Method for assisting driving of rotorcraft in fuel economy mode

Abstract

A method for assisting the driving of a rotorcraft, the aircraft comprising at least two engines, the first engine being able to be placed in a standby state to ensure that the second engine operates in a fuel economy mode (so-called ECO mode), a method for assisting the driving of a rotorcraft, in the method, a determined number of flight hours between two overhauls is achieved by limiting wear of the second engine in the ECO mode, an engine control temperature (TCPME) associated with the second engine is calculated in the flight computer as a function of a predefined maximum power (PME) in the ECO mode of the second engine, the engine control temperature represents a current damage state of the second engine and is displayed on the flight screen to attract the attention of the aircraft pilot to allow it to remain below the engine control temperature.

Description

Technical Field

[0001] The present invention relates to the field of assisted control of rotorcraft, in particular helicopters or drones, and more particularly to a fuel economy mode or "ECO mode" consisting in placing one of the two engines of a twin-engine aircraft in standby mode, for example during cruising or waiting flight and search phases (loitering), in order to save fuel. Background Art

[0002] Climate change is a major concern for many legislators and regulators worldwide. Specifically, states have already adopted, are currently adopting, or will soon adopt various measures to limit carbon emissions. In particular, an ambitious standard applies to both new and existing aircraft, requiring the implementation of technical solutions to bring them into compliance with existing regulations. In recent years, civil aviation has been committed to contributing to the fight against climate change.

[0003] Technological research has led to significant improvements in the environmental performance of aircraft. The applicant considers factors influencing all stages of design and development to achieve components and aviation products that consume less energy, are more environmentally friendly, and can be integrated and used in civil aviation with only a moderate environmental impact, with the goal of improving aircraft energy efficiency. Therefore, the applicant is committed to reducing its impact on the climate by using environmentally friendly methods that minimize greenhouse gas emissions and utilizing corresponding development and manufacturing processes, thereby reducing the environmental footprint of its activities.

[0004] This ongoing research and development effort also focuses on next-generation aircraft engines, lightweighting of aircraft (particularly through the materials used and lighter onboard equipment), the development of electronic technologies to provide propulsion, and ultimately, aviation biofuels.

[0005] In this context, it is known that twin-engine aircraft, during the cruising or loitering phase, use the engines in a fuel economy mode (so-called ECO mode), either with the combustion chambers of the engines open or closed. In this mode, which is used, for example, in rotary twin-engine aircraft, one of the aircraft's engines is in standby mode.

[0006] However, if used improperly, this mode of operation can lead to premature wear of the engines that provide propulsion power to the aircraft, particularly the hot parts of gas turbines, a phenomenon known as endocreep.

[0007] However, this wear of the engine directly affects the number of flight hours between two overhauls (TBO or Time Between Overhaul) indicated by the engine manufacturer. Summary of the Invention

[0008] The subject of the present invention is therefore a method for informing a pilot of the damage state of an aircraft engine so that he can always maintain the flight hours (or TBO) targets required by the engine manufacturer.

[0009] These objects are achieved by a method for assisting the piloting of a rotorcraft comprising at least two engines, a first engine being capable of being placed in standby to ensure the operation of the second engine in a fuel economy mode (so-called ECO mode), the method for assisting piloting being characterized in that a determined number of flight hours between overhauls is achieved by limiting the wear of the second engine in ECO mode, an engine control temperature (TC_PME) associated with the second engine being 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) representing the current damage state of the second engine and being displayed on a flight screen in order to draw the attention of the aircraft pilot, thereby allowing him to remain below said engine control temperature (TC_PME).

[0010] Therefore, if in ECO mode the pilot keeps the engine temperature below the engine control temperature (TC_PME), he will achieve the mean time between overhauls (TBO) required by the engine manufacturer.

[0011] Preferably, the engine control temperature (TC_PME) is determined based on the values ​​of the creep counters of both engines and the number of flight hours performed since the last overhaul.

[0012] Advantageously, the value of the creep counter associated with the engine ageing model takes into account the damage state of the engines when all engines are running and the damage state of the engines when they are in standby mode.

[0013] Preferably, the engine control temperature is a maximum temperature or an average temperature.

[0014] According to a contemplated embodiment, the engine control temperature is determined for a mission representative of the missions performed by the aircraft and including at least one activation phase of the ECO mode, and the engine control temperature is further determined based on the value of the cycle counter of the engine. It can also take into account the alternation of engines operating in the ECO mode.

[0015] Advantageously, the engine control temperature is displayed on the flight screen in a first limit indicator incorporated into the aircraft.

[0016] The method according to the invention can be applied to multi-engine helicopters or multi-engine UAVs, as well as single-engine or multi-engine aircraft, in which engine temperature control is used outside of ECO mode to preserve the life of the engines.

[0017] The invention also relates to a rotorcraft comprising a flight computer and a flight screen, each configured to implement the method for assisted piloting as defined above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other characteristics and advantages of the present invention will become apparent from the description given below, with reference to the accompanying drawings, which show, without any limitation, exemplary embodiments of the invention, in which:

[0019] [ Figure 1 ] Figure 1 shows an example of mission distribution for a rotorcraft, and

[0020] [ Figure 2 ] Figure 2 Different steps of a method for determining an engine control temperature in ECO mode according to an example of the present invention are shown. DETAILED DESCRIPTION

[0021] The present invention proposes creating a new nominal value associated with ECO mode: the so-called PME (maximum power in ECO mode). This nominal value is not a limit, i.e., the power is not saturated, but rather an item of information communicated to the aircraft pilot to help him control damage to the aircraft engine. Therefore, the problem is to take into account the actual use of the engine and update in real time the item of information communicated to the pilot via the flight control indicators available in the cockpit, such as the first limit indicator, known as the FLI.

[0022] Figure 1 An example of a partial mission profile for implementing this ECO mode is shown. The horizontal axis represents the duration of the pending mission segment, while the vertical axis represents the engine control temperature (TC), which represents the engine power. This mission includes different phases, but only the mission segment during the cruise phase 12, during which the ECO mode is triggered, is shown. In this ECO mode, the temperature shown by the dashed line 10 represents the maximum recommended temperature (or power) for the operating engine, while the other engine is in standby mode. The temperature indicated by the dotted line 14 corresponds to the associated average temperature (or power). The engine control temperature (TC_PME), for example, corresponds to the temperature indicated by the dotted line 14.

[0023] from Figure 1 As can be seen in FIG1 , both the maximum temperature and the average temperature are greater than the power (or temperature) required in the cruise phase 12, which is performed with all engines providing power (= normal operation, so-called all-engines-operated AEO), without of course exceeding the maximum take-off power (PMD).

[0024] Figure 2 The steps of the method of the invention are shown which allow the determination of TC_PME.

[0025] In a first step 100, it begins with the definition of a mission that corresponds to an average of the missions previously performed by the aircraft (standard mission) and more generally represents the mission of the aircraft (including, for example, joint missions). Alternatively or in addition, temporary standard missions or joint missions can be considered.

[0026] Preferably, the seasonality of the aircraft's flights is taken into account. More specific missions defined at the pilot's request (eg according to a predetermined trajectory and a specific load) can also be taken into account.

[0027] In the following step 102 , the phases of the mission in which the ECO mode is activated are determined (cruise, or surveillance / search / hover phase (loitering), etc.).

[0028] In the following step 104, the percentage of flight hours performed since the engine's last overhaul is read from the flight computer, along with the status of two creep counters per engine: one associated with the engine's damage while powered (current wear) and the other associated with the engine's damage while in standby. Preferably, using the results of step 102 and a gas turbine aging model, one predicted damage for the AEO phase and another predicted damage for the standby phase are determined. When the engine is powered (AEO mode), the aforementioned count of engine damage is added to the predicted aging of the gas turbine in AEO mode to provide the parameter EndoAEO. Similarly, the parameter EndoVeille is calculated based on the engine's current wear in the standby phase and the predicted aging of the gas turbine in standby mode (ECO mode).

[0029] In the following step 106 , the percentage of remaining impairment available in ECO mode is calculated (100% for a new engine) by subtracting the two impairment values ​​EndoAEO and EndoVeille mentioned above.

[0030] In a final step 108 , the TC_PME is determined using the remaining damage available in the ECO mode and displayed on a flight screen in the aircraft cockpit, typically on its FLI (First Limit Indicator).

[0031] Therefore, the present invention allows pilot guidance on the use of ECO mode by proposing to update TC_PME throughout the life of the engine according to the data possessed by the flight computer, namely the state of the creep (and / or cycle) instruments and the number of flight hours since the last overhaul (TBO is considered a level 3 maintenance operation).

[0032] So, for example, assuming a TBO of 5000 flight hours for a given engine, if the pilot overuses his engine, the TC_PME displayed on the dial with said indicator will decrease with flight hours, requiring him to adjust his mission to maintain a TBO of 5000FH.

[0033] However, it should be noted that the indicator indicating the maximum power that can be observed to achieve the TBO required by the engine manufacturer can also be used outside of ECO mode, especially in single-engine helicopters. For example, a pilot who often flies at high power may prematurely wear out the engine and fail to reach TBO.

[0034] It will also be noted that the TC_PME can be determined taking into account maintenance operations and, in particular, the alternation of the engines in operation during ECO mode (preferably not always the same one, but rather one or the other of the two engines can be interchanged). In particular, the use of ECO mode leads to asymmetrical wear of the engines, and it seems useful to seek to make the progression of creep and cycle counters more symmetrical by replacing an engine, for example, every 1000 flight hours during the corresponding maintenance period (the engine in operation during the first time slot being on standby during the next, and so on in the subsequent slots).

[0035] Furthermore, if reference is mainly made to the traditional application of twin-engine helicopters, the invention can naturally be applied to multiple engines, such as in the field of drones, where the use of each engine can also be recommended to the pilot.

Claims

1. A method for assisting the piloting of a rotary-wing aircraft comprising at least two engines, a first engine being capable of being placed in a standby state to ensure operation of the second engine in a fuel economy mode, so-called ECO mode, The method for assisting piloting is characterized in that a determined number of flight hours between overhauls is achieved 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 the flight computer according to a predetermined maximum power (PME) of the second engine in ECO mode, the engine control temperature (TC_PME) representing the current damage state of the second engine and displayed on a flight screen to draw the attention of the aircraft pilot, allowing him to stay below the engine control temperature (TC_PME).

2. The method according to claim 1, wherein The engine control temperature (TC_PME) is determined based on the values ​​of the creep counters of the two engines and the number of flight hours performed since the last overhaul.

3. The method according to claim 2, wherein The value of the creep counter associated with the engine aging model takes into account both the damage state of the engines when all engines are operating and the damage state of the engines when they are in standby mode.

4. The 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. The method according to any one of claims 1 to 4, wherein The engine control temperature (TC_PME) is determined for a mission representative of missions performed by the aircraft and including at least one phase in which an ECO mode is activated.

6. The method according to any one of claims 1 to 5, wherein The engine control temperature (TC_PME) is also determined based on a value of a cycle counter of the engine.

7. The method according to any one of claims 1 to 6, wherein The engine control temperature (TC_PME) takes into account the alternating operation of the engine in ECO mode.

8. The method according to any one of claims 1 to 7, wherein Suitable for multi-engine helicopters or multi-engine UAVs.

9. The method according to any one of claims 1 to 8, wherein The flight screen on which the engine control temperature (TC_PME) is displayed is integrated into the first limit indicator of the aircraft.

10. A rotary-wing aircraft comprising a flight computer and a flight screen, each configured to implement the method for assisted piloting according to any one of claims 1 to 9.

Images