Method for assisting the piloting of a rotary wing aircraft in a fuel-economy mode

Abstract

Method for assisting the piloting of a rotary wing aircraft, the aircraft comprising at least two engines, a first engine capable of being placed on standby to ensure an operation of a second engine in the fuel-economy mode, called ECO mode, in which method, in order to reach a determined time between overhauls by limiting the wear of the second engine in the ECO mode, an engine control temperature (TC_PME) associated with the second engine is calculated in a flight computer as a function of a predefined maximum power (PME) of the second engine in ECO mode, the engine control temperature being representative of a current state of damage of the second engine and displayed on a flight screen for the attention of a pilot of the aircraft, so as to allow said pilot to keep below this engine control temperature.

Description

[0001] Description

[0002] Title of the invention: Method for assisting in piloting a rotary-wing aircraft in a fuel-saving mode

[0003] Technical Field

[0004] The present invention relates to the field of assistance in piloting rotary-wing aircraft, in particular helicopters or drones, and it refers more particularly to a fuel-saving mode or "ECO mode" consisting of putting one of the two engines of a twin-engine aircraft in standby mode (in English "stand-by state") during the cruising or waiting or surveillance and / or search flight phases (in English "loitering"), in order to achieve fuel savings.

[0005] Prior art

[0006] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and those currently in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change.

[0007] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into consideration the impacting factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft. Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible to reduce the environmental footprint of its activity.

[0008] This ongoing research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and finally aeronautical biofuels.

[0009] In this context, it is known for twin-engine aircraft to resort to using the engines in fuel-saving mode, known as ECO mode, whether carried out with the engine combustion chamber on or off, during cruise or holding flight or surveillance and / or search phases ("loitering"). In such a mode, used for example in twin-engine rotary-wing aircraft, one of the aircraft's engines is placed in standby mode.

[0010] However, if used incorrectly, this mode of operation can lead to premature wear of the engine providing the aircraft's propulsion power, particularly for the hot parts of the gas turbine, a phenomenon known as endocreep.

[0011] However, this engine wear has a direct influence on the number of flight hours between two overhauls (known by the acronym TBO, for "Time Between Overhauls") indicated by the engine manufacturer.

[0012] Statement of the invention

[0013] The present invention therefore relates to a method for informing the pilot about the state of damage to the aircraft's engines so that he can maintain at all times the objective of the number of flight hours (or TBO) claimed by the engine manufacturer.

[0014] These aims are achieved by a method for assisting the piloting of a rotary wing aircraft, the aircraft comprising at least two engines, a first engine being able to be put on standby to ensure operation of a second engine in fuel economy mode called ECO mode, the piloting assistance method being characterized in that, to achieve a determined number of flight hours between two overhauls by limiting the wear of the second engine in ECO mode, an engine control temperature (TC_PME) associated with the second engine is calculated in a flight computer as a function of a predefined maximum power (PME) in ECO mode of said second engine, the engine control temperature (TC_PME) being representative of a current state of damage to the second engine and displayed on a flight screen for the attention of a pilot of the aircraft, so as to allow him to remain below said engine control temperature (TC_PME).

[0015] Thus, if in ECO mode, the driver maintains the engine temperature below this engine control temperature (TC_PME), he will reach the average time between two revisions (TBO) claimed by the engine manufacturer.

[0016] Preferably, the engine control temperature (TC_PME) is determined from values ​​of the creep counters of the two engines and a number of flight hours carried out since the last overhaul.

[0017] Advantageously, the value of the creep counters, combined with a motor aging model, takes into account both the motor damage state when all motors are active and the motor damage state when they are in standby mode.

[0018] Preferably, the engine control temperature is a maximum temperature or an average temperature.

[0019] According to the embodiment envisaged, the engine control temperature is determined for a mission representative of the missions carried out by the aircraft and comprising at least one phase of activation of the ECO mode and it is further determined from a value of the engine cycle counters. It can also take into account an alternation of the engines operating in ECO mode.

[0020] Advantageously, the engine control temperature is displayed on a flight screen integrated into a first limit dial of the aircraft.

[0021] The method according to the invention can be applied to a multi-engine helicopter or a multi-engine drone as well as to a single or multi-engine aircraft in which the engine control temperature is used outside of ECO mode to preserve the engine life.

[0022] The invention further relates to a rotary wing aircraft comprising a flight computer and a flight screen, each configured to implement the piloting assistance method as defined above.

[0023] Brief description of the drawings

[0024] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character and in which:

[0025] [Fig. 1] Figure 1 shows an example of a rotary-wing aircraft mission profile, and

[0026] [Fig. 2] Figure 2 illustrates the different steps of the method for determining the engine control temperature in ECO mode, according to an example of the invention.

[0027] Description of the embodiments

[0028] The invention proposes to create a new regime associated with the ECO mode: the so-called PME regime (Maximum Power in ECO mode). This regime is not a limit, that is to say that the power is not saturated, but information that will be communicated to the pilot of the aircraft to help him contain damage to the engines of this aircraft. It is therefore a question of taking into account the actual use of the engine and updating in real time the information communicated to the pilot by means of a piloting indicator available in the cockpit, for example at the level of the first limit dial known by the acronym FLI.

[0029] Figure 1 shows an example of a partial mission profile implementing this ECO mode. The abscissa shows the duration of the mission segment concerned, and the ordinate shows the engine control temperature (TC) representative of the engine power. This mission comprises different phases, but only the mission segment in which an ECO mode phase is triggered during a cruise phase 12 is illustrated. In this ECO mode, the temperature illustrated in dotted lines 10 is the maximum recommended temperature (or power) of the active engine, the other engine being in standby mode. The temperature in dashed lines 14 corresponds to the associated average temperature (or power). The engine control temperature (TC_PME) corresponds, for example, to said temperature in dashed lines 14.

[0030] As can be seen in Figure 1, this maximum temperature and this average temperature are both higher than the power (or temperature) requested in cruise phase 12 carried out with all the engines providing power (= conventional operation, called AEO mode for "all engines operating"), without of course being able to exceed the maximum starting power (PMD).

[0031] Figure 2 shows the different steps of the method of the invention allowing the determination of the TC_PME.

[0032] It begins, in a first step 100, with the definition of a mission corresponding to the average of the missions previously carried out by the aircraft (typical mission) and more generally representative of the missions of the aircraft (for example integrating a mixed mission). Alternatively or in addition, a typical mission or a forecast mixed mission can be considered.

[0033] The seasonality of aircraft operations is preferably taken into account. A more specific mission defined at the pilot's request (for example, based on a predefined route and a specific load) can also be taken into account.

[0034] In a following step 102, the phases of this mission where the ECO mode is active are determined (cruise, or surveillance / search / loitering phase, etc.).

[0035] In a subsequent step 104, the flight computer records the percentage of the number of flight hours already completed since the previous engine overhaul, as well as the status of the creep counters (two for each engine), one associated with damage (current wear) of the engine when it is providing power, and the other with damage to the engine when it is in standby mode. A predictive damage for the AEO phases and another for the standby phases are determined, preferably using the results of step 102 and a gas turbine aging model. The aforementioned engine damage counter when it is providing power (AEO mode) is added to the projection of aging of the gas turbine in AEO to provide an EndoAEO parameter. In the same way, an EndoVeille parameter is calculated from the current wear of the engine in the standby phase and the projection of aging of the gas turbine in standby mode (ECO mode).

[0036] In a following step 106, the remaining damage available in ECO mode is calculated as a percentage (100% corresponding to a new engine) by subtracting the two aforementioned damage values ​​EndoAEO and EndoVeille.

[0037] In a final step 108, the TC_PME is determined using the remaining damage available in ECO mode and displayed in the cockpit of the aircraft at a flight screen, typically on its FLI dial, for “First Limit Indicator” or first limit dial.

[0038] The invention thus allows pilots to be supported specifically in the use of ECO mode by proposing to carry out, throughout the life of the engine, an update of the TC_PME, based on data available to the flight computer, namely the state of the creep (and / or cycle) counters and the number of flight hours since the last overhaul (TBO considered as a level 3 maintenance operation).

[0039] Thus, for example, assuming a TBO of 5000 flight hours for a given engine, if the pilot over-uses his engine, the TC_PME displayed on the dial bearing this indicator will decrease with the flight hours, requiring him to adapt his missions to maintain this TBO of 5000HV.

[0040] It should be noted, however, that this indicator, indicating a maximum power to be respected to reach the TBO claimed by the engine manufacturer, can also be applied outside of ECO mode, particularly on a single-engine helicopter. For example, a pilot often flying at high power will wear out the engines prematurely and the TBO will not be reached. It should also be noted that maintenance operations and in particular the alternation of the active engine during ECO mode (which preferably is not always the same but, on the contrary, can be either of the two engines) can be taken into account to determine the TC_PME.Indeed, using ECO mode can lead to asymmetrical wear of the engines and it appears useful to try to symmetrize the progress of the creep and cycle counters by carrying out an exchange of the engines for example every 1000 flight hours during the corresponding maintenance (the engine active during the first time slot being the one put on standby in the following one and so on for the following time slots).

[0041] Furthermore, while reference has been made essentially to classic applications of twin-engine helicopters, the invention naturally finds application to multiple engines such as in drones where a recommendation for the use of each of the engines can then also be provided to the pilot.

Claims

Claims

1. Method for assisting in piloting a rotary wing aircraft, the aircraft comprising at least two engines, a first engine being able to be put on standby to ensure operation of a second engine in fuel economy mode called ECO mode, the piloting assistance method being characterized in that, to achieve a determined number of flight hours between two overhauls by limiting the wear of the second engine in ECO mode, an engine control temperature (TC_PME) associated with the second engine is calculated in a flight computer as a function of a predefined maximum power (PME) in ECO mode of said second engine, the engine control temperature (TC_PME) being representative of a current state of damage to the second engine and displayed on a flight screen for the attention of a pilot of the aircraft, so as to allow him to remain below said engine control temperature (TC_PME).

2. Method according to claim 1, in which the engine control temperature (TC_PME) is determined from values ​​of the creep counters of the two engines and a number of flight hours carried out since the last overhaul.

3. A method according to claim 2, wherein the value of the creep counters takes into account, associated with an aging model of the motor, both the damage state of the motor when all the motors are active and the damage state of the motor when they are in standby mode.

4. A method according to any one of claims 1 to 3, wherein the engine control temperature (TC_PME) is a maximum temperature or an average temperature.

5. Method according to any one of claims 1 to 4, in which the engine control temperature (TC_PME) is determined for a mission representative of the missions carried out by the aircraft and comprising at least one phase of activation of the ECO mode.

6. Method according to any one of claims 1 to 5, in which the engine control temperature (TC_PME) is further determined from a value of the cycle counters of the engines.

7. Method according to any one of claims 1 to 6, in which the engine control temperature (TC_PME) takes into account an alternation of the engines operating in ECO mode.

8. Method according to any one of claims 1 to 7, applied to a multi-engine helicopter or a multi-engine drone.

9. Method according to any one of claims 1 to 8, in which the flight screen, on which the engine control temperature (TC_PME) is displayed, is integrated at the level of a first limit dial of the aircraft.

10. Rotary wing aircraft comprising a flight computer and a flight screen, each configured to implement the pilot assistance method according to any one of claims 1 to 9.

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