. Abstract figure: [Fig. 2]

Description

Title of the invention: Method for assisting with management of at least one cumulative aging event Technical field of the invention

[0001] The invention relates to a method of piloting assistance for an operator, for example a pilot, or for an automated system, for example an automatic pilot, 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 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 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 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. Presentation of the invention

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

[0012] 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 automatic pilot, said assistance relating to at least one cumulative aging, for example the fining, 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,

[0013] and we define for the calculation of the aging progression score: the mission quota, Q = ,

[0014] where - QFactor is a factor between 0.1 and 10, for example, to be made modifiable by the operator if possible, QFactorageing is a factor, DQdbie, QFactoring = - SD is a major maintenance trigger threshold for a meter cumulative aging CV, in hours, DQ j is the target lifetime of said part of the gas turbine, in hours, over an engine life before deep maintenance or minimum power margin reached, DQ is the service life between two overhauls of said part of the gas turbine, in flight hours, preferably a service life targeted for current flight, assuming that all flights are made with the same power margin, DQ = DQmin + ÇEPCTifj^ yx (DQtarget — DQmin) — (ePCT4mo(f) x (DQmax — DQmin) EPCT4Mny x [(FPCr4„ J2 - EPCT4^ x ËPCT4Moy] x EP Ct^. + [EPCT4Moy DQmin) EPCT4>, x [(EPC™,.} — EPCrt., x epcT4„ ] {_ ^Avg [V 1 l^New J^AvgJ X (EPCTi)2

[0015] - the default quota of the mission, „ sd , ^Fe

[0016] - a measure of the current power margin of the engine, EPCT4, for example between 0 and 10,

[0017] - a margin of verification of the estimated power of a new engine, EPCT4New, by example equal to 10,

[0018] - an average margin for verifying the power of a new engine,

[0019] EPCT4Moy = X* EPCT4New,

[0020] - a coefficient X, X preferably being equal to 1 / 3,

[0021] - a minimum duration, DQmin, of major maintenance trigger threshold for the engine, for example if it were to operate for a lifetime without power margin, such as EPCT4 = 0,

[0022] - a duration, DQmax, 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 = EPCT4\ew for example DQmax= DQtarget *3,

[0023] - 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, ^def, 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 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 defined by the time 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, also defined so that:

[0024] — tl - tO is greater than a duration between 1 and 15 minutes, and / or

[0025] — 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

[0026] — tl is the first instant t greater than tO for which the altitude of the aircraft by ground clearance, also called ground clearance, is greater than a certain 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 sliding gradient over X seconds, _ _ cv (t) - cv(tx), (t) ~ Qm - 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, CV (t) - cv (tO) ' B(t) = QT(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, Y being a parameter to be adapted to the application context, chosen between MDEr / 2 and cy _ cy C(t) =--—-----:—— 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, 5(0 = CV (t) - CV (tO) Q *M

[0027] TERM 1 => S2, ' ( otherwise, 0 ' f 2, if t > tl and M = MDEF and Q = QDEF and D(t) > (T(t) / M), TERM2 = |sûîonl,if t > tl and if tendency of B(t) over X seconds monotonically increasing, 1 otherwise, 0 _ | 2, if t > tl and M — MDEF and Q — QDEF and C(t) > 1, , TERM 3 = j otherwise l, if t > tl and (M * MDEF or Q QDEF) and C(t) > 1, '■ otherwise, 0

[0028] - (1, if t > tl and (M * MDEF or Q #= QDEF) and D(t) > (Tft) / M) ' and X JS I 1 'XI t smon, 0 SCORE -

[0029] - r _ (Lsi t > tl and (M #= MDEF or Q #= QDEF ) andD(t) > 1 , ic nM b — ) . _ ( smon, O

[0030] said method comprising a step of providing information on said at least one cumulative aging to the operator or to the automated system for said piloting assistance, according to said aging progression score.

[0031] The aging progression score can be defined as follows: Q, if ?l(t) < IF TERM1 + TERM2 + TERM3 + TERM4 + TERM5, otherwise

[0032] The step of providing said information to an operator can be carried out by display.

[0033] As previously stated, cumulative aging of a part of a gas turbine is the damage to the affected part that increases with time. Such aging is primarily the fining phenomenon, but may also be oxidation, corrosion, or mechanical wear of the parts of the affected part.

[0034] 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 relevant part or module of the gas turbine.

[0035] A mission of the aircraft is defined by a succession of flight phases between a start and an end of the mission. Typically, such a mission may in particular include one or more takeoff and landing phases, and flight phases at more or less significant speeds.

[0036] 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 the proper functioning of the gas turbine or to avoid premature damage to it. Such an operation generally requires the removal of the gas turbine.

[0037] DQ is defined as a second-degree function of the verification margin

[0038] of the current engine power, 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 accessible performance (beyond what is guaranteed) that varies significantly depending on the engine margins. In the limiting case, DQmin = DQmax = DQtarget, and - more consistent aircraft performance over the life of the engine, always maintaining an identical overall life target. This can for example be achieved by choosing DQmin = DQtarget / 5 and DQmax = DQtarget *3.

[0039] DQ therefore takes into account the life of the engine and produces a compensation, called

[0040] engine margin compensation: - at the start of the engine's life, compensation leads to targeting a quota lower than the average target 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, compensation leads to targeting a higher quota than the average target quota to enable higher aircraft performance to continue to be achieved.

[0041] The amplitude of this compensation with regard to the life of the motor (the difference between the compensation at the start of the motor's life and the compensation at the end of the motor's life) is adjusted according to:

[0042] - on the one hand, the acceptability of an operational constraint at the start of the engine's life while the visible damage will be less than a linear progression, and

[0043] - on the other hand, the desired engine operating proportion. For a func linear operation there will be no compensation and for non-linear operation there will be strong compensation leading to more constant aircraft performance.

[0044] The flight time between two general overhauls is known by the abbreviation TBO for “Time Between Overhauls”.

[0045] 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.

[0046] 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.

[0047] M will be filled in with the collection value of MDEF if M is not filled in by the operator.

[0048] 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 terminated by the application and calculated as an average of the flight durations of the aircraft's previous missions less than MDEF in the interval, from MDEF / 2 to

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The fact of inhibiting the calculations of TERM2, TERM3, TERM4 and TERM5, 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.).

[0054] Each term serves a different purpose and therefore allows them to be combined.

[0055] 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 significantly changes the final total, there is no need to continue to encourage reducing the load. This avoids unnecessarily limiting solutions operationally since exceeding the quota does not carry any risk and the following missions always offer possibilities for compensation.

[0056] The current engine power verification margin, EPCT4, estimated new engine power verification margin, EPCT4New, and average mid-life hot parts power verification margin, 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.

[0057] 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 intuitive perception of the operator in relation to the situation.

[0058] The second term TERM 2 makes it possible to reinforce the score if the level of solicitation 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 request is made at a high rate. It is an intermediate variant between the gradient and the cumulative aging which integrates possible previous debits and credits and allows a report 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 request remains truly excessive.

[0059] 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”).

[0060] The third 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).

[0061] 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.

[0062] 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 of less than 5 (“option 2”).

[0063] 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 the displays and low use, for example in a context of too much variability of the missions).

[0064] The fourth 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,

[0074] - TERM 6 = This allows vigilance to be reinforced early and precisely enough, and indicates that moderation or action by the pilot is desirable.

[0065] The fifth 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.

[0066] 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.

[0067] It is also possible to display a warning light, for example a green warning light, if A(t) < SI (or other value) in the area displaying the engine speed limits of the aircraft (first limit indicator, NI margin, T45H - defined above), this area being a priority attention area for the pilot.

[0068] 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.

[0069] 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 for both TERM2 and TERM3.

[0070] It is also possible to manage the case of several cumulative agings (both fining and corrosion for example, which are two different cumulative agings).

[0071] We can further define for the calculation of the aging progression score:

[0072] - a first component, _Comp_FBtime, for example equal to -0.1 per flight hour (or “Flight Hours” in English),

[0073] - a second component, _Comp_FBageing, for example equal to -0, l / (EPCT4 / EPCT4New* 100), _Comp_FBtime + _Comp_FBaqeing x )] x [E - T(t)] '

[0075] the plurality of terms further comprising TERM 6.

[0076] The aging progression score can then be defined as follows: SCORE — f Si' [TERM1 + TERM2 + TERM3 + TERM4 + TERM5 + TERM6, otherwise

[0077] The sixth term TERM 6 makes it possible to add compensation to the score to take into account the lightening of the aircraft, called lightening compensation. TERM 6 produces an average compensation of the progression of the score so as to correct the decrease in progression of the damage, under given flight conditions, of the lightening of aircraft with an associated standard average consumption, itself dependent on the power margin of the engine. The value of a slope of this lightening compensation is adjusted to avoid any overcompensation.

[0078] TERM 6 is the product of a first compensation slope parameter [YT(tJ] and

[0079] of a second compensation slope parameter \_Comp_FBtime+ _Comp_FBageing * (EPCT4 / EPCT4New)].

[0080] The first compensation slope parameter [YT(tJ] is mission time dependent and zero for T(t) = Y. It is calculated to produce the average compensation for the score progression. In this way, it compensates for the decrease in damage progression at the desired standard average speed, due to the aircraft being lighter.

[0081] and its guaranteed average reference consumption.

[0082] The second compensation slope parameter [_Comp_FBrime+ _Comp_FBageing * (EPCT4 / EPCT4New)] has a component proportional to EPCT4. It is calculated to adjust the compensation slope on average for engines from new to aged condition.

[0083] Compensating for the weight reduction helps to avoid a degree 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 where the need for speed is at the start of the mission.

[0084] The calculated terms are relatively stable, but instabilities may exist. In order to overcome such instabilities, it is possible to put hysteresis on the score display. Some terms may have an adapted hysteresis, for example greater than other terms.

[0085] The aging progression score can be defined as follows: SCORE = TERM1 + TERM2 + TERM3 + TERM4 + TERM3 + TERM6'

[0086] The method may further comprise a step of determining an inverted aging progression score defined as follows: f 100, if SCORE < 1 Reversed score = I 1 5 [AMX {0; MZN{1; (—- * SCORE + -)}} * 100, smon

[0087] 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.

[0088] The aging progression score can in some cases be too demanding for the operator, because he must adjust the piloting to a median value. The reversed 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 can limit the visibility on possibilities of increasing the flight conditions in particular cases (significant payload deposit mid-mission for example).

[0089] Cumulative aging can be fining, and / or oxidation, and / or corrosion.

[0090] 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.

[0091] Whether or not t is outside the mission start phase may be determined 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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 based on flight phases, aging, or at the operator's request.

[0096] 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).

[0097] 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.)

[0098] These indications encourage and guide the pilots, to act on the long and stable phases of flight, for the management, flight after flight, of a cumulative aging of major components of the propulsion system. As indicated previously, these indications can be adjusted according to the score or the previous cumulative aging, according to the types and business objectives of the missions, and the operating context.

[0099] 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).

[0100] 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.).

[0101] Unlike existing applications in a non-versatile usage context, this score does not derive from an invariable cost calculation.

[0102] 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.

[0103] 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 flight conditions. the most economical stables.

[0104] The present 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.

[0105] The display unit may be an information bar.

[0106] The aircraft may be a rotary wing aircraft, in particular a helicopter. Brief description of the figures

[0107] [Fig-1] is a trend diagram illustrating an evolution of the damage engine over the engine life, this diagram representing the aircraft speed and the cumulative aging counter CV without engine margin compensation,

[0108] [Fig.2] is a trend diagram illustrating an evolution of the damage engine over the engine lifetime, this diagram representing the aircraft speed and the cumulative aging counter CV with engine margin compensation according to one embodiment,

[0109] [Fig.3] is a trend diagram illustrating an evolution in the accumulation of engine tuning, this diagram representing the aircraft speed and the cumulative aging counter CV with engine margin compensation according to one embodiment,

[0110] [Fig.4] is a trend diagram illustrating an evolution 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,

[0111] [Fig.5] is a trend diagram illustrating an evolution over time of a mission, this diagram representing the aircraft speed and the aging progression score without weight reduction compensation, in the case of a substantially constant aircraft speed, and

[0112] [Fig.6] is a trend diagram illustrating an evolution over time of a mission, this diagram representing the aging progression score with lightening compensation according to one embodiment. Detailed description of the invention

[0113] The diagram in [Fig. 1] represents the case for which DQ=DQciMe and therefore Q = QFactor * SD / DQcibie. In other words, DQ is a constant and corresponds to the target life of the 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 counter of aging means cumulative damage.

[0114] The diagram in [Fig.2] represents an embodiment for which DQ is a second-degree function of the current engine power verification margin, 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 [Fig.l], 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 [Fig.2]) makes it possible to maintain more constant aircraft performance (i.e. a more constant speed) over the life of the engine. The aircraft speed is greater, at the end of the engine's life, compared to the case without engine margin compensation in [Fig.l].

[0115] The diagram in [Fig.3] represents a particular example of the embodiment in [Fig.2] in which the engine life is linked to the cumulative finage. In other words, it is the finage which produces the achievement of the overhaul criterion for 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 cumulative finage equal to 100%. At point P, the major parts concerned must therefore be overhauled. In other examples, it is possible that the engine must be stopped according to other wear characteristics.

[0116] The diagram in [Fig.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_l, is substantially constant from point PL. We note that for a substantially constant aging progression score, the speed of the aircraft, here V_aeronef_def_l, is not constant, but increasing throughout the mission.

[0117] The diagram in [Fig.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 PI). To have a substantially constant aging progression score (i.e. corresponding to SCORE_def_l), we note that compensation at the level of the aging progression score must be applied: - between P2' and P2”, the compensation (noted Al) must be positive (for

[0123] - TERM 6 = “raise the curve”); - at point P2”, the compensation must be zero; - from P2”, the compensation (noted A2) must be negative (to “lower the curve”).

[0118] The compensation to be applied must therefore increase 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.

[0119] In order to have both a substantially constant aircraft speed and a substantially constant aging progression score, it is necessary to apply the weight reduction compensation.

[0120] The diagram in [Fig.6] represents an embodiment for which the compensation for the lightening is applied. It is recalled that, in this embodiment, we define:

[0121] - a first component, _Comp_FBtime, for example equal to - 0.1 per flight hour (or “Flight Hours” in English),

[0122] - a second component, _Comp_FBageing, for example equal to -0, l / (EPCT4 / EPCT4New* 100), PPC 1 Comp_FBtime + _CompFBageing x ( 4 ) x [F — T(t)] '

[0124] It is also recalled that the aging progression score, in this embodiment, is equal to: SCORE = I 0'sî" -^(0 < ^1- (TERM1 + TERM2 + TERM3 + TERM4 + TERM5 + TERM6, otherwise

[0125] TERM 6 adds the lightening compensation, TERM 6 being an increasing function, and zero for T(t) = Y. We note that the lightening compensation makes it possible to obtain a substantially constant aircraft speed, V_aeronef', from point P3 (equivalent to points PI and P2') and a substantially constant aging progression score, SCORE, from point P3' (equivalent to point P2).

Claims

Claims

1. 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 (CV), 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 (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: — the mission quota, q _ Qpactor * QFactorWjnff * ——— ' Or QFactor is a factor between 0.1 and 10, for example, to be made modifiable by the operator if possible, QFactorageing is a factor, DQtarget QFactor^n^a = —:--- SD is a major maintenance trigger threshold of a cumulative aging counter CV, in hours, DQ. jhl cst 'a target lifetime of said part of the gas turbine, in hours, over an engine life before deep maintenance or minimum power margin reached, DQ is the lifetime between two overhauls of said part of the gas turbine, in flight hours, preferably a targeted lifetime for the current flight, assuming that all flights are made with the same power margin, [2 / 1 (EPCT4 ) x (DQtarget — DQmin) — (EPCT4 ) x (DQ-max — DÇmin) -----—-------? -----— ----=-------- x EP CT4 EPC- x ) -epcT4„ xEPCT4m [ePCT4mo^ x (DQmax - DQmin) - EPCT4!,lew x (DQtarget - DQmin) Fr T? ï * Ota.) EPCT4 X (EPC7-4) — EPCT4 x epcT4 1*Avg [x 1 V / ms - the mission's default quota, n _ sa ^DEF nQcible - 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 margin for verifying the power of a new engine, EPCT4Moy = X* EPCT4New, - a coefficient X, X preferably being equal to 1 / 3, - a minimum duration, DQmin, of major maintenance trigger threshold for the engine, for example if it had to operate for its entire life without power margin, such as EPCT4 = 0, - a maximum duration, DQmax, of major maintenance trigger threshold for the engine, for example if it had to operate for its entire life with the maximum power margin, such as EPCT4Moy = EPCT4\ew 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, M, for example between 0.2 and 3 hours, - the default forecast flight duration of the mission in hours, ^def, 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 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 defined by the instant t= tO of the start of flight, - an instant t= tl of the end of a phase called the start of mission, also defined so that: — tl - tO is 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 included between 10 and 30 seconds, for example around 20 seconds, the average gradient sliding over X seconds, A(t) = CV (t) - CV(tX) , Q*( ) the cumulative total per flight hour since the start of mission tO, at a time t of the mission without information on the flight duration mission forecast M, = CV (t)--CV (tO) 1 ' 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, Y being a parameter to be adapted to the application context, chosen between MD£f / 2 and MD£f, cv(t)_cv(t0), ” Q*max(Y,T(t)) the cumulative flight time per hour since the start of the mission, at a instant t of the mission anticipating the forecast flight duration of mission informed M, — CV ftOl ' o(t) = _Lz---- 7 Q * M TERM 1 = I1'> S (otherwise, 0 r 2. if t > tl and M = MDEF and Q = QDEF and D(t) > (T(t) / M), TERM2 = {otherwise1, if t > tl andif trend of B(t) over X seconds monotonically increasing, t otherwise, 0 i 2, if t>tlet M = MDEF and Q = QDEF and C(t) > 1, TERM 3 = otherwise 1, if t > tl and ( M MDEF or Q =F QDEF ) and C(t) > 1, ( otherwise, 0 fl.if t > tl and (M ï MDEF or Q QDEF) and D(t) > (T(Q / M) 1 d KM 4 — > . t otherwise, 0 , And TERM 5 = fl, if t > tl and ( M MDEF or Q QDEF ) and D(t) > 1 , otherwise, 0 said method comprising a step of providing information on said at least one cumulative aging to the operator or to the 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: STnoF-f 0, siA(t) <ST {TERM1 + TERM2 + TERM3 + TERM 4 + TERM5, sinon

3. The method of claim 1, wherein the following are further defined for calculating 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), TERM 6 = \_Comp_FBtime + _Comp_FBageing X )] X [K - T(t)] EPCT4New J the plurality of terms further comprising TERM 6.

4. Method according to the preceding claim, in which the aging progression score (SCORE) is defined as follows: f 0,SI zUf) < SI Sï ( / nr = 4 (TERM1 + TERM2 4- TERM3 + TERM4 4- TERM5 4- TERM 6, otherwise

5. The method of claim 3, wherein the aging progression score (SCORE) is defined as follows: SCORE = TERM1 + TERM2 + TERM3 + TERM4 + TERM5 4- TERM6 ' said method further comprising a step of determining an inverted aging progression score defined as follows: 100, if SCORE < 1 SCORE _inverted — ■ 1 5 MAX {0; (— - * SCORE 4- -)}[* 100, otherwise •> and said method further comprising a step of providing inverted information of said at least one cumulative aging to the operator or the automated system for said piloting assistance, according to said reverse aging progression score.

6. A method according to any preceding claim, wherein the cumulative aging is fining, 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. A method according to any preceding claim, wherein it is determined whether or not t is outside the mission start phase 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. A method according to any preceding claim, wherein the level or quantity of information of said at least one cumulative aging provided to the operator varies as a function of the aging progression score, and / or the value of A(t), and / or the flight phase concerned.

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

Images