초록 ▼

A method of assisting the piloting of a multi-engined rotorcraft in the event of an engine failure. A main rotor of the rotorcraft is driven at a variable NR speed under the control of a control unit. Calculation means identify an authorized margin of mechanical power usable by the pilot depending o

A method of assisting the piloting of a multi-engined rotorcraft in the event of an engine failure. A main rotor of the rotorcraft is driven at a variable NR speed under the control of a control unit. Calculation means identify an authorized margin of mechanical power usable by the pilot depending on a rating for regulating the operation of each of the engines under the control of a regulator unit. Outside an engine-failure situation, and providing the main rotor is being driven at a low NR speed, the mechanical power margin that is usable by the pilot and that is displayed on a screen, is in fact a limited margin of a value less than the authorized margin. Under such conditions, and in an engine-failure situation, the mechanical power reserve that is actually available enables the pilot to counter rapidly the sudden drop in the NR speed of rotation of the main rotor as induced by the engine failure.

대표청구항 ▼

1. A method of assisting the piloting of a multi-engined rotorcraft in the event of a failure of one of the main engines of a power plant of the rotorcraft, referred to as an engine-failure situation, the power plant delivering the mechanical power needed at least for driving rotation of at least on

1. A method of assisting the piloting of a multi-engined rotorcraft in the event of a failure of one of the main engines of a power plant of the rotorcraft, referred to as an engine-failure situation, the power plant delivering the mechanical power needed at least for driving rotation of at least one main rotor of the rotorcraft providing the rotorcraft at least with lift, the main rotor, outside an engine-failure situation, being driven by the power plant in compliance with applying a speed setpoint, referred to as the NR setpoint, of variable value that is calculated by a flight control unit depending on the current flight conditions of the rotorcraft so as to lie in a range of NR setpoint values that are proportional to the value of a predefined nominal speed for driving the main rotor,the flight control unit supplying the NR setpoint to a regulator unit for regulating the individual operation of each of the main engines for driving the main rotor at a speed, referred to as the NR speed, in compliance with applying the NR setpoint, the regulator unit applying various regulation ratings to the individual operation of each of the main engines depending on the current flight state of the rotorcraft, including:in a current flight state of the rotorcraft that is outside an engine-failure situation, first regulation ratings, referred to as AEO ratings, defining a maximum authorized rating for each of the main engines for respective predefined durations at each of the AEO ratings;in a current flight state of the rotorcraft that is an engine-failure situation, second regulation ratings, referred to as OEI ratings, defining a contingency rating authorized for at least one of the main engines remaining operational for respective predefined durations corresponding to each of the OEI ratings; andthe rotorcraft being fitted with a unit, referred to as a display unit, using a display screen for displaying at least one value relating to the mechanical power margin that is authorized for use by the pilot, referred to as the authorized margin, which value is deduced by calculation means depending on at least the current regulation rating of the main engines while taking account at least of limit criteria identifying the operating states of the main engines;wherein, outside an engine-failure situation, the value displayed by the screen relating to the authorized margin, then referred to as the limited margin, is the value of the authorized margin after a predefined value, referred to as the safety margin, has been subtracted therefrom by a computer, on condition at least of driving the main rotor at an NR speed, referred to as “low” speed, under the control of the flight control unit and identified as being below a predefined speed threshold for driving the main rotor, referred to as the NR speed threshold, such that in an engine-failure situation and in the event that, prior to the engine-failure situation, the rotorcraft was operating at a drive NR speed for the main rotor below the NR speed threshold, the pilot of the rotorcraft has a mechanical power reserve making it easier for the pilot to take action on the behavior of the rotorcraft in order to re-establish control quickly over its progress, while avoiding any significant drop in the number of revolutions per second in the rotation of the main rotor. 2. A method according to claim 1, wherein the reduction of the authorized margin by the safety margin, as performed outside an engine-failure situation by the computer prior to displaying the value of the limited margin on the screen, is conditional on the main engines being regulated specifically in an MCP mode defining a maximum authorized continuous rating for the main engines. 3. A method according to claim 1, wherein the value of the NR speed threshold corresponds at most to a little less than the value of the predefined nominal speed for driving the main rotor. 4. A method according to claim 3, wherein the value of the NR speed threshold corresponds at most to the value of the predefined nominal speed for driving the main rotor minus a value lying in the range 2% to 5% of the nominal speed. 5. A method according to claim 1, wherein the value of the safety margin is predefined proportionally to the mechanical power limit authorized by the current AEO rating. 6. A method according to claim 5, wherein the value of the safety margin is predefined in proportion to the mechanical power limit authorized by the current AEO rating, the proportion lying in the range 8% to 25%. 7. A method according to claim 1, wherein the value of the safety margin (Ms) is predefined to be variable as a function of the current NR speed. 8. A method according to claim 1, wherein the method comprises the following operations outside an engine-failure situation: generating the NR setpoint by means of the flight control unit and transmitting the generated NR setpoint to the regulator unit;outside an engine-failure situation, the regulator unit applying an AEO rating depending on the stage of flight of the rotorcraft;the computer having transmitted thereto firstly the current AEO rating by the regulator unit applying the AEO rating, and secondly the operating state of the main engines as identified as a function of the values of the limit criteria from the on-board instrumentation of the rotorcraft; and thenthe computer identifying firstly the value of the authorized margin as a result of applying the current AEO rating, and secondly the safety margin, and then the computer deducing the value of the limited margin and the computer transmitting the value of the limited margin to the display unit, causing the value to be displayed on the screen; andthe pilot of the rotorcraft generating flight controls in compliance with using the mechanical power supplied by the power plant and in accordance with the value of the limit margin as deduced by the computer. 9. A method according to claim 1, wherein the position of a human-driven manual flight control member operated by a human pilot to vary the pitch of the blades of the main rotor is servo-controlled by the flight control unit in compliance with the value of the limited margin. 10. A method according to claim 9, wherein the manual flight control member is fitted with a generator of haptic signals that vary at least depending on variation in the value of the limited margin. 11. A method according to claim 1, wherein the rotorcraft has an autopilot, and outside an engine-failure situation, automatic flight controls are generated by the autopilot, when it is in operation, by taking account of the limited margin, and providing the main rotor is being driven at a low NR speed. 12. A power plant of a multi-engined rotorcraft, the power plant including main engines and providing assistance in piloting a multi-engined rotorcraft in an engine-failure situation as a result of one of the main engines of a power plant of the rotorcraft failing, the power plant delivering mechanical power needed at least for driving rotation of at least one main rotor of the rotorcraft providing the rotorcraft at least with lift, the main rotor, outside an engine-failure situation, being driven by the power plant in compliance with applying a speed setpoint, referred to as the NR setpoint, of variable value that is calculated by a flight control unit depending on the current flight conditions of the rotorcraft so as to lie in a range of NR setpoint values that are proportional to the value of a predefined nominal speed for driving the main rotor,the flight control unit supplying the NR setpoint to a regulator unit for regulating the individual operation of the main engines for driving the main rotor at a speed, referred to as the NR speed, in compliance with applying the NR setpoint, the regulator unit applying various regulation ratings to the individual operation of each of the main engines depending on the current flight state of the rotorcraft, including:in a current flight state of the rotorcraft that is outside an engine-failure situation, first regulation ratings, referred to as AEO ratings, defining a maximum authorized rating for each of the main engines for respective predefined durations at each of the AEO ratings;in a current flight state of the rotorcraft that is in an engine-failure situation, second regulation ratings, referred to as OEI ratings, defining a contingency rating authorized for at least one of the main engines remaining operational for respective predefined durations corresponding to each of the OEI ratings; andthe rotorcraft being fitted with a unit, referred to as a display unit, using a display screen for displaying at least one value relating to the mechanical power margin that is authorized for use by the pilot, referred to as the authorized margin, which value is deduced by calculation means depending on at least the current regulation rating of the main engines while taking account at least of limit criteria identifying the operating states of the main engines;wherein, outside an engine-failure situation, the value displayed by the screen relating to the authorized margin, then referred to as the limited margin, is the value of the authorized margin after a predefined value, referred to as the safety margin, has been subtracted therefrom by computer, on condition at least of driving the main rotor at an NR speed, referred to as “low” speed, under the control of the flight control unit and identified as being below a predefined speed threshold for driving the main rotor, referred to as the NR speed threshold, such that in an engine-failure situation and in the event that, prior to the engine-failure situation, the rotorcraft was operating at a drive NR speed for the main rotor that is below the NR speed threshold, the pilot of the rotorcraft has a mechanical power reserve making it easier for the pilot to take action on the behavior of the rotorcraft in order to re-establish control quickly over its progress, while avoiding any significant drop in the number of revolutions per second in the rotation of the main rotor. 13. A multi-engined rotorcraft having a power plant with main engines; the multi-engined rotorcraft providing assistance in piloting a multi-engined rotorcraft in an engine-failure situation as a result of one of the main engines of a power plant of the rotorcraft failing, the power plant delivering the mechanical power needed at least for driving rotation of at least one main rotor of the rotorcraft providing the rotorcraft at least with lift, the main rotor, outside an engine-failure situation, being driven by the power plant in compliance with applying a speed setpoint, referred to as the NR setpoint, of variable value that is calculated by a flight control unit depending on the current flight conditions of the rotorcraft so as to lie in a range of NR setpoint values that are proportional to the value of a predefined nominal speed (NRnom) for driving the main rotor,the flight control unit supplying the NR setpoint to a regulator unit for regulating the individual operation of the main engines for driving the main rotor at a speed, referred to as the NR speed, in compliance with applying the NR setpoint, the regulator unit applying various regulation ratings to the individual operation of each of the main engines depending on the current flight state of the rotorcraft, including:in a current flight state of the rotorcraft that is outside an engine-failure situation, first regulation ratings, referred to as AEO ratings, defining a maximum authorized rating for each of the main engines for respective predefined durations at each of the AEO ratings;in a current flight state of the rotorcraft that is in an engine-failure situation, second regulation ratings, referred to as OEI ratings, defining a contingency rating authorized for at least one of the main engines remaining operational for respective predefined durations corresponding to each of the OEI ratings; andthe rotorcraft being fitted with a unit, referred to as a display unit, using a display screen for displaying at least one value relating to the mechanical power margin that is authorized for use by the pilot, referred to as the authorized margin, which value is deduced by calculation means depending on at least the current regulation rating of the main engines while taking account at least of limit criteria identifying the operating states of the main engines;wherein, outside an engine-failure situation, the value displayed by the screen relating to the authorized margin, then referred to as the limited margin, is the value of the authorized margin after a predefined value, referred to as the safety margin, has been subtracted therefrom by computer, on condition at least of driving the main rotor at an NR speed, referred to as “low” speed, under the control of the flight control unit and identified as being below a predefined speed threshold for driving the main rotor, referred to as the NR speed threshold, such that in an engine-failure situation and in the event that the rotorcraft was operating prior to the engine-failure situation, at a drive NR speed for the main rotor below the NR speed threshold, the pilot of the rotorcraft has a mechanical power reserve making it easier for the pilot to take action on the behavior of the rotorcraft in order to re-establish control quickly over its progress, while avoiding any significant drop in the number of revolutions per second in the rotation of the main rotor.