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, 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 (SCORE) which is a function of a plurality of terms, said plurality of terms comprising TERM1, TERM2, and TERM3, 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). Abstract figure: [Fig. 1]

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 autopilot, 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. 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] Now in this context, concerning these complex cumulative agings, such a a posteriori monitoring does not provide any useful prospective indication for subsequent flights and is not in a position to help the pilot meet an accumulation 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 piloting assistance method for an operator, for example a pilot, or for an automated system, for example an autopilot, 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, said plurality of terms comprising TERM1, TERM2, and TERM3,

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

[0014] where

[0015] - QFactor is a factor between 0.1 and 10, for example, to be returned if possible modifiable by the operator,

[0016] - SD is a major maintenance trigger threshold for a counter cumulative aging CV, in hours,

[0017] - DQ is the flight duration between two overhauls of said part of the gas turbine or the target lifetime of said part of the gas turbine, in hours,

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024] - the default quota of the mission, - DQ - the maximum quota, QmAx — a*QDEF' with 4 5, - the minimum quota, QMW — P*QDEF, with 0 < [3 < 1, - 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 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 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) , the cumulative total per flight hour since the start of mission tO, at a time t of the mission without information on the forecast flight duration of mission M, CTftb-CVW. Q > T(t) the cumulative total per flight 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, CV(t)-CV(tO) ' D(t) =--—---- Q * M

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] , with y a coefficient, TERHl = MAX ¢0 ; MIN {r; Qdef Qdef Qdef ^def TERM2 = I | Bf*) if t > tl: MAX] 0; MIN1; - l) / ( Qmx / QDEr - f | — A ) VL 3600 ( [ $(0 ]) + MAX j 0 ; MIN 1 ; y-yy - 1 > ll ~xr B otherwise, 0 Qmin / Qdef) * (Qmin7 QnEFy (Qmax / Qdef Qmin / Qdef.) ,rcr,„ o _ (If t > tl: 2 X MAX{0 ; ; C(t)]} ' IchM 3 — y . ( smon,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. The step of providing said information to an operator can be carried out by display. The coefficient y can be equal to 2, the aging progression score being defined as follows: SCORE = TE RM 1 + TERM 2 + TE RM 3, said method further comprising a step of determining an inverted aging progression score defined as follows: 100, if SCORE < 1 1 5 MAX (0-, MIN {1-,(-- * SCORE + -)}}* 100, otherwise 4 4 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. Defining the aging progression score as a sum of TERM1, TERM2 and TERM3 results in a continuous aging progression score (as opposed to a case of a discretized aging progression score). If there is Reversed SCORE = step of determining the reverse aging progress score in the process, the reverse aging progress score will also be continuous accordingly.

[0034] The aging progression score may in some cases be too demanding for the operator, because he must adjust the piloting to a median value and therefore be tempted to control the situation more often. Providing reversed information according to 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 control later, the objective will still be globally achieved. Conversely, this may prevent him from seeing possibilities of increasing the flight conditions in particular cases (for example: significant payload deposition mid-mission). The choice to use the information or the reversed information according to the aging progression score or the reversed aging progression score respectively is a choice arbitrated by the operator.

[0035] The reverse aging progression score allows a clipped result to be obtained.

[0036] Optionally, the reverse aging progression score may be rounded. to the upper fifth, to the lower fifth (minimum desirable resolution for example) or be truncated to the upper fifth, to the lower fifth. Optionally, the reversed aging progression score can be rounded up to the upper hundredth, to the lower hundredth, or be truncated to the upper hundredth, to the lower hundredth.

[0037] Qmax and QM1N are used to define the sensitivity zone of TERM 1 and TERM 2.

[0038] Qmax is a high threshold (or high sensitivity threshold) which allows the ceiling to be reached calculation and then clip above (i.e. clip the plurality of terms of the score so that the score is less than or equal to the ceiling).

[0039] Qmin is a low threshold (or low sensitivity threshold) which makes it possible to reach the floor 0 and then clip below it (i.e. clip the plurality of terms of the score so that the score is greater than or equal to the floor).

[0040] The coefficient y can be equal to 1, the aging progression score being defined as follows: 0, if 4(t) < IF TERM1 + TERM2 + TERM3, otherwise

[0041] The coefficient y makes it possible to adjust the sensitivity of the aging progression score to variations in unstabilized flight phases, the coefficient being proportional to this sensitivity. The fact that the coefficient y is equal to 1 therefore makes it possible to reduce the sensitivity.

[0042] As previously stated, cumulative aging of a part of a gas turbine is the damage to the affected part that increases over time. SCORE = Such aging is mainly the phenomenon of fining, but can also be oxidation, corrosion, or mechanical wear of the parts of the part concerned.

[0043] The cumulative aging counter CV is a value generally provided by the computer of the gas turbine, and proportional to the cumulative aging, measured or determined by calculation, from values from sensors (rotation speed of the gas generator, 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.

[0044] 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.

[0045] 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.

[0046] The flight time between two general overhauls is known by the abbreviation TBO for “Time Between Overhauls”.

[0047] The target lifetime D may be a flight duration greater than the duration between two overhauls, for example equal to twice the duration between two overhauls.

[0048] 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.

[0049] 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.

[0050] M will be filled in with the collection value of MDEF if M is not filled in by the operator.

[0051] 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 = 1.5 hours, 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

[0052] 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.

[0053] The cumulative flight duration of the mission at a time t, T(t) is the time elapsed between the start of mission tO and time t.

[0054] 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.

[0055] 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.

[0056] Each term serves a different purpose and therefore allows them to be combined.

[0057] 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.

[0058] 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.

[0059] 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.In addition, the second term TERM 2 allows the score to be reinforced 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 allows vigilance to be reinforced early enough and precisely enough, and indicates that moderation or action by the pilot is desirable.

[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 duration of flight Y being exceeded, the cumulative has converged again under the quota. This term allows a first level of progression of the score in absolute value of the cumulative hourly, 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). In addition, the third term TERM 3 makes it possible to reinforce the score by comparing the cumulative 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.

[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] 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.

[0063] 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 area of the aircraft engine speed limits (first limit indicator, NI margin, T45H - defined above), this area being a priority attention area for the pilot. It is also possible to manage the case of several cumulative agings (both fining and corrosion for example, which are two different cumulative agings).

[0064] 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. Cumulative aging may be fining, and / or oxidation, and / or corrosion.

[0065] Said method can provide 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.

[0066] Whether or not t is outside the mission start phase may be determined using an elapsed flight time since the start of the mission, the aircraft flight speed, and / or the aircraft altitude relative to the ground.

[0067] 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.

[0068] 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 by not displaying such a value or even by not displaying it outside of stabilized flight phases.

[0069] 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.

[0070] 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.

[0071] 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).

[0072] These indications are preferably not unnecessarily disruptive, particularly in the flight phases that require particular attention from the pilot. (For example, they will be displayed so as to be visible during long phases - cruise or climb flight (discreet flashing for example) - and in constant, non-distracting, or even inhibited display (no flashing, etc.) during phases with strong power variations),

[0073] 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 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.

[0074] 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).

[0075] Such indications make it possible to identify the phases which cause more or less pronounced cumulative aging, and can also contribute to more ecological management decisions (CO2 emissions, etc.).

[0076] Unlike existing applications in a non-versatile usage context, this score does not derive from an invariable cost calculation.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] The aircraft may be a rotary wing aircraft, in particular a helicopter.

[0081] The display unit may be an information bar. Brief description of the figures

[0082] [Fig.l] is a trend diagram illustrating the evolution over time of a mission (i.e. on a mission), this diagram representing the aging progression score according to an embodiment, and a previous aging progression score, during a mission of the aircraft,

[0083] [Fig.2] is a trend diagram illustrating the evolution over time of a mission, this diagram representing the reversed aging progression score, according to the embodiment of [Fig.l], and a previous aging progression score, during a mission of the aircraft,

[0084] [Fig.3] is an example of displaying to the operator an information bar of a lifetime of aircraft blades in a condition, following the previous aging progression score,

[0085] [Fig.4] is an example of displaying to the operator an information bar of a lifetime of the blades of an aircraft in the state of [Fig.3], according to the aging progression score, according to the embodiment of [Fig.l], and

[0086] [Fig.5] is an example of displaying to the operator an information bar of a lifetime of the blades of an aircraft in the state of [Fig.3], according to the aging progression score, according to the embodiment of [Fig.2]. Detailed description of the invention

[0087] An example of a prior art aging progression score, referred to as SCORE_prior in Figures 1 and 2 or prior aging progression score, is defined as follows: ■ f O,sM'(0 <Sr Previous score = 1 iTERMl' + TERM2 + TERM3 + TERM4 + TERM, otherwise

[0088] for the calculation of which we define: - the quota of the mission, , sn> , 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 of a cumulative aging counter CV', 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.

[0089] - the default quota of the mission, f _ sd>

[0090] - the cumulative aging counter CV', which is a value proportional to the cumulative aging the expected 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, MD£.F\ for example of the order of 1 hour, Y' a parameter to adapt to the application context, chosen between MnFF7 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= t0' of the start of flight an instant t = tl' of the end of a phase called the start of mission is also defined so that: tl' -10' greater than a duration between 1 and 15 minutes, and / or tl' is the first instant 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 tl' is the first instant t greater than t0' for which the altitude of the aircraft relative to the ground, also called ground clearance, is greater than a value determined, 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, (tj - cvf(t-xn , A (t) ~ / X' \ the cumulative flight time per hour since the start of the mission (t0'), 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)

[0091] - the cumulative total per flight hour since the start of the mission, at a time t of the mission, anticipating a flight duration of Y's “usual short missions”, in hours, . CV' <0 " CV'(tO') ' (.y — ?------ x 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', cv'(t)-cvW) DW =------777---- Q * M TERM 1' => S2'.' t smon, 0 r 2, « t > tl' and M' = MDEF' and Q' = QDEF' and D'(t) > (T'(t) / M'), TERM2' = jotherwise 1, if t > tl' and if tendency of B'(t) on X' seconded monotonically increasing 'otherwise, 0 - (1, if t > tl' and { M' MDEF' or Q' QDEF1) and D'(t) >(T'(t) / M') ( smon, 0 , And fl-t > £1' (M' MDEF'or Q' * QDEF') andD'(Û > 1' t smon, 0

[0092] Reference is now made to [Fig. 1] which compares this prior aging progression score, SCORE_prior, with the aging progression score, SCORE, according to one embodiment. In this embodiment, we define: SCORE = TERM 1 + TERM 2 + TERM 3 •

[0093] SCORE and SCORE_anterior show substantially similar developments. However, SCORE_prior is a discretized score, unlike SCORE. Indeed, SCORE_prior presents abrupt variations between different constants of SCORE_inverted = values (for example between points PI and P2), and SCORE presents a continuity which is due to its expression with a sum of TERM1, TERM2 and TERM3. This continuity results in a better resolution and a better sensitivity. In this way, SCORE allows the operator to have more precise and faithful information for piloting assistance compared to SCORE_previous.

[0094] Reference is now made to [Fig. 2] which compares the prior aging progression score, SCORE_prior, with the reverse aging progression score, SCORE_inverted, according to the embodiment of [Fig. 1]. In this embodiment, we define: 100, if SCORE < 1 1 5 MAX {O;M]N{1;(-- * SCORE + -)}} * 100, otherwise

[0095] SCORE_inverted is also continuous, unlike SCORE_prior.

[0096] Clipping above SCORE_inverted is shown in [Fig.2]. Indeed, it can be seen that when SCORE_inverted reaches 100% at point P, clipping is carried out, while SCORE illustrated in [Fig.l] has not reached a zero value for a point P' with the same abscissa as point P. As mentioned in the presentation of the invention, the choice of using the information or the inverted information according to the aging progression score or the inverted aging progression score respectively is a choice arbitrated by the operator. Indeed, the aging progression score and the inverted aging progression score each have their advantage.

[0097] Figures 3 and 4 show an example of displaying to the operator an information bar 3 of a lifespan of the blades of an aircraft in the same first state. [Fig.3] illustrates the display according to the previous aging progression score SCORE_anterior and [Fig.4] illustrates the display according to the aging progression score, SCORE, according to one embodiment.

[0098] SCORE_prior is discretized can only include the integer values 0; 1; 2; 3; 4; and 5 which correspond to the filling of the information bar 3 up to the filling line 30, 31, 32, 33, 34, 35 respectively. As illustrated in [Fig.3], SCORE_prior is equal to 3 and the progress bar 33 is filled up to the line 33. For SCORE_prior, this state corresponds to the point P3 in [Fig.l]

[0099] SCORE is continuous and can include decimal values between 1 and 6. In the embodiment of [Fig.4], the information bar 3 is enlarged to include a sixth box between line 35 and a filling line 36. SCORE is equal to approximately 2.3 and the progress bar 3 is filled up to the intermediate line 32' located between line 32 and line 33. For SCORE, the state corresponds to point P4 on [Fig.l], P4 having the same abscissa as P3. We note that SCORE offers better intuition and better judgment of the blade flight defect to the operator, in particular thanks to the continuity and the better resolution (i.e. thanks to the decimal values between 1 and 6).

[0100] The fact that the information bar 3 includes a sixth box is optional, other embodiments do not include the sixth box since a clipping can be carried out (to keep a score less than or equal to 5). For example, this clipping can be carried out with a display following the reversed aging progression score SCORE_inversé, like that of [Fig.5].

[0101] SCORE_inverted is continuous and can include percentage values between 0% (fill line 30) and 100% (fill line 35). As illustrated in [Fig.5], SCORE_inverted is equal to 90% and progress bar 3 is filled up to line 34'. For SCORE_inverted, the state corresponds to point P5 in [Fig.2], P5 having the same abscissa as P3. The pilot can for example understand that he must adjust the piloting of the rest of the mission to a displayed value of 100% which he will soon reach.

Claims

Claims

1. A method of piloting assistance for an operator, for example a pilot, or for an automated system, for example an autopilot, 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 (SCORE) which is a function of a plurality of terms, said plurality of terms comprising TERM1, TERM2, and TERM3, and for the calculation of the aging progression score (SCORE) it is defined: - the mission quota, 4 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 of a cumulative aging counter CV, 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 mission's default quota, SD, Qdef = - the maximum quota, Q,,, „ = with a > 5, 1 zVï / iÆ 'LsiLr - the minimum quota, = with 0 < P - 1, - 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, for example of the order of 1 hour, - Y a parameter to be adapted to the application context, chosen between 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 flight, - a time t= tl of the end of a phase called the start of 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 sliding gradient over X seconds, CV (t) - CV(tX), q4—) the cumulative flight time per hour since the start of mission tO, at an instant t of the mission without information on the forecast flight duration of mission M, CV(t)-CV(tO) ' Q * T(t) the cumulative flight time per hour since the start of the mission, at an instant 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)) A(t) = B(t) = C(t) = the cumulative flight time per hour since the start of the mission, at a time t of the mission anticipating the forecast flight duration of the mission provided M, D(t) = CV (t) - CV (tO) Q * M TE RMI = MAX {0 ; MIN {y; 5p 1 ' {; ' QMAX QmSN Qdef Qdef Qmtn Qdef Qmax Qmjn Qdef Qdef , with y a coefficient, ( ^DEr. Bit') if L > il: MAX 10 ; MIN H ; (—=—)(——l) / ( Qmax / Qdef “ Qmîn / Qdef) “ (Qmin / Qdef) / ( Qmax / Qdef “ Qmîn / Qdef): ( A dtr — a ), < L 3600 : ( [ ï) s L m U otherwise, 0 ' „„„„„ f if t> tl ■ 2 X MA¥{0; W / V[l ; C(t)]} ' / b RM 3=1. _ J [ 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 y is equal to 2, the aging progression score (SCORE) being defined as follows: SCORE = TERM 1 + TERM 2 + TERM 3, said method further comprising a step of determining an inverted aging progression score (SCORE_inverted) defined as follows: 100, if SCORE < 1 Reversed score = 1 5 MAX {0; MIN* SCORE + -)}} * 100, otherwise 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 (SCORE_inverted).

3. The method of claim 1, wherein y is equal to 1, the aging progression score (SCORE) being defined as follows: SC0RF = { Q,siA(t) <sl {te rmi + term2 term3, sinon

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

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

6. 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, the flight speed of the aircraft and / or the altitude of the aircraft relative to the ground.

7. A method according to any preceding claim, wherein the level or amount of information provided to the operator varies as a function of the aging score, and / or the value of A(t), and / or the flight phase concerned.

8. A method according to any preceding claim, wherein the aircraft is a rotary wing aircraft.

9. Aircraft comprising a display unit (3) 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.< / sl>

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