RE-IGNITIONING OF A MULTIPLE OF AN AIRCRAFT'S ENGINES DURING FLIGHT

Description

TECHNICAL FIELD

[0001] The present invention relates to the management of re-ignition of aircraft engines in flight. STATE OF PRIOR ART

[0002] Engine flameout in flight is a well-known incident in aviation. In the case of a turbine engine flameout, this phenomenon is referred to as "flame out" in English to illustrate the cessation of combustion.

[0003] Engine flameout can have many causes: power failure (for example, fuel starvation for a thermal engine), pumping, lack of oxygen at high altitude, ingestion (eg, of birds) ...

[0004] The incident itself is unlikely to cause a loss of control of the aircraft, as they are designed to continue flying even in the event of an engine failure. However, the rest of the flight is carried out in degraded mode: loss of thrust, partial loss of electrical and / or hydraulic and / or pneumatic power.

[0005] It is then the pilot's responsibility to attempt to relight an engine that has been shut down in flight, whenever he / she deems it prudent to do so. When several engines are simultaneously shut down, the pilot will attempt to relight at least one engine in order to land at a diversion airport. The pilot will attempt to relight the engines in turn, until at least one engine can be relighted. This procedure can be lengthy, especially since the pneumatic or electrical power source fitted to the aircraft (depending on the technology of the engine starting systems fitted to the aircraft) is not designed to provide sufficient power to attempt to relight several engines in a row in a short period of time, which also delays the potential relighting of at least one engine.

[0006] It is therefore desirable to overcome these disadvantages of the state of the art. In particular, it is desirable to provide a solution that makes it possible to accelerate the relighting of at least one engine when several engines of an aircraft are switched off in flight.

[0007] Note that document EP 2636596 A2 is known, which discloses a rotorcraft electric motor starting system, which comprises a controller which selects at least one of a plurality of power sources to power a starter of the electric motor. STATEMENT OF THE INVENTION

[0008] According to claim 1, there is then proposed a method of relighting several extinguished engines from a set of N engines of an aircraft in flight, N ≥ 2,the method being implemented by an automated in-flight engine relighting management system which includes controllers, each engine of the aircraft being managed by a said controller, in which each controller, which is in charge of a said engine i of the said set, i = 1,...,N, and which detects that said engine i is off, performs the following steps: cut off the power supply to said motor i; perform ventilation of said motor i; check whether at least one other motor of said assembly is off; when no other motor of said assembly is off, perform (408) an attempt to relight said motor i. Additionally, when at least one other engine j, j = 1, ...,N, j ≠ i,said assembly is switched off, at least one said controller performs a prioritization of engine re-ignition including the following steps: collecting, from the controllers in charge of said engines, information concerning a state of health of each engine; determining, from the information collected, information representative of a probability of re-ignition of each switched off engine; determining a sequential order of re-ignition of the switched off engines, based on the information representative of the probability of re-ignition of each switched off engine; and maintaining ventilation of engine i, by the controller which is in charge of said engine i, until selection of said engine iin the sequential order of relighting of the extinguished engines. Thus, thanks to their ventilation, the extinguished engines are quickly put into conditions of potential relighting, and the prioritization thus carried out allows, as far as possible, that the operational state of the aircraft is improved as quickly as possible. If at least one engine can be restarted, the appropriate selection of engine to be relighted is made.

[0009] According to a particular embodiment, the collected information includes: an indication of an operating mode in which the engine in question is located; an indication of vibrations sensed by sensors of the engine in question; an indication of temperature sensed by sensors of the engine in question; an indication of status of a starting system of the engine in question; and an indication of power supply status of the engine in question.

[0010] According to a particular embodiment, the information representative of the probability of re-ignition of said engine is a health status score of said engine, and in which the health status score depends on: a temperature margin of said engine relative to one or more predefined first thresholds; a peak value of vibrations captured at said engine during the flight relative to one or more predefined second thresholds; an operational state of a starting system of said engine; and an operational state of the power supply of said engine.

[0011] According to a particular embodiment, each controller, which is in charge of a said motor i of the said set, i = 1, ...,N, and which detects that said engine i is off, perform the following steps: determine if an engine self-reignition iis in progress; when an auto-reignition of the engine i is in progress, monitor the progress of the auto-reignition of the engine i ; when no engine self-reignition i is not in progress or when the engine self-reignition i is a failure, include the engine i in the prioritization of engine re-ignition.

[0012] According to claim 5, there is also provided an automated management system for in-flight relighting of engines of an aircraft comprising a set of N engines, N ≥ 2, including controllers, each engine of the aircraft being managed by a said controller, wherein each controller, which is in charge of a said engine i of the said set, i = 1,...,N, and which detects that said engine i is turned off, includes electronic circuitry configured to implement the following steps: cut off the power supply to said motor i; carry out ventilation of said engine i ; check whether at least one other engine of said assembly is off; when no other engine of said assembly is off, attempt to relight said engine i . In addition, when at least one other engine j, j = 1, .... N, j ≠ i, said assembly is switched off, at least one said controller includes electronic circuitry configured to implement a prioritization of engine re-ignition including the following steps: collecting, from the controllers in charge of said engines, information concerning a state of health of each engine; determining, from the information collected, information representative of a probability of re-ignition of each switched off engine; determining a sequential order of re-ignition of the switched off engines, based on the information representative of the probability of re-ignition of each switched off engine; and maintaining the engine in ventilationi, by the controller who is in charge of said motor i, until selection of said engine i in the sequential order of relighting the extinguished engines.

[0013] An aircraft is also proposed comprising a set of N engines, N ≥ 2, and an automated in-flight engine re-ignition management system as mentioned above.

[0014] Also provided is a computer program product according to claim 7 and a computer-readable information storage medium according to claim 8. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of at least one exemplary embodiment, said description being made in relation to the attached drawings, among which: [ Fig. 1 ] schematically illustrates, in top view, an aircraft equipped with an automated in-flight relighting management system for aircraft engines; [ Fig. 2 ] schematically illustrates an example of the hardware architecture of the controller of the automated re-ignition management system; [ Fig. 3 ] schematically illustrates an algorithm for managing the in-flight re-ignition of a extinguished engine; [ Fig. 4 ] schematically illustrates an algorithm for joint management of in-flight relighting of several engines; and [ Fig. 5 ] schematically illustrates an algorithm for prioritizing the in-flight relighting of several engines. DETAILED PRESENTATION OF IMPLEMENTATION METHODS

[0016] There Fig. 1 schematically illustrates, in top view, an aircraft 100 equipped with a set of N engines ( N ≥ 2) 110 and a system 120 for automated management of in-flight engine relighting.

[0017] Preferably, the 130 engines are turbojets. The 130 engines may, however, be of another type, for example hydrogen engines.

[0018] The system 120 comprises at least one controller 130 per engine. The controllers 130 are interconnected to each other, as well as to the avionics 150, by means of a communication system 140.

[0019] Note that most current engines are equipped with advanced electronic circuitry, with numerous sensors, which may include an automatic self-ignition system, "auto-relight" in English.

[0020] As detailed below, the system 120 implements a joint management function for in-flight relighting of the engines, when several engines are switched off. A switched-off engine is an engine whose rotating parts are stopped, or an engine that provides no thrust but whose fan is rotating, driven by the air in the manner of a wind turbine (this is referred to as ventilation (“windmilling” in English). In contrast, an engine in the process of self-relighting, in the process of relighting (either by action of the pilot, or automatically), or in operation (the rotating parts are rotating and the engine provides thrust, “running” in English), is not a switched-off engine.

[0021] The joint in-flight engine relighting management function can be implemented in parallel by the controllers 130, so that each controller 130 is able to determine independently, but in the same way, what priority to give to which engine in the engine relighting order.

[0022] Alternatively, the system 120 further comprises a central controller 160, integrated for example into the avionics 150, which determines which priority to give to which engine in the engine re-ignition order and which instructs the controllers 130 accordingly.

[0023] There Fig. 2 schematically illustrates an example of a hardware architecture of controller 200 of the system 120, whether the central controller 160 and / or the controllers 130.

[0024] The controller 200 then comprises, connected by a communication bus 210: a processor or CPU (Central Processing Unit) 201; a RAM (Random Access Memory) 202; a ROM (Read Only Memory) 203, for example a Flash memory; a data storage device, such as a hard disk drive (HDD), or a storage media reader, such as an SD (Secure Digital) card reader 204; at least one communication interface 205 allowing the controller 200 to interact with other equipment of the aircraft 100 and more particularly with at least one other controller of the system 120.

[0025] The processor 201 is capable of executing instructions loaded into the RAM 202 from the ROM 203, an external memory (not shown), a storage medium, such as an SD card, or a communications network (not shown). When the controller 200 is powered on, the processor 201 is capable of reading instructions from the RAM 202 and executing them. These instructions form a computer program causing the processor 201 to implement the behaviors, steps, and algorithms described herein.

[0026] All or part of the behaviors, steps and algorithms described herein may thus be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller, or be implemented in hardware form by a machine or a dedicated component (chip) or a set of components (chipset), such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). Generally speaking, the system 120 comprises electronic circuitry arranged and configured to implement the behaviors, steps and algorithms described herein.

[0027] There Fig. 3 schematically illustrates an algorithm for managing the in-flight re-ignition of a extinguished engine. The algorithm of the Fig. 3 is implemented by each controller 130.

[0028] In a step 301, the controller 130 in charge of the motor i ( i = 1, ..., N ) detects a shutdown of said engine i. As already mentioned, the engines that power aircraft today are equipped with a multitude of sensors and advanced electronic circuitry that allow them to collect and process a lot of information in real time regarding their operational status.

[0029] In a step 302, the controller 130 in charge of the motor i determines whether the engine will self-ignite i is in progress. Such self-reignition of the engine i may for example have been triggered by another controller integrated into the motor i.For example, this other controller is provided and managed by the engine manufacturer (for example in a FADEC (“Full Authority Digital Engine Control”) type system), and the controllers 130 are provided and managed by the aircraft manufacturer. Typically, in a combustion engine, self-reignition is performed by injecting kerosene and lighting the spark plugs, when sensors detect combustion misfires. If self-reignition is in progress, a step 305 is performed; otherwise, a step 303 is performed.

[0030] In step 303, the controller 130 in charge of the motor i cuts off the energy supply (kerosene, hydrogen, electricity, etc.) to the engine i. For example, the 130 controller in charge of the motor i cuts off the fuel supply (chemical energy) to the engine i., and in the case of an electric motor, the controller 130 in charge of the motor i cuts off the power supply (electrical energy) to the motori. An attempt to self-reignite the engine i by another controller (for example integrated into the engine) would then be inoperative. The energy supply (kerosene, hydrogen, electricity, etc.) to the engine i is preferably cut off upstream of the engine i (rather than within the engine i ) .

[0031] In a following step 304, the controller 130 in charge of the engine i enters into a joint engine management procedure, so as to take into account the possibility of at least one other engine 130 than the engine i. The algorithm is then terminated. Fig. 3 .

[0032] In step 305, the controller 130 in charge of the motor i monitors the progress of the self-reignition of the engine i. And in a step 306, the controller 130 in charge of the engine i checks if the engine self-reignites iwas completed successfully. If so, a step 307 is performed; otherwise, the algorithm switches to step 303 so as to cut off the power supply and enter the joint engine management procedure. Engine i can thus be included in an engine re-ignition prioritization procedure.

[0033] In step 307, the controller 130 in charge of the engine i terminates the in-flight relighting management of the engine i.

[0034] There Fig. 4 schematically illustrates an algorithm for joint management of in-flight relighting of several extinguished engines. The algorithm of the Fig. 4 provides a detailed particular embodiment of the aforementioned step 304. At the beginning of the algorithm of the Fig. 4 , the power supply to the engine i is cut (following step 303).

[0035] In a step 401, the controller 130 in charge of the motor iperforms a ventilation start induced by the movement of the aircraft in the air ("windmilling start" in English) of the engine i. Putting an engine into ventilation means rotating the engine using the relative air speed. On a turbojet, putting it into ventilation turns the fan in order to drive the N2 shaft. When a compression threshold is reached (e.g., 20%), the spark plugs can be fired to restart the engine without using a starting system (pneumatic or electric), unlike starting the engine on the ground (a longer procedure than a windmilling start).

[0036] In a step 402, the controller 130 in charge of the motor ichecks whether the aircraft 100 meets the conditions to allow engine relighting according to the applicable engine relight envelope. The characteristics of the engine relight envelope are stored in a memory available to said controller 130. The engine relight envelope is a profile, which depends at least on airspeed and altitude information of the aircraft 100, and which defines the conditions to be met so that the probability of restarting the engine i is greater than or equal to a predefined threshold. This in-flight information is provided by the avionics 150 of the aircraft 100. The engine re-ignition envelope may define profile portions specifically for re-ignition assisted by a starting system (whether a starter or a pneumatic starting system) and for re-ignition in ventilation.

[0037] In a step 403, the controller 130 in charge of the engine i checks whether several engines of the aircraft 100 are switched off. The controllers 130 are interconnected, or connected to the central controller 160, so that each controller 130 is able to obtain information concerning the current operating mode of each engine 110 of the aircraft 100, as well as other information relating to said engines 110 (sensed vibrations, temperature, power supply, etc.). If several engines 110 are switched off, a step 404 is performed; otherwise a step 408 is performed.

[0038] In step 404, the controller 130 in charge of the motor ichecks whether a parallel relighting of the switched-off engines is possible and / or authorized. For example, the controller 130 in charge of engine i checks whether the aircraft 100 has sufficient electrical energy to carry out this parallel start. According to another example, the controller 130 in charge of engine i checks whether the aircraft 100 is of a type allowing a simultaneous start of two or more engines. This information is provided by the avionics 150 of the aircraft 100. If a parallel relighting of the switched-off engines is possible, step 408 is carried out; otherwise, a step 405 is carried out.

[0039] Step 404 is optional. If it is omitted (for example, because it is pre-established in the controller 130 that, as soon as several engines are switched off, a procedure for prioritizing the re-ignitions of the switched off engines is necessarily carried out), the algorithm goes from step 403 to step 405 if several engines 110 are switched off.

[0040] In step 405, the controller 130 in charge of the engine i enters into a procedure for prioritizing the re-ignitions of the switched-off engines. This procedure aims to define in which sequential order the re-ignitions of the switched-off engines must take place to maximize the chances of restarting at least one engine 110 among the switched-off engines. The procedure for prioritizing the re-ignitions of the switched-off engines can be carried out, in the same way (to obtain the same result), by each of the controllers 130. Alternatively, the procedure for prioritizing the re-ignitions of the switched-off engines can be centralized at the level of the central controller 160, which then instructs the controllers 130 accordingly.

[0041] A particular embodiment of step 405 is detailed below in relation to the Fig. 5 .

[0042] Then, in a step 406, the controller 130 in charge of the motor i check if the engine iis selected for re-ignition according to the sequential order determined in step 405. If so, step 408 is performed; otherwise, step 407 is performed.

[0043] In step 407, the controller 130 in charge of engine i waits for its turn to be selected according to the sequential order determined in step 405. When the controller 130 in charge of engine i receives information (from another controller 130 or from the central controller 160) indicating the end of the relighting of another engine 110 (whether successfully or not), the controller 130 in charge of engine i repeats step 406 to determine whether its turn has arrived. As long as its turn to be selected has not arrived (and as long as no relight abort instruction is received), the controller 130 in charge of engine i maintains the ventilation of the engine i, so that the said engine i be in the best possible conditions to be rekindled.

[0044] In step 408, the controller 130 in charge of the motor i attempts to restart the engine i. The 130 controller in charge of the motor i then reactivates the power supply, which had been cut off in step 303. The controller 130 of the motor i informs the other controllers 130, i.e. the controllers 130 in charge of the motors j ( j = 1,..,N, j ≠i ), of the engine re-ignition process i. The relight attempt may be made with or without the aid of a starting system, depending on the conditions of the aircraft 100 relative to the engine relight envelope.

[0045] In the event that the attempt to relight the engine i fails, the engine ipasses its turn and priority is then given to the next engine in the sequential order determined in step 405. In a particular embodiment, a new prioritization of the relighting of the extinguished engines is carried out taking into account the failure to relight engine i. This makes it possible to take into account a new situation of the aircraft 100, and to review accordingly the prioritization of the remaining engines possibly to be relighted.

[0046] There Fig. 5 schematically illustrates an algorithm for prioritizing the in-flight relighting of several extinguished engines. The algorithm of the Fig. 5 provides a particular detailed embodiment of the aforementioned step 405. Consider for illustrative purposes that the algorithm of the Fig. 5 is implemented by the central controller 160.

[0047] In a step 501, the central controller 160 collects information relating to a health status of each engine 110. This information includes an indication of the operating mode in which the engine in question is located: stopped, in the process of self-reignition, in ventilation, in the process of reigniting, in operation. This information preferably includes an indication of vibrations captured by sensors of the engine 110 in question. This information preferably includes an indication of temperature captured by sensors of the engine 110 in question. This information preferably includes an indication of the power supply status of the engine 110 in question. This information preferably includes an indication of the status of the starting system of the engine 110 in question. The information may be collected or alternatively be collected systematically or, alternatively, as needed.For example, information relating to the status of the engine starting system 110 may be collected by the central controller 160 only if a restart of the engine 110 in question using the starting system is envisaged.

[0048] In a step 502, the central controller 160 determines, for each engine 110 switched off (in view of its operational state) among all the engines of the aircraft 100, information representative of a probability of re-ignition of said engine 110, from the information collected in step 501.

[0049] In a particular embodiment, the information representative of the probability of re-ignition of a said engine 110 is a health status score of said engine 110. The health status score is for example a weighted sum of a set of parameters relating to the ability of said engine 110 to be re-ignited. The health status score then depends on a temperature margin of said engine with respect to one or more predefined thresholds (e.g., with respect to an acceptable theoretical upper limit to prevent said engine from being damaged), a peak value of vibrations captured at said engine 110 during the flight (which could be symptomatic of a weakness of an engine shaft) with respect to one or more predefined thresholds, an operational state of the starting system of said engine 110, an operational state of the energy supply (fuel supply, electrical supply, etc.) of said engine 110.The health score may take into account the engine relight envelope. Indeed, an engine that would require relighting by the starting system according to the engine relight envelope given the altitude and speed of the aircraft 100, and whose collected information indicates a faulty starting system, is not given priority in the order of relighting of the shut down engines.

[0050] Other criteria may be used, provided that they address a parameter relating to the ability of said engine 110 to be restarted.

[0051] In a step 503, the central controller 160 determines a re-ignition order for the extinguished engines, based on the information representative of the probability of re-ignition of each extinguished engine 110. The higher the probability of re-ignition of a said engine 110, the higher the priority this engine 110 has in the order of re-ignition of the engines.

[0052] In a step 504, the central controller 160 selects the highest priority engine 110 according to the re-ignition order determined in step 503. The controller 130 in charge of this engine then attempts to re-ignite said engine, in accordance with steps 407 and 408 above.

[0053] In a step 505, the central controller 160 waits for the re-ignition procedure of the engine selected in step 504 to end, whether it results in success or failure.

[0054] In a step 506, the central controller 160 checks whether there is still at least one engine to be reignited. If this is the case, step 504 is repeated and the next highest priority engine 110 according to the reignition order determined in step 503 is selected for reignition. In a particular embodiment, if there is more than one engine to be reignited, the algorithm loops back to step 501, thus making it possible to take into account any changes (operating mode, temperature, etc.) that have occurred since the last execution of step 503. If there are no engines left to be reignited, a step 507 is performed.

[0055] In a particular embodiment, the central controller 160 waits for confirmation from the cockpit of the aircraft 100, via the avionics 150, before attempting to relight another extinguished engine.

[0056] In step 507, the central controller 160 terminates the procedure for relighting the extinguished engines.

Claims

1. Method of relighting several flamed-out engines in a set of N engines (110) of an aircraft (100) in flight, N ≥ 2, the method being implemented by an automated in-flight engine relighting management system (120) that includes controllers (130, 160), each engine (110) of the aircraft (100) being managed by one of said controllers (130), wherein each controller (130), which is in charge of one of said engines i of said set, i = 1,...,N, and which detects that said engine i has flamed out, executes the following steps: - cutting off (303) the energy supply to said engine i; - windmilling (401) said engine i; - checking (403) whether at least one other engine of said set has flamed out; - if no other engine of said set has flamed out, attempting (408) to relight said engine i; characterized in that, if at least one other engine j, j = 1,...,N, j ≠ i, of said set has flamed out, at least one of said controllers (160, 130) effects (405) an engine relighting prioritization including the following steps: - collecting (501), from the controllers (130) in charge of said engines (110), information concerning the state of health of each engine (110); - determining (502), from the collected information, information representing a probability of relighting each flamed-out engine; - determining (503) a sequential order of relighting the flamed-out engines as a function of the information representing the probability of relighting each flamed-out engine; and - keeping (407) the engine i windmilling, using the controller (130) in charge of said engine i, until said engine i is selected in the sequential order of relighting the flamed-out engines.

2. Method according to Claim 1, wherein the collected information includes: - an indication of an operating mode of the engine in question; - an indication of vibrations sensed by sensors of the engine in question; - an indication of the temperature sensed by sensors of the engine in question; - an indication of the status of a starting system of the engine in question; and - an indication of the status of the energy supply to the engine in question.

3. Method according to Claim 2, wherein the information representing the probability of relighting one of said engines is a state-of-health score of said engine, and wherein the state-of-health score depends on: - a temperature margin of said engine relative to one or more first predefined thresholds; - a peak value of the vibrations sensed in said engine during the flight relative to one or more second predefined thresholds; - an operational state of the starting system of said engine; and - an operational state of the energy supply to said engine.

4. Method according to any one of Claims 1 to 3, wherein each controller, which is in charge of one of said engines i of said set, i = 1,...,N, and which detects that said engine i has flamed out, executes the following steps: - determining (302) whether auto-relighting of the engine i is under way; - if auto-relighting of the engine i is under way, monitoring (305) the progress of the auto-relighting of the engine i; - if auto-relighting of the engine i is not under way or if the auto-relighting of the engine i has failed, including the engine i in the engine relighting prioritization.

5. Automated in-flight engine relighting management system (120) of an aircraft (100) including a set of N engines, N ≥ 2, said system including controllers (130, 160), each engine (110) of the aircraft (100) being managed by one of said controllers (130), wherein each controller (130), which is in charge of one of said engines i of said set, i = 1,...,N, and which detects that said engine i has flamed out, includes electronic circuitry configured to implement the following steps: - cutting off the energy supply to said engine i; - windmilling said engine i; - checking whether at least one other engine of said set has flamed out; - if no other engine of said set has flamed out, attempting to relight said engine i; characterized in that, if at least one other engine j, j = 1,...,N, j ≠ i, of said set has flamed out, at least one of said controllers (160, 130) includes electronic circuitry configured to implement an engine relighting prioritization including the following steps: - collecting, from the controllers (130) in charge of said engines (110), information concerning the state of health of each engine (110); - determining, from the collected information, information representing a probability of relighting each flamed-out engine; - determining a sequential order of relighting the flamed-out engines as a function of the information representing the probability of relighting each flamed-out engine; and - keeping the engine i windmilling, using the controller (130) in charge of said engine i, until said engine i is selected in the sequential order of relighting the flamed-out engines.

6. Aircraft (100) including a set of N engines, N ≥ 2, and an automated in-flight engine relighting management system (120) according to Claim 5.

7. Computer program product comprising instructions that cause the system in Claim 5 to execute the method according to any one of Claims 1 to 4.

8. Computer-readable information storage medium, on which the computer program product according to Claim 7 is saved.