System and method for assisting in restarting at least one engine of aircraft, aircraft, computer program product and storage medium

Abstract

The invention relates to a system and method for assisting restart of at least one engine of an aircraft, an aircraft, a computer program product, and a storage medium. The method includes determining that at least one engine of the aircraft has been stalled, and controlling the aircraft to automatically descend to a predetermined target height below which the height of the aircraft facilitates at least one attempt for restarting the at least one stalled engine.

Description

Technical Field

[0001] The present invention relates to a method and a system for automatically assisting in the restart of at least one engine of an aircraft in the event of the shutdown of at least one engine of the aircraft. Specifically, the present invention relates to the implementation of an automatic guidance mode in order to fly the aircraft under conditions favorable for restarting one or more stopped engines. Background Art

[0002] In a multi-engine aircraft, the accidental shutdown of one or more engines is generally related to the flameout of the combustion chamber. Such flameout of the engine may have various causes, such as for example lack of fuel, lack of oxygen at high altitude, compressor breakage, damage caused by foreign objects (such as abnormal rainfall, debris, birds, volcanic ash, etc.). In particular, a distinction is made between: all engines are stopped (i.e., the engines of the aircraft are completely flameout, which corresponds to the situation here referred to as TEFO, TEFO being the abbreviation for "Total Engine Flameout"); or only one engine is stopped (this situation is here referred to as OEI, OEI being the abbreviation for "One Engine Inoperative").

[0003] In the event of flameout, the engines of the aircraft still retain the ability to restart. For this purpose, various restart procedures can be carried out to allow the crew of the aircraft (e.g., one or two pilots) to restart one or more stopped engines.

[0004] According to a first restart procedure for restarting the engine, at a first moment after TEFO or OEI, the engine control system or FADEC (abbreviation for "Full Authority Digital Engine Control") attempts to automatically restart one or more engines. If the automatic restart of one or more engines by FADEC is not successful, then a manual procedure for restarting one or more engines, such as one of the manual procedures described below, needs to be carried out.

[0005] The "assisted restart" procedure consists of using air drawn from the bleed system of an auxiliary power unit (or APU) to provide pneumatic power to one or more stopped engines. The APU is an independent system that is designed to operate on the ground and in flight. The main function of the APU is to supply the energy required to provide electrical power and pneumatic power for use as support or in an emergency.

[0006] The restart procedure called the "windmill mode" uses the relative wind to power the engine. More specifically, under the action of the flight speed, the rotating part (i.e., the windmill) of one or more stopped engines is rotated, and thus generally there is no need to use the starter of the aircraft. In the windmill mode, the restart ability depends on the altitude and speed of the aircraft at the time when one or more engines flameout.

[0007] During low-altitude and low-speed flight, restarting one or more engines is relatively easy. Therefore, it is only possible to restart one or more engines when the aircraft descends below 25,000 feet (or 7.62 km). If the aircraft's normal airspeed (or CAS) is less than 250 knots (or 463 kph), and if air from the bleed system of the APU can be used, then an assisted restart procedure can be performed. Conversely, if the aircraft's normal speed is high enough (i.e., CAS is above 250 knots or 463 kph), then a windmilling restart procedure can be performed. It should be noted that since the torque provided via the windmilling mode according to the manual procedure is usually high, this manual procedure for restarting the engine is preferred over the assisted restart procedure.

[0008] In order to be able to perform one of these engine restart procedures under the best possible conditions, the aircraft must be within the flight envelope suitable for engine restart. Hereinafter, for simplicity, the flight envelope suitable for performing one of the procedures (automatic or manual) used to restart the engine is referred to as the engine restart flight envelope. The flight envelope is a set of conditions composed of the altitude and speed of the aircraft that are particularly conducive to engine restart. In other words, the flight envelope is defined by a specific altitude and a specific speed of the aircraft. Therefore, the engine restart flight envelope is such a flight envelope: within this flight envelope, the above-mentioned procedures (automatic or manual) for restarting the engine can be adopted.

[0009] Therefore, the flight envelope suitable for performing one of these engine restart procedures corresponds to an altitude of less than or equal to 25,000 feet (i.e., 7.62 km) and an aircraft speed within the range between 130 knots (i.e., 240.76 kph) and 340 knots (i.e., 629.68 kph). Therefore, if the aircraft's current flight envelope (i.e., when one or all engines fail) is different from the flight envelope suitable for performing one of these engine restart procedures, the flight crew will need to direct the aircraft towards this engine restart flight envelope.

[0010] Currently, in the case of TEFO, the functions of the automatic flight system (or AFS) are disengaged. In particular, the functions of the autopilot (or AP) device, the flight director (or FD) device, and the automatic thrust (or A / THR) device are disengaged to allow the flight crew to take over the manual guidance of the aircraft. In particular, the flight crew may: execute a manual guidance procedure to place the aircraft within the engine restart flight envelope, or re-engage one of the devices in the AFS system and perform a descent towards the engine restart flight envelope in a guided manner (e.g., with the help of the flight director FD device). When the flight crew consists of two persons, the operating pilot (denoted by the abbreviation PF) operates the flight controls of the aircraft and provides manual guidance for the aircraft. The other pilot, called the monitoring pilot (denoted by the abbreviation PM), executes and follows the procedures applicable to the situation for restarting the engine. Thus, when necessary, in the event of the failure of one or all engines, the operating pilot PF manually guides the aircraft (e.g., with or without the help of the flight director FD device) towards the engine restart flight envelope, while the monitoring pilot PM supervises the engine restart procedure.

[0011] All these procedures for restarting the engine and for manually guiding the aircraft towards the engine restart flight envelope are cumbersome and require at least two persons in the cockpit to share the tasks. Thus, in the event of the incapacitation of one of the pilots, or when only one pilot is provided to perform the flight, all these procedures are not easily manageable.

[0012] Therefore, it is desirable to overcome this drawback of the prior art.

[0013] In particular, it is desirable to provide a solution that allows one or more pilots to be assisted during the execution of the engine restart procedure. In particular, it is desirable to assist the operating pilot PF in guiding the aircraft towards the engine restart flight envelope. SUMMARY OF THE INVENTION

[0014] Here, a system for assisting in the restart of at least one engine of an aircraft is provided. The assistance system includes an electronic circuit configured to:

[0015] - determine that at least one engine of the aircraft has failed;

[0016] - control the aircraft to automatically descend to a predetermined target altitude below which the altitude of the aircraft is conducive to at least one attempt to restart at least one stopped engine.

[0017] Advantageously, in the case where one or all of the aircraft's engines fail, it is possible to assist the flight crew in guiding the aircraft towards the engine restart flight envelope. Thus, it is easier for the flight crew to monitor and execute the various engine restart procedures. In other words, in such a case, the flight crew can be assisted by reducing their workload. Alternatively or additionally, even if the flight crew consists of only one pilot (e.g., when only one pilot is provided on the flight, or when one of the two pilots becomes incapacitated), or when the sole pilot is unable to fly the aircraft, it is possible to assist the flight crew in monitoring and executing the procedures for restarting one or more engines.

[0018] According to one embodiment, the system for assisting in restarting at least one engine of an aircraft further includes an electronic circuit configured to control the automatic descent of the aircraft while reducing the aircraft's normal speed to a predetermined target normal speed below which the aircraft's normal speed is conducive to restarting the at least one stopped engine.

[0019] According to one embodiment, the system for assisting in restarting at least one engine of an aircraft further includes an electronic circuit configured to generate a message for executing at least one program for restarting the at least one stopped engine so as to perform at least one attempt to restart the at least one stopped engine when the aircraft reaches a target altitude and / or a target normal speed.

[0020] According to one embodiment, the system for assisting in restarting at least one engine of an aircraft further includes an electronic circuit configured to control the automatic descent of the aircraft based on at least one of the following parameters:

[0021] - The number of stopped engines;

[0022] - The enabled state of the aircraft's autopilot;

[0023] - The enabled state of the aircraft's flight director device;

[0024] - The state of the aircraft's current guidance mode;

[0025] - The number of pilots present in the aircraft's cockpit;

[0026] - The number of pilots capable of flying the aircraft present in the aircraft's cockpit.

[0027] According to one embodiment, the system for assisting in restarting at least one engine of an aircraft is implemented in the aircraft's guidance controller device.

[0028] Here, a method for assisting in restarting at least one engine of an aircraft is also provided. This method is implemented by an auxiliary system in the form of an electronic circuit. The method includes:

[0029] - Determining that at least one engine of the aircraft has stopped;

[0030] - Controlling the aircraft to automatically descend to a predetermined target altitude, below which the altitude of the aircraft is conducive to at least one attempt to restart the at least one stopped engine.

[0031] According to one embodiment, the method for assisting in restarting at least one engine of an aircraft further includes controlling the aircraft to automatically descend while reducing the normal speed of the aircraft to a predetermined target normal speed, below which the normal speed of the aircraft is conducive to restarting the at least one stopped engine.

[0032] According to one embodiment, the method for assisting in restarting at least one engine of an aircraft further includes generating a message for executing at least one program for restarting the at least one stopped engine, so as to perform at least one attempt to restart the at least one stopped engine when the aircraft reaches the target altitude and / or the target normal speed.

[0033] According to one embodiment, the method for assisting in restarting at least one engine of an aircraft further includes controlling the aircraft to automatically descend based on at least one of the following parameters:

[0034] - The number of stopped engines;

[0035] - The enabled state of the autopilot device of the aircraft;

[0036] - The enabled state of the flight director device of the aircraft;

[0037] - The state of the current guidance mode of the aircraft;

[0038] - The number of pilots present in the cabin of the aircraft;

[0039] - The number of pilots capable of flying the aircraft present in the cabin of the aircraft.

[0040] Here, according to one embodiment, an aircraft is provided, which includes a system for assisting in restarting at least one engine of the aircraft as described above.

[0041] A computer program product is also provided, which includes instructions that, when executed by a processor, cause the processor to execute the method described above according to any one of the embodiments of the present invention. A storage medium for storing these instructions is also provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and other features of the present invention will become more apparent when reading the following description of at least one exemplary embodiment, which is presented in conjunction with the accompanying drawings, in which:

[0043] Figure 1 A side view schematically illustrates an aircraft equipped with a system for assisting in restarting an engine of the aircraft according to one embodiment;

[0044] Figure 2 Schematically illustrates a system for assisting in restarting at least one engine in an engine of an aircraft according to one embodiment;

[0045] Figure 3 Schematically illustrates an example of a hardware platform that allows an assisting system according to one embodiment to be implemented in the form of an electronic circuit;

[0046] Figure 4 Schematically illustrates the steps of a method for assisting in restarting one or more engines of an aircraft performed by an engine restart assisting system according to one embodiment. DETAILED DESCRIPTION

[0047] The general principles disclosed below relate to performing an automatic guidance function of an aircraft and a related automatic descent mode of the aircraft in the case where at least one engine in the engines of the aircraft stalls. Thus, it is possible to help the crew of the aircraft automatically guide the aircraft towards a flight envelope that is conducive to restarting the one or more stopped engines. The workload of the crew is correspondingly reduced, especially when there is only one pilot (e.g., the pilot flying PF) in the cabin of the aircraft or when this pilot is unable to fly the aircraft.

[0048] Figure 1 A side view schematically illustrates an aircraft 100 according to one embodiment, the aircraft 100 being equipped with a system 101 for assisting in restarting an engine of the aircraft. Hereinafter, for simplicity, this system 101 for assisting in restarting an engine of the aircraft is referred to as "assisting system 101".

[0049] According to Figure 1In an embodiment, the auxiliary system 101 is an on-board electronic device in the aircraft 100. For example, the auxiliary system 101 forms part of the electronic circuitry of the avionics of the aircraft 100. Preferably, the auxiliary system 101 is incorporated into a guidance controller device of the aircraft 100, such as a guidance computer of the FGS (denoting "Flight Guidance System") type of the aircraft.

[0050] In Figure 2 FIG. schematically and integrally illustrates an auxiliary system 101 according to an embodiment. According to this embodiment, the auxiliary system 101 is incorporated into the guidance controller device FGS of the aircraft 100.

[0051] The auxiliary system 101 is configured to receive information representing the engine performance characteristics PERF of each engine of the aircraft 100. This information regarding the engine performance characteristics PERF is transmitted by a system for controlling the engines of the aircraft 100, such as, for example, the FADEC and / or the engine controller computer EEC (denoting "Electronic Engine Controller"). The FADEC and the EEC are systems that control all aspects of the performance of the engines of the aircraft 100. Hereinafter, these systems (i.e., the FADEC and the EEC) or any other system for controlling the performance of the engines of the aircraft 100 are referred to as the engine performance control systems. The FADEC also controls the start and restart of the engines.

[0052] This information regarding the engine performance characteristics PERF particularly includes information on various indicators of engine performance, such as, for example, indicators N1, N2, N3... an indication of the operating state (e.g., normal state or fault state) of the EEC for each engine, an indication of the position of the control lever for each engine (e.g., the lever is in the position "on").

[0053] The auxiliary system 101 is further configured to transmit the guidance information GD used for the guidance of the aircraft 100 to the autopilot device AP and the flight director device FD of the aircraft 100. This guidance information GD particularly includes information on lateral guidance and / or longitudinal guidance regarding the altitude to be followed and the speed to be achieved, and more generally any information that allows the aircraft 100 to be guided towards a specific point or along a specific flight path.

[0054] The auxiliary system 101 is further configured to receive from other avionics systems of the aircraft 100 ( Figure 2Various information (not shown in the figure). Such information is, for example, information related to the operating state of certain guidance functions (standby, engaged, disengaged, etc.), and information related to the operating state of the guidance mode potentially associated therewith and not managed by the auxiliary system 101, and information related to the altitude of the aircraft, the speed of the aircraft, the number of pilots present in the cockpit, etc.

[0055] Figure 3 Schematically illustrates an example of a hardware platform according to an embodiment, which allows the auxiliary system 101 to be implemented in the form of an electronic circuit.

[0056] The hardware platform includes the following components connected via the communication bus 310: a processor or CPU (representing "Central Processing Unit") 301; a volatile memory RAM (representing "Random Access Memory") 302; a non-volatile memory 303, such as a non-volatile memory of the ROM type (representing "Read Only Memory") or EEPROM (representing "Electrically Erasable Programmable ROM") type, such as a flash memory; a storage unit, such as a hard disk HDD (representing "Hard Disk Drive") 304, or a storage medium reader, such as an SD (representing "Secure Digital") card reader; and an interface manager COM 305.

[0057] The interface manager COM 305 allows the auxiliary system 101 to interact with other avionics systems of the aircraft 100, such as, for example, systems for monitoring the performance characteristics of the engine (FADEC, EEC, etc.), the flight systems of the aircraft 100 (autopilot AP, flight director device FD, etc.), and the display systems of the human-machine interface in the cockpit of the aircraft 100 (e.g.: CDC representing "Cockpit Display Computer", PFD representing "Primary Flight Display", FMA representing "Flight Mode Annunciator").

[0058] The processor 301 is designed to execute instructions loaded from the non-volatile memory 303, an external memory, a storage medium (such as an SD card), or a communication network into the volatile memory 302. When the hardware platform is powered on, the processor 301 is designed to read the instructions from the volatile memory 302 and execute these instructions. These instructions form a computer program, thereby implementing all or part of the steps or methods of the aircraft described in this specification, or more generally the operating sequence of the aircraft, by the processor 301.

[0059] Accordingly, all or part of the steps, methods, and operations described herein can be implemented in software by a programmable machine, such as a processor or microcontroller of the DSP (representing "Digital Signal Processor") type, executing a set of instructions, or can be implemented in hardware by a machine or dedicated electronic components (or "chips") or a set of dedicated electronic components (or "chipset"), such as FPGA (representing "Field Programmable Gate Array") or ASIC (representing "Application Specific Integrated Circuit") components. Generally speaking, the auxiliary system 101 includes electronic circuits designed and configured to implement all or part of the operations, methods, and steps described herein.

[0060] In conjunction Figure 4 , according to one embodiment, the steps of a method for assisting in restarting at least one engine of the aircraft 100 are presented in graphical form. All or part of the method for assisting in restarting at least one engine of the aircraft 100 is implemented by the auxiliary system 101 described above.

[0061] During step 401, denoted as RCP_INFO_ENG, the auxiliary system 101 receives information about the performance PERF of each engine of the aircraft 100 from one or more systems (such as FADEC or EEC) for monitoring the performance characteristics of the engine.

[0062] It should be noted that an engine is considered to be in an "operating state" when all of the following conditions are met:

[0063] - The main lever corresponding to the engine is in the operating position (i.e., the lever is set to the "on" position);

[0064] - The EEC associated with the engine (i.e., the EEC that controls the engine) has no defects;

[0065] - When the EIF (representing "Engine Interface Function") or EEC measures that the actual performance indicator N3 is higher than 50%, the engine is declared by the EIF or EEC to be "in the operating state".

[0066] The indicator N3 is a nacelle instrument that indicates the rotational speed of the high-pressure (i.e., high-speed) coil of the aircraft engine. The speed of this coil is called N3. The indicator N3 is typically calibrated as a percentage of revolutions per minute based on the rotational speed defined by the engine manufacturer and corresponding to 100%.

[0067] Accordingly, for each engine, the information about the performance characteristics PERF of the engine particularly includes indications related to the position of the main lever of the engine, the state of the EEC of the engine, and the indicator N3.

[0068] During step 402, denoted ALL_ENG_STOP, the auxiliary system 101 uses information about the engine performance characteristics PERF of each engine to determine the operating state of each engine of the aircraft 100. The auxiliary system 101 then determines whether all engines ( Figure 4 Indicate "Yes" in the ) or a single engine ( Figure 4 When the information about the performance characteristic PERF of the engine indicates that the engine does not meet at least one of the above conditions, the auxiliary system 101 determines that the engine is stopped or “inoperative”.

[0069] After determining the number of stopped engines, assistance system 101 controls aircraft 100 for an automatic descent. Here, "controlling aircraft 100 for an automatic descent" is understood to refer to all the successive steps leading to arming, then engaging the automatic descent mode, designated AUTO DES, and until the automatic descent mode is disengaged. In other words, controlling aircraft 100 for an automatic descent corresponds to steps 403 to 407, 409, and 411 to 412.

[0070] During step 403, designated ATEFOR_ARM, the auxiliary system 101 has previously determined that all engines are stopped (step 402, "yes" result). The auxiliary system 101 then arms a guidance function of the aircraft 100 called "Automatic All Engines Out Re-establishment After All Engines Out" or guidance function ATEFOR (standing for "Automatic All Engines Out Re-establishment"). It is to be understood that the guidance mode or function designated "armed" corresponds to a state that will be activated if and when the aircraft 100 passes a target (e.g., a target altitude, a target speed, etc.).

[0071] This guidance function ATEFOR is limited to a configuration of the aircraft 100 called “CLEAN”, in other words, according to which the landing gear, any flaps or any device for increasing the drag or lift of the wings are not deployed, etc.

[0072] The purpose of the guidance function ATEFOR is to reduce the workload of the crew in the event of an unexpected shutdown of all engines. In particular, the guidance function ATEFOR allows the aircraft 100 to be automatically guided towards the engine restart flight envelope. Thus, the crew can focus on executing the various available engine restart procedures.

[0073] The engagement of the guidance function ATEFOR via the assistance system 101 is affected by the operating state of the aircraft 100. It should be understood here that the guidance mode or function referred to as "engagement" corresponds to the state in which the autopilot AP remains active. In addition, the "operating state" is understood here to refer to the number of pilots present in the cockpit during each flight phase of the aircraft 100 (e.g., takeoff, cruise, landing, etc.). In other words, the engagement of the guidance function ATEFOR depends on the fact that the aircraft 100 is in an operating state referred to as "out of EMCO" or in an operating state referred to as "in EMCO" (which means "extended minimum crew operation"). According to the "out of EMCO" operating state or dual control operation, there are at least two pilots in the cockpit, namely the pilot flying PF and the pilot monitoring PM. In contrast, during EMCO or single control operation, there is only one pilot in the cockpit, i.e., only the pilot flying PF is present. This is the case, for example, during the flight phase of the aircraft 100 referred to as "cruise".

[0074] The engagement of the ATEFOR function also depends on the state (i.e., engaged or disengaged) of the autopilot AP when all engines have failed.

[0075] Thus, during step 404, the assistance system 101 obtains information about the operating state of the aircraft 100, i.e., information indicating whether the aircraft 100 is in the "in EMCO" operation ( Figure 4 with the indication "yes" in Figure 4 or "out of EMCO operation" (

[0076] with the indication "no" in

[0077] According to one embodiment, this information about the operating state of the aircraft 100 is obtained from the human-machine interface of the CDS. The CDS (or "cockpit display system") allows the flight crew to enable or disable the function "in EMCO" via the human-machine interface of the CDS. In other words, the flight crew selects between the "in EMCO" operating state enabling this function or the "out of EMCO" operating state disabling the "in EMCO" function via interaction with the human-machine interface of the CDS.

[0078] In a particular embodiment, the assistance system 101 also obtains one or more information representing the current state of the flight director device FD (i.e., at the time of detection of TEFO). This information regarding the state of the flight director device FD respectively indicates whether the flight director device FD is engaged or disengaged. Based on this information related to the state of the flight director device FD, the assistance system 101 determines whether the flight director device FD is engaged or disengaged.

[0079] If the autopilot device AP has been engaged at the time of all engines shutting down, the assistance system 101 keeps the autopilot device AP engaged. Then, the assistance system 101 engages the guidance function ATEFOR.

[0080] If the autopilot device AP is disengaged at the time of all engines shutting down, the assistance system 101 does not automatically engage the autopilot device AP to avoid any unwanted automatic control of the guidance of the aircraft 100. Thus, in one embodiment, within the framework of the "disengagement from EMCO" operation, when TEFO is detected and the autopilot device AP is disengaged, during step 405 ATEFOR_EN, the assistance system 101 asks the flight crew (especially the pilot flying PF) whether to engage the autopilot device AP in order to engage the guidance function ATEFOR. In one example, the assistance system 101 will transmit a message intended for the flight crew to the man-machine interface in the cabin of the aircraft 100. This message indicates that the guidance function ATEFOR is on standby and can be engaged at any time when the flight crew needs this guidance function ATEFOR. In order to engage the guidance function ATEFOR, the flight crew then has to engage the autopilot device AP.

[0081] In the case where the pilot flying PF wants to manually descend the aircraft 100 towards the engine restart flight envelope (step 408, denoted as M_DES), then he / she does not engage the autopilot device AP and the guidance function ATEFOR is not engaged (step 405 ATEFOR_EN, result is "no"). Thus, generally, the guidance of the aircraft 100 towards the engine restart flight envelope is manually performed by the pilot flying PF, while the pilot monitoring PM supervises and implements the engine restart procedure.

[0082] On the other hand, if the operating pilot PF wants to automatically descend the aircraft 100 towards the engine restart flight envelope (step 407 denoted as AUTO_DES), he / she engages the autopilot AP (e.g., by pressing a button set on the human-machine interface in the cockpit of the aircraft 100). The assistance system 101 then receives the command to engage the autopilot AP, for example, via the human-machine interface in the cockpit of the aircraft 100. Then, the assistance system 101 engages the guidance function ATEFOR (step 405ATEFOR_EN, result "yes"). Thus, when all engines are stopped, during normal operation called "out of EMCO", the guidance function ATEFOR is engaged only if the autopilot AP has been engaged.

[0083] In one embodiment, during step 405ATEFOR_EN, when the function ATEFOR is on standby, the assistance system 101 automatically engages the flight director FD, regardless of the state of the flight director FD when all engines are shut down.

[0084] Therefore, when the function ATEFOR is not engaged (i.e., when the autopilot AP is not engaged), the operating pilot PF can manually perform the descent of the aircraft 100 towards the engine restart flight envelope with the help of the flight director FD (step 408, denoted as M_DES).

[0085] On the other hand, when the function ATEFOR is engaged (i.e., when the autopilot AP has been engaged or when the operating pilot PF engages the autopilot), the autopilot AP then follows the guidance instructions of the flight director device FD (step 407, denoted as AUTO_DES).

[0086] If the aircraft 100 is in the "in EMCO" operating state (step 404, result "yes"), there is only one pilot in the cockpit (i.e., the operating pilot PF). In this case, during step 406 denoted as ATEFOR_AUTO_EN, the assistance system 101 automatically engages the autopilot AP, even if the autopilot AP was not previously engaged. Since the autopilot AP is automatically engaged, the engagement of the guidance function ATEFOR by the assistance system 101 is automatic.

[0087] In a particular embodiment, during step 406ATEFOR_AUTO_EN, the assistance system 101 also automatically engages the flight director device FD, even if the flight director device FD was not previously engaged. Then, the autopilot AP follows the guidance instructions of the flight director device FD.

[0088] During the "EMCO release" operation, the engagement guidance function ATEFOR can be disengaged at any time by disconnecting the autopilot AP. For example, the operating pilot PF wishes to take over control and manually guide the aircraft 100 towards the engine restart flight envelope. Alternatively, the engagement guidance function ATEFOR can be disengaged by changing the guidance command to the "selected mode". In other words, when the operating pilot switches the guidance to the "selected mode" and changes the flight targets of the flight parameters such as speed, flight path, altitude, etc., the engagement guidance function ATEFOR is disengaged.

[0089] During the "EMCO active" operation, the guidance function ATEFOR allows:

[0090] - When the operating pilot PF is present in the cockpit and conscious: reducing the workload of the operating pilot PF, because in the absence of the guidance function ATEFOR, he / she is assumed to perform the guidance of the aircraft 100 towards the engine restart flight envelope and simultaneously monitor one or more procedures for restarting the engine;

[0091] - When the operating pilot PF is in a critical physiological state: increasing the "survivability" (or lifespan) of the aircraft 100 within 5 minutes after all engines of the aircraft 100 have shut down;

[0092] - When the operating pilot PF is present in the cockpit but he / she is incapacitated: increasing the "survivability" of the aircraft 100 within 40 minutes after all engines have shut down.

[0093] Therefore, in the case of all engines shutting down, the auxiliary system 101 can modify the engagement state or disengagement state of the autopilot AP according to the above various operation scenarios, and optionally modify the engagement state or disengagement state of the flight director device FD. Therefore, the auxiliary system 101 can engage the guidance function ATEFOR to reduce the workload of the crew related to guiding the aircraft 100 towards the engine restart flight envelope. In fact, during the "EMCO release" or "EMCO active" operation, during the engagement of the guidance function ATEFOR, the autopilot AP automatically guides the aircraft 100 towards the engine restart flight envelope. Therefore, the guidance function ATEFOR is a beneficial automatic guidance function for the aircraft 100. Therefore, the crew, especially the operating pilot PF, does not have to complete the task of manually guiding the aircraft 100 to descend to the engine restart flight envelope.

[0094] When the guidance function ATEFOR is engaged, the following results occur:

[0095] - The air brakes of the aircraft 100 automatically retract if they have been deployed previously;

[0096] - During the entire period when the guidance function ATEFOR is engaged, the managed speed (i.e., the speed target given by the FMS or "Flight Management System") is disabled, and a new speed target, called the target speed, is calculated by the auxiliary system 101 and is displayed on the PFD ("Primary Flight Display");

[0097] - The automatic descent mode designated as AUTO DES described below is on standby. This automatic descent mode AUTO DES can be used for "disengaging EMCO" operations or "being in EMCO" operations. It should be noted that once all engine flameouts are detected (i.e., TEFO detection), the automatic descent mode AUTO DES is on standby.

[0098] The engagement of the guidance function ATEFOR (step 405, result "yes", and step 406) allows the auxiliary system 101 to engage the automatic descent mode AUTO DES if necessary. Thus, during steps 407 and 409, in order to be able to automatically guide the aircraft 100 towards the engine restart flight envelope, the auxiliary system 101 sends guidance information GD about the aircraft 100 to the autopilot AP (e.g., information about lateral guidance, longitudinal guidance, target altitude, and target speed, etc.).

[0099] (a) Lateral guidance

[0100] Before engaging the automatic descent mode AUTO DES, the auxiliary system 101 transmits information related to lateral guidance to the autopilot AP, thereby allowing the current path of the aircraft 100 to be modified considering a predetermined bank angle. The information related to lateral guidance depends in particular on the enabled state of the current guidance mode of the aircraft 100. Thus, this information related to lateral guidance allows the autopilot AP to execute the following procedure:

[0101] - If the guidance mode called "navigation" or NAV (i.e., the guidance mode in which the aircraft 100 follows the flight path defined in the flight plan and flies along a predetermined flight path) is engaged during all engine flameouts, the autopilot AP exits this guidance mode NAV and guides the aircraft 100 to perform a lateral step according to a predetermined bank angle. This lateral step allows the aircraft 100 to move away from the current path. An offset relative to the current path of the aircraft 100 is defined in order to allow the aircraft 100 to be positioned parallel to the axis of its current path while remaining within the air corridor and without the risk of interfering with air traffic. For this purpose, the autopilot AP changes from the guidance mode NAV to the guidance mode called "tracking" or TRK. This guidance mode allows the autopilot AP to follow or maintain a course rather than a predetermined flight path;

[0102] - If the guidance mode TRK is engaged, the autopilot AP follows this guidance mode and maintains the flight path or the current flight path angle of the aircraft 100.

[0103] To limit the energy loss during the lateral step maneuver, a 15° limit is imposed on the maximum tilt angle (Phi) of the wings of the aircraft 100. This limit is cancelled if the crew stops the lateral step along the lateral axis, or if the guidance function ATEFOR is no longer enabled, or if the auto - descent mode AUTO DES is disengaged.

[0104] (b) Vertical guidance: Engagement of the AUTO DES automatic descent mode

[0105] Once the auxiliary system 101 determines that all engines have stopped, the auto - descent mode AUTO DES stands by. When the guidance function ATEFOR is engaged, once the conditions allow, the auto - descent mode AUTO DES is then authorized to engage, namely:

[0106] - The conventional airspeed CAS (V CAS ) of the aircraft reached in the current longitudinal guidance mode (e.g., the guidance mode for maintaining altitude, such as the guidance mode ALT for "altitude") is lower than the target speed of the guidance function ATEFOR, and the additional margin is 5 knots (i.e., 9.26 kph). The auto - descent mode AUTO DES is engaged directly after standing by; or

[0107] - When the conventional airspeed V CAS of the aircraft reached in the current longitudinal guidance mode is higher than the target speed of the guidance function ATEFOR, the additional margin is 5 knots (i.e., 9.26 kph), and when the conventional airspeed V CAS becomes lower than the target speed of the guidance function ATEFOR, the additional margin is 5 kts (i.e., 9.26 kph); or

[0108] - When the aircraft 100 is in a climb, the guidance function ATEFOR first allows the autopilot AP to perform level flight. Then, when the conventional airspeed V CAS of the aircraft is lower than the target speed of the guidance function ATEFORE and the additional margin is 5 knots (i.e., 9.26 kph), the auto - descent mode AUTO DES is engaged; or

[0109] - When the aircraft 100 is in a descent and its speed V CAS is higher than the target speed of the guidance function ATEFOR and the additional margin is 5 knots (i.e., 9.26 kph), and when a request for an auxiliary restart procedure is made, the guidance function ATEFOR first allows the autopilot AP to perform level flight. When the conventional airspeed V CASWhen the target speed is lower than that of the ATEFOR guidance function and there is an additional margin of 5 knots (i.e., 9.26 kph), the AUTO DES (Automatic Descent) mode is engaged; or

[0110] - When the aircraft 100 is in descent (e.g., in the managed mode, in the descending longitudinal guidance mode, such as in the "DES" mode for "descent"), its speed V CAS is higher than the target speed of the ATEFOR guidance function and there is an additional margin of 5 knots (i.e., 9.26 kph), and when the auxiliary restart procedure is not requested, then the AUTO DES mode is directly engaged after standby.

[0111] The condition for the disengagement of the AUTO DES mode is that the crew engages another longitudinal guidance mode (e.g., engages the "selected" mode of the OP DES (Open Descent) guidance mode for "open descent").

[0112] In the case of the disengagement of the AUTO DES mode, the target speed becomes the current speed in the so-called "selected" mode.

[0113] During the engagement of the AUTO DES mode, in the "EMCO" operation (i.e., there is one pilot in the cockpit) and when the autopilot AP is engaged, the buttons on the flight control unit (denoted by the abbreviation FCU) for altitude ALT, approach APPR, and localizer LOC are disabled. In fact, in the "EMCO" situation, it is desired that the ATEFOR guidance function be engaged. To prevent in advance any accidental actions that might prevent the engagement of the ATEFOR guidance function, these altitude ALT, approach APPR, and localizer LOC buttons are disabled.

[0114] Outside of the "EMCO" operation (i.e., there are at least two pilots in the cockpit), the use of these buttons and the engagement or standby of the corresponding guidance modes are still possible.

[0115] When the AUTO DES mode is engaged, regardless of the disabling of the FCU buttons, the approach guidance mode cannot be engaged because engine restart is given priority.

[0116] (c) Target altitude

[0117] When the AUTO DES mode is engaged, for example, at 1000 feet (i.e., 304.8 meters), a new predetermined altitude target (i.e., the target altitude) is synchronized on the FCU. Thus, the AUTO DES mode allows the aircraft 100 to descend to this target altitude.

[0118] (d) Target speed

[0119] When the guidance function ATEFOR is engaged, the auxiliary system 101 calculates a predetermined target speed to be achieved when the automatic descent mode AUTO DES is engaged.

[0120] In one embodiment, when the crew has not yet decided which manual procedure to perform for engine restart (i.e., auxiliary restart or windmill restart), the target speed is calculated based on the maximum L / D (i.e., lift-to-drag ratio) speed of the aircraft 100. During the engagement of the automatic descent mode AUTO DES, in the case where the maximum L / D speed is not available, the target speed is a default speed, such as 250 knots (i.e., 463 kph).

[0121] In another embodiment, when the crew decides which procedure to perform for engine restart (i.e., auxiliary restart or windmill restart), the target speed is adjusted according to the selected restart strategy, and thus the vertical speed is also adjusted.

[0122] When the automatic descent mode AUTO DES is disengaged, the target speed is updated to correspond to the current maximum L / D speed in the "selected" mode (i.e., the value displayed on the FCU).

[0123] In one embodiment, on the flight mode annunciator FMA, the automatic descent mode AUTO DES is announced by the autopilot AP or the flight director device FD like any other guidance mode, while generating a white box and an audible sound (e.g., three clicks).

[0124] In one embodiment, when the automatic descent mode AUTO DES is engaged, for the standby mode, the term "AUTO DES" is displayed in cyan on the FMA, and for the engaged mode, "AUTO DES" must be displayed in green on the FMA with a normal white box.

[0125] Therefore, the automatic descent mode AUTO DES allows the autopilot AP to automatically guide the aircraft 100 towards the engine restart flight envelope. Thus, once the aircraft 100 reaches this engine restart flight envelope, the various engine restart procedures described previously can be performed.

[0126] In one embodiment, during step 410, denoted as RAL_ENG, the auxiliary system 101 sends a message for executing the program used to restart the engine in order to perform at least one attempt to restart the stopped engine. In other words, once the aircraft reaches the engine restart flight envelope, the auxiliary system 101 transmits a message for executing the program for restarting the engine to the system that controls the performance characteristics of the engine (e.g., FADEC) to execute the program for automatically restarting the engine, or transmits a message for executing the program for restarting the engine to the man-machine interface in the cabin of the aircraft 100 to ask the flight crew about the manual program to be performed for restarting the engine.

[0127] In one embodiment, when the guidance function ATEFOR is engaged, the auxiliary system 101 transmits this message for executing the program used to restart the engine to the system for controlling the performance characteristics of the engine, such as for example FADEC, to restart the engine. Thus, in the case where all engines flame out, FADEC automatically attempts consecutive restarts until at least one engine is restarted. Thus, the duty of the flight crew to monitor the automatic restart of FADEC can be alleviated. Thus, the ATEFOR function depends on the improvement of the program for automatically restarting the engine, especially to assist the flight crew in the case of pilot physiological impairment or incapability to fly during "EMCO" operations.

[0128] In one embodiment, in parallel with FADEC executing the program for automatically restarting the engine, the auxiliary system 101 also transmits this message for executing the program used to restart the engine to the man-machine interface in the cabin of the aircraft 100 to ask the flight crew about the manual program to be performed for restarting the engine. The flight crew (i.e., one or two pilots) can perform one of the manual programs for restarting the engine in a conventional manner according to the situation.

[0129] If the aircraft 100 restores at least one engine after executing one or another or multiple engine restart programs, then:

[0130] - The function of the automatic thrust device A / THR is engaged at maximum continuous thrust (or MCT), even when the thrust lever is at "idle".

[0131] - Regarding lateral guidance, the guidance mode TPK remains engaged, and the guidance of the route or flight path defined during the execution of the automatic descent mode AUTO DES is retained.

[0132] - Regarding longitudinal guidance:

[0133] (i) If the target altitude of the AUTO DES (automatic descent) mode is higher than the upper limit altitude of OEI (One Engine Inoperative), the AUTO DES mode remains engaged, where the new target altitude corresponds to the upper limit altitude of OEI to be reached. The guidance function ATEFOR is disengaged, but the "drift down" guidance function (described below) is responsible for the guidance of the aircraft 100 while the AUTO DES mode remains engaged;

[0134] (ii) If the target altitude of the AUTO DES mode is lower than the upper limit altitude of OEI, the AUTO DES mode is disengaged, and the VS / FPA (vertical speed or angle of attack flight path selection navigation mode) guidance mode is engaged to perform level flight of the aircraft 100. The guidance function ATEFOR is disengaged.

[0135] The upper limit altitude of OEI corresponds to the altitude at which, after an engine failure above the upper limit altitude of OEI, the aircraft will descend and maintain level flight while using the maximum available power / thrust on the serviceable engine(s) and while maintaining the expected OEI speed.

[0136] The new target speed is calculated by the auxiliary system 101 as the current maximum L / D speed.

[0137] In one embodiment, on the FMA (Flight Mode Annunciator), in the section dedicated to the vertical mode, the engagement of the new guidance mode is displayed after "AUTO DES" when exiting the AUTO DES mode. The display of the new guidance mode can be performed manually or can be performed after an engine restart event.

[0138] When a multi-engine aircraft experiences an engine failure during flight, the "drift down" guidance function (or involuntary altitude reduction) is performed. When one engine fails, the aircraft 100 cannot maintain its flight altitude due to the thrust generated by the remaining one or more engines and must therefore descend. Thus, the "drift down" guidance function represents all the descent procedures and strategies performed by the aircraft 100 when such a problem occurs.

[0139] During step 402 ALL_ENG_STOP, the auxiliary system 101 determines based on the engine performance information PERF that only one engine of the aircraft 100 is no longer running (represented as "No" in Figure 4 ). Thus, during step 411 represented as DRIFT_DOWN_ARM, if the current altitude at the time of one engine flameout is higher than the upper limit altitude of OEI, the auxiliary system 101 stands by and then engages the "drift down" guidance function.

[0140] In order to be able to guide the aircraft 100 towards the engine restart flight envelope, the auxiliary system 101 makes the AUTO DES standby by engaging the "drift down" guidance function. Thus, in the case of a single engine failure, the AUTO DES mode provides assistance to the crew in guiding the aircraft 100 towards the engine restart flight envelope.

[0141] The guidance of the aircraft 100 via the AUTO DES mode is similar to the guidance performed when the AUTO DES mode is used with the ATEFOR guidance function engaged.

[0142] However, in one embodiment, when the "drift down" guidance function is engaged, if the altitude at which the engine flameout occurs is higher than the upper limit altitude of OEI, the AUTO DES mode stands by. In fact, below the upper limit altitude of OEI, with one engine still running, the use of the AUTO DES mode does not achieve automatic guidance.

[0143] (a) Lateral guidance

[0144] In the same way as the ATEFOR guidance function, the auxiliary system 101 transmits information about the lateral guidance of the aircraft 100 to the autopilot AP.

[0145] However, compared to the ATEFOR guidance function, in the case of the "drift down" guidance function, there is no limit on the bank angle of the lateral step before engaging the descent mode AUTODES.

[0146] (b) Vertical guidance: Engagement of the AUTO DES automatic descent mode

[0147] The longitudinal guidance is similar to the ATEFOR function, and the AUTO DES mode is engaged in the same switching manner according to the speed and the climb or descent phase. Thus, when necessary, the auxiliary system 101 engages the AUTO DES mode during step 412.

[0148] (c) Target altitude

[0149] If the current altitude of the aircraft 100 (i.e., at the time of engine flameout) is higher than the upper limit altitude of OEI, then during the engagement of the AUTO DES mode, the target altitude to be reached is the upper limit altitude of OEI.

[0150] For the guidance function ATEFOR with the automatic descent mode AUTO DES, during step 410 represented as RAL_ENG, the auxiliary system 101 sends a message for executing the program used to restart the engine to perform at least one attempt to restart a stopped engine. In other words, once the aircraft reaches the engine restart flight envelope, the auxiliary system 101 sends a message for executing the program used to restart the engine to the system (e.g., FADEC) for controlling the performance characteristics of the engine to execute the program for automatically restarting the engine, or sends a message for executing the program used to restart the engine to the man-machine interface in the cabin of the aircraft 100 to ask the crew which manual program for restarting the engine to execute.

[0151] If the last shut-down engine is restarted before reaching the upper limit altitude of OEI, the auxiliary system 101 engages the guidance mode VS / FPA to perform the level flight of the aircraft 100. In other words, if all engines are running after performing the "drift-down" function and the automatic descent mode AUTO DES, the aircraft 100 no longer needs to descend and can perform level flight.

[0152] According to one embodiment, when an engine fails, if the emergency descent procedure and its associated guidance mode (e.g., the emergency descent mode EMER DES) have been engaged, the "drift-down" guidance function is not engaged, and thus the automatic descent mode AUTO DES is not on standby. In fact, since one engine is still running and has sufficient power, the emergency descent is still given priority for the survival of the crew.

[0153] According to one embodiment, when the "drift-down" guidance function is enabled, the function of the automatic thrust device A / THR is automatically adjusted if it has not been engaged yet.

[0154] In a specific embodiment, when the ATEFOR guidance function or the "drift-down" guidance function is engaged, TCAS (representing "Traffic Collision Avoidance System") switches to the "traffic advisory only" mode (i.e., TCAS will not provide avoidance instructions).

[0155] In one embodiment, in the case where all engines are shut down, when the descent mode AUTO DES is engaged, the descent mode AUTO DES takes precedence over the emergency descent mode EMER DES in order to prioritize energy conservation of the aircraft 100 with respect to the descent rate. However, as previously described, in the case where the "drift down" guidance function is engaged, when the emergency descent mode EMER DES has been enabled, the emergency descent EMER DES remains enabled and the automatic descent mode AUTO DES is not on standby (in the case where one engine remains and the emergency descent has been enabled, restoring oxygen and saving the crew has a higher priority).

[0156] In a specific embodiment, the automatic descent mode AUTO DES can also be used in the case where a failure of two air bleed systems of the engine (referred to as "double bleed failure", denoted by the abbreviation DBL) is detected. The consequence of a double bleed failure of the engine is that a turn must be made during flight, the aircraft cabin is depressurized, and then a diversion is made. In the case of DBL, an attempt is made to reset the two air bleed systems of the engine. It should be noted that this reset is only authorized in the absence of an air leak. If the reset is unauthorized (e.g., in the case of a leak) or unsuccessful, a warning is generated and the crew must descend. The automatic descent mode AUTO DES is on standby, and then, in an appropriate case, the automatic descent mode AUTO DES is engaged in order to assist the crew in guiding the aircraft 100 towards a suitable flight envelope and thus avoid cabin depressurization. Therefore, the workload of one or more pilots can be reduced (e.g., in order to assist the handling pilot during "in EMCO" operations).

[0157] In this specific embodiment, the auxiliary system 101 determines that there is a double bleed failure of the engine of the aircraft 100. Then, the auxiliary system 101 places the automatic descent mode AUTO DES on standby. When necessary, for example, in the case where the reset of the two air bleed systems fails or is unauthorized, the auxiliary system 101 engages the automatic descent mode AUTO DES.

[0158] The automatic descent mode AUTO DES can be engaged in order to perform a first descent to 24,000 feet (i.e., approximately 7.32 km), for example because this is within the flight envelope within which air bleed from the APU can be used instead of the double bleed failure of the engine and cabin depressurization can be avoided.

[0159] When necessary, when the air bleed from the APU cannot be used to avoid cabin depressurization, the automatic descent mode AUTO DES can be engaged in order to perform a second descent from 24,000 feet to 10,000 feet (i.e., from approximately 7.32 km to 3.048 km).

[0160] Alternatively, if the likelihood of not being able to use the air discharge from the APU is low due to the absence of two air discharge systems in the engine, it is acceptable to avoid a second descent, and if the cabin depressurizes (e.g., due to the ultimate inability to use the air discharge from the APU) after the first automatic descent to 24,000 feet (i.e., approximately 7.32 km), then an automatic emergency descent (known) is engaged.

Claims

1. A system (101) for assisting in restarting at least one engine of an aircraft (100), the assisting system (101) including an electronic circuit configured to: - Determine that at least one engine of the aircraft (100) has stalled, - Control the aircraft (100) to automatically descend to a predetermined target altitude below which the altitude of the aircraft (100) is conducive to at least one attempt to restart at least one stopped engine, and - Generate a message for executing at least one program for restarting the at least one stopped engine so as to perform at least one attempt to restart the at least one stopped engine when the aircraft (100) reaches the target altitude and / or target normal speed.

2. The system (101) for assisting in restarting at least one engine of an aircraft (100) according to claim 1, the system (101) further including an electronic circuit configured to control the automatic descent of the aircraft (100) while reducing the normal speed of the aircraft (100) to a predetermined target normal speed below which the normal speed of the aircraft (100) is conducive to restarting the at least one stopped engine.

3. The system (101) for assisting in restarting at least one engine of an aircraft (100) according to any one of claims 1 and 2, the system (101) further including an electronic circuit configured to control the automatic descent of the aircraft (100) based on at least one of the following parameters: - The number of stopped engines, - The enabled state of the autopilot (AP) device of the aircraft (100), - The enabled state of the flight director (FD) device of the aircraft (100), - The state of the current guidance mode of the aircraft (100), - The number of pilots present in the cockpit of the aircraft (100), - The number of pilots capable of flying the aircraft (100) present in the cockpit of the aircraft (100).

4. A system (101) for assisting in restarting at least one engine of an aircraft (100), according to any one of claims 1 to 3, wherein, The system (101) for assisting in restarting the at least one engine of the aircraft (100) is implemented in the guidance controller device of the aircraft (100).

5. A method for assisting in restarting at least one engine of an aircraft (100), the method being implemented by an assisting system (101) in the form of an electronic circuit, the method including: - Determine that at least one engine of the aircraft (100) has stalled, - Control the aircraft (100) to automatically descend to a predetermined target altitude below which the altitude of the aircraft (100) is conducive to at least one attempt to restart at least one stopped engine, and - Generate a message for executing at least one program for restarting the at least one stopped engine so as to perform at least one attempt to restart the at least one stopped engine when the aircraft (100) reaches the target altitude and / or target normal speed.

6. The method for assisting in restarting at least one engine of an aircraft (100) according to claim 5, the method further comprising controlling the automatic descent of the aircraft (100) while reducing the normal speed of the aircraft (100) to a predetermined target normal speed, below which the normal speed of the aircraft (100) is conducive to restarting the at least one stopped engine.

7. The method for assisting in restarting at least one engine of an aircraft (100) according to any one of claims 5 and 6, the method further comprising controlling the automatic descent of the aircraft (100) based on at least one of the following parameters: - The number of stopped engines, - The enabled state of the autopilot (AP) device of the aircraft (100), - The enabled state of the flight director (FD) device of the aircraft (100), - The state of the current guidance mode of the aircraft (100), - The number of pilots present in the cabin of the aircraft (100), - The number of pilots capable of piloting the aircraft (100) present in the cabin of the aircraft (100).

8. An aircraft (100) comprising the assistance system (101) according to any one of claims 1 to 4.

9. A computer program product comprising instructions which, when executed by a processor, cause the processor to execute the method according to any one of claims 5 to 7.

10. A storage medium storing a computer program product, the computer program product comprising instructions which, when read and executed by a processor, cause the processor to execute the method according to any one of claims 5 to 7.

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