Method for providing operator with information for managing at least one cumulative aging process

Abstract

The present invention relates to a method capable of providing information to an operator, such as a pilot, or an automation system, such as an autopilot, to assist in managing at least one cumulative aging process, such as creep, of at least a portion of a gas turbine of a generic aircraft, such as a helicopter, in a secondary flight in order to optimally utilize the gas turbine for a long period of time.

Description

Technical Field

[0001] The present invention relates to a method capable of providing information to an operator, such as a pilot, or to an automated system, such as an autopilot, which method can help manage at least one cumulative aging process, such as creep, of at least a portion of a gas turbine of a general aviation aircraft, such as a helicopter, from flight to flight, in order to optimize the long-term utilization of the gas turbine. Background Art

[0002] Aircraft pilots typically have access to flight information related to the propulsion system displayed in the cockpit. This information relates in particular to certified limits, which are maximum limits that must not be exceeded, limits specified in the flight manual, and which are managed by the pilot or by a computer.

[0003] Such limits include, for example, N1 (the speed of the gas generator at the high-pressure shaft), the T45H rated temperature of the high-pressure turbine, the power shaft torque, or an indicator combining this information. These limits constitute thresholds that must not be exceeded, for example, in stable flight, and for which the maximum time for continuous operation may be specified by regulations.

[0004] These directives do not take into account mission objectives, such as quotas, or concepts of acceptable cumulative aging. They are purely momentary and are not intended to prevent cumulative aging patterns that would cause a turbine engine to require premature overhaul, such as before its scheduled major overhaul.

[0005] In environments where usage variability is low and predictable, such as airliner missions, there are prediction methods that set binary indicators for throttle position that accurately match maintenance costs. These prediction methods also typically integrate maintenance costs and fuel consumption costs.

[0006] However, for general-purpose applications, such as helicopter missions, the cost-effectiveness of binary setpoints (whether torque, gas generator speed, or temperature) is not reliable. Currently, in such cases, only ground-based monitoring of instrumentation exists, particularly regarding creep, which is performed manually or with tools.

[0007] In this case, for these complex cumulative aging processes, such ex post monitoring does not provide any useful forward-looking information for subsequent flights and, in its current state, is unlikely to help pilots achieve cumulative targets during flight, such as those set by fleet managers.

[0008] Nor does such monitoring or indication provide information that enables pilots to understand and develop an intuitive understanding of the actions needed to manage these degradation patterns. These degradation phenomena involve multiple factors and are nonlinear. Therefore, without additional guidance, pilots cannot develop a reliable intuition about the conditions under which these degradation patterns accelerate or decelerate.

[0009] Cumulative aging is a form of damage that increases over time. In the context of the intended application, this aging certainly corresponds to the phenomenon of turbine blade creep, but it can also be oxidation, corrosion or mechanical wear of components (e.g. friction wear or bearing wear).

[0010] Other types of aging may also occur, such as aging patterns that are primarily “cyclic” and are related to the number of times a stress threshold is crossed (low cycle fatigue (LCF), thermal cycling, number of starts / stops, etc.). However, it is difficult to act on such cyclic aging and is therefore not covered in this document. Summary of the Invention

[0011] This paper aims to address the above shortcomings.

[0012] To this end, a method is proposed herein that enables information to be provided to an operator, such as a pilot, or an automated system, about at least one accumulated aging process, such as creep, of at least one portion of a gas turbine of an aircraft during a mission of the aircraft. The method comprises a step of determining an aging progression score, which is defined as follows:

[0013]

[0014] The calculation for this is defined as follows:

[0015] -Task quota,

[0016] in:

[0017] The Q factor is, for example, a factor between 0.1 and 10, possibly modifiable by the operator;

[0018] SD is the overhaul trigger threshold of the aging instrument CV in hours;

[0019] • DQ is the flight time between overhauls of the component of the gas turbine or the target service life of the component of the gas turbine in hours.

[0020] -Default task quota,

[0021] - Cumulative aging meter CV, which is a value proportional to the cumulative aging;

[0022] - a mission-specified predicted flight duration M in hours, e.g. between 0.2 and 3 hours;

[0023] - The default predicted flight duration of the mission in hours M DEF , for example, about 1 hour;

[0024] -Y, parameters adjusted according to the application background, in M DEF / 2 and M DEF Choose between;

[0025] - the mission cumulative flight duration T(t) in hours at mission time t;

[0026] a first threshold S1, for example between 0.3 and 0.8, for example equal to 0.5;

[0027] a second threshold S2, for example between 3 and 10, for example equal to 5;

[0028] - The mission start is defined by the flight start time t = t0;

[0029] - A phase ending time t=t1, called the task start phase, is also defined such that:

[0030] - t1–t0 duration greater than 1 to 15 minutes, and / or;

[0031] - t1 is the first time t greater than t0, at which the aircraft's flight speed is greater than a predetermined speed, such as 40 kts for a helicopter, and / or;

[0032] t1 is the first time t greater than t0 when the aircraft's altitude relative to the ground, also known as ground clearance, is greater than a certain value, such as 500 feet;

[0033] a rolling time frame X in seconds, e.g. between 10 and 30 seconds, e.g. about 20 seconds;

[0034] - moving average gradient over X seconds,

[0035] - the cumulative total of flights per hour since the start of the mission (t0) at mission time t, without taking into account the information of the mission's predicted flight duration M,

[0036]

[0037] - the cumulative total for each hour of flight since the start of the mission at mission time t, for an estimated "typical short mission" flight duration of Y hours,

[0038]

[0039] - the cumulative total of each hour of flight since the start of the mission at mission time t, for a mission with a specified predicted flight duration of M hours,

[0040]

[0041] -

[0042] -

[0043] -

[0044] -

[0045] -

[0046] The method comprises the step of providing said information to an operator or an automated system based on said aging score.

[0047] The step of providing said information to the operator may be performed by means of a display.

[0048] As mentioned above, the cumulative aging of a part of a gas turbine is the damage to the relevant components that increases over time. This aging is mainly a creep phenomenon, but it can also be oxidation, corrosion or mechanical wear of the relevant components.

[0049] The cumulative aging instrument (CV) is typically provided by the turbine computer and is a value proportional to the accumulated aging. This value is determined through measurement or calculation based on the values ​​sent by sensors (gas generator speed, temperature within the turbine, torque, external temperature, deformation, etc.). The higher the CV value, the greater the accumulated aging of the relevant component or turbine module.

[0050] An aircraft mission is defined as a series of flight phases between the start and end of the mission. Typically, such a mission may include one or more takeoff and landing phases, as well as flight phases at different speeds.

[0051] The overhaul trigger threshold is a threshold predetermined by the turbine manufacturer that requires a major maintenance operation, called an overhaul, to ensure proper operation of the turbine or prevent premature failure. This operation typically requires disassembly of the turbine.

[0052] The flight time between two overhauls is represented by the abbreviation TBO, which stands for "Time Between Overhaul".

[0053] The target useful life (DQ) may be a flight time greater than the time between overhauls, such as twice the time between overhauls.

[0054] The specified predicted flight duration M is a value determined before the start of the mission and input into the aircraft's computer, for example, via an interface. This duration can be input by an operator, such as a pilot.

[0055] The specified predicted flight duration of the mission, default or otherwise M DEF Or M, for example, between 0.2 and 3 hours. M DEF For example, it is approximately 1.5 hours.

[0056] If the operator does not input M, then M will be set to the value of M DEF value.

[0057] The "typical short mission" flight duration Y will either be defined as a fixed value for a given application, for example, if M DEF = 1.5 hours, then it is approximately 0.8 hours, or it will be determined by the application and calculated as the average of the flight durations of previous missions of the aircraft that are shorter than M DEF and within the range of M DEF / 2 to M DEF interval.

[0058] The parameter Y can be adjusted, for example, within this interval according to the frequency of missions much shorter than M DEF of the mission.

[0059] At time t, the cumulative flight duration T(t) of the mission is the time elapsed between the start of the mission t0 and time t.

[0060] At time t, the CV movement value within X seconds is equal to the difference between the CV value at time t and the CV value at time t - X.

[0061] The calculation of some or all of these terms can be performed in real time, for example, within a time period less than 1 second, such as approximately 500 milliseconds.

[0062] During the mission start phase (T(t) < t1), the calculation of items 2, 3, 4, and 5 is disabled, that is, these items are set to 0, to avoid distractions to the operator, such as a pilot, by indicators during the most complex flight phases (such as takeoff, etc.).

[0063] Each item has a different purpose, so they can be combined.

[0064] When the engine load level at time t results in a slight degradation (S1, as defined by the engine manufacturer), the score is set to zero, regardless of the values ​​of the various terms. In practice, if the engine load no longer significantly alters the final total, there's no need to provide information, such as by displaying that there's no need to continue encouraging lower loads. This is a crucial element of the present invention, as it avoids unnecessarily restricting operational solutions, since exceeding the quota carries no risk and subsequent tasks always offer the possibility of compensation.

[0065] The first item, TERM1, alerts the operator to very high loads, which has no apparent relationship to indications of acceptable engine speed limits. This is the operator's initial signal that current flight conditions may result in significant cumulative degradation, and this can be displayed from the start of the flight. It is also a general message to enhance the operator's intuitive understanding of the situation.

[0066] The second term, TERM2, can be used to increase the score when the load level at time t causes an increase in aging that is not offset by an increase in mission duration relative to the quota, Q, or is greater than a linear progression (if the operator has not defined M and Q values). This indication increases the score when loads occur at a high cadence, especially at the beginning of a mission. This is an intermediate variant between gradient and cumulative aging, integrating any previous debits and credits and allowing notification early in the mission. It gradually loses relevance as the mission lengthens and then no longer contributes to the score unless the applied loads are still truly excessive.

[0067] In the absence of efforts to customize future mission goals (i.e., when the operator does not define quota Q or mission flight duration M), instead of assigning a weight of 2 to TERM2 (“Option 1”), the weight can be kept at 1, which results in a maximum score lower than 5 (“Option 2”).

[0068] The third term, TERM3, allows to increase the score if the quota is exceeded, considering that the mission will last Y hours, and to decrease the score if the cumulative total has converged back below the quota after exceeding the flight duration Y. This term allows a first level score progression (absolute value) of the cumulative total per hour, avoiding premature increases in the score at the beginning of the mission if the minimum duration of Y hours has not been used (this is why the absolute value of B(t) is not used).

[0069] This approach may also provide assistance to the pilot and / or guide the operator regarding critical conditions that may lead to increased cumulative degradation.

[0070] In the absence of efforts to customize future mission goals (i.e., when the operator does not define a quota Q or mission flight duration M), instead of assigning a weight of 2 to TERM3 (“Option 1”), the weight can be kept at 1, which results in a maximum score lower than 5 (“Option 2”).

[0071] When there is no effort to customize future mission goals (i.e., when the operator does not define the quota Q or the mission flight duration M), terms TERM4 and TERM5 are disabled (equal to 0). These terms may also be disabled for other reasons (such as the need for cautious display and low usage, for example, in the case of highly variable missions).

[0072] The fourth term TERM4 allows the score to increase when the cumulative total follows a progression greater than linear with respect to the specified quota Q relative to the specified predicted flight duration M of the mission. Since the mission start usually requires more, this allows for early and fairly accurate vigilance and allows indication that moderation or pilot action is desirable.

[0073] The fifth term TERM5 allows the score to increase by comparing the cumulative total with the quota Q, especially in cases where it is not possible to stay within the quota during the mission but overspending can still be limited.

[0074] It is also possible to freeze the score display during transient flight phases when the pilot is busy with other things. In particular, such phases can be determined by a significant change in the moving average of the engine torque (e.g., over a defined period of time) that falls outside a limited range (e.g., ±5%) around the moving average. This allows the display to be frozen during such maneuvers.

[0075] It is also possible to display a warning light when A(t) < S1 (or other value), such as a green warning light in the aircraft engine limit display area (the first limit indicator, N1 amplitude, T45H as defined above), which is a priority area for the pilot's attention.

[0076] - In the case of "Option 2", three alarm states can be allowed:

[0077] - No alarm: No score indication;

[0078] - Moderate alarm: M = M DEF , Q = Qdef, in the case of "Option 2", then the maximum score is equal to 3;

[0079] - High alarm: Invited to enter M ≠ M DEF and M ≠ M DEF , then the maximum score is equal to 5.

[0080] Conversely, in the case of "Option 1", a scale of 5 is preferred and the indication accuracy is reduced, where the scores of TERM2 and TERM3 change by 2 points each time.

[0081] It is also possible to manage multiple cumulative aging processes (e.g., manage creep and corrosion simultaneously, which are two different cumulative aging processes).

[0082] The calculated terms are relatively stable, but may exhibit instability. To compensate for this instability, a hysteresis can be applied to the score display. Some terms may have an appropriate hysteresis, for example, greater than others.

[0083] The cumulative aging processes can be creep, oxidation and / or corrosion.

[0084] The method can provide information about at least two different cumulative aging processes. A separate score is determined for each aging process, and an overall score is calculated based on these separate scores, for example in the form of an average or weighted average. The information provided to the user depends on this overall score.

[0085] Whether t is outside the mission start phase may be determined by using the flight time that has elapsed since the start of the mission, the flight speed of the aircraft, and / or the altitude of the aircraft relative to the ground.

[0086] The level or amount of information provided to the operator may vary depending on the ageing score, the value of A(t) and / or the relevant phase of flight.

[0087] The level of information may change gradually, for example by displaying a value between 0 and 5 or by displaying a progress bar, or may not display such a value at all.

[0088] The amount of information may also be varied by adding or removing information to provide more or less detail depending on the circumstances.

[0089] In particular, information may not be provided (e.g., not displayed) during certain critical flight phases, such as mission start, or if aging is small (low score or A(t)). Increasingly complex information (different levels of information) may be provided or displayed depending on the flight phase, aging, or upon operator request.

[0090] In general, the invention proposes determining or calculating laws in real time and performing tests based on these laws in real time, thereby generating indications (which may or may not be displayed in the cockpit, with different levels of detail or depending on the phase of flight) regardless of the aircraft and installation (single-engine or multi-engine).

[0091] These indicators should preferably not be pointlessly distracting, particularly during phases of flight that require the pilot's particular attention. (For example, they should be displayed so that they are visible (e.g., flashing with caution) during long phases—cruise or climb—and displayed in a constant, non-distracting, or even disabled display (non-flashing, etc.) during phases where power changes are significant.)

[0092] These instructions encourage and guide the pilot to take actions during long, stable flight phases to manage the cumulative degradation of major propulsion system components from flight to flight. As mentioned above, these instructions can be adjusted based on the score or previous cumulative degradation, mission type and business objectives, and operational context.

[0093] These indications must be progressive (multiple alert levels rather than binary). This progressive nature is particularly useful in situations where degradation is difficult to predict, the short-term consequences are minor, and the aircraft is used in a general purpose environment, providing the pilot with an understanding of the flight conditions that produce cumulative degradation (which is unintuitive if there is no such indication or only a binary indication).

[0094] Such an indication, which allows the identification of stages leading to more or less noticeable cumulative aging, may also contribute to more environmentally friendly driving decisions (CO2 emissions, etc.).

[0095] Unlike existing applications in non-general purpose contexts, this score is not derived from a constant cost calculation.

[0096] Here, fleet managers who wish to optimize the utilization of their gas turbines will be able to modify the quotas and fractional set points that pilots need to adhere to by monitoring trends ex post in order to manage a generally controlled path of cumulative aging. This can be achieved by taking into account the full commonality of their priorities, geographic operating context, seasonality, engine age, inlet protection requirements, and all other influencing factors using the scaled, practical learning and coaching approach of the present invention.

[0097] However, it is a reasonable association to combine this indicator with an indicator of fuel efficiency conditions, such as adding a fuel economy score that varies between 0 and 2 depending on the deviation from the most fuel-efficient stable flight conditions.

[0098] The aircraft may be a rotary wing aircraft, in particular a helicopter. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] [ Figure 1 ] is a graph showing the change in score over time during an aircraft mission without pilot action. The graph also shows the change in power, cumulative damage CV, temperature of the turbine hot parts, and altitude.

[0100] [ Figure 2 ] is a graph showing changes in items A(t), B(t), C(t), D(t), TERM 1, TERM 2, TERM 3, TERM 4, and TERM 5 during the task period.

[0101] [ Figure 3 ] corresponds to Figure 1 chart, where the pilot's actions allowed the score to be reduced to 3.

[0102] [ Figure 4 ] corresponds to Figure 1 chart, where the pilot's actions allowed the score to be reduced to 2.

[0103] [ Figure 5 ] corresponds to Figure 1 chart, where the pilot's actions allow the score to be reduced to 1. DETAILED DESCRIPTION

[0104] exist Figures 1 to 5 In the graph of FIG4 , curves Score, Pw, Cumul, T45H and Z respectively show the changes in the aging progress score, output shaft power, cumulative damage, temperature and height of the hot parts of the gas turbine over time.

[0105] It should be recalled that the aging progression score can be defined as follows:

[0106]

[0107] The calculation for this is defined as follows:

[0108] -Task quota,

[0109] in:

[0110] The Q factor is, for example, a factor between 0.1 and 10, possibly modifiable by the operator;

[0111] SD is the overhaul trigger threshold of the aging instrument CV in hours;

[0112] DQ is the flight time between overhauls of the component of the gas turbine or the target service life of the component of the gas turbine in hours;

[0113] -Default task quota,

[0114] - Cumulative aging meter CV, which is a value proportional to the cumulative aging;

[0115] - a mission-specific predicted flight duration M in hours, for example between 0.2 and 3 hours, possibly modifiable by the operator;

[0116] - The default predicted flight duration of the mission in hours M DEF , for example, about 1 hour;

[0117] -Y, parameters adjusted according to the application background, in M DEF / 2 and M DEF Choose between / 2;

[0118] - the mission cumulative flight duration T(t) in hours at mission time t;

[0119] a first threshold S1, for example between 0.3 and 0.8, for example equal to 0.5;

[0120] a second threshold S2, for example between 3 and 10, for example equal to 5;

[0121] - The mission start is defined by the flight start time t = t0;

[0122] - A phase ending time t=t1, called the task start phase, is also defined such that:

[0123] - t1–t0 duration greater than 1 to 15 minutes, and / or;

[0124] - t1 is the first time t greater than t0, at which the aircraft's flight speed is greater than a predetermined speed, such as 40 kts for a helicopter, and / or;

[0125] t1 is the first time t greater than t0 when the aircraft's altitude relative to the ground, also known as ground clearance, is greater than a certain value, such as 500 feet;

[0126] - a rolling time frame X in seconds, e.g. between 10 and 30 seconds, e.g. about 20 seconds;

[0127] - moving average gradient over X seconds,

[0128] - the cumulative total of flights per hour since the start of the mission (t0) at mission time t, without taking into account the information of the mission's predicted flight duration M,

[0129]

[0130] - the cumulative total for each hour of flight since the start of the mission at mission time t, for an estimated "typical short mission" flight duration of Y hours,

[0131]

[0132] - the cumulative total of each hour of flight since the start of the mission at mission time t, for a mission with a specified predicted flight duration of M hours,

[0133]

[0134] -

[0135] - - - -

[0136] Figures 1 to 5 The mission shown is for a helicopter mission:

[0137] - Take off from point A (time = 0);

[0138] - Move to point B and land at point B;

[0139] - Take off from point B, move to point C and land at point C;

[0140] - Take off from point C, move back to point A and land at point A.

[0141] exist Figure 1 As can be seen from the graph of , the fraction (here the creep fraction, calculated using the above formula for adding the terms TERM 1 to TERM 6) changes as Figure 2 ) reaches a maximum value of 4. In this case, the quota Q at the end of the task reaches twice the required quota and thus significantly exceeds the required quota.

[0142] Figure 3 The graph shows a scenario where the pilot takes actions that reduce the score to 3 during the same mission. Figure 3 In the case shown, the pilot takes action each time the score reaches 4. Thus, the pilot reduces the horizontal speed by 1 ktas the first time, and then a second time a little later. In this case, the quota Q at the end of the mission reaches 1.8 times the required quota. Figure 1 The task was also extended by 30 seconds compared to the case shown.

[0143] Figure 4 The graph shows a scenario where the pilot takes action to reduce the score to 2 during the same mission. Figure 4 In the case shown, the pilot takes action each time the score reaches 3. Thus, the pilot first reduces the horizontal speed by 4 kts, then again by 6 kts, and then at the end of the climb reduces the vertical speed by 100 ft / min. In this case, the quota Q at the end of the mission is 1.2 times the required quota. Figure 1 Compared to the situation shown, the task was extended by 2 minutes.

[0144] Figure 5 The graph shows a scenario where the pilot takes action to reduce the score to 1 during the same mission. Figure 5In the case shown, the pilot takes action each time the fraction reaches a value of 2. Thus, the pilot first reduces the vertical speed by 100 ft / min, then reduces the horizontal speed by 4 kTAS, then again by 2 kTAS, and then again by 5 kTAS. In this case, the quota Q at the end of the mission is 0.7 times the required quota. Figure 1 The mission was also extended by 4.6 minutes compared to the scenario shown in Figure 2. As can be seen, this extension is relatively small compared to the total mission duration.

[0145] Depending on the constraints on mission duration and on the instructions of the fleet manager, the pilot (directly or via the autopilot) will be able to select a target score of 4, 3, 2 or 1 and be confident that only those strict limits are applied to the flight that allow the pilot to approach the quota.

Claims

1. A method for providing information to an operator or an automated system, said operator being, for example, a pilot, about at least one accumulated aging process, such as creep, of at least one portion of a gas turbine of an aircraft during a mission of the aircraft, said method comprising the step of determining an aging progression score, said score being defined as follows: The calculation for this is defined as follows: -Task quota, in: The Q factor is, for example, a factor between 0.1 and 10, possibly modifiable by the operator; SD is the overhaul trigger threshold of the aging instrument CV in hours; DQ is the flight time between two overhauls of the components of the gas turbine in hours or the target service life of the components of the gas turbine; -Default task quota - Cumulative aging meter CV, which is a value proportional to the cumulative aging; - a mission-specified predicted flight duration M in hours, e.g. between 0.2 and 3 hours; - The default predicted flight duration of the mission in hours M DEF , for example, about 1 hour; -Y, parameters adjusted according to the application background, in M DEF / 2 and M DEF Choose between; - the cumulative flight duration T(t) of the mission in hours at mission time t; a first threshold S1, for example between 0.3 and 0.8, for example equal to 0.5; a second threshold S2, for example between 3 and 10, for example equal to 5; - The mission start is defined by the flight start time t = t0; - A phase ending time t=t1, called the task start phase, is also defined such that: - t1–t0 duration greater than 1 to 15 minutes, and / or; -t1 is the first time t greater than t0, at which the aircraft's flight speed is greater than the predetermined speed, For example, a helicopter is 40KTAS, and / or; t1 is the first time t greater than t0 when the aircraft's altitude relative to the ground, also known as ground clearance, is greater than a certain value, such as 500 feet; a rolling time frame X in seconds, e.g. between 10 and 30 seconds, e.g. about 20 seconds; - moving average gradient over X seconds, - the cumulative total of flights per hour since the start of the mission (t0) at mission time t, without taking into account the information of the mission's predicted flight duration M, - the cumulative total for each hour of flight since the start of the mission at mission time t, with an estimated "typical short mission" flight duration of Y hours, - the cumulative total of each hour of flight since the start of the mission at mission time t, for a mission with a specified predicted flight duration of M hours, The method comprises the step of providing said information to an operator or an automated system based on said aging progression score.

2. The method according to any one of the preceding claims, characterized in that Cumulative aging is creep, oxidation and / or corrosion.

3. The method according to any one of the preceding claims, characterized in that The method is capable of providing information about at least two different cumulative aging processes, determining an individual score for each aging process, and calculating an overall score based on the individual scores, for example in the form of an average or weighted average, the information provided to the user depending on the overall score.

4. The method according to any one of the preceding claims, characterized in that Whether t is outside the mission start phase is determined by using the flight time that has 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. The method according to any one of the preceding claims, characterized in that The level or amount of information provided to the operator varies depending on the ageing score, the value of A(t) and / or the relevant flight phase.

6. The method according to any one of the preceding claims, characterized in that The aircraft is a rotary wing aircraft.

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