Method and system for limiting engine power

Abstract

Systems and methods for limiting the power of a gas turbine engine of an aircraft are described herein. A blade angle of a propeller blade of the engine and a commanded power for the engine are acquired. A thrust transition direction is determined. The commanded power is compared to a threshold selected based on the blade angle and the thrust transition direction. When the commanded power exceeds the selected threshold, the power of the engine is limited.

Description

Technical Field

[0001] This disclosure generally relates to engine control, and more specifically to limiting engine power. Background Technology

[0002] Turboprop engines used in aircraft can reverse the angle of their propeller blades to generate reverse thrust during landing or ground maneuvers. When thrust is commanded to reverse, the propeller blades pass through a disking range, where the blade angle changes from a positive to a negative angle. If engine power is not controlled while passing through the disking range, the propeller may overspeed or vibrate.

[0003] Therefore, there is room for improvement. Summary of the Invention

[0004] In one aspect, a method for limiting the power of a gas turbine engine in an aircraft is provided. The method includes: acquiring the blade angles of the engine's propeller blades and a commanded power for the engine; determining the thrust reversal direction of the engine; comparing the commanded power with a threshold selected based on the blade angles and the thrust reversal direction; and limiting the engine power when the commanded power exceeds the selected threshold.

[0005] On the other hand, a system for limiting the power of a gas turbine engine in an aircraft is provided. The system includes a processing unit and a non-transitory computer-readable storage device on which program instructions executable by the processing unit are stored. The program instructions, executable by the processing unit, are used to: acquire the blade angles of the engine's propeller blades and a commanded power for the engine; determine the thrust conversion direction of the engine; compare the commanded power with a threshold selected based on the blade angles and the thrust conversion direction; and limit the engine power when the commanded power exceeds the selected threshold.

[0006] On the other hand, a non-transitory computer-readable medium is provided on which program instructions for limiting the power of an aircraft's gas turbine engine are stored. These program instructions are executable by a processing unit to: acquire the blade angles of the engine's propeller blades and a commanded power for the engine; determine the thrust reversal direction of the engine; compare the commanded power with a threshold selected based on the blade angles and the thrust reversal direction; and limit the engine power when the commanded power exceeds the selected threshold. Attached Figure Description

[0007] Now referring to the attached diagram, in which:

[0008] Figure 1 This is a schematic cross-sectional view of an example aircraft engine;

[0009] Figure 2 It is a flowchart illustrating an example method for limiting engine power according to an embodiment;

[0010] Figure 3A This is an example illustration of a first threshold used to limit power;

[0011] Figure 3B This is an example illustration of a second threshold used to limit power;

[0012] Figure 4 Here is an example illustration of a propeller speed limiter; and

[0013] Figure 5 This is for implementation according to the embodiments. Figure 2 A schematic diagram of an example computational system for the method.

[0014] It will be noted that, throughout the accompanying figures, similar features are identified by similar figure reference numerals. Detailed Implementation

[0015] Figure 1 The illustration shows a gas turbine engine 10 for which power can be limited using the systems and methods described herein. It should be noted that although engine 10 is a turboprop engine, the methods and systems for limiting engine power are applicable to other types of propeller-driven aircraft engines.

[0016] Engine 10 typically includes a series flow communication: a propeller 120 attached to a shaft 108 and propelling surrounding air through the propeller; a compressor section 114 for pressurizing the air; a combustion chamber 116 in which compressed air is mixed with fuel and ignited to generate an annular hot combustion gas flow; and a turbine section 106 for extracting energy from the combustion gas.

[0017] The propeller 120 includes one or more propeller blades 122. The blade angle of the propeller blade 122 can be adjusted from a positive blade angle to a negative blade angle, or vice versa. The blade angle may be referred to as the angle of attack or blade pitch. When the blade angle changes between a positive and a negative blade angle, or vice versa, the blade angle change is achieved through a rotation range. The rotation range refers to the range of blade angles that produce minimal drag from the propeller 120.

[0018] Reference Figure 2 A flowchart is shown, illustrating the methods used to limit the engine (e.g.) Figure 1 Example method 200 for the power of engine 10). Although referenced herein. Figure 1 Method 200 is described using engine 10 as an example; however, this is for illustrative purposes. Method 200 can be applied to other types of engines depending on the actual implementation.

[0019] At step 202, the blade angle is obtained. The blade angle can be obtained from one or more of the propeller blades 122. In some embodiments, the blade angle is obtained from a blade angle measuring device comprising one or more sensors for measuring the angle of one or more propeller blades 122. The blade angle can be measured at a specific point along the length of one of the propeller blades 122. The obtained blade angle can be in degrees or radians. In some embodiments, the blade angle can be obtained by measuring the position or movement of a beta ring of the engine 10, wherein the position of the beta ring depends on the blade angle. For example, a beta valve can be connected to the propeller 120 via the beta ring, wherein the beta valve is used to control the blade angle. The movement or position of the beta ring can be measured in inches, centimeters, etc. The blade angle can be determined from the movement or position of the beta ring.

[0020] In some embodiments, the blade angle of the propeller blade 122 is obtained from a control system or aircraft engine computer that generates the blade angle for controlling the propeller blade 122. For example, the blade angle may be obtained from a database associated with the control system or aircraft engine computer.

[0021] The blade angle can be obtained dynamically in real time as needed, or periodically at any predetermined time interval. The blade angle can be actively retrieved or passively received. For example, the blade angle can be retrieved and / or received from a blade angle measuring device, a control system, or an aircraft / engine computer. In some embodiments, the blade angle is obtained via existing components that are part of engine control and / or operation. Alternatively, for the purposes of method 200, only the blade angle is provided. In some embodiments, the blade angle measuring device may be separate from engine 10 and associated with other components of the aircraft. In some embodiments, step 202 includes triggering the measurement of the blade angle whenever method 200 begins.

[0022] At step 204, the commanded power of engine 10 is obtained. The commanded power of engine 10 refers to the power commanded by the aircraft's pilot. For example, the commanded power may correspond to the power commanded by one or more engine control sticks, which can be controlled by the pilot. The one or more engine control sticks may include one or more of the following: a thrust stick, a power stick, and / or any other suitable mechanism for commanding the power of engine 10. The commanded power of engine 10 may be obtained based on the position of one or more engine control sticks (e.g., by monitoring the position of one or more engine control sticks). The position of each engine control stick may be defined by an angle. For example, the position of the power stick may be referred to as the power stick angle (PLA). In some embodiments, the commanded power of engine 10 is obtained based on the position of the PLA.

[0023] Command power can be acquired dynamically and in real time as needed, or periodically at any predetermined time intervals. Command power can be actively retrieved or passively received. For example, command power can be retrieved and / or received from a command power measurement device that includes one or more sensors for measuring command power. By another example, command power can be retrieved and / or received from one or more engine control sticks, control systems, or aircraft / engine computers. In some embodiments, command power is acquired via existing components that are part of engine control and / or operation. In some embodiments, step 204 includes triggering a measurement of command power whenever method 200 begins.

[0024] At step 206, the thrust reversal direction is determined. Thrust refers to the force generated by engine 10 through propeller 120. The thrust of engine 10 typically depends on the blade angle and rotational speed of propeller blade 122. In some embodiments, the thrust of engine 10 is a forward thrust used to move the aircraft forward. When engine 10 generates forward thrust, the blade angle of propeller blade 122 is at a positive angle. In some embodiments, the thrust of engine 10 is a reverse thrust used to move the aircraft in the opposite direction or for braking. When engine 10 generates reverse thrust, the blade angle of propeller blade 122 is at a negative angle. The thrust reversal direction can be a forward-to-reverse thrust reversal or a reverse-to-forward thrust reversal. When the thrust reversals from forward thrust to reverse thrust, the blade angle of propeller blade 122 changes from a positive blade angle to a negative blade angle, and through a rotation range. Similarly, when the thrust changes from reverse thrust to forward thrust, the blade angle of the propeller blade 122 changes from a negative blade angle to a positive blade angle, and through the rotation range.

[0025] Thrust can be controlled via one or more engine control levers. One or more engine control levers may include one or more of the following: a thrust lever, a power lever, and / or any other suitable mechanism for controlling the thrust of engine 10. For example, an engine control lever may include a mechanism for controlling the direction of thrust. The direction of thrust change may be determined based on the position of one or more engine control levers. For example, the direction of thrust change may be determined by monitoring one or more engine control levers (such as a mechanism for controlling the direction of thrust). The direction of thrust change may be determined by dynamically acquiring the position of one or more engine control levers in real time when needed, or by periodically acquiring the position of one or more engine control levers at any predetermined time interval. The position of one or more engine control levers may be actively retrieved or passively received.

[0026] At step 208, the commanded power is compared with a threshold selected based on the blade angle and thrust change direction.

[0027] Additional references Figure 3A and Figure 3B The first threshold 301 and the second threshold 302 are illustrated. One of the first threshold 301 and the second threshold 302 can be selected based on the blade angle and the thrust change direction for comparison with the commanded power.

[0028] In some embodiments, when the thrust change direction is a forward-to-reverse thrust change, the commanded power is compared with a first threshold 301 until the blade angle reaches a first shift angle 321, and after the blade angle reaches the first shift angle 321, the commanded power is compared with a second threshold 302. In other words, for a forward-to-reverse thrust change, the first threshold 301 can be selected when the blade angle is greater than the first shift angle 321, and the second threshold 302 can be selected when the blade angle is less than the first shift angle 321. The first shift angle 321 is a negative angle. The first shift angle 321 can be -1°, -2°, -3°, -4°, -5°, -6°, -7°, -8°, -9°, or any other suitable value. The first shift angle 321 can be in the range of -10° to -0.1°. Other values ​​of the first shift angle 321 are also considered.

[0029] In some embodiments, when the thrust change direction is a reverse-to-forward thrust change, the commanded power is compared with a second threshold 302 until the blade angle reaches a second shift angle 322, and after the blade angle reaches the second shift angle 322, the commanded power is compared with a first threshold 301. In other words, for a reverse-to-forward thrust change, the second threshold 302 can be selected when the blade angle is less than the second shift angle 322, and the first threshold 301 can be selected when the blade angle is greater than the second shift angle 322. The second shift angle 322 is a positive angle. The second shift angle 322 can be 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, or any other suitable value. The second shift angle 322 can be in the range of 0.1° to 10°. Other values ​​for the second shift angle 322 are also considered.

[0030] According to an embodiment, the first threshold 301 varies as a function of the blade angle. For example, as... Figure 3A As shown, for a first positive range 331 of blade angle, the first threshold 301 may increase with the increase of blade angle. For a second range 332 of blade angle, the first threshold 301 may be constant, wherein the second range 332 is smaller than the first positive range 331. In some embodiments, the first positive range 331 of blade angle is defined as the range between the second turning angle 322 and the upper endpoint 352. When the blade angle is greater than the upper endpoint 352, the thresholds 301 and 302 may become ineffective.

[0031] According to an embodiment, the second threshold 302 varies as a function of the blade angle. For example, as... Figure 3B As shown, for a first negative range 341 of the blade angle, the second threshold 302 may decrease as the blade angle increases. For a second range 332 of the blade angle, the second threshold 302 may be constant, wherein the second range 332 is greater than the first negative range 341. In some embodiments, the first negative range 341 of the blade angle is defined as the range between the lower endpoint 351 and the first turning angle 321. When the blade angle is less than the lower endpoint 351, the thresholds 301 and 302 may become ineffective.

[0032] The second range 332 may be defined as the range between the first turning angle 321 and the second turning angle 322. The second range 332 may be selected such that all or part of the rotation range is included within the second range 332.

[0033] Refer back Figure 2 In step 210, when the commanded power exceeds the selected threshold, the power of engine 10 is limited.

[0034] When the first threshold 301 is selected, the power of the engine 10 can be limited based on the first threshold 301. As an example, and referring to... Figure 3A When the thrust reversal direction is from forward to reverse, as set by the pilot, the pilot may additionally set the engine control lever from the first commanded power 369 to the second commanded power 370 to increase the commanded power. The first commanded power 369 and the second commanded power 370 illustrate the commanded power as set by the engine control lever and not the actual power of engine 10. Curve 371 illustrates the power of engine 10 as a function of blade angle. In this example, when the blade angle decreases due to the thrust reversal from forward to reverse, and when the commanded power has increased, the engine power (as illustrated by curve 371) is limited by a first threshold 301. When the blade angle reaches the first reversal angle 321, a second threshold 302 is then selected to limit the power of engine 10, and is not described in this example.

[0035] Similarly, when the second threshold 302 is selected, the power of the engine 10 can be limited based on the second threshold 302. For example, and referring to... Figure 3B When the thrust reversal direction is reversed to forward, as set by the pilot, the pilot may additionally shift the engine control lever from the third commanded power 379 to the fourth commanded power 380 to increase the commanded power. The third commanded power 379 and the fourth commanded power 380 illustrate the commanded power as set by the engine control lever and not the actual power of engine 10. Curve 381 illustrates the power of engine 10 as a function of blade angle. In this example, when the blade angle increases due to the thrust reversal to forward, and when the commanded power has already increased, the engine power (as illustrated by curve 381) is limited by a second threshold 302. When the blade angle reaches the second reversal angle 322, the first threshold 301 is then selected to limit the power of engine 10, and is not described in this example.

[0036] The power of engine 10 can be limited in several ways. For example, limiting the power of engine 10 may include limiting the engine rotation speed by adjusting an engine rotation speed schedule used to control the engine rotation speed as a function of engine power. For example, a modified core rotation speed (NgN) may be limited. For example, power limits in one or more NgN schedules may be adjusted to limit the power of engine 10. This may be suitable for systems where propeller speed control has limited authority within the turn range and / or reverse thrust range.

[0037] By way of another example, limiting the power of engine 10 may include directly controlling the rotational speed of propeller blades 122 by adjusting the fuel flow to engine 10. Since torque is a function of blade angle, the power of engine 10 can be limited by adjusting the fuel flow based on a propeller speed limiter. The propeller speed limiter can be implemented through one or more schemes that vary with ambient conditions, engine control levers (e.g., PLA), and / or blade angle. (See reference...) Figure 4 An example propeller speed limiter 402 is shown. Additionally, a first curve 404 is shown, illustrating an example of the rotational speed of the propeller blade 122 as a function of the blade angle for landing maneuvers. A second curve 406 is also shown, illustrating an example of the rotational speed of the propeller blade 122 as a function of the blade angle for ground maneuvers. As shown, the propeller speed limiter 402 varies as a function of the blade angle. In some embodiments, the propeller speed limiter 402 has a first constant value for the reverse thrust range of the blade angle corresponding to the reverse thrust of the engine 10, a second constant value for the turn range of the blade angle 424 corresponding to the turn range of the engine 10, and a third constant value for the forward thrust range of the blade angle 426 corresponding to the forward thrust of the engine 10. Accordingly, limiting the power of the engine 10 may include limiting the rotational speed of the propeller blades such that the rotational speed of the propeller blade 122 does not exceed the propeller speed limiter 402.

[0038] By way of another example, limiting the power of engine 10 may include controlling one or more of the following: variable inlet guide vanes of engine 10, electronically actuated vent valve, direct fuel flow scheme and / or any other mechanical components and / or control systems. Other methods for limiting the power of engine 10 are also considered.

[0039] In some embodiments, at least one threshold 301, 302 is selected for the entire range of movement of the engine control lever (e.g., PLA). For example, a first threshold 301 may be selected when the engine is started. The first threshold 301 is selected when the engine 10 is operated to generate forward thrust. The first threshold 302 is selected when the engine control lever is moved from forward thrust to reverse thrust. The threshold changes from the first threshold 301 to the second threshold 302 when the blade angle is less than the first turn angle 321. The second threshold 302 is selected for all engine control lever movements when the blade angle is less than the second turn angle 322. The second threshold 302 is selected when the engine control lever is moved from reverse thrust to forward thrust. The threshold changes from the second threshold 302 to the first threshold 301 when the blade angle is greater than the second turn angle 322.

[0040] In some embodiments, thresholds 301 and 302 are selected for only specific ranges of movement of the engine control lever (e.g., PLA). For example, when the engine is started, neither the first threshold 301 nor the second threshold 302 is selected. In other words, there may be no power limitation on engine 10 until the pilot commands reverse thrust by reversing the engine control lever. When the engine control lever moves in the opposite direction, the first threshold 301 may then be selected until the blade angle is less than the first turn angle 321 position, and then the threshold transitions from the first threshold 301 to the second threshold 302. When the engine control lever moves from reverse thrust to forward thrust, the second threshold is selected until the blade angle is greater than the second turn angle 322; then the threshold transitions from the second threshold 302 to the first threshold 301. After the blade angle is greater than the upper endpoint 352, the first threshold 301 is deactivated, such that neither the first threshold 301 nor the second threshold 302 is selected.

[0041] The effect of limiting the power of engine 10 based on thresholds 301 and 302 is that the protection of engine 10 is not achieved mechanically through linkage mechanisms or friction (e.g., by limiting the movement of one or more control levers), but rather through power limiting on engine 10. This protection is effective even if the pilot forcefully moves the control lever from the forward thrust power or idle position to the maximum reverse power position and / or when the pilot forcefully moves the control lever from the reverse thrust power position to the maximum takeoff position.

[0042] As described herein, thresholds 301 and 302 can be selected based on the blade angle and thrust change direction. The selection of thresholds 301 and 302 based on blade angle and thrust change direction is designed to produce hysteresis in limiting the power of engine 10 during the turn range. Therefore, it can prevent or reduce initial acceleration caused by the pilot abruptly moving the control stick to the maximum reverse power position or the maximum takeoff position. That is, if the power of engine 10 initially increases after the blade angle has reached the point where the limiter is activated and limits the power of engine 10, initial acceleration will occur.

[0043] Thresholds 301 and 302 may depend on operating conditions, such as aircraft speed, altitude, air temperature, and / or any other suitable ambient conditions. Accordingly, thresholds 301 and 302 used in method 200 may be selected from a set of thresholds based on the ambient conditions. For example, sensors may be used to measure the ambient conditions.

[0044] Thresholds 301 and 302 can be determined through computer simulation and / or engine testing.

[0045] It should be understood that, according to method 200, limiting the power of engine 10 prevents an increase in the power of engine 10 when one or more propeller blades 122 pass through the rotation range.

[0046] Reference Figure 5 Method 200 may be implemented via a computing device 510, which includes a processing unit 512 and a memory 514 in which computer-executable instructions 516 are stored. The processing unit 512 may include any suitable means configured to implement a system such that when the instructions 516 are executed by the computing device 510 or other programmable device, the instructions 516 cause the functions / behaviors / steps of method 200 as described herein to be performed. The processing unit 512 may include, for example, any type of general-purpose microprocessor or microcontroller, digital signal processing (DSP) processor, central processing unit (CPU), integrated circuit, field-programmable gate array (FPGA), reconfigurable processor, other suitable programmable or programmable logic circuitry, or any combination thereof.

[0047] Memory 514 may include any suitable known or other machine-readable storage medium. Memory 514 may include non-transitory computer-readable storage media, such as, but not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any suitable combination thereof. Memory 514 may include suitable combinations of any type of computer memory located internally or externally to the device, such as random access memory (RAM), read-only memory (ROM), optical disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), ferroelectric RAM (FRAM), etc. Memory 514 may include any storage mechanism (e.g., device) adapted to retrievably store machine-readable instructions 516 executable by processing unit 512. Note that computing device 510 may be implemented as part of a full authority digital engine control (FADEC) or other similar devices including electronic engine control (EEC), engine control unit (EUC), etc.

[0048] The methods and systems for limiting power described herein can be implemented in a high-level procedural or object-oriented programming language or scripting language, or a combination thereof, to communicate with or assist the operation of a computer system, such as computing device 510. Alternatively, the methods and systems for limiting power can be implemented in assembly language or machine language. The language can be a compiled language or an interpreted language. The programming code for implementing the methods and systems for limiting power can be stored on a storage medium or device, such as ROM, magnetic disk, optical disk, flash drive, or any other suitable storage medium or device. When the storage medium or device is read by a computer to perform the processes described herein, the programming code can be read by a general-purpose or special-purpose programmable computer for configuring and operating the computer. Embodiments of the methods and systems for limiting power can also be conceived as being implemented via a non-transitory computer-readable storage medium on which a computer program is stored. The computer program may include computer-readable instructions that cause the computer, or in some embodiments, the processing unit 512 of computing device 510, to operate in a particular and predetermined manner to perform the functions described herein.

[0049] Computer-executable instructions can take many forms, including program modules, which are executed by one or more computers or other devices. Generally, program modules include programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. Typically, in various embodiments, the functionality of program modules can be combined or allocated as needed.

[0050] The above description is intended to be illustrative only, and those skilled in the art will recognize that variations may be made to the described embodiments without departing from the scope of the disclosed invention. In light of this review, other modifications falling within the scope of the invention will be apparent to those skilled in the art.

[0051] Various aspects of the methods and systems for limiting the power of an aircraft engine may be used individually, in combination, or in various arrangements not specifically discussed in the embodiments described above. Therefore, in their application, they are not limited to the details and arrangements of the components stated in the above description or illustrated in the accompanying drawings. For example, aspects described in one embodiment may be combined in any way with aspects described in other embodiments. Although specific embodiments have been shown and described, it will be apparent to those skilled in the art that variations and modifications may be made in their broader aspects without departing from the invention. The scope of the appended claims is not to be limited by the embodiments set forth in the examples, but should be given the widest reasonable interpretation in accordance with the specification.

Claims

1. A method for limiting the power of a gas turbine engine of an aircraft, the method comprising: obtaining a blade angle of a propeller blade of an engine and a command power for the engine; determining a thrust conversion direction of the engine; selecting a threshold based on the thrust transition direction and the blade angle, the threshold defining a power limit of the engine as a function of the blade angle for the thrust transition direction; comparing a commanded power to a selected threshold based on the blade angle and the thrust transition direction; as well as When the commanded power exceeds a selected threshold, the engine power is limited.

2. The method of claim 1, wherein: Comparing the command power to a selected threshold includes: When the thrust change direction is a thrust change from forward to reverse, comparing the command power with a first threshold until the blade angle reaches a first change angle; and After the blade angle reaches the first transition angle, the command power is compared with a second threshold.

3. The method of claim 2, wherein: The first threshold increases with increasing blade angle for a first positive range of blade angles and is constant for a second range of blade angles, the second range being smaller than the first positive range.

4. The method of claim 3, wherein: For a first negative range of blade angles, the second threshold increases as the blade angle decreases, and for a second range of blade angles, the second threshold is constant, the second range being larger than the first negative range.

5. The method of claim 1, wherein: Comparing the command power to a selected threshold includes: When the thrust transition direction is a thrust transition from reverse to forward, comparing the command power with a second threshold until the blade angle reaches a second transition angle; and After the blade angle reaches the second transition angle, the command power is compared with a first threshold.

6. The method of claim 1, wherein: Limiting the power of the engine includes adjusting the rotational speed of the engine.

7. The method of claim 1, wherein: Limiting the power of the engine involves directly controlling the speed of the propeller blades by regulating the flow of fuel to the engine.

8. The method of claim 1, wherein: Limiting the power of the engine includes controlling one or more of variable inlet guide vanes, electronically actuated blowdown valves, and direct fuel flow scheduling.

9. The method of claim 1, further comprising selecting the threshold based on ambient conditions.

10. A system for limiting the power of a gas turbine engine of an aircraft, the system comprising: Processing unit; as well as a non-transitory computer readable memory having stored thereon program instructions executable by the processing unit for: obtaining a blade angle of a propeller blade of the engine and a command power for the engine; Determine the direction of engine thrust change; selecting a threshold based on the thrust transition direction and the blade angle, the threshold defining a power limit of the engine as a function of the blade angle for the thrust transition direction; comparing a commanded power to a selected threshold based on the blade angle and the thrust transition direction; as well as When the commanded power exceeds a selected threshold, the engine power is limited.

11. The system of claim 10, wherein: Comparing the command power to a selected threshold includes: When the thrust change direction is a thrust change from forward to reverse, comparing the command power with a first threshold until the blade angle reaches a first change angle; and After the blade angle reaches the first transition angle, the command power is compared with a second threshold.

12. The system of claim 11, wherein: The first threshold increases with increasing blade angle for a first positive range of blade angles and is constant for a second range of blade angles, the second range being smaller than the first positive range.

13. The system of claim 12, wherein: For a first negative range of blade angles, the second threshold increases as the blade angle decreases, and for a second range of blade angles, the second threshold is constant, the second range being larger than the first negative range.

14. The system of claim 10, wherein: Comparing the command power to a selected threshold includes: When the thrust transition direction is a thrust transition from reverse to forward, comparing the command power with a second threshold until the blade angle reaches a second transition angle; and After the blade angle reaches the second transition angle, the command power is compared with a first threshold.

15. The system of claim 10, wherein: Limiting the power of the engine includes adjusting the rotational speed of the engine.

16. The system of claim 10, wherein: Limiting the power of the engine involves directly controlling the speed of the propeller blades by regulating the flow of fuel to the engine.

17. The system of claim 10, wherein: Limiting the power of the engine includes controlling one or more of variable inlet guide vanes, electronically actuated blowdown valves, and direct fuel flow scheduling.

18. The system of claim 10, wherein: The program instructions may be further executed by the processing unit to select the threshold value based on the surrounding conditions.

19. A non-transitory computer readable medium having stored thereon program instructions for limiting the power of a gas turbine engine of an aircraft, the program instructions being executable by a processing unit for: obtaining a blade angle of a propeller blade of the engine and a command power for the engine; Determine the direction of engine thrust change; selecting a threshold based on the thrust transition direction and the blade angle, the threshold defining a power limit of the engine as a function of the blade angle for the thrust transition direction; comparing a commanded power to a selected threshold based on the blade angle and the thrust transition direction; as well as When the commanded power exceeds a selected threshold, the engine power is limited.

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