Method for assisting propulsion by detecting failure of aircraft turboshaft engine

Abstract

The invention relates to a method for auxiliary propulsion by detecting a malfunction of a turboshaft engine of an aircraft operating in nominal mode, the aircraft comprising an auxiliary engine deactivated, the method comprises: a step (2) of comparing operating parameters of the turboshaft engine with equivalent parameters of a model representing a good turboshaft engine; a step (4) of detecting a fault of the turboshaft engine by detecting an anomaly in at least one operating parameter of the turboshaft engine; a step (6) of selecting an activation mode of the auxiliary engine on the basis of operating parameters of the turboshaft engine and / or flight parameters of the aircraft; and a step (8) of activating the auxiliary engine if the activation mode is selected.

Description

Technical Field

[0001] The invention relates to assisting a turboshaft engine of an aircraft after a fault in the aircraft has been detected.

[0002] In particular, the invention relates to a helicopter with a twin-engine architecture, one of the two engines of the helicopter being able to operate in a deactivation mode or in an energy-saving mode, also called standby mode.

[0003] In general, the invention is applicable to all aircraft comprising at least two engines. Background Art

[0004] A turboshaft engine, in particular an aircraft turboshaft engine (for example, a helicopter turboshaft engine) must be started before being able to provide thrust power or mechanical power to a rotor. In particular, starting includes heating of components of the turboshaft engine and rotation of the turbine.

[0005] During a flight phase of an aircraft comprising an architecture with two turboshaft engines, one turboshaft engine may sometimes be shut down due to the use of a specific flight mode, for example an energy saving mode (also called standby mode), the other turboshaft engine operating in nominal mode.

[0006] In this standby mode, which is also described in detail in document FR 2 967 132 A1, the turboshaft engine is kept rotating at a low speed, driven by the combustion gases or by auxiliary means such as an electric motor. In this standby mode, the combustion chamber may be closed. In a variant, the combustion chamber is ignited with or without assistance in the rotation of the turboshaft engine.

[0007] In order to exit this standby mode, in particular in the event of a fault in the turboshaft engine operating in nominal mode, it is possible to restart the turboshaft engine by means of a normal restart or by means of a rapid restart. Document FR3027058A1 specifically mentions that a normal restart takes place within a period of time between 10 seconds and 1 minute, while a rapid restart takes place within a period of time between 5 seconds and 15 seconds.

[0008] In order to detect faults or damage in a turboshaft engine having an architecture with two turboshaft engines, the performance and parameters of the two turboshaft engines are usually compared or compared when the two turboshaft engines are operated in the same way and at the same speed.

[0009] However, it is not possible to detect a fault by comparing the two turboshaft engines and the consistency of their performance and the consistency of their operating parameters when one of the two turboshaft engines is in standby mode, the rotation speed and temperature of the turboshaft engine in standby mode being lower than those of the turboshaft engine in nominal mode. Summary of the invention

[0010] The object of the present invention is therefore to overcome the above-mentioned drawbacks and to improve the detection of faults in a turboshaft engine and better management of the activation of auxiliary engines when a fault is detected.

[0011] The object of the invention is a method for propulsion assistance by detecting a fault in a turboshaft engine of an aircraft operating in a nominal mode, the aircraft comprising a deactivated auxiliary engine. The nominal mode refers to a normal operating mode in which the engine is supplying power. The method comprises: a step of comparing the operating parameters of the turboshaft engine with equivalent parameters of a model representing a healthy turboshaft engine; a step of detecting a fault in the turboshaft engine by detecting an anomaly in at least one operating parameter of the turboshaft engine; a step of selecting an activation mode of the auxiliary engine as a function of the operating parameters of the turboshaft engine and / or of the flight parameters of the aircraft; and a step of activating the auxiliary engine if the activation mode is selected.

[0012] Thus, a fault of a turboshaft engine is not detected by comparison with another active turboshaft engine, but with an internal model representing a good turboshaft engine.

[0013] In one embodiment, the flight parameters of the aircraft include a flight altitude of the aircraft, and the activation mode of the auxiliary engines is selected according to the possibility of maintaining the flight altitude of the aircraft during the time required to activate the auxiliary engines.

[0014] Advantageously, the step of comparing the operating parameters of the turboshaft engine with equivalent parameters of a model representing a good turboshaft engine is implemented by a computer of the turboshaft engine storing a model representing a good turboshaft engine.

[0015] In one embodiment, the step of detecting a fault in the turboshaft engine comprises measuring a significant difference between an operating parameter of the turboshaft engine and an equivalent parameter of a model representing a good turboshaft engine.

[0016] Advantageously, the activation mode of the auxiliary engine is selected between a normal activation mode having a first activation duration, an acceleration activation mode having a second activation duration, and a fast activation mode having a third activation duration, the first duration being longer than the second duration and the second duration being longer than the third duration, the normal activation mode being superior to the acceleration activation mode, which in turn is superior to the fast activation mode.

[0017] In a particular embodiment, the auxiliary engine is a second turboshaft engine.

[0018] Advantageously, the normal activation mode comprises a step of thermal stabilization at a predefined temperature of the auxiliary engine and is preferentially adopted when no fault of the turboshaft engine is detected and for this purpose the aircraft's onboard computer and / or the pilot issues a command to the auxiliary engine.

[0019] Advantageously, operating parameters of the turboshaft engine or detectable faults include: the fuel flow rate, and / or the temperature and / or the rotational speed at the output end of the high-pressure turbine of the turboshaft engine, and / or the output pressure of the compressor of the turboshaft engine, and / or the torque, and / or the flameout of the combustion chamber of the turboshaft engine, and / or the leakage of the oil circuit, and / or the leakage of the fuel circuit, and / or the detection of debris, and / or the inability to regulate the performance of the turboshaft engine, and / or the inconsistency between the power demand and the power supplied, and / or the potential impact on the trajectory of the aircraft.

[0020] In one embodiment, the auxiliary engine is a second turboshaft engine; and the normal activation mode, the accelerated activation mode and the rapid activation mode include assistance of the second turboshaft engine by an electric motor of the aircraft, the normal activation mode includes thermal stabilization at a predefined temperature of the second turboshaft engine and the use of a fuel flow rate law that allows an activation time between 1 minute and 3 minutes, the accelerated activation mode includes the use of a fuel flow rate law that allows an activation time between 10 seconds and 1 minute, and the rapid activation mode includes the use of a specific starting system that is configured to use auxiliary torque and a fuel flow rate law that allows an activation time of the second turboshaft engine between 5 seconds and 15 seconds.

[0021] In a particular embodiment, the deactivated auxiliary engine corresponds to an operating mode of the auxiliary engine which corresponds to a standby mode or to a mode intermediate between the standby mode and the nominal operating mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other objects, features and advantages of the present invention will become apparent on reading the following description given only as a non-limiting example and with reference to the accompanying drawings, in which:

[0023] [ Figure 1 ] shows the steps of the method according to the present invention;

[0024] [ Figure 2 ] is a summary diagram of the various states of the auxiliary engine according to the activation mode selected for the auxiliary engine during the implementation of the method according to the invention. DETAILED DESCRIPTION

[0025] In one embodiment, the method according to the invention is implemented in an aircraft (for example a helicopter) comprising a turboshaft engine and an auxiliary engine which can supply power to a main transmission of the aircraft.

[0026] The auxiliary engine is, for example, an electric machine or a second turboshaft engine. The present description will be made with reference to the second turboshaft engine, the aforementioned turboshaft engine being considered as the first turboshaft engine.

[0027] The first turboshaft engine and the second turboshaft engine each comprise, for example, a compressor which increases the pressure of the gas at the inlet of the turboshaft engine, a combustion chamber which increases the temperature of the compressed gas, and an expansion turbine which also drives the compressor.

[0028] In particular, the first turboshaft engine and the second turboshaft engine are, for example, turboshaft engines with a free turbine, the expansion turbine being divided into a high-pressure turbine (also referred to as the gas generator's turbine) and a power turbine (also referred to as the free turbine).

[0029] The method according to the invention is particularly implemented when the aircraft is operating in a specific consumption mode such as an energy-saving mode, in particular when one of the two turboshaft engines (for example, the first turboshaft engine) is operating in a nominal mode (in other words, in an operating mode that provides standard performance and enables the aircraft to move in the atmosphere), and when the second turboshaft engine is operating in a deactivated mode. In particular, the deactivated mode refers to a standby mode of the second turboshaft engine, or to a consumption mode intermediate between the standby mode and the nominal mode of the second turboshaft engine.

[0030] The intermediate consumption mode is, for example, the operating mode of the second turboshaft engine when the second turboshaft engine changes from its nominal mode to its standby mode, or from its standby mode to its nominal mode.

[0031] The standby mode is a consumption mode that provides the second turboshaft engine of the aircraft with low fuel consumption while allowing rapid activation for situations in which the aircraft would need two turboshaft engines or in the event of a failure of the first turboshaft engine.

[0032] Figure 1The various steps of a method for propulsion assistance by detecting a fault in an aircraft turboshaft engine are schematically shown.

[0033] In an embodiment of the method, step 2 is first carried out: comparing the operating parameters of the first turboshaft engine with equivalent parameters of a model representing a good turboshaft engine.

[0034] The model representing a good turboshaft engine is, for example, stored in a computer of the first turboshaft engine, said computer implementing step 2 of comparing operating parameters.

[0035] Next, a step 4 of detecting an anomaly in at least one operating parameter of a plurality of operating parameters of the first turboshaft engine is carried out.

[0036] Step 4 of detecting anomalies comprises, for example, measuring significant differences between operating parameters of the first turboshaft engine and equivalent parameters of a model representing a good turboshaft engine. Significant differences are differences whose values ​​are predetermined for each operating parameter and are a symptom of a malfunction of the first turboshaft engine.

[0037] In particular, operating parameters of the first turboshaft engine and more broadly detectable faults include anomalies related to: fuel flow rate, and / or temperature at the output end of the high-pressure turbine of the turboshaft engine and / or rotational speed at the output end of the high-pressure turbine of the turboshaft engine, and / or output pressure of the compressor of the turboshaft engine, and / or torque, and / or flameout of the combustion chamber of the turboshaft engine, and / or leakage in the oil circuit, and / or leakage in the fuel circuit, and / or detection of debris, and / or inability to regulate the performance of the turboshaft engine, and / or inconsistency between power demand and power supplied, and / or potential impact on the trajectory of the aircraft (for example, detected via anomalies in the rotational speed of the free turbine of the rotor (indicating overspeed or underspeed), detected via changes in atmospheric pressure indicating that the aircraft is moving away from or closer to the ground, detected via changes in power demand, or detected via changes in power consumed by the engine).

[0038] Next, step 6 is performed: selecting the activation mode of the second turboshaft engine according to the previously detected fault and more generally according to the operating parameters of the first turboshaft engine and / or the flight parameters of the aircraft and / or the potential impact on the trajectory of the aircraft.

[0039] Finally, once an activation mode has been selected, step 8 is implemented: activating the second turboshaft engine according to said activation mode selected.

[0040] Figure 2A schematic overview of various states of the second turboshaft engine is shown, depending on the activation mode selected for the second turboshaft engine.

[0041] In particular, Figure 2 A nominal consumption mode 10, a standby mode 12, and a consumption mode 14 intermediate between the standby mode 12 and the nominal mode 10 of the second turboshaft engine are shown. In particular, when the second turboshaft engine is in an operating mode such as the standby mode 12 or the intermediate consumption mode 14, a step 8 of activating the second turboshaft engine according to the selected activation mode is applied to the second turboshaft engine. In the standby mode and the intermediate consumption mode, the combustion chamber can be turned off, while the turbine of the gas generator is slightly rotated, for example by means of an electric motor. In a variant, the combustion chamber is ignited and the turbine of the gas generator includes or does not include a rotation assistance.

[0042] During step 8 , it is possible to implement three different activation modes, the selection between which is made automatically by the computer of the second turboshaft engine or manually by the pilot of the aircraft.

[0043] In particular, the three activation modes may have different effects on the aging of the second turboshaft engine.

[0044] Of these three possible modes, when the aircraft and / or the first turboshaft engine and / or the pilot meet the first condition C1, a step of using a normal activation mode 16 of a first duration in the nominal mode of the second turboshaft engine can be implemented. This is the case of the longest possible activation mode, which in particular makes it possible to maintain the mechanical integrity of the second turboshaft engine.

[0045] In one embodiment, the first condition C1 consists in receiving, by the second turboshaft engine, an activation command sent by an onboard computer of the aircraft and / or by a pilot.

[0046] This normal activation mode 16 comprises a step of thermal stabilization at a predefined temperature of the second turboshaft engine. In a variant, this mode 16 comprises a step of gradually increasing the power of the second turboshaft engine to balance the power supplied between the first turboshaft engine and the second turboshaft engine.

[0047] Normal activation mode 16 also includes the use of fuel flow rate regulation and torque optimization allowing activation times between 1 minute and 3 minutes.

[0048] This mode 16 thus makes it possible to gradually vary the temperature of a component of the second turboshaft engine.

[0049] This normal activation mode 16 is the most commonly used activation mode when it is in a situation of activation that is usually not urgent. This is the mode with the least influence on the aging of the turboshaft engine, and is therefore preferred.

[0050] A second possible activation type is to use an acceleration activation mode 18 with a second duration of the second turboshaft engine in nominal mode of the second turboshaft engine and when the aircraft and / or the first turboshaft engine meet a second condition C2 .

[0051] The second condition C2 includes, for example, detection of damage to the first turboshaft engine and / or the second turboshaft engine, and / or damage to the rest of the aircraft, as well as more generally detection of anomalies indicative of a malfunction (e.g. loss of sensor redundancy, excessive oil temperature, or loss of energy to the aircraft).

[0052] In a variant, the second condition C2 consists in detecting a flight condition that requires operation in nominal mode 10 of the second turboshaft engine. For example, the measured atmospheric pressure is incompatible with the use of a single turboshaft engine in nominal mode, making it necessary to activate the second turboshaft engine. In a variant, the second condition C2 consists in the second turboshaft engine receiving an activation command sent by an onboard computer of the aircraft and / or by the pilot.

[0053] The accelerated activation mode 18 is substantially similar to the normal activation mode 16, but includes the use of a fuel flow rate pattern that allows an activation time of between 10 seconds and 1 minute. Thus, in particular due to the lack of a thermal stabilization step, this accelerated activation mode 18 is shorter, allowing a rapid activation of the second turboshaft engine. However, this activation has a significant impact on the aging of the second turboshaft engine.

[0054] The third activation mode is the use of a rapid activation mode 20 with a third duration of the second turboshaft engine in the nominal mode 10 of the second turboshaft engine when the aircraft and / or the first turboshaft engine meets a third condition C3 .

[0055] The third condition C3 also includes the detection of damage to the first turboshaft engine, for example, or more generally the detection of anomalies indicating a fault leading to a loss of power, such as the detection of anomalies in the value of the fuel flow rate, and / or the temperature and / or the rotational speed at the output of the high-pressure turbine of the first turboshaft engine, and / or the output pressure of the compressor of the turboshaft engine, and / or the torque, and / or the detection of a flameout of the combustion chamber of the turboshaft engine, and / or a leak in the oil circuit, and / or a leak in the fuel circuit, and / or the detection of debris, and / or the inability to regulate the performance of the turboshaft engine, and / or the discrepancy between the power demand and the power supplied, and / or the potential impact on the trajectory of the aircraft. These anomalies generally require the rapid activation of the second turboshaft engine, as they may be a sign of a significant loss of power of the first turboshaft engine.

[0056] In a variant, the third condition C3 consists in detecting a flight condition requiring operation in the nominal mode 10 of the second turboshaft engine, or in receiving by the second turboshaft engine an activation command sent by an onboard computer and / or by the pilot of the aircraft.

[0057] The fast activation mode 20 is different from the first two activation modes. Specifically, the fast activation mode 20 includes the use of a specific start-up system that is configured and sized to use a fuel flow rate pattern that allows an activation time of between 5 and 15 seconds (approximately 10 seconds).

[0058] However, the rapid activation mode 20 does have a significant impact on the aging of the second turboshaft engine and is only used in emergency situations.

[0059] Among the three activation modes, the normal activation mode 16 is preferred to the accelerated activation mode 18, and the accelerated activation mode 18 is preferred to the fast activation mode 20. This is because although the first duration is longer than the second duration, and the second duration is longer than the third duration, the activation with less aging effect is preferred.

[0060] Optionally, the second turboshaft engine comprises an electric auxiliary machine, and each of the normal activation mode, the acceleration activation mode or the rapid activation mode comprises the step of assisting the second turboshaft engine by the electric auxiliary machine of the aircraft.

[0061] In other words, the electric auxiliary machine participates in the rotation of the second turboshaft engine when the second turboshaft engine is activated, so as to accelerate the activation.

[0062] Advantageously, the flight parameters of the aircraft include its altitude and the auxiliary engine activation mode, in other words the second turboshaft engine activation mode, is selected according to the possibility of maintaining the altitude for the time required to activate the second turboshaft engine.

[0063] Therefore, the first condition, the second condition and the third condition each include an additional condition of maintaining the flight altitude of the aircraft during the time required to activate the second turboshaft engine. This is because, although the normal activation mode 16 is preferred due to only a slight impact on the aging of the second turboshaft engine, if this cannot guarantee the maintenance of the flight altitude of the aircraft, a faster activation mode will be preferred. The same applies to the accelerated activation mode 18.

[0064] Furthermore, one activation mode may be interrupted in favor of another activation mode when the conditions of the other activation mode are met.

[0065] For example, when the normal activation mode 16 is in progress but a major fault is detected, the fast activation mode 20 is implemented. However, if a specific starting system fails 22, the accelerated activation mode 18 is ultimately implemented.

[0066] In one embodiment, the method is continuously implemented by the computer of the second turboshaft engine as long as the second turboshaft engine is not in its nominal operating mode 10. Thus, step 2 of comparing parameters and step 4 of detecting faults are stopped only when the second turboshaft engine is in its nominal operating mode 10.

Claims

1. A method for propulsion assistance by detecting a fault in a turboshaft engine of an aircraft operating in nominal mode, said aircraft comprising a deactivated auxiliary engine, characterized in that The method comprises: a step (2) of comparing the operating parameters of the turboshaft engine with equivalent parameters of a model representing a good turboshaft engine; a step (4) of detecting a fault in the turboshaft engine by detecting an anomaly in at least one operating parameter of the turboshaft engine; a step (6) of selecting an activation mode of the auxiliary engine according to the operating parameters of the turboshaft engine and / or the flight parameters of the aircraft; and a step (8) of activating the auxiliary engine if the activation mode is selected.

2. The method according to claim 1, wherein: The flight parameters of the aircraft include a flight altitude of the aircraft, and the activation mode of the auxiliary engines is selected according to the possibility of maintaining the flight altitude of the aircraft during the time required to activate the auxiliary engines.

3. The method according to claim 1, wherein: The step (2) of comparing the operating parameters of the turboshaft engine with the equivalent parameters of the model representing a good turboshaft engine is implemented by a computer of the turboshaft engine, the computer of the turboshaft engine storing the model representing a good turboshaft engine.

4. The method according to any one of claims 1 to 3, wherein: The step (4) of detecting a fault in the turboshaft engine comprises measuring a significant difference between an operating parameter of the turboshaft engine and an equivalent parameter of the model representing a good turboshaft engine.

5. The method according to any one of claims 1 to 4, wherein: The activation mode of the auxiliary engine is selected between a normal activation mode (16) having a first activation duration, an acceleration activation mode (18) having a second activation duration, and a fast activation mode (20) having a third activation duration, the first duration being longer than the second duration and the second duration being longer than the third duration, the normal activation mode (16) being superior to the acceleration activation mode (18), which in turn is superior to the fast activation mode (20).

6. The method according to any one of claims 1 to 5, wherein: The auxiliary engine is a second turboshaft engine.

7. The method according to claims 5 and 6, wherein: The normal activation mode (16) comprises a step of thermal stabilization at a predefined temperature of the auxiliary engine and is preferentially adopted when no fault of the turboshaft engine is detected and for this purpose the onboard computer of the aircraft and / or the pilot issues a command to the auxiliary engine.

8. The method according to any one of claims 1 and 7, wherein: The operating parameters of the turboshaft engine or the detectable faults include: the fuel flow rate, and / or the temperature and / or the rotational speed at the output end of the high-pressure turbine of the turboshaft engine, and / or the output pressure of the compressor of the turboshaft engine, and / or the torque, and / or the flameout of the combustion chamber of the turboshaft engine, and / or the leakage of the oil circuit, and / or the leakage of the fuel circuit, and / or the detection of debris, and / or the inability to adjust the performance of the turboshaft engine, and / or the inconsistency between the power demand and the power supplied, and / or the potential impact on the trajectory of the aircraft.

9. The method according to any one of claims 5 to 8, wherein: The auxiliary engine is a second turboshaft engine, and wherein the normal activation mode (16), the accelerated activation mode (18) and the rapid activation mode (20) comprise assistance of the second turboshaft engine by the electric machine of the aircraft, the normal activation mode (16) comprising thermal stabilization at a predefined temperature of the second turboshaft engine and the use of a fuel flow rate pattern allowing an activation time between 1 minute and 3 minutes, the accelerated activation mode (18) comprising the use of a fuel flow rate pattern allowing an activation time between 10 seconds and 1 minute, and the rapid activation mode (20) comprising the use of a specific starting system configured to use an auxiliary torque and a fuel flow rate pattern allowing an activation time of the second turboshaft engine between 5 seconds and 15 seconds.

10. The method according to any one of claims 1 to 9, wherein: The deactivated auxiliary engine corresponds to an operating mode of the auxiliary engine that is equivalent to a standby mode or to a mode intermediate between the standby mode and a nominal operating mode.

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