Method for simulating an engine failure in an aircraft

Abstract

This method simulates an engine failure in an aircraft with at least one first engine and one second engine, each engine having a gas generator configured to drive a free-spinning turbine mounted on an output shaft of said engine, each of said output shafts being coupled to the same rotor of the aircraft. It comprises the following steps: - transmission (B20) of a first message indicating that the first engine (M2) is going into standby mode and that all the power delivered to said rotor (M2) is being taken over by the second engine (M1), while the two engines (M1, M2) are actually synchronized; - desynchronization (B40) of the two engines (M1, M2) without putting them into standby mode; - transmission (B60) of a second message representing a failure of said second engine (M1). Figure 4

Description

Title of the invention: Method for simulating an engine failure in an aircraft. Technical field

[0001] The present invention relates to the field of aircraft such as airplanes or helicopters comprising at least two engines such as turboshaft engines or turboprop engines.

[0002] It relates more specifically to systems and methods for training the pilot of a multi-engine aircraft in flight procedures for critical situations. Prior art

[0003] In a known manner, a turbomachine, for example a turbomotor, particularly for a helicopter, comprises a gas turbine having a gas generator and a free turbine driven in rotation by the gas flow generated by the gas generator.

[0004] Traditionally, the gas generator comprises at least one compressor and one turbine coupled in rotation. The operating principle is as follows: fresh air entering the gas turbine is compressed by the rotation of the compressor before being sent to a combustion chamber where it is mixed with a fuel. The exhaust gases from combustion are then expelled at high speed. A first expansion then occurs in the gas generator turbine, during which the turbine extracts the energy necessary to drive the compressor. The gas generator turbine does not absorb all the kinetic energy of the exhaust gases, and the excess kinetic energy corresponds to the gas flow generated by the gas generator.The latter therefore provides kinetic energy to the free turbine, causing a second expansion in the free turbine which transforms this kinetic energy into mechanical energy in order to drive a receiving element, such as the helicopter rotor.

[0005] Some aircraft have two or more turbomachines, each comprising a gas turbine as described above. This is particularly true of twin-engine or multi-engine helicopters. Such aircraft allow operation in SEO (Single Engine Operative) mode. SEO mode is an operating mode for a twin-engine configuration in which one of the gas turbines is intentionally shut down, while the other provides all the power. This mode optimizes specific fuel consumption, as efficiency improves when the power delivered by a turbomachine approaches its design power. It is therefore preferable to deliver 100% of the power with one turbine, rather than 50% from each of them.

[0006] In particular, the invention relates to systems and methods for training the pilot of a multi-engine aircraft in flight procedures with one engine inoperative (in English OEI - one engine inoperative).

[0007] US6917908, which illustrates the prior art, describes a method for simulating an engine failure in a multi-engine aircraft in which, while all the aircraft's engines are active (AEO: Ail Engines Operating), the output power of a first engine is reduced to simulate an engine failure and the output power of another engine is increased to compensate for the reduction in the output power of the first engine.

[0008] The prior art documents do not describe a method for training multi-engine aircraft pilots in the emergency situation in which a failure affects the only engine under power while the aircraft is operating in ECO mode.

[0009] As is known, in a twin-engine context for example, ECO mode comprises several phases: (i) a so-called "standby" phase during which one engine decelerates to a standby state, while the other engine takes over all the power; (ii) a so-called "standby mode" phase in which the engine runs at a very low gas generator speed; (iii) a reactivation phase during which the standby engine is restarted to bring it back to the normal operating gas generator speeds.

[0010] The situation of failure of the only engine in power when the aircraft is operating in ECO mode is an extremely critical situation because when it occurs the aircraft's rotor is no longer driven.

[0011] There is therefore a need to be able to train pilots for these situations. Object and summary of the invention

[0012] Thus, and according to a first aspect, the invention relates to a method for simulating an engine failure in an aircraft comprising at least a first engine and a second engine, each of said engines comprising a gas generator configured to drive in rotation a free turbine mounted on an output shaft of said engine, each of said output shafts being coupled to the same rotor of the aircraft, said method comprising the following steps:

[0013] - desynchronization of the first motor, so that the second motor delivers all the power to the rotor;

[0014] - desynchronization of the second motor without putting it into standby; - transmission of a message indicating a failure of the second engine.

[0015] Correspondingly, the invention relates to a computer configured to simulate an engine failure in an aircraft comprising at least one first engine and a second engine, each of said engines comprising a gas generator configured to drive in rotation a free turbine mounted on an output shaft of said engine, each of said output shafts being coupled to the same rotor of the aircraft, said computer being configured to:

[0016] - desynchronize the first motor, so that the second motor delivers all the power to the rotor;

[0017] - desynchronize the second motor without putting it to standby; - to emit a message representative of a failure of the second engine.

[0018] Thus, and according to this first aspect, the invention proposes a method of simulating failure in an aircraft comprising two engines in which a failure of the second engine is simulated, this second engine being the only one to supply power to the rotor, the first engine having been desynchronized.

[0019] According to this variant of the invention, the second motor is desynchronized without however being put into standby mode.

[0020] Desynchronizing the first engine can consist of putting this first engine into standby mode. In which case, during the time interval between the desynchronization of the first engine and the second engine, the aircraft operates in conventional ECO mode, with one engine in standby mode and the other supplying full power to the rotor.

[0021] Alternatively, when the first engine loses synchronization, the first engine is not put into standby mode. In which case, when the second engine loses synchronization, the aircraft is not actually operating in conventional ECO mode since none of its engines are in standby mode.

[0022] In any case, when the message representing the failure of the second motor is emitted, at least one of the two motors is not in standby.

[0023] However, with the two motors out of sync, the rotor no longer receives any power and the pilot can train for a situation similar to that of a motor failure or loss of power in ECO mode.

[0024] But this training takes place under safe conditions since at least one of the unsynchronized motors can be quickly resynchronized.

[0025] According to a second aspect, the invention relates to a method for simulating an engine failure in an aircraft comprising at least a first engine and a second engine, each of said engines comprising a gas generator configured to drive in rotation a free turbine mounted on an output shaft of said engine, each of said output shafts being coupled to the same rotor of the aircraft, said method comprising the following steps:

[0026] - emission of a first message indicating that a first engine is going into standby mode and that all the power delivered to said rotor is taken up by the second motor while the two motors are actually synchronized;

[0027] - desynchronization of the two motors without putting them into standby;

[0028] - emission of a second message representative of a failure of said second engine.

[0029] Correspondingly, the invention relates to a computer configured to simulate an engine failure in an aircraft comprising at least one first engine and a second engine, each of said engines comprising a gas generator configured to drive a free turbine mounted on an output shaft of said engine, each of said output shafts being coupled to the same rotor of the aircraft, said computer being configured to:

[0030] - emit a first message indicating that the first engine is going into standby mode and that all the power delivered to the rotor is taken up by the second motor while the two motors are actually synchronized;

[0031] - desynchronize the two motors without putting them to standby;

[0032] - emit a second message representative of a failure of the second motor.

[0033] Thus, in this variant, an initial message is sent to the pilot indicating that the aircraft has switched to ECO mode when this is not actually the case. ECO mode (one engine in standby and one engine taking over full power) is simulated because at that moment the two engines share power, for example, 50% each.

[0034] When the user receives the second message indicating the loss of the second motor, he therefore believes that the failure affects the only motor in power since he considers that the first motor is in standby.

[0035] With the two motors out of sync, the rotor no longer receives power and the pilot can train for this situation similar to that of the loss of power to the only motor in ECO mode.

[0036] But this training is carried out under safe conditions since neither of the two engines has been put on standby.

[0037] In a particular embodiment applicable to all variants of the invention, desynchronizing a motor without putting it into standby mode includes checking that the difference between: (i) the rotational speed of the output shaft of said motor; and (ii) the rotor rotation speed is kept below a predetermined value.

[0038] This difference is advantageously small so that the rotational speed of the motor output shaft remains close to the rotational speed of the rotor (for example between 90% and 99% of the rotor speed) so that the rotational speed of the motor output shaft can quickly catch up with the rotational speed of the rotor.

[0039] In a particular embodiment, desynchronizing a motor without putting it into standby mode involves setting a setpoint for the rotational speed of the output shaft of said motor to a lower speed (for example, equal to 90%) than the rotor rotation speed. In this embodiment, the rotor rotation speed must be acquired regularly by the computer to adjust the setpoint value.

[0040] Implementing such a setpoint prevents excessive drops in rotor speed. The effect of this logic is indeed to trigger a release of motor power if the rotor speed ever falls below this minimum setpoint.

[0041] In one embodiment, the process includes a step to interrupt the process when an emergency condition is detected. Non-limiting examples of emergency conditions are: (i) a rotor speed NR that is too low; (ii) an engine failure or undesired engine behavior; (iii) a request from the pilot or avionics.

[0042] These exits from the process in case of emergency combined with the simulation process secure the pilot training by ensuring that dangerous flight situations such as excessively low rotor speeds are not reached.

[0043] In a particular embodiment, the simulation process includes a step to limit each of said motors to 50% of the maximum torque that this motor can produce while respecting all of its stops.

[0044] Thus, the invention makes it possible to simulate the behavior that the aircraft would have with: (i) a first engine failure and (ii) a second motor taking over all the power supplied to the rotor by actually using two motors that share the power of a single motor.

[0045] In a particular embodiment, the different stages of the process of simulations according to the invention are determined by computer program instructions.

[0046] Consequently, the invention also relates to a computer program, on a first information medium, this first program comprising instructions adapted to the implementation of the steps of a simulation process according to the invention.

[0047] This program may use any programming language, and be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0048] This information medium can be any entity or device capable of storing the program. For example, each of these media can include a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a hard disk drive.

[0049] Furthermore, each of these information carriers can be a transmissible medium such as an electrical or optical signal, which can be transmitted via an electrical or optical cable, by radio, or by other means. Each of the programs according to the invention can, in particular, be downloaded onto an Internet-type network.

[0050] Alternatively, each information carrier can be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the process in question.

[0051] The invention also relates to a calculator as mentioned above. Brief description of the drawings

[0052] Other features and advantages of the present invention will become apparent from the description below, with reference to the accompanying drawings, which illustrate an example of an embodiment without being limiting in any way. In the figures:

[0053] - Fig. 1 represents, schematically, a cross-sectional view of an assembly propulsion of an aircraft conforming to a particular embodiment of the invention.

[0054] [Fig.2] represents, in the form of a flowchart, the main steps of a simulation process conforming to a first variant of the invention.

[0055] [Fig.3] represents an example of the evolution of the torques of the motors and the actual speeds of their shafts during different phases of a particular example of this first embodiment variant.

[0056] [Fig.4] represents, in the form of a flowchart, the main steps of a simulation process according to a second variant of the invention.

[0057] [Fig.5] represents an example of the evolution of the torques of the motors and the actual speeds of their shafts during different phases of this second embodiment variant.

[0058] [Fig.6] represents torques of the motors and speeds of their shafts as presented to the pilot in different phases of the first and second variant embodiments presented in figures 3 and 5.

[0059] [Fig.7] represents the architecture of a computer that can be used in the invention. Detailed description

[0060] Figure 1 schematically represents a propulsion system of a twin-engine aircraft 100, comprising a first turbomachine M1 and a second turbomachine M2, driving in rotation transmission components 60 of a helicopter carrying a propeller or a main rotor 62. The turbomachines may be turboshaft engines or turboprop engines. Although the propulsion system described below comprises two turbomachines, this example is not limiting, the invention also applies to propulsion systems of multi-engine aircraft comprising more than two engines and implementing an ECO mode.

[0061] The first turbomachine M1 and the second turbomachine M2 are preferably identical and have the same characteristics. Therefore, the description below refers to both the first and second turbomachines M1 and M2.

[0062] The first turbomachine M1 and the second turbomachine M2 respectively comprise a gas turbine 10, 20 having a gas generator 12, 22 and a free turbine 11, 21 capable of being driven in rotation by a gas flow generated by the gas generator 12, 22. The free turbine 11, 21 is mounted on an output shaft 13, 23 which transmits the rotational motion to a receiving element such as a main rotor 62 of the helicopter via the transmission elements 60. According to this example, the gas turbine 10, 20 shown in [Fig. 1] is of the front-drive type with coaxial shaft drive. Without departing from the scope of the present invention, one could very well consider a gas turbine with a front-drive type with internal or external shaft drive, or a turbomachine with a rear-drive type with a free turbine.Similarly, the turbine can be directly driven or incorporate a speed reducer without calling into question the principle of the invention.

[0063] The gas generator 12, 22 comprises a rotating shaft 14, 24 on which are mounted a compressor 15, 25 and a turbine 16, 26, as well as a combustion chamber 17, 27 arranged axially between the compressor 15, 25 and the turbine 16, 26 when the gas generator 12, 22 is considered along the axial direction of the rotating shaft 14, 24. The gas turbine 10, 20 has a casing 18, 28 equipped with an air inlet 19, 29 through which fresh air enters the gas generator 12, 22. After entering the chamber of the gas generator 12, 22, the fresh air is compressed by the compressor 15, 25, which forces it towards the inlet of the combustion chamber 17, 27 where it is mixed with fuel.The combustion which takes place in the combustion chamber 17, 27 causes the burnt gases to be evacuated at high speed towards the turbine 16, 26, which in turn causes the shaft 14, 24 of the gas generator 12, 22 to rotate and, consequently, the compressor 16, 26. The rotational speed of the shaft 14, 24 of the gas generator 12, 22 is determined by the fuel flow rate entering the combustion chamber 17, 27.

[0064] Despite the extraction of kinetic energy by the turbine 16, 26, the gas flow exiting the gas generator possesses significant kinetic energy. As can be seen from [Fig. 1], the gas flow F is directed towards the free turbine 11, 21, which causes an expansion in the free turbine 11, 21, leading to the rotation of the turbine wheel and the shaft 13, 23.

[0065] The main rotor 62 is coupled, via the transmission members 60, to the shaft 13 of the free turbine 11 of the first gas turbine 10 by means of a first main coupling means 51. The main rotor 62 is also coupled, via the transmission members 60, to the shaft 23 of the free turbine 21 of the second gas turbine 20 by means of a second main coupling means 52.

[0066] Preferably, the first and second main coupling means 51, 52 comprise a freewheel mounted such that the rotation of the shaft 13, 23 can drive the main rotor 62 in rotation, but conversely, the rotation of the main rotor 62 cannot drive the shaft 13, 23 of the free turbine 11, 21 in rotation. In other words, the freewheel of the first and second main coupling means 51, 52 can only transfer rotational torque in the direction from the free turbine 11, 21 to the main rotor 62, but not the other way around. On a helicopter, this freewheel is commonly called a "motor freewheel." It should be noted that the use of a freewheel for the main coupling means 51, 52 is not limiting; the freewheel can be replaced by any dog ​​clutch or clutch system.

[0067] The aircraft 100 further comprises a computer 70 electronically interconnected to individual sensors c62, cl4, c24, cl3, c23 respectively configured to obtain: - the NR speed of the rotor 62; - the speed N1Mi of the rotating shaft 14 of the gas generator of the Ml engine; - the speed N1M2 of the rotating shaft 24 of the gas generator of the engine M2; - the speed N2Mi of the rotating shaft 13 of the motor Ml; - the speed N2M2 of the rotating shaft 23 of the motor M2.

[0068] The computer 70 is interconnected to a display unit (or display) 75 and is configured to emit messages intended to be displayed by the display unit 75. These messages may include at least one piece of information from among: - the speed NR of the rotor 62; - a speed N1AMi intended to be presented as that of the rotating shaft 14 of the gas generator of the Ml engine; - a speed N1AM2 intended to be presented as that of the rotating shaft 24 of the gas generator of the engine M2; - a speed N2M[ intended to be presented as that of the output shaft 13 of the M1 motor; and - a speed N2M2 intended to be presented as that of the output shaft 23 of the ML motor

[0069] In the embodiment described here, the rotor speed displayed on the display unit 75 is the actual rotor speed.

[0070] On the other hand, the speeds N1AMb N1AM2, N2AMb N1AM2 intended for display unit 75 may be different values ​​from the actual speeds N1Mi, N1M2, N2Mb N1M2 to make the pilot believe that the aircraft is in a different situation than its actual situation so as to encourage the pilot to react to an emergency situation when the helicopter is not actually in that emergency situation.

[0071] When a displayed value is different from the measured value in order to trigger a reaction from the pilot to a situation that is not the real situation, the value is said to be "rigged".

[0072] The calculator 70 is also connected to a bus enabling it to send signals to directly or indirectly control the speeds NR, NlMb N1M2, N2Mi, N1m2.

[0073] In this document, it will be said that the motor M1 (respectively the motor M2) is synchronized when the speed N2Mi (respectively the speed N2M2) of the output shaft 13 (respectively 23) of this motor is equal to the speed NR of the rotor 62.

[0074] Correspondingly, we will say that the motor M1 (respectively the motor M2) is out of sync when the speed N2M[ (respectively the speed N2M2) of the output shaft 13 (respectively 23) of this motor is strictly less than the speed NR of the rotor 62.

[0075] The NR speed of the rotor can also be described as the "resynchronization speed" since as soon as the speed of the output shaft of a motor reaches this speed, the motor resynchronizes. Reminders about ECO mode

[0076] It should be noted that in ECO mode, one of the aircraft's two engines is in standby mode, while the other engine operates at optimal power and reduced fuel consumption. In this mode, the standby engine can be automatically and very quickly restored to full power by means of an electric motor.

[0077] The present invention thus relates to a method and a system for training a pilot in the situation of engine power loss during ECO mode. This is a very critical situation because, transiently, no engine power is supplied to the helicopter. This situation requires a specific training mode, hereinafter referred to as "ECO-school" mode.

[0078] Existing motor loss training methods (hereafter referred to as "classical" training methods) cannot meet this specific need. Review of the concept of "#stop#"

[0079] It is recalled that it is common to define "limits" which correspond to maximum values ​​not to be exceeded in order not to damage the engine of an aircraft.

[0080] In the following description, three types of stops will be considered, namely: - a temperature stop, which defines the maximum acceptable temperature within an engine; - a speed stop NI, which defines the maximum speed NI of rotation of the rotating shaft of the gas generator of an engine; - a torque stop, which defines the maximum torque (or maximum power) for a motor.

[0081] Each of these stops (temperature stop, NI speed stop, torque stop) can be fixed differently depending on a phase of flight or a state of the engine.

[0082] In the description below, a value will be defined for each of these stops: - in normal flight; - in ECO mode; - in case of engine loss detection. Notations

[0083] In the rest of the description, it will be noted: NR Rotor speed NRA Rotor speed as presented to the pilot N2m1 Actual speed N2 of engine 1 N2m2 Actual speed N2 of engine 2 N2CV Flight set speed N2 N2ce Training mode set speed N2 N2AMi Speed ​​N2 of engine 1 as presented to the pilot N2Am2 Speed ​​N2 of engine 2 as presented to the pilot NImi Actual speed NI of engine 1 N1m2 Actual speed NI of engine 2 N1Am1 Speed ​​NI of engine 1 as presented to the pilot niaM2 Speed ​​NI of engine 2 as presented to the pilot Nlv Speed ​​NI in standby mode ni50 Speed ​​NI of each of engines M1 and M2 so that the speeds N2M[ and N2M2 of These engines reach the flight set speed N2CV when each of these engines delivers 50% of the power required for the helicopter to fly. The speed NI of an engine M1 or M2 for the speed N2M[ or N2M2 of this engine to reach the flight set speed N2CV 1 when this engine alone delivers 100% of the power required for the helicopter to fly. Cm1 Actual torque (or power) of engine 1 Cm2 Actual torque (or power) of engine 2 CAm1 Torque (or power) of engine 1 as presented to the pilot caM2 Torque (or power) of engine 2 as presented to the pilot C50 / 50 Normal torque (or power) of each of the engines M1 and M2 when the power is equally distributed between the two engines C100 Normal torque (or power) of an engine M1 or M2 when it delivers all the power required for the aircraft to fly, the other engine delivering no power CMAXvn, N1MAXvn, tmaxvn Maximum torque values,of speed N1 and temperature in normal flight. CMAXeco, N1 MAXeco, TMAXeco Maximum values ​​of torque, speed N1 and temperature in ECO mode. CMAXpm, NIMAXpm, TMAXpm Maximum values ​​of torque, speed N1 and temperature in case of engine loss. BCMi, Actual torque limit of engine Mi (M1 or M2). BNlMi Actual speed limit NI of engine Mi (M1 or M2). BTMi Actual temperature limit of motor Mi (M1 or M2) BACMi Torque limit of motor Mi as presented to the pilot BANlMi Speed ​​limit NI of motor Mi as presented to the pilot BATMü, BATM2 Temperature limit of motor Mi as presented to the pilot C#N1eco Torque limit allowing the motor to be supplied with power equivalent to the power of this motor when the speed Nid of its shaft is equal to the limit N1MAXECo C#N1pm Torque limit allowing the motor to be supplied with power equivalent to the power of this motor when the speed Nid of its shaft is equal to the limit N1MAXpm C#Teco Torque limit allowing the motor to be supplied with power equivalent to the power of this motor when its temperature is equal to the limit TMAXECO c#tpm Torque limit allowing the motor to be supplied with power equivalent to the power of this motor when its temperature is equal to the TMAXpm stop

[0084] In the different embodiment variants described below, two processes are considered, namely a main PSPM process for simulating engine failure and a simulation exit PS process which allows exiting the main simulation process at any time when a condition (see S10 below) is verified.

[0085] General presentation of a first embodiment of the invention

[0086] In this first embodiment of the invention, it is assumed, with reference to [Fig. 2], that the helicopter is initially in a flight phase M10 in which power is delivered to the rotor by the two engines M1 and M2. For example, each of the engines M1 and M2 delivers the same power C50 / 50-

[0087] For both motors, the actual torque, speed NI and temperature BCMi, BNlMi and BTMi limits were set equal to the maximum torque, speed NI and temperature in normal flight, respectively CMAXVN, N1MAXvn, TMAXvn (stage M5).

[0088] In the embodiment described here, the calculator 70 sends a message to the display calculator 75 to display to the pilots that the BACMi, BANlMi and BATMi stops are equal to the actual stops.

[0089] In this first embodiment variant, we enter a simulation phase of the real ECO mode (SIM_ECO_R on the [Fig.2]).

[0090] The actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi are then set equal to the maximum values ​​of torque, speed NI and temperature in ECO mode, respectively CMAXECo, N1MAXECo, TMAXECo (step M15).

[0091] For example, to simulate the real ECO mode, during an M30 step, the M2 engine (M30 step) is desynchronized by setting the target speed in N2CE training mode just below the NR rotor speed (resynchronization speed) to secure the helicopter flight.

[0092] Different solutions can be considered for setting the N2CE setpoint speed, and these different solutions are feasible in all the embodiments described below. For example, the N2CE setpoint is: - a fixed speed calculated from the minimum speed of the rotor's rotation (for example 90% of this value); - a variable speed calculated from the current speed NR of the rotor rotation (for example 90% of NR).

[0093] Thus, the motor M2 no longer delivers power but the speed N2M2 of its output shaft 23 remains just below the speed of the rotor NR so as to allow a rapid resynchronization of the motor M2.

[0094] After the desynchronization of the M2 engine, the power delivered to the rotor 62 is then entirely supplied by the M1 engine, but the aircraft is not properly in a real classic ECO mode since the M2 engine is not in standby.

[0095] The ECO mode is thus simulated. The computer 70 sends a message to the display 75 to present to the driver the presented limits BACMi, BANlMi and BATMi equal to the real limits, namely CMAXECo, N1MAXECo, TMAXECo (step M15).

[0096] In this first variant of the embodiment, we enter into a simulation phase of the standby mode (SIM_V on the [Fig.2]).

[0097] For example, to simulate this standby mode, during a step M50, the computer 70 sends a message to the display unit 75 containing a rigged N2AM2 speed to make the driver believe that the speed of the output shaft 23 drops to zero or a very low value, as if the motor M2 were in standby.

[0098] In the embodiment described here, the process includes a simulation phase of a loss of motor power (SIM_PMP on [Fig.2]), namely in this example the Ml motor.

[0099] More specifically, while the helicopter is in simulated ECO mode, the computer 70 desynchronizes (step M70) the engine Ml, which is then the only engine delivering power to the rotor. This operation consists of controlling the rotational speed of the output shaft 13 of the engine Ml so that it rotates slower than the rotor, in other words, setting N2Mi strictly less than NR.

[0100] According to the invention, the Ml engine is not actually put into standby mode.

[0101] In the embodiment described here, this control is carried out by setting (step M70) the setpoint of the actual speed N2Mi of the output shaft 13 of the motor Ml equal to N2Ce which remains just below the speed of the rotor NR so as to allow a rapid resynchronization of the motor Ml.

[0102] In a particular embodiment, the computer 70 sends a message to the display unit 75 (step M90) to present to the pilot a rigged zero speed N1AMi and / or a rigged speed N2AMi which drops very rapidly towards zero speed to simulate a failure of the Ml engine.

[0103] The pilot can thus train to react to this emergency situation (loss of the only engine in power in ECO mode) but in a simulated ECO mode, the M2 engine not being in standby.

[0104] At this moment, neither motor is supplying power to the engine, but the two motors are configured such that the respective speeds N2Mi and N2M2 of their output shafts 13 and 23 are close to the rotor speed NR. The aircraft's flight is safe because, if needed, power can be quickly supplied to the rotor again.

[0105] The embodiment described here includes a phase of detecting the loss of motor M1 and reactivating motor M2 (REAC on [Fig.2]).

[0106] More specifically, in the embodiment described here, the detection of the loss of motor Ml starts during a step M95 when it is detected that the torque of motor Ml is very low (r _ A

[0107] During this REAC phase, the actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi are set equal to the maximum values ​​of torque, speed NI and temperature in case of motor loss CMAXpm, N1MAXpm, TMAXpm.

[0108] The calculator 70 sends a message to the display 75 so that it displays to the pilot stops BACMi, BANlMi and BATMi equal to the actual stops, namely CMAXpm, N1MAXpm, TMAXpm.

[0109] In this first embodiment, after simulating the detection of the failure of the M1 motor, the computer 70 reactivates the M2 motor (step M1 10) after a time delay A (step M100) to simulate the time required for a motor in standby to provide power.

[0110] In one embodiment, the process continues (step M120) as in the classic single-engine training mode, with the entire power being taken over by engine M2.

[0111] When exiting ECO school mode (described later with reference to the PS exit process), the computer 70 sets the actual torque, speed NI and temperature BCMi, BNlMi and BTMi limits equal to the maximum values ​​of torque, speed NI and temperature in normal flight CMAXVN, N1MAXVn, TMAXvn.

[0112] The calculator 70 sends a message to the display 75 so that it displays stops equal to the actual stops, namely CMAXVN, N1MAXvn, TMAXvn.

[0113] The computer can then, for example, switch to a classic twin-engine trainer mode. Presentation of a second variant

[0114] In the first variant described above, before simulating the loss of engine power M1, the control unit 70 desynchronizes the engine M2 to enter a simulated ECO mode without putting this engine into standby (step M30).

[0115] Alternatively, the computer can actually enter ECO mode by putting the M2 engine into standby mode before simulating the loss of the ML engine

[0116] In this variant, when the M1 engine detects that it is losing power, it reactivates the M2 engine according to the rapid reactivation mechanism of the traditional ECO mode.

[0117] The first variant described above is advantageous in that it is more secure and in that it puts less strain on the M2 motor through rapid reactivations.

[0118] Detailed description of an embodiment of the first variant

[0119] Figure 3 shows, in an example, the evolution over time: - actual torques CMi, CM2 of the engines Ml, M2, and - actual speeds N2Mb N2M2 of the rotating shafts 13, 23 of these motors, during different phases of an example of the first embodiment variant.

[0120] Fig. 6 illustrates the values ​​of these torques and speeds as presented to the pilot by the display 75 from the messages of the computer 70.

[0121] The NI speeds and the stops (actual and displayed) have not been shown so as not to overload figures 3 and 6 but their values ​​are detailed below.

[0122] In this embodiment, it is assumed that the helicopter is in a normal flight phase (stage M10) in which each of the engines M1 and M2 delivers the same power C50 / 50- The speeds N2Mi and N2M2 of the engines Ml and M2 are equal to the flight set speed N2Cv- The speeds N1Mi and N1M2 of the engines Ml and M2 are equal to the speed Nl50.

[0123] The actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi were set by computer 70 equal to the maximum values ​​of torque, speed NI and temperature in normal flight, respectively CMAXVN, N1MAXvn, TMAXvn (step M5) The limits presented to the pilot BACMi, BANlMi and BATMi by display 75 are equal to the actual limits.

[0124] In this normal flight phase, the torques and speeds NI, N2 presented to the pilot on the display unit 75 reflect reality. Normal flight Actual Values ​​Displayed Values ​​Engine Ml Cmi C50 / 50 cam1 C50 / 50 N1m1 ni50 N1Am1 ni50 N2Mi N2Cv N2AMi N2Cv Actual Values ​​Displayed Values ​​Engine M2 Cm2 C50 / 50 CAm2 C50 / 50 N1m2 ni50 N1Am2 ni50 N2m2 N2CV N2Am2 N2CV

[0125] In the embodiment described here, the method according to the invention includes a phase (SIM_ECO_R) of simulating a switch to ECO mode.

[0126] The actual torque, speed NI, and temperature limits BCMi, BNlMi, and BTMi are set by the control unit 70 to equal the maximum values ​​of torque, speed NI, and temperature in ECO mode, respectively CMAXECo, N1MAXECo, and TMAXECO. The limits presented to the driver BACMi, BANlMi, and BATMi by the display 75 are equal to the actual limits.

[0127] During this phase, the computer 70 progressively reduces the CM2 power of the M2 engine to zero power and progressively increases the CMi power of the M1 engine to the Cioo power, all the flight power required by the aircraft then being delivered by the M1 engine (N2Mi=N2cv)-

[0128] This operation can be carried out by setting the N2 speed setpoint of the output shaft 23 of the motor M2 to the N2CE setpoint in school mode, this value being strictly less than the rotor speed (step M30).

[0129] This results in a progressive decrease in the N1M2 velocity and a progressive increase in the N1Mi velocity.

[0130] In the embodiment described here, during a SIM_V phase of engine M2 standby and simulation of switching to ECO mode, the method simulates (step M50) the engine M2 standby by displaying on display 75 for presentation to the pilot: - a CAM2 power of the M2 motor decreasing, until it shows that the M2 motor no longer delivers any power (CAM2 = 0) and that the Ml motor delivers a Cioo power; - a N1AM2 speed of the M2 engine decreasing to the standby speed Nlv; - a CAMi power and a N1AMi speed of the Ml engine increasing until reaching the NI speed; - a speed N2AM[ of the motor Ml equal to N2ML Simulation of switching to ECO mode Actual values ​​Displayed values ​​Engine Ml Cmi X Cioo CAMi / Cioo N1m1 y? N1Am1 / NIioo N2m1 N2CV N2AMi N2m[ Actual values ​​Displayed values ​​Engine M2 Cm2 \ 0 CAm2 \ 0 N1m2 niaM2 \ Nlv N2m2 => N2ce N2Am2 \ 0

[0131] In the embodiment described here, the process includes a SIM_PMP phase for simulating a loss of power in the only motor, in this case a loss of motor Ml.

[0132] In the embodiment described here, the calculator 70 desynchronizes the engine Ml by bringing it to a low speed without switching it off so that it no longer delivers power (CMi=0).

[0133] This desynchronization can be achieved by the computer 70 by setting (step M70) the speed setpoint N2M[ of the output shaft of the motor Ml to the setpoint N2CE of the school mode.

[0134] The consequence of this operation is a decrease in the value of N1Mi down to the level which guarantees that N2M[= N2CE and a decrease in the speed N2M[ down to N2CE.

[0135] The speed N1M2 is, for example, substantially constant.

[0136] The control unit 70 sends a message to the display 75 to present the pilot (step M90) with a message representative of a fault in engine M1. This message includes, for example, at least one piece of information from among: - a rapid decrease in the CMi power of the Ml engine down to zero power, - a very rapid (almost instantaneous) decrease in the N1AMi speed down to zero or very low speed, - a slower decrease in N2AMi speed down to zero or very low speed Simulation of engine power loss (Ml in the example) Actual values ​​Displayed values ​​Engine Ml Cmi 0 cam1 0 nim1 N1Am1 X o N2Mi X N2ce N2AMi Actual values ​​Displayed values ​​Engine M2 Cm2 0 caM2 0 N1m2 N1Am2 Nlv N2m2 N2ce N2Am2 0

[0137] In the embodiment described here, the method includes a REAC phase for detecting the loss of motor power and reactivating motor M2.

[0138] The detection of the loss of motor Ml is, for example, effective during a step M95 when the computer 70 detects that the torque of motor Ml is very low <„1=4

[0139] During this REAC phase, the actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi are set by the computer 70 equal to the maximum values ​​of torque, speed NI and temperature in case of engine failure CMAXpm, NIMAXpm, TMAXpm (step M97).

[0140] The calculator 70 sends a message to the display 75 to display BACMi, BANlMi and BATMi limits equal to the actual limits, namely CMAXpm, N1MAXpm, TMAXpm.

[0141] For example, during this phase, the computer 70 sends messages to the display 75 to indicate to the pilot: - that the Ml engine no longer delivers any power (CAMi = 0) - that the speed N1AMi of the engine Ml is very low or zero - that the speed N2AM[ decreases; - that the speeds N1AM2 and N2AM2 of the motor M2 begin to increase, but that at this instant the torque CAM2 of the motor M2 is still zero. Engine power loss detection Actual values ​​Displayed values ​​Engine M1 Cmi 0 CAm1 0 N1m1 N1Am1 0 N2Mi N2ce N2AMi Actual values ​​Displayed values ​​Engine M2 Cm2 0 CAm2 0 N1m2 N1Am2 N2m2 N2ce N2Am2

[0142] In the embodiment described here, after a predetermined delay of duration A, the method includes a step M1 10 during which the computer 70 actually restores power to the engine M2 so that it delivers all the power necessary for the aircraft to fly (CM2=C100). The speed N1M2 increases up to NI100. The speed N2M2 increases up to the flight setpoint N2CV.

[0143] Meanwhile, the computer 70 simulates (step M1 10) the rapid reactivation of engine M2 by sending a message to the display 75 to show the pilot information indicating that engine M2, which was rigged to appear to be in standby mode, is leaving standby mode. At this stage, both engines are still presented as delivering zero power (CAMi=CAM2=0).

[0144] The speed N1Mi is, for example, substantially constant.

[0145] Then, the computer 70 sends messages to the display 75 so that it can then show the pilot values ​​representative of the fact that the engine M2 gradually recovers torque until it reaches Cioo- The speed N1AM2 of the engine N2 increases until it reaches Nlioo and the value N2AM2 remains at the flight setpoint value N2Cv- Engine reactivation simulation Actual values ​​Displayed values ​​Engine Ml Cmi 0 CAM1 0 N1m1 N1AMi 0 N2Mi N2ce N2Ami 0 Actual values ​​Displayed values ​​Engine M2 Cm2 Cioo CAM2 o 7 c100 N1m2 7 Nl100 N1Am2 7 Nlioo N2M2 / N2CV N2Am2 / N2CV

[0146] In this embodiment, the engine loss learning process then includes a conventional single-engine training phase. The actual situation is that of normal single-engine flight, with all power delivered by a single engine (here M2, CAM2=Cioo). Classic single-engine training phase Actual Values ​​Displayed Values ​​Engine Ml Cmi 0 CAM1 0 N1m1 N1Am1 0 N2Mi N2CE N2AMi 0 Actual Values ​​Displayed Values ​​Engine M2 Cm2 C100 CAm2 C100 N1m2 N lioo niaM2 NI ioo N2m2 N2CV N2Am2 N2CV

[0147] It is assumed that we then exit ECO school mode and return to a normal flight situation.

[0148] The actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi are set equal to the maximum values ​​of torque, speed NI and temperature in normal flight CMAXVN, N1MAXvn, TMAXvn.

[0149] The stops presented to the pilot BACMi, BANlMi and BATMi are equal to the actual stops, namely CMAXVN, N1MAXvn, TMAXvn.

[0150] .The computer then presents the pilot with indicators that conform to reality. Exiting training mode, normal flight Actual Values ​​Displayed Values ​​Engine Ml Cmi C50 / 50 CAMi C50 / 50 N1Mi ni50 N1AMi ni50 N2m[ N2CV N2AMi N2CV Actual Values ​​Displayed Values ​​Engine M2 Cm2 C50 / 50 CAM2 C50 / 50 N1m2 ni50 N1Am2 ni50 N2m2 N2CV N2AM2 N2CV General presentation of a third variant of the implementation of the invention

[0151] This third variant is first presented in its generality with reference to [Fig.4],

[0152] In this embodiment, it is assumed that the helicopter is in a normal flight phase (step B10) in which each of the engines M1 and M2 delivers the same power C50 / 50-

[0153] For both engines, the actual torque, speed NI and temperature stops BCMi, BN1 Mi and BTMi were set by computer 70 equal to the maximum values ​​of torque, speed NI and temperature in normal flight, respectively CMAXVN, NIMAXvn, TMAXvn (step B5).

[0154] The BACMi, BANlMi and BATMi stops displayed for the pilot are equal to the actual stops.

[0155] In this variant, before the simulation of the loss of engine power, the helicopter does not actually switch to ECO mode, because the two engines M1 and M2 remain synchronized.

[0156] The calculator 70 however simulates the ECO mode (phase SIM_ECO_R on the [Fig.4]) by sending a message to the display 75 (step B20) to display a rigged information according to which the motor M2 goes into standby, all the power delivered to the rotor being taken over by the motor ML. However, at this moment, because the two motors Ml and M2 are still synchronized.

[0157] The temperature stops BATMi, torque stops BACMi, and speed stops NI BANlMi presented to the pilot are those of ECO mode (step B15).

[0158] The actual speed limits NI BNlMi and temperature limits BTMi are not modified.

[0159] However, in a particular embodiment, to simulate ECO mode, the control unit 70 limits the M1 and M2 engines by reducing their BCMi- torque stops

[0160] In the embodiment described here, this BCMi stop is fixed (step B15) equal to 50% of the minimum value chosen from: - the maximum torque value CMAXECo in ECO mode; - a torque stop C#N1ECo allowing the motor to be supplied with power equivalent to the power of this motor when the speed N1 is equal to the stop NlMAXEC0; and - a torque stop C#TECo allowing the motor to be supplied with a power equivalent to the power of this motor when the temperature of this motor is equal to the stop TMAXECo.

[0161] A person skilled in the art will understand that the value of 50% is justified by the fact that the aircraft has two engines. In the general case of an aircraft with N engines, this ratio would be (Nl) / N.

[0162] By taking the minimum value of these three stops, the computer 70 limits the engine by the smallest of these three stops. Other stops can be considered.

[0163] While the pilot considers that only the Ml engine is powered, the computer 70 simulates the loss of this Ml engine (SIM_PMP phase).

[0164] More specifically, in the embodiment described here (step B40), the control unit 70 desynchronizes the two motors M1 and M2, for example simultaneously, without putting them into standby mode. Indeed, as soon as the two motors M1 and M2 are desynchronized, no power is supplied to the rotor; this situation is analogous to the loss of power to the single motor in ECO mode.

[0165] To perform this double desynchronization, the computer 70 can set the target speed in N2CE training mode just below the NR rotor speed (resynchronization speed). Setting these speeds just below the NR rotor speed allows for rapid resynchronization of the M1 and M2 engines, thus ensuring safe helicopter flight.

[0166] In a particular embodiment, the computer 70 sends a message to the display 75 to present (step B60) to the pilot a rigged zero speed N1AMi and / or a rigged speed N2AM[ which drops very rapidly towards zero speed.

[0167] The pilot can thus train to react to this emergency situation (loss of the only engine in power in ECO mode) but in a simulated ECO mode, neither of the M1, M2 engines being actually in standby.

[0168] The method then includes a REAC phase for detecting the loss of the M1 engine and simulating the rapid reactivation of the M2 engine, during which the computer 70 presents the pilot with rigged information according to which the M2 engine restarts from its standby state.

[0169] More specifically, in the embodiment described here, the detection of the loss of motor Ml is carried out during a step B70 when the computer detects that the torque of motor Ml is very low (CWf = e)-

[0170] During this REAC phase, the calculator 70 sends a message to the display 75 so that it displays temperature limits BATMi, torque limits BACMi, and speed limits NI BANlMi corresponding to the engine loss situation (step B75).

[0171] The actual speed limits NI BNlMi and temperature limits BTMi are not modified.

[0172] The torque stops actually applied to the motor are limited to the same principle that in ECO mode. In the embodiment described here, the calculator 70 sets the BCMi stop (step B75) equal to 50% of the minimum value chosen from: - the maximum torque value CMAXpm in case of engine loss; - a torque stop C#N1PM allowing the motor to be supplied with power equivalent to its power when the speed N1 is equal to the stop N1MAXpm; and - a torque stop C#TPM allowing the motor to be supplied with a power equivalent to the power of this motor when the temperature of this motor is equal to the stop TMAXpm.

[0173] The display of this rigged information can be carried out after a delay A (step B80) equivalent to the fast reactivation delay of a motor (the time it takes a motor to complete its cycle after detecting the failure of another motor).

[0174] In the embodiment described here, during a step B100, the computer 70 resynchronizes the two engines to return to a conventional twin-engine trainer situation, in which: (i) the load is actually distributed across both motors; but (ii) the display 75 shows the pilot information that one engine is out of order, the other taking all the load.

[0175] As in the first embodiment, when exiting ECO school mode via the PS exit process, the actual torque, speed NI and temperature BCMi, BNlMi and BTMi limits are set equal to the maximum values ​​of torque, speed NI and temperature in normal flight CMAXVN, N1MAXvn, TMAXvn.

[0176] The stops presented to the pilot BACMi, BANlMi and BATMi are equal to these actual stops

[0177] Detailed description of an embodiment of the third variant

[0178] Figure 6 shows, in an example, the evolution: - actual torques CMi, CM2 of the engines Ml, M2, and - actual speeds N2Mb N2M2 of the rotating shafts 13, 23 of these motors, during different phases of this third embodiment variant.

[0179] The information presented to the pilot is identical to that described with reference to the first variant and is therefore illustrated in [Fig.4] already described, which applies in the same way to this third variant.

[0180] In this embodiment, it is assumed that the helicopter is in a normal flight phase (step B10) in which each of the engines M1 and M2 delivers the same power C50 / 50- The speeds N2M[ and N2M2 of the engines M1 and M2 are equal to the flight set speed N2Cv- The speeds N1Mi and N1M2 of the engines M1 and M2 are equal to the speed N150.

[0181] The actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi were set by computer 70 equal to the maximum values ​​of torque, speed NI and temperature in normal flight, respectively CMAXVN, N1MAXvn, TMAXvn (step M5) The stops presented to the pilot BACMi, BANlMi and BATMi are equal to the actual stops.

[0182] In this normal flight phase, the displays presented to the pilot reflect reality. Normal flight Actual Values ​​Displayed Values ​​Engine Ml Cmi C50 / 50 cam1 C50 / 50 N1m1 ni50 N1Am1 ni50 N2Mi N2Cv N2AMi N2Cv Actual Values ​​Displayed Values ​​Engine M2 Cm2 C50 / 50 CAm2 C50 / 50 N1m2 ni50 N1Am2 ni50 N2m2 N2CV N2Am2 N2CV

[0183] In the embodiment described here, the engine loss learning process includes a step B20 of simulating a switch to ECO mode (phase SIM_ECO_R on the [Fig.6]).

[0184] This is a simulation because in reality, each of the engines M1 and M2 continues to deliver the same power C50 / 50, the actual speeds N1Mi, N1M2; N2M[, N2M2 and NR being unchanged.

[0185] The temperature limits BATMi, torque limits BACMi, and speed limits NI BANlMi presented to the pilot on display 75 are those of ECO mode.

[0186] The actual speed limits NI BNlMi and temperature limits BTMi are not modified, but as described above, the calculator 70 sets BCMi such that: BCMi = min (CMAXEco, C#N1eco, C#Teco) / 2

[0187] To simulate the switch to ECO mode, the control unit 70 simulates (step B20) the standby mode of the M2 motor by sending a message to the display 75 indicating: - a CAM2 power of the M2 motor decreasing, until it displays that the M2 motor no longer delivers any power (CAM2 = 0) and that the M1 motor delivers all the power to the rotor; - a N1AM2 speed of the M2 engine decreasing to the standby speed Nlv; - a CAM power and a N1AMi speed of the Ml engine increasing until reaching the NI speed; - a speed N2AM[ of the motor Ml equal to N2ME Simulation of switching to ECO mode Actual values ​​Displayed values Engine Ml Cmi C50 / 50 CAmi 7 C100 nim1 ni50 N1Am1 7 NI 100 N2m1 N2CV N2AMi N2m1 Actual values ​​Displayed values ​​Engine M2 Cm2 C50 / 50 caM2 \ 0 N1m2 ni50 niaM2 \ Nlv N2m2 N2CV N2Am2 \ 0

[0188] In the embodiment described here, the learning process includes a SIM_PMP phase of simulating a loss of power of the only motor, in this case a loss of motor Ml.

[0189] In the embodiment described here, the process includes a step B40 of simulating a loss of power of the only motor, in this case a loss of motor Ml (phase SIM_PMP on the [Fig.5]).

[0190] This is a simulation phase because in reality, the computer 70 simultaneously reduces the power CMi, CM2 delivered by each of the two motors Ml and M2 while simulating the loss of power of only one motor.

[0191] During this phase, the calculator70 desynchronizes the two motors without switching them off so that they no longer deliver power (Cmi=CM2=0).

[0192] The consequence of this operation is a decrease in the values ​​of N1Mi, N1M2; N2Mi and N2m2.

[0193] The calculator 70 sets the speed setpoint N2Mi and N2M2 of the output shafts 13, 23 of the motors Ml and M2 to the setpoint N2CE of N2 in school mode.

[0194] Still during this DIM_PMP phase, during a step B60, the computer 70 sends a message to the display 70 to present the pilot with at least one piece of information from among: - a rapid decrease in the CMi power of the Ml engine down to zero power, - a very rapid (almost instantaneous) decrease in the N1AMi speed down to zero or very low speed, - a slower decrease in N2AMi speed down to zero or very low speed Simulation of engine power loss (Ml in the example) Actual values ​​Displayed values ​​Engine Ml Cmi 0 CAMi 0 nim1 NIAmi \ 0 N2Mi => N2ce N2Ami \ 0 Actual values ​​Displayed values ​​Motor M2 Cm2 0 CAm2 0 N1m2 N1Am2 Nlv N2m2 => N2ce N2Am2 0

[0195] The method then includes a REAC phase for detecting the loss of motor power and for rapidly reactivating motor M2.

[0196] In the embodiment described here, this REAC phase includes step B70 for detecting the loss of engine power, when the computer 70 detects that the torque of the engine Ml is very low (ç = g)-

[0197] The temperature stops presented to the pilot are those of an engine loss situation (step B75).

[0198] The actual speed limits NI BNlMi and temperature limits BTMi are not modified, but as described previously: BCMi = min (CMAXpm, C#N1pm, C#Tpm) / 2

[0199] At this moment, the motors M1 and M2 no longer deliver power, resulting in a decrease in the speeds N1Mb and N1M2. The speeds N2M[, N2M2 decrease until they reach the setpoint value in school mode N2Ce.

[0200] In the embodiment described herein, the pilot is instructed: - that the Ml engine no longer delivers any power (CAMi = 0) - that the speed N1AMi of the motor Ml is very low or zero, that the speed N2AM[ decreases; - that the speeds N1AM2 and N2AM2 of the motor M2 begin to increase, but that at this instant the torque CAM2 of the motor M2 is still zero. Motor power loss detection Actual values ​​Displayed values ​​Motor M1 Cmi 0 CAm1 0 nim1 N1Am1 0 N2m1 N2ce N2Am1 X Actual values ​​Displayed values ​​Motor M2 Cm2 0 caM2 0 N1m2 \ niaM2 N2m2 N2ce N2Am2

[0201] In the embodiment described here, after a predetermined time delay A (step B 80), the method includes a step B100 during which the computer 70 actually restores power simultaneously to both engines M1 and M2 so that each delivers the same power CMi=CM2=C50 / 50. The speeds N1Mi and N1M2 increase up to the speed N150. The speeds N2Mb and N2M2 increase up to the flight setpoint N2CV-

[0202] The control unit 70 then simulates the rapid reactivation of engine M2 by displaying information to the pilot indicating that engine M2, which was rigged to appear to be in standby mode, is exiting standby mode. At this stage, both engines are still presented as delivering zero power (CAMi=CAM2=0).

[0203] Then, the computer 70 sends a message to the display 75 to show the pilot that engine M2 is gradually regaining torque until it reaches Cioo. The speed N1AM2 of engine N2 increases until it reaches NI»» and the value N2AM2 remains at the flight setpoint value N2Cv- Engine reactivation simulation Actual Values ​​Displayed Values ​​Engine Ml Cmi C50 / 50 CAMi 0 nim1 7 ni50 N1Am1 0 N2m1 7 N2CV N2AMi 0 Actual Values ​​Displayed Values ​​Engine M2 Cm2 C50 / 50 caM2 0 7 C1OO N1m2 7 ni50 niaM2 7 NI 100 N2m2 7 N2CV N2Am2 7 N2CV

[0204] In the embodiment, the method then includes a conventional twin-engine training phase. The actual situation is that of normal twin-engine flight, with each engine delivering the same C50 / 50 power.

[0205] But in this training mode phase, the pilot is simulated as if all the power is delivered by the M2 engine (CAm2=Cioo) Conventional twin-engine training phase Actual values ​​Displayed values ​​Engine Ml Cmi C50 / 50 CAM1 0 nim1 ni50 N1Am1 0 N2m1 N2CV N2AMi 0 Actual Values ​​Displayed Values ​​Engine M2 Cm2 C50 / 50 CAm2 C100 N1m2 ni50 N1Am2 NI 100 N2m2 N2CV N2Am2 N2CV

[0206] In the embodiment described here, when exiting ECO school mode, the computer 70 reconfigures the aircraft in a normal flight situation.

[0207] The actual torque, speed NI and temperature limits BCMi, BNlMi and BTMi are set equal to the maximum values ​​of torque, speed NI and temperature in normal flight CMAXVN, N1MAXvn, TMAXvn.

[0208] The stops presented to the pilot BACMi, BANlMi and BATMi are equal to the actual stops, namely CMAXVN, N1MAXVn, TMAXvn.

[0209] The indicators presented to the pilot are consistent with reality. Exiting training mode, normal flight Actual Values ​​Displayed Values ​​Engine Ml Cmi C50 / 50 CAMi C50 / 50 nim1 ni50 N1Am1 ni50 N2m1 N2CV N2Am1 N2CV Actual Values ​​Displayed Values ​​Engine M2 Cm2 C50 / 50 caM2 C50 / 50 N1m2 ni50 niaM2 ni50 N2m2 N2CV N2Am2 N2CV PS process for exiting ECO-school mode

[0210] In the embodiment described here, and as illustrated in Figures 2 and 5, the simulation methods according to the invention comprise, an output PS process.

[0211] This exit process must trigger an exit (step S20) from the ECO school mode at any time when an exit situation is detected (positive result of S10), for example when: (i) rotor speed NR too low; (ii) engine failure or undesired engine behavior; (iii) request from the pilot or avionics.

[0212] The motors are then resynchronized. In addition, other settings normally made in classic school mode can be made.

[0213] When exiting ECO school mode, the actual torque, speed NI and temperature BCMi, BNlMi and BTMi limits are set (steps S25) equal to the values maximum torque, speed NI and temperature in normal flight CMAXVN, NIMAXvn, TMAXvn.

[0214] The stops presented to the pilot BACMi, BANlMi and BATMi are equal to the actual stops, namely CMAXpm, N1MAXpm, TMAXpm. Time Delay

[0215] In the embodiments described above, the simulation method includes a timing step (for example M100 or B80 respectively in Figures 2 and 5) to simulate the time required to detect the loss of the M1 motor.

[0216] This step may consist of waiting for a predetermined duration A.

[0217] Alternatively, the computer can implement the actual power loss detection logic used in ECO mode and provide the pilot with spoofed data corresponding to the data produced by this algorithm. This variant allows for the provision of data adapted to each flight situation.

[0218] Figure 7 illustrates the hardware architecture of the computer 70 in a particular embodiment of the invention. It comprises a processor 71, a random access memory 72, a rewritable non-volatile memory 73 and a read-only memory of the ROM type 74 in which a computer program PG according to the invention is stored.

[0219] This computer program PG includes instructions which, when executed by the processor 71, enable the implementation of a simulation process as described below with reference to Figures 2 to 6.

Claims

Demands

1. Method for simulating an engine failure in an aircraft comprising at least one first engine (M1) and a second engine (M2), each of said engines (M1, M2) comprising a gas generator (12, 22) configured to drive in rotation a free turbine (11, 21) mounted on an output shaft (13, 23) of said engine, each of said output shafts (13, 23) being coupled to the same rotor (62) of the aircraft, said method comprising the following steps: - emission (B20) of a first message indicating that the first engine (M2) goes into standby and that all the power delivered to said rotor (62) is taken over by the second engine (M1) while the two engines (M1, M2) are actually synchronized; - desynchronization (B40) of the two engines (M1, M2) without putting them into standby; - emission (B60) of a second message representing a failure of said second engine (M1).

2. Simulation method according to claim 1, wherein said desynchronization of a motor (M1, M2) without putting it to standby comprises checking that the difference between: (i) the rotational speed (N2M2) of the output shaft (13, 23) of said motor (M1, M2); and (ii) the rotational speed (NR) of the rotor (62) is kept below a predetermined value.

3. Simulation method according to claim 1 or 2, wherein said desynchronization of a motor (M1, M2) without putting it to standby comprises setting a setpoint (N2CE) for the rotational speed (N2M2) of the output shaft (13, 23) of said motor (M1, M2) at a speed lower than the minimum permissible rotational speed (NR) of the rotor.

4. Simulation method according to any one of claims 1 to 3 comprising a step (S20) for interrupting said method when an emergency condition is detected (S10).

5. Simulation method according to any one of claims 1 to 4 comprising a step (B 15, B75) for restricting each of said motors to 50% of the maximum torque that this motor can produce while respecting all of its stops.

6. Computer (70) configured to simulate an engine failure in an aircraft comprising at least one first engine (M1) and a second engine (M2), each of said engines (M1, M2) comprising a gas generator (12, 22) configured to drive a free turbine (11, 21) mounted on an output shaft (13, 23) of said engine, each of said output shafts (13, 23) being coupled to the same rotor (62) of the aircraft, said computer being configured to: - issue (B20) a first message indicating that the first engine (M2) goes into standby and that all the power delivered to said rotor (62) is taken over by the second engine (M1) while the two engines (M1, M2) are actually synchronized; - desynchronize (B40) the two engines (M1, M2) without putting them into standby; - emit (B60) a second message representative of a failure of said second engine (Ml).

7. Computer program (PG) comprising instructions which, when the program is executed by a computer, cause the computer to carry out a process according to any one of claims 1 to 5.

8. Computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to carry out a method according to any of claims 1 to 5.

9. Aircraft (100) comprising a computer (70) according to claim 6.

Images