System and method for detecting uncommanded or uncontrollable high thrust events in an aircraft

Abstract

A system and method for detecting an uncommanded high thrust (UHT) event in an aircraft. The method includes enabling a UHT function associated with an engine when an enabling condition is met. When the UHT function is enabled, the UHT event is detected when a power lever of the aircraft is in a given position, a parameter indicating engine speed or power is above a first threshold, and a rate of change of the engine speed is above a second threshold. In response to detecting the UHT event, an alert is output to trigger an adjustment of the engine for the UHT event.

Description

Technical Field

[0001] The present disclosure generally relates to detecting asymmetric thrust on a multi-engine aircraft. Background Art

[0002] A malfunction in an aircraft engine thrust control system may result in an uncommanded or uncontrollable high thrust (UHT) event. On a multi-engine aircraft, a UHT event may result in asymmetric thrust provided by the engine banks. This may lead to hazardous situations during certain critical flight phases. For example, during landing or takeoff, a UHT event may result in the aircraft running laterally or off the runway edge.

[0003] Pilot workload is high and reaction to UHT events during critical flight phases requires split-second decision making. Therefore, there is a need to provide for detection and regulation of UHT along with the pilot's stated intent to command low thrust. Summary of the invention

[0004] According to a broad aspect, there is provided a method for detecting an uncommanded high thrust (UHT) event in an aircraft. The method includes enabling a UHT function associated with an engine when an enabling condition is met. When the UHT function is enabled, the UHT event is detected when a power lever of the aircraft is in a given position, a parameter indicative of engine speed or power is above a first threshold, and a rate of change of the engine speed is above a second threshold. In response to detecting the UHT event, an alert is output to trigger an adjustment of the engine for the UHT event.

[0005] According to another broad aspect, there is provided a system for detecting an uncommanded high thrust (UHT) event in an aircraft. The system includes at least one processing unit and a non-transitory computer readable medium having program code stored thereon, the program code executable by the at least one processing unit for enabling a UHT function associated with an engine when an enabling condition is met. When the UHT function is enabled, a UHT event is detected when a power lever of the aircraft is in a given position, a parameter indicative of engine speed or power is above a first threshold, and a rate of change of the engine speed is above a second threshold. In response to detecting the UHT event, an alert is output to trigger an adjustment of the engine for the UHT event.

[0006] According to the embodiments described herein, features of the systems, devices, and methods described herein may be used in various combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Reference is now made to the accompanying drawings, in which:

[0008] Figure 1 is a schematic cross-sectional view of a gas turbine engine and propulsion system according to at least some embodiments;

[0009] Figure 2 is a block diagram of a system for operating a power plant according to at least some embodiments;

[0010] Figure 3 is a flow chart of a method for detecting a UHT event according to at least some embodiments;

[0011] Figure 4 is a graph illustrating a rate of change of engine speed according to at least some embodiments;

[0012] Figure 5 is a flow chart of a method for detecting a UHT event having four states for a UHT function according to at least some embodiments;

[0013] 6a-6b are graphs illustrating example scenarios of fault conditions leading to UHT events; and

[0014] Figure 7 According to an illustrative embodiment, Figure 2 Block diagram of the computing device of the control system.

[0015] It will be noted that throughout the drawings, like features are identified by like reference numerals. DETAILED DESCRIPTION

[0016] A detection method and system for an uncommanded or uncontrollable high thrust (UHT) event is described herein. Throughout the disclosure, references to an "uncommanded high thrust event" will also include an "uncontrollable high thrust event" and vice versa. A UHT event is defined as a failure to respond to a low thrust command on an engine section, thereby resulting in excessive thrust relative to the command. Many types of faults may cause a UHT event, such as, but not limited to, a runaway or stuck fuel metering valve (FMV). In both cases, the fuel flow does not correspond to the position of the power lever or throttle.

[0017] A turboprop engine has thrust contributions from the engine as well as from the propeller (depending on the propeller blade position). As such, UHT detection for a turboprop engine is different than UHT detection for an engine without a propeller, such as a turbofan engine.

[0018] Example turboprop engine in Figure 110. The aircraft power plant 100 generally includes an engine 100 and a propeller 120. The power plant 100 includes, in serial flow communication, a propeller 120 (which is attached to a shaft 108 and through which ambient air is propelled), a compressor section 114 for pressurizing the air, a combustor 116 (where the compressed air is mixed with fuel and ignited for generating a hot annular flow of combustion gases), and a turbine section 106 for extracting energy from the combustion gases, thereby driving the combustor through the shaft 107 and driving the propeller 120 through the shaft 108 to rotate. The turbine section is formed by a high-pressure turbine 115 and a low-pressure turbine 117. The high-pressure turbine 115 and the compressor section 114 together form a gas generator of the engine 110.

[0019] The propeller 120 converts the rotational motion of the shaft 108 from the engine 110 to provide propulsion, also known as thrust, for the aircraft. The propeller 120 can be a variable pitch propeller capable of generating forward and reverse thrust. The propeller 120 includes two or more propeller blades 122. The blade angle of the propeller blades 122 can be adjusted. The blade angle can be referred to as a β angle, an angle of attack, or a blade pitch. The power plant 100 can be implemented to include a single or multi-shaft gas turbine engine, wherein the turbine section 106 is typically connected to the propeller 120 through a reduction gearbox (RGB).

[0020] refer to Figure 2 , a system 200 for operating the powerplant 100 is illustrated. The control system 210 receives a power lever or throttle position from a power lever 212 of the aircraft under the control of a pilot or other operator of the aircraft. The power lever position indicates the type of thrust required by the power lever 212. Several power lever positions can be selected, including those for: (1) maximum forward thrust (MAX FWD), which is typically used during takeoff; (2) flight idle (FLT IDLE), which can be used during an in-flight approach or during ground gliding; (3) ground idle (GND IDLE), at which the propellers 120 are rotating but providing very low thrust; and (4) maximum reverse thrust (MAX REV), which is typically used during landing to slow the aircraft. Intermediate positions between the above-mentioned positions can also be selected. The power lever position can vary depending on the actual implementation of the power lever 212.

[0021] The control system 210 receives inputs related to the operation of the propeller 120, the engine 110, and / or the aircraft. The control system 210 is configured to detect a UHT event using one or more of the received inputs. In the illustrated embodiment, the control system 210 receives engine speed and / or power. The engine speed and / or power may be received from one or more sensors provided at or near the power plant 100. For example, the engine speed may refer to the rotation speed of the shaft 108, or it may refer to the rotation speed of the gas generator (also referred to as "Ng"). These values ​​may be measured directly from the engine 110 and provided to the control system 210. In some embodiments, the engine power (e.g., the horsepower (also referred to as "SHP") of the shaft 108) may be determined using the shaft rotation speed as received by the control system 210. In some embodiments, the engine speed and / or power is provided to the control system 210 from another engine and / or aircraft system.

[0022] In some embodiments, control system 210 receives an engine acceleration / deceleration rate, such as a rate of change of gas generator speed (also referred to as "NgDot") or a rate of change of rotational speed of shaft 108. Alternatively, the engine acceleration / deceleration rate is calculated by control system 210 based on engine speed.

[0023] In some embodiments, the control system 210 receives aircraft parameters, such as aircraft altitude and flight phase. For example, the flight phase may indicate that the aircraft is in any of the takeoff, final approach, landing, or cruise phases. The flight phase parameters may take various forms, such as a weight on wheels indicator, aircraft airspeed, cockpit inputs, and the like. The aircraft parameters may be received from an aircraft computer. In some embodiments, the flight phase is determined by the control system 210 based on a combination of inputs received by the control system 210.

[0024] The additional inputs received by the control system 210 may vary depending on the actual implementation.

[0025] In general, the control system 210 is configured to control the engine 110 and the propeller 120 based on the received input. The control system 210 controls the engine 110 by outputting a fuel flow request for adjusting the engine fuel flow to the engine actuator 216 and controls the propeller 120 by outputting a propeller blade angle request for adjusting the blade angle of the propeller 120 to the propeller actuator 214. The engine actuator 216 and / or the propeller actuator 214 can each be implemented as a torque motor, a stepper motor or any other suitable actuator. The engine actuator 216 can be implemented as one or more valves that regulate the fuel flow from the fuel source to the engine 110. The control system 210 determines the fuel flow request for adjusting the engine fuel flow and the propeller blade angle request for adjusting the blade angle of the propeller 120 based on the received input. The propeller actuator 214 can control the hydraulic oil pressure to adjust the blade angle based on the propeller blade angle request. In some embodiments, the propeller blade angle request is an oil flow request for setting the propeller blade angle. The engine actuator 216 may adjust the fuel flow to the engine 110 based on the fuel flow request. Although the engine actuator 216 and the propeller actuator 214 are illustrated as being part of the engine 110 and the propeller 120, respectively, it should be understood that this is for illustration purposes only and the engine actuator 216 and / or the propeller actuator 214 may be separate from the power-plant 100 in some embodiments. Although the controller 210 is illustrated as being separate from the power-plant 100, it should be understood that this is for illustration purposes only and the controller 210 may be integrated with the power-plant 100 in some embodiments.

[0026] Reference now Figure 3 , there is illustrated an example method 300 for detecting a UHT event associated with a powerplant 100, such as by a control system 210. Note that the control system 210 may be an electronic engine controller (EEC), a thruster electronic controller (PEC), or a combination thereof. The EEC and PEC may communicate with each other to exchange parameters of the powerplant 100.

[0027] In step 302, the UHT function is enabled when an enabling condition is met. The enabling condition may include aircraft altitude, flight phase, and / or any other condition that is desired to limit the application of the UHT detection method. In some embodiments, the enabling condition is that the aircraft is at an altitude of less than 15,000 feet. Other altitudes may also be used. In some embodiments, the enabling condition is a constant value in software that may be modified for various applications.

[0028] At step 304, once the UHT function is enabled, a UHT event is detected when a UHT condition is met. In some embodiments, the UHT condition includes the position of a power lever of the aircraft. The position may correspond to a particular setting for the power lever, such as flight idle or ground idle, or to an angular position of the power lever. For example, the power lever position may be determined based on a power lever angle (PLA), and the UHT condition may be met when the PLA is less than a value "x". In some embodiments, the value "x" is a constant value in software that may be modified for various applications.

[0029] In some embodiments, the UHT condition includes engine power or speed being above a first threshold. For example, the first threshold may be a power threshold and the UHT condition is met when the SHP of the engine increases above the power threshold. In another example, the first threshold is the requested Ng and the UHT condition is met when the actual Ng increases above the requested Ng.

[0030] In some embodiments, the UHT condition includes a rate of change of engine speed above a second threshold. For example, the second threshold may be the requested NgDot and the UHT condition is satisfied when the actual NgDot increases above the requested NgDot. The second threshold may be the requested NgDot + margin. When considering a positive rate of change of engine speed (i.e., acceleration), the margin may be set using a typical or known response time for an efficient engine. When considering a negative rate of change of engine speed (i.e., deceleration), the margin may be set using a typical or known response time for an inefficient engine. That is, the margin corresponds to a value greater than the expected response time for an efficient or inefficient engine, depending on the circumstances. Reference Figure 4 , graph 400 illustrates the rate of change of engine speed as requested (graph 402) and actual (graph 404). A threshold (graph 406) is separated from the requested rate of change (graph 402) by a margin (ΔAccel / ΔDecel). Regardless of whether the engine is accelerating or decelerating, the UHT condition is satisfied when the actual rate of change (graph 404) is above the threshold (graph 406).

[0031] In some embodiments, the UHT condition is satisfied when a combination of conditions exists. For example, the UHT condition is satisfied when the power lever is in a given position, the engine speed or power is above a first threshold, and the rate of change of the engine speed is above a second threshold.

[0032] Return to reference Figure 3, in step 306, in response to detecting a UHT event, an alert is output to trigger regulation of the UHT event. The alert may be sent to the cockpit of the aircraft, an aircraft computer, an engine computer, or any other aircraft or engine system. In some embodiments, according to step 308, in response to the alert, the engine providing uncommanded high thrust is shut down and the corresponding propeller downstream pitch is engaged. Propeller downstream pitch (which is possible for variable pitch propellers) refers to turning the blades of the propeller so that they are roughly parallel to the airflow and they form a minimum air resistance. On a multi-engine aircraft, engaging the propeller downstream pitch on the ineffective engine reduces the drag and thrust from the ineffective engine and helps maintain the speed and attitude of the effective engine.

[0033] In some embodiments, engine shutdown and thruster downstream spacing are automatically performed upon detection of a UHT event. Automatic engine shutdown and thruster downstream spacing is understood to mean performed without additional pilot input or without an explicit request or command from the aircraft operator. Figure 2 , the control system 210 will shut down the engine 110 via a fuel flow request and pitch the propeller 120 downstream via a propeller blade angle request.

[0034] Specific and non-limiting examples of methods for detecting UHT events are described in Figure 5 6a-6b . In this example, there are four states for the UHT function, namely, preparation 502, enable 504, arm 506, and activation 508. The UHT function is in preparation 502 when the enable condition has not been met. In this example, the enable condition includes a given altitude for the aircraft. When the aircraft is below the given altitude, the UHT function becomes enabled 504. When enabled, the method 500 can detect the UHT condition that will cause the UHT function to become equipped 506. In this example, there are three UHT conditions for confirming a UHT event: power lever position, flight phase, and one of the following: SHP increases above a threshold and NgDot> requested NgDot + margin; or SHP does not fall below a threshold and NgDot> requested NgDot + margin. An example of a scenario represented by the last condition is illustrated in Figures 6a-6b.

[0035] FIG. 6a illustrates a specific UHT scenario where the power of the powerplant increases faster than it should. As shown from graph 600, the SHP accelerates beyond the threshold regardless of the power lever position. This scenario illustrates an uncontrolled FWV, which may occur, for example, during landing, where the PLA is in the flight idle position and the power of the powerplant is reduced. However, due to the uncontrolled FMV, the power of the powerplant begins to increase and continues to increase above the threshold.

[0036] FIG. 6 b illustrates a specific UHT scenario where the power of the powerplant is not decelerating fast enough. Although the power is decelerating, when the PLA moves to idle, the curve 604 exceeds the threshold. This scenario may occur, for example, during an aborted takeoff, where the PLA is set to the takeoff position and the power of the powerplant is at takeoff power. When the takeoff is aborted, the pilot moves the power lever from the takeoff position to the flight idle position. However, due to the FMV being stuck, the power of the powerplant is not reduced fast enough or remains at high power regardless of the PLA position.

[0037] Return to reference Figure 5 , when the UHT function is armed 506, additional verification that the enablement condition is still met may be performed. This allows for scenarios where parameters associated with the enablement condition change during the transition from enable 504 to arm 506. If the enablement condition is no longer met, the UHT function returns to prepare 502. In some embodiments, the UHT function will move from the arm 506 to the activated 508 state only if the UHT condition persists for a given amount of time, such as "Y" seconds. In some embodiments, the value "Y" is a constant value in software that can be modified for various applications.

[0038] When the UHT function is activated 508, UHT adjustments may be performed, such as shutting down the engines and pitching the thrusters downstream. A restart request received by the pilot or other aircraft operator may transition the UHT function back to the ready 502 state.

[0039] Note that more or fewer states may be provided for the UHT function. For example, in some embodiments, the UHT function may transition from enabled to activated without passing through the armed state, thus omitting additional verifications for the enabled condition and the sustained UHT condition. In some embodiments, additional verifications are performed concurrently with detecting the UHT condition when the UHT function is in the enabled state. Other embodiments may also apply.

[0040] Methods 300, 500 therefore provide detection of UHT events and, in some cases, command engine shutdown and thruster downstream spacing. Asymmetric thrust above the UHT threshold is therefore minimized to a level that is controllable by the pilot and the aircraft. In some embodiments, the control system 210 is configured to provide (one or more) cockpit indications that convey the current state of the UHT function, such as ready, enabled, equipped or activated. Other cockpit indications include indicating command engine shutdown and / or command thruster downstream spacing. In some embodiments, they are also displayed in the cockpit when enabling and / or UHT conditions are met.

[0041] refer to Figure 7, illustrating an example of a computing device 700. The control system 210 may be implemented with one or more computing devices 700. For example, each of a thruster controller and an engine controller may be implemented by a separate computing device 700 to perform the functions of the control system 210. The computing device 700 includes a processing unit 712 and a memory 714 having computer executable instructions 716 stored therein. The processing unit 712 may include any suitable device configured to implement the method 300, 500 so that the instructions 716, when executed by the computing device 700 or other programmable device, may cause the functions / actions / steps performed as part of the method 300, 500 as described herein to be performed. The processing unit 712 may include, for example, any type of general purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitable programmed or programmable logic circuits, or any combination thereof.

[0042] The memory 714 may include any suitable known or other machine-readable storage medium. The memory 714 may include a non-transitory computer-readable storage medium, such as, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or apparatus, or any suitable combination of the foregoing. The memory 714 may include a suitable combination of any suitable type of computer memory located inside or outside the device, such as a random access memory (RAM), a read-only memory (ROM), a compact disk read-only memory (CDROM), an electro-optical memory, a magneto-optical memory, an erasable programmable read-only memory (EPROM) and an electrically erasable programmable read-only memory (EEPROM), a ferroelectric RAM (FRAM), or the like. The memory 714 may include any storage component (e.g., a device) suitable for retrievably storing machine-readable instructions 716 executable by the processing unit 712. Note that the computing device 700 may be implemented as part of a full authority digital engine control (FADEC) or other similar device, including an electronic engine control (EEC), an engine control unit (ECU), an electronic thruster control, a thruster control unit, and the like.

[0043] The methods and systems for detecting UHT events described herein may be implemented in a high-level procedural or object-oriented programming or scripting language or a combination thereof to communicate with or help operate a computer system (e.g., computing device 700). Alternatively, the methods and systems for detecting UHT events may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for detecting UHT events may be stored on a storage medium or device, such as a ROM, a disk, an optical disk, a flash drive, or any other suitable storage medium or device. The program code may be readable by a general or special purpose programmable computer for configuring and operating a computer when the storage medium or device is read by the computer to execute the program described herein. Embodiments of the methods and systems for detecting UHT events may also be viewed as being implemented by a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may include computer-readable instructions that cause a computer, or more specifically a processing unit 712 of a computing device 700, to operate in a specific and predefined manner to perform the functions described herein, such as those described in methods 300, 500.

[0044] Computer executable instructions can take many forms, including program modules, that are executed by one or more computers or other devices. Generally speaking, program modules include routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. Typically, the functionality of program modules can be combined or distributed in various embodiments as desired.

[0045] The above description is intended to be exemplary only, and those skilled in the art will recognize that changes can be made to the described embodiments without departing from the scope of the disclosed invention. In view of a review of this disclosure, still other modifications falling within the scope of the invention will be apparent to those skilled in the art.

[0046] Various aspects of the method and system for detecting UHT events may be used alone, in combination, or in a variety of settings not specifically discussed in the previously described embodiments, and are therefore not limited in its application to the details and settings of the components set forth in the previous description or illustrated in the figures. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. Although specific embodiments have been shown and described, changes and modifications may be made in its broader aspects without departing from the present invention, which will be apparent to those skilled in the art. The scope of the following claims should not be limited by the embodiments set forth in the examples, but should be given the broadest reasonable interpretation consistent with the entire description.

Claims

1. A method for operating a power plant of an aircraft during an uncommanded high thrust (UHT) event of the power plant, the power plant comprising an engine and a variable pitch propeller driven by the engine, the method comprising: enabling a UHT detection function associated with the power unit when an enabling condition is met; When the UHT detection function is enabled, the UHT event is detected when a power lever associated with the powerplant is in a given position, a parameter indicative of engine speed or engine power is above a first threshold, a rate of change of the engine speed is above a second threshold, and the aircraft is in a final approach phase of flight; as well as In response to detecting the UHT event: outputting an alert to trigger regulation of the UHT event to the engine; automatically commanding shutdown of said engine of said powerplant; and The variable pitch propeller of the power plant is automatically commanded to intersect downstream. 2 . The method of claim 1 , wherein the enabling condition comprises a predetermined altitude of the aircraft.

3. The method of claim 1, wherein the parameter indicative of engine speed or engine power is shaft horsepower of the engine.

4. The method of claim 1, wherein the parameter indicative of engine speed or engine power is an actual gas generator speed of the engine, and wherein the first threshold is a requested gas generator speed of the engine.

5. The method of claim 1 wherein said second threshold is a requested rate of change of said engine speed plus a margin.

6. The method of claim 5 wherein said rate of change of said engine speed is a rate of acceleration of said engine, and wherein said margin comprises a response time for a high efficiency engine.

7. The method of claim 5 wherein said rate of change of said engine speed is a rate of deceleration of said engine, and wherein said margin includes a response time for an inefficient engine.

8. The method of claim 1, further comprising detecting the UHT event for a predetermined time before outputting the alert to trigger the adjusting.

9. A system for operating a power plant of an aircraft during an uncommanded high thrust (UHT) event of the power plant, the power plant comprising an engine and a variable pitch propeller driven by the engine, the system comprising: at least one processing unit; as well as a non-transitory computer readable medium having program code stored thereon executable by the at least one processing unit, the program code being configured to: enabling a UHT detection function associated with the power unit when an enabling condition is met; When the UHT detection function is enabled, the UHT event is detected when a power lever associated with the powerplant is in a given position, a parameter indicative of engine speed or engine power is above a first threshold, a rate of change of the engine speed is above a second threshold, and the aircraft is in a final approach phase of flight; as well as In response to detecting the UHT event: outputting an alert to trigger regulation of the UHT event to the engine; automatically commanding shutdown of said engine of said powerplant; and The variable pitch propeller of the power plant is automatically commanded to intersect downstream.

10. The system of claim 9, wherein the enabling condition comprises a predetermined altitude of the aircraft.

11. The system of claim 9, wherein the parameter indicative of engine speed or engine power is shaft horsepower of the engine.

12. The system of claim 9, wherein the parameter indicative of engine speed or engine power is an actual gas generator speed of the engine, and wherein the first threshold is a requested gas generator speed of the engine.

13. The system of claim 9 wherein said second threshold is a requested rate of change of said engine speed plus a margin.

14. The system of claim 13 wherein said rate of change of said engine speed is an acceleration rate of said engine, and wherein said margin comprises a response time for a high efficiency engine.

15. The system of claim 13 wherein said rate of change of said engine speed is a rate of deceleration of said engine, and wherein said margin includes a response time for an inefficient engine.

16. The system of claim 9, wherein the program code is further executable to detect the UHT event for a predetermined time before outputting the alert to trigger the adjustment.

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