Method of assisting in piloting a rotorcraft and rotorcraft so equipped.

Abstract

The present invention relates to a method for assisting the piloting of a rotorcraft (1) comprising a first engine (2) and a second engine (3) each capable of transmitting, except in the event of a failure, an engine torque to at least one rotor (4) ensuring at least one lift of the rotorcraft (1) in the air, the rotorcraft (1) comprising aerodynamic members (6) making it possible to pilot the rotorcraft (1). Such an assistance method comprising an asymmetrical regulation of the first engine (2) and said second engine (3), an identification of an engine failure of the first engine (2) using a failure controller (7) and in the presence of an engine failure of the first engine (2), acceleration of the second engine (3) from the standby regime to a synchronization regime in which the second engine (3) alone transmits the engine power to said at least one rotor (4), Abstract figure: figure 1

Description

Title of the invention: Method for assisting in piloting a rotorcraft and rotorcraft thus equipped.

[0001] The present invention relates to a method for assisting the piloting of a rotorcraft, an assistance system and a rotorcraft thus equipped.

[0002] Such a rotorcraft is equipped with a power unit comprising at least two engines and at least one lift rotor driven in rotation by the power unit.

[0003] Furthermore, the operation of the engines is managed by a regulation system. This regulation system makes it possible to implement an engine operating mode commonly referred to as AEO mode (from the acronym for "Ail Engine Operative") in which all the engines in the power unit are operational and each transmits engine power to the power-consuming components of the rotorcraft such as the rotor(s).

[0004] In order to reduce the fuel consumption of the aircraft's thermal engines, a so-called "economical" operating mode can be used, mainly during a cruising flight phase. According to this economical operating mode, a single thermal engine provides the power necessary to rotate the rotor(s) of the rotorcraft. The other thermal engine(s) do not provide significant mechanical power, or even provide no power at all.

[0005] According to a first variant, a single thermal engine operates and alone ensures the rotational drive of the rotorcraft rotor. The other thermal engine(s) are stopped and are not supplied with fuel. In the case of a free turbine turboshaft engine, the rotating members of the gas generator can however be kept rotating by an electric motor to facilitate and accelerate the restarting of the engine.

[0006] According to a second variant, all the engines are started and supplied with fuel, but only one thermal engine provides significant mechanical power so as to drive the rotor(s) of the rotorcraft into rotation. The other thermal engine(s) are started, but operate in a so-called “super idle” operating state and therefore do not provide any mechanical power.

[0007] Whatever the variant of this economical mode of operation, the operation of thermal engines is therefore asymmetrical, the thermal engines not operating in an identical manner.

[0008] Thus, document EP3738888 discloses a method of operating a rotorcraft comprising a plurality of engines designed to provide motive power to at least minus one rotor.

[0009] Furthermore, an asymmetrical operating mode is implemented, in which at least one first motor is a so-called “active” motor, i.e. providing motive power to at least one rotor, and at least one second motor is a so-called “inactive” motor, i.e. providing substantially no motive power.

[0010] This method comprises monitoring for a failure of the active engine. In the presence of such a failure, the output power of the inactive engine is automatically increased. The reactivated inactive engine then operates according to a so-called "OEI" regime (from the acronym designating in English "One Engine Inoperative"). An available engine operating in OEI mode provides sufficient power until landing, to temporarily allow the rotorcraft to progress in flight despite the unavailability of one of the engines.

[0011] During the transient phase from the failure of the active motor to the reactivation of the inactive motor, the mechanical power transmitted to the rotor(s) is then temporarily zero or greatly reduced.

[0012] The present invention therefore aims to propose a method and an assistance system making it possible to contain the workload of the pilot(s) during the transitional phase.

[0013] Thus, one aim of the invention is to assist pilots and enable them to perform other tasks during this transitional phase, in particular during a flight with low visibility.

[0014] The invention therefore relates to a method for assisting the piloting of a rotorcraft comprising a first engine and a second engine each capable of transmitting, except in the event of a failure, an engine torque to at least one rotor ensuring at least one lift of the rotorcraft in the air, the rotorcraft comprising aerodynamic members making it possible to pilot the rotorcraft, the assistance method comprising the following steps: - asymmetric regulation of the first motor and the second motor, the first motor providing only motive power to said at least one rotor, the second motor operating in a standby mode in which the second motor does not provide any motive power to said at least one rotor, - identification of an engine failure of the first engine using a failure controller, and - in the presence of a said engine failure of the first engine, acceleration of the second engine from the standby mode to a synchronization mode in which the second engine alone transmits the driving power to said at least one rotor.

[0015] This method is remarkable in that, following the identification of the engine failure of the first engine and as long as the operating speed of the second engine is lower than a synchronization speed, the assistance method comprises the following steps performed several times or repeated: - periodic in-flight detection of current values ​​of at least two state parameters by means of at least two separate sensors, said at least two state parameters being of separate natures and comprising a first state parameter representative of an environmental physicochemical condition or of a position of the rotorcraft relative to an external environment and a second state parameter representative of an operation of the rotorcraft, and - periodic generation with an automatic pilot controller of control orders to control actuators connected to the aerodynamic members during a phase of flight in automatically piloted autorotation, the periodic generation implementing a predetermined control law depending on said at least two state parameters, the predetermined control law being specifically applicable to the assistance method.

[0016] In other words, such an assistance method makes it possible to automatically pilot a rotorcraft during an autorotation flight phase following the failure of the active engine during an asymmetric flight. Furthermore, such a rotorcraft may comprise one or more first engines initially active and one or more second engines initially inactive. However, for the sake of clarity and simplification, the rotorcraft is described as having a first and a second engine in a non-exhaustive manner.

[0017] Thus, the periodic generation of control orders is implemented automatically as soon as the failure controller detects a motor failure of the first motor rendering it inoperative.

[0018] Such an autorotational flight phase ends when the second engine, initially inactive, has become active and thus transmits the required engine torque to said at least one rotor.

[0019] The pilot can then pilot the rotorcraft by maneuvering control members to control the actuators connected to the aerodynamic members. The pilot can thus continue the flight with only the second engine becoming active or decide to carry out a landing.

[0020] The control law for generating the control commands during the periodic generation can advantageously be predetermined by tests, flight tests and / or simulations. This control law can for example consist of a computer algorithm, artificial intelligence, a mathematical formula, a table of values ​​or an abacus. The control law can use the current values ​​of at least two state parameters so as to automatically generate the control commands without any particular action from the pilot(s) who can thus concentrate on other actions such as terrain monitoring, obstacle detection, re starting and synchronizing the second engine and a power transmission box, etc.

[0021] Furthermore, the values ​​of the state parameters can be evaluated periodically in flight, with a predetermined detection frequency, by sensors comprising dedicated sensors or sensors shared with other systems of the rotorcraft.

[0022] The failure controller and the autopilot controller may each comprise, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression "controller". The term processor may designate a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc. The failure controller and the autopilot controller may form a single controller.

[0023] Furthermore, the synchronization regime of the second motor can be defined by a differential in rotational speeds between two shafts connected by a freewheel. Such a freewheel allows the second motor(s) to rotate a power transmission kinematic chain. An engine torque can thus be transmitted from an output shaft of the second motor to an input shaft of a main power transmission gearbox.

[0024] Alternatively, as long as the output shaft of the second motor rotates at a speed lower than that of the input shaft of the main power transmission box, the freewheel does not allow this second motor to transmit engine torque to the transmission kinematic chain and therefore to the rotor(s).

[0025] Furthermore, the first and second engines may be thermal engines and the acceleration of the second engine from the standby speed to a synchronization speed may be achieved for example by increasing a fuel flow rate supplied to the second engine. A fuel metering device is then controlled by a controller as a function of the rotational speed of the output shaft of the second engine and that of the input shaft of the main power transmission box.

[0026] In practice, the first state parameter can be chosen from the group comprising an air temperature, an atmospheric pressure, an altitude, an air density, an air speed of the rotorcraft relative to the air, a ground speed of the rotorcraft relative to the ground, a vertical acceleration of the rotorcraft relative to the ground and an attitude of the rotorcraft in a terrestrial reference frame.

[0027] Thus, the current values ​​of this first state parameter are linked to the air in the vicinity of the rotorcraft and / or to the movement of the rotorcraft relative to the air.

[0028] Furthermore, the second state parameter can be chosen from the group comprising a rotation speed NR of said at least one rotor, a power transmitted by the second engine to said at least one rotor, an engine torque transmitted by the second engine to said at least one rotor, a rotational speed of a gas generator NI of the second engine, a rotational speed N2 of a free turbine of the second engine, a temperature TET of the gases at the inlet of a high-pressure turbine of a gas generator of the second engine and a temperature T45 of the gases at the inlet of a free turbine of the second engine.

[0029] The current values ​​of this second state parameter are therefore linked to the operation of an internal organ of the rotorcraft and are thus of a nature distinct from that of the first state parameter.

[0030] Advantageously, the first state parameter may be the air speed of the rotorcraft relative to the air and the second state parameter may be the rotation speed NR of said at least one rotor.

[0031] Such a combination of the first and second state parameters in fact allows the control law to generate control orders guaranteeing the safe performance of an autorotation flight phase of the rotorcraft.

[0032] According to an exemplary embodiment of the invention, the aerodynamic members may comprise blades of said at least one rotor, the actuators controlling at least one pitch of the blades.

[0033] Thus, the assistance method makes it possible to control the pitch of the blades of the rotor(s). The actuators can in particular act directly or via a kinematic chain on pitch control plates and pitch connecting rods connected to the blades.

[0034] In practice, the control commands can be transmitted to the actuators to generate a collective and identical reduction of a pitch of the blades and / or a cyclical modification of the pitch of the blades.

[0035] Such a collective reduction in the pitch of the blades makes it possible in particular to maintain constant or to increase the rotation speed of the rotor and the cyclic modification of the pitch of the blades makes it possible to control and stabilize the descent trajectory of the rotorcraft.

[0036] Furthermore, the assistance method may comprise a display on a display of at least one item of information chosen from the group comprising the current values ​​of said at least two state parameters and of information representative of a transmission of control orders from the automatic pilot controller to the actuators.

[0037] Such a display further allows the pilot to follow the actions performed by the autopilot controller and the actuators. This display may, for example, comprise a screen making it possible to display dials each with a movable needle or scales each with a movable index forming information carrying the current values ​​of said at least two state parameters.

[0038] The present invention also relates to a computer program comprising instructions which, when the program is executed, lead to the implementation of the aforementioned assistance method.

[0039] The program is for example executed by a computer or a calculator, comprising at least one processor, at least one integrated circuit, at least one programmable system, at least one logic circuit, and a memory, these examples not limiting the scope given to the expression “computer” or “calculator”.

[0040] The memory makes it possible to store the computer program as well as various information used by the computer program, namely the control instructions to be transmitted to said actuators, the current values ​​of said at least two state parameters and the predetermined control law to be implemented.

[0041] The invention also relates to a rotorcraft comprising a first engine and a second engine each capable of transmitting, except in the event of a failure, an engine torque to at least one rotor ensuring at least one lift of the rotorcraft in the air.

[0042] According to the invention, such a rotorcraft is remarkable in that it comprises a rotorcraft piloting assistance system configured to implement the aforementioned assistance method, the system comprising the failure controller, the automatic pilot controller, the actuators and said at least two sensors.

[0043] Such a system is then integrated into a rotorcraft and as such constitutes equipment of the rotorcraft. The pilot assistance system can then be connected to a flight management device of the rotorcraft. The autopilot controller can furthermore be dedicated to the pilot assistance system or be shared with an autopilot device of the rotorcraft conventionally used during a flight of the rotorcraft and except in the event of engine failure.

[0044] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent:

[0045] [Fig.l], a schematic diagram of a rotorcraft equipped with an assistance system making it possible to implement the assistance method according to the invention, and

[0046] [Fig.2], a flowchart illustrating the steps of an assistance method according to the invention.

[0047] Elements present in several distinct figures are assigned a single reference.

[0048] As already mentioned, the invention relates to a method for assisting in piloting a rotorcraft.

[0049] As shown in [Fig.l], such a rotorcraft 1 comprises at least two engines, including a first engine 2 and a second engine 3, each capable of transmitting, except in the event of a failure, an engine torque to at least one main rotor 4 ensuring at least one lift in the air of the rotorcraft 1. The engines 2, 3 are thus connected to a power transmission kinematic chain leading to at least one main rotor 4.

[0050] The rotorcraft 1 also comprises aerodynamic members 6 for piloting the rotorcraft 1 in the air. These aerodynamic members 6 may comprise at least one blade 9 of the main rotor(s) 4, at least one blade 19 of a tail rotor 16, and / or flaps.

[0051] Furthermore, such a rotorcraft 1 also comprises actuators 10 comprising, for example, servocontrols and / or jacks making it possible to move the aerodynamic members 6 directly or indirectly. For example, series and parallel jacks move a mechanical chain controlling a servocontrol engaged on a set of swashplates connected by pitch rods to blades 9.

[0052] These actuators 10 can thus receive control orders generated by an automatic pilot controller 8. The automatic pilot controller 8 can comprise, for example, a control unit of an automatic pilot system known by the acronym AFCS, meaning “Automatic Flight Control System”.

[0053] Furthermore, such a rotorcraft 1 also comprises at least two sensors 13, 14 distinct from one another, these sensors 13, 14 emitting analog or digital signals by wired or wireless means to the automatic pilot controller 8.

[0054] The sensor(s) 13 make it possible to detect in flight current values ​​of a first state parameter representative of a physicochemical environmental condition of the rotorcraft 1 or of a position of the rotorcraft 1 relative to an external environment EXT. The sensor(s) 13 may in particular have position, speed or acceleration sensors of the rotorcraft 1, an inertial unit or an anemobarometric system.

[0055] Furthermore, the first state parameter may be selected from the group comprising an air temperature, an atmospheric pressure, an altitude, an air density, an air speed of the rotorcraft 1 relative to the air, a ground speed of the rotorcraft 1 relative to the ground, a vertical acceleration of the rotorcraft 1 relative to the ground and an attitude of the rotorcraft 1.

[0056] The sensor(s) 13 may thus comprise a thermometer measuring the air temperature, a barometer measuring the atmospheric pressure outside the rotorcraft 1 and an altimeter measuring the altitude of the rotorcraft 1.

[0057] Air density can be estimated using air temperature and atmospheric pressure values.

[0058] The anemobarometric system can allow the air speed of the rotorcraft 1 to be measured relative to the air, the altitude.

[0059] The sensor(s) 14 allow current values ​​to be detected in flight. of a second state parameter representative of an operation of the rotorcraft 1.

[0060] The second state parameter can be chosen from the group comprising a rotation speed NR of said at least one rotor 4, a power transmitted by the second engine 3 to said at least one rotor 4 via the transmission kinematic chain, an engine torque transmitted by the second engine 3 to said at least one rotor 4 via the transmission kinematic chain, a rotation speed of a gas generator NI of the second engine 3, a rotation speed N2 of a free turbine of the second engine 3, a temperature TET of the gases at the inlet of a high-pressure turbine of a gas generator of said second engine 3 and a temperature T45 of the gases at the inlet of a free turbine of the second engine 3.

[0061] The sensor(s) 14 may in particular have position, speed or acceleration sensors for measuring or determining the rotation speed NR, position, speed or acceleration sensors for measuring or determining a rotation speed of the gas generator NI of the second engine 3, position, speed or acceleration sensors for measuring or determining a rotation speed N2 of a free turbine of the second engine 3 or of an output shaft of the second engine 3, a torque meter measuring a torque transmitted by the output shaft of the second engine 3 to said at least one rotor 4.

[0062] The sensor(s) 14 may also have temperature sensors such as thermometers measuring the temperature TET of the gases at the inlet of a high-pressure turbine of a gas generator of the second engine 3 and the temperature T45 of the gases at the inlet of a free turbine of the second engine 3.

[0063] By sensors, we mean here physical sensors capable of directly measuring the parameter in question, but also a system which may comprise one or more physical sensor(s) as well as signal processing means making it possible to provide an estimate of the parameter from the measurements provided by this or these physical sensors. Similarly, the term current value or measurement of this parameter will denote both a raw measurement from a physical sensor and a value obtained by signal processing from this raw measurement.

[0064] Furthermore, said at least two sensors 13, 14 make it possible to measure and transmit to the automatic pilot controller 8 data varying according to the control orders transmitted to the actuators 10. This data makes it possible to implement a regulation loop aimed, for example, at ensuring an autorotation flight phase thanks to the predetermined control law.

[0065] Furthermore, the rotorcraft 1 may comprise at least one mission system 15 connected by wire or wireless means to the automatic pilot controller 8 and possibly to said at least two sensors 13, 14. Such a mission system 15 is configured to configure the automatic pilot controller 8 and possibly said at least two sensors 13, 14. at least two sensors 13, 14 depending on flight constraints linked to the mission that the rotorcraft 1 must carry out or piloting preferences.

[0066] This mission system 15 may in particular comprise a human-machine interface allowing the pilot to enter piloting preferences relating to an autorotation flight phase. Such preferences may, for example, make it possible to adapt or replace the predetermined control law with another predetermined control law.

[0067] Furthermore, the rotorcraft 1 may comprise a display 11 connected by wire or wireless means to the automatic pilot controller 8 and possibly to said at least two sensors 13, 14.

[0068] Such a display 11 may in particular make it possible to display information visible to a pilot such as the current values ​​of said at least two state parameters and / or information representative of a transmission of control orders from the automatic pilot controller 8 to the actuators 10. Thus, the pilot may in particular be informed that the automatic pilot controller 8 is active and is piloting the rotorcraft 1 to perform an autorotation flight phase.

[0069] Furthermore, in the event of failure of the first engine 2, a method 20 for assisting the piloting of the rotorcraft 1 as shown in [Fig.2] can be implemented.

[0070] Such an assistance method 20 thus comprises a plurality of steps and in particular an asymmetric regulation 21 of the first engine 2 and of the second engine 3 implemented for example by the AFCS system. Such a regulation 21 thus makes it possible to control fuel metering devices of the engines 2, 3 so that the first engine 2 alone provides motive power to said at least one rotor 4 and so that the second engine 3 operates at a standby speed in which this second engine 3 does not provide any motive power to said at least one rotor 4.

[0071] The assistance method 20 then comprises an identification 22 of an engine failure of the first engine 2 using a failure controller 7 possibly connected to at least one sensor having a position, speed or acceleration sensor or a temperature sensor configured to measure a parameter linked to the operation of the first engine 2.

[0072] Such a failure controller 7 is then a standard controller capable of carrying out conventional control operations and in particular of comparing the current value generated by a sensor with a threshold value and then possibly emitting an alarm signal in the event of crossing this threshold value which may be, for example, a minimum engine torque.

[0073] The assistance method 20 then comprises an acceleration 23 implemented for example by the AFCS system to increase the operating speed of the second engine 3 from the standby speed to a synchronization speed. in which this second motor 3 alone provides motive power to said at least one rotor 4.

[0074] Such an acceleration 23 can be implemented by the AFCS system controlling at least one fuel metering device of the second engine 3 so that its speed increases and goes from the standby speed to the synchronization speed. Once this synchronization speed is reached, the AFCS system can control the fuel metering device to maintain constant or increase the operating speed of the second engine 3,

[0075] In parallel with this acceleration 23, upon identification of a failure of the first engine and as long as the operating speed of the second engine 3 is lower than the synchronization speed, the assistance method 20 comprises a step 24 of periodic detection in flight of current values ​​of at least two state parameters with the sensors 13, 14.

[0076] The sensors 13, 14 are connected by wire or wireless means to the automatic pilot controller 8 and thus each transmit analog or digital, electrical or optical signals, carrying the respective current values ​​of the at least two state parameters. The periodic detection 24 then makes it possible to detect and transmit these current values ​​of the at least two state parameters according to a first predetermined time interval.

[0077] The assistance method 20 comprises a periodic generation 25 with the automatic pilot controller 8 of control orders to control the actuators 10 connected to the aerodynamic members 6 and to pilot the rotorcraft 1 according to an autorotation flight phase.

[0078] Such periodic generation 25 of the control orders is thus also carried out according to a second predetermined time interval as a function of the variations of the at least two state parameters. Optionally the first and second time intervals may be equal.

[0079] Furthermore, such periodic generation 25 is implemented by an automatic pilot controller 8 which determines the control orders by applying a control law stored in a memory which may be independent or included in the automatic pilot controller 8, said control law being a function of the at least two state parameters to generate the control orders.

[0080] Advantageously, the assistance method 20 can also include a display 26 on the display 11 of the current values ​​of said at least two state parameters and / or of information representative of a transmission of the control orders from the automatic pilot controller 8 to the actuators 10.

[0081] Such a display 11 is thus connected by wire or wireless means to the automatic pilot controller 8 and receives analog or digital, electrical or optical signals, carrying the current values ​​of the at least two state parameters and / or of a transmission of the control orders from the automatic pilot controller 8 to the actuators 10 when said periodic generation 25 of the control orders is implemented.

[0082] Similarly, such an assistance method 20 may possibly include a preliminary step 27 of determining a type of mission or preferences. Such a determination 27 of a type of mission may for example be implemented by means of the mission system 15 which then transmits a signal representative of the type of mission or preferences to the automatic pilot controller 8.

[0083] Once this determination step 27 has been implemented, the rotorcraft 1 can then take off and carry out or begin its mission.

[0084] Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims

Claims

1. Method for assisting (20) the piloting of a rotorcraft (1) comprising a first engine (2) and a second engine (3) each capable of transmitting, except in the event of a failure, an engine torque to at least one rotor (4) ensuring at least one lift of said rotorcraft (1) in the air, said rotorcraft (1) comprising aerodynamic members (6) making it possible to pilot said rotorcraft (1), said assistance method (20) comprising the following steps: • asymmetric regulation (21) of the first motor (2) and said second motor (3), the first motor (2) providing only motive power to said at least one rotor (4), said second motor (3) operating according to a standby regime in which said second motor (3) does not provide any motive power to said at least one rotor (4), • identification (22) of an engine failure of said first engine (2) using a failure controller (7), and • in the presence of a said engine failure of said first engine (2), acceleration (23) of said second engine (3) from said standby mode to a synchronization mode in which said second engine (3) alone transmits the driving power to said at least one rotor (4), characterized in that, following the identification (22) of the engine failure of the first engine (2) and as long as an operating speed of said second engine (3) is lower than said synchronization speed, said assistance method (20) comprises the following steps: • periodic detection (24) in flight of current values ​​of at least two state parameters by means of at least two distinct sensors (13, 14), said at least two state parameters being of distinct natures and comprising a first state parameter representative of an environmental physicochemical condition or of a position of the rotorcraft (1) relative to an external environment (EXT) and a second state parameter representative of an operation of said rotorcraft (1), and • periodic generation (25) with a pilot controller au- automatic (8) of control orders for controlling actuators (10) connected to said aerodynamic members (6) during a phase of flight in automatically piloted autorotation, said periodic generation (25) implementing a predetermined control law depending on said at least two state parameters, said predetermined control law being specifically applicable to said assistance method (20).

2. Method according to claim 1, characterized in that said first state parameter is chosen from the group comprising an air temperature, an atmospheric pressure, an altitude, an air density, an air speed of said rotorcraft (1) relative to the air, a ground speed of said rotorcraft (1) relative to the ground, a vertical acceleration of said rotorcraft (1) relative to the ground and an attitude of said rotorcraft (1) in a terrestrial reference frame.

3. Method according to any one of claims 1 to 2, characterized in that said second state parameter is chosen from the group comprising a rotation speed NR of said at least one rotor (4), a power transmitted by said second motor (3) to said at least one rotor (4), an engine torque transmitted by said second motor (3) to said at least one rotor (4), a rotation speed of a gas generator NI of said second motor (3), a rotation speed N2 of a free turbine of said second motor (3), a temperature TET of the gases at the inlet of a high pressure turbine of a gas generator of said second motor (3) and a temperature T45 of the gases at the inlet of a free turbine of said second motor (3).

4. Method according to claims 2 and 3, characterized in that said first state parameter is the air speed of said rotorcraft (1) relative to the air and said second state parameter is the rotation speed NR of said at least one rotor (4).

5. Method according to any one of claims 1 to 4, characterized in that said aerodynamic members (6) comprise blades (9) of said at least one rotor (4), said actuators (10) controlling at least one pitch of said blades (9).

6. Method according to claim 5, characterized in that said control orders are transmitted to said actuators (10) for generating a collective and identical decrease in a pitch of said blades (9) and / or a cyclical modification of said pitch of said blades (9).

7. Method according to any one of claims 1 to 6, characterized in that said assistance method (20) comprises a display (26) on a display (11) of at least one item of information chosen from the group comprising said current values ​​of said at least two state parameters and information representative of a transmission of said control orders from said automatic pilot controller (8) to said actuators (10).

8. Computer program comprising instructions which, when said program is executed, lead to implementing the assistance method (20) according to any one of claims 1 to 7.

9. Rotorcraft (1) comprising a first engine (2) and a second engine (3) each capable of transmitting, except in the event of a failure, an engine torque to at least one rotor (4) ensuring at least one lift of said rotorcraft (1) in the air, characterized in that said rotorcraft (1) comprises a system (12) for assisting the piloting of said rotorcraft (1) configured to implement the assistance method (20) according to any one of claims 1 to 7, said system (12) comprising said failure controller (7), said automatic pilot controller (8), said actuators (10) and said at least two sensors (13, 14).

Images