Patent Description:
Engines such as gas turbines are used to produce thrust for vehicles such as aircraft. It is important to monitor engine health over course of use in order to troubleshoot potential damage and/or changes in engine performance. The ability to accurately monitor engine health helps extend the overall lifespan of the engine and improve its efficiency. Engine health can be determined by monitoring the engine's parameters. By monitoring the changes in the engine's parameters over the course of the engine's life, potential engine health issues and/or engine damage can be efficiently and effectively attended to and/or altogether avoided.

Current methods for monitoring engine health for aircraft include observing an engine parameter(s) such as turbine gas temperature (TGT) and monitoring how the parameter(s) changes over course of use for that engine. In one example, data corresponding to TGT of an engine is obtained for several flights. The data may be normalized in an attempt to correct for various conditions. This data is then trended chronologically to determine if there are any changes in TGT. A sudden increase or decrease in TGT may, for example, indicate a change in engine health. Unfortunately, even with attempting to correct for various conditions, external factors resulting in flight-to-flight variations such as engine idle time or the like produce significant noise in the trended data that make it difficult to accurately determine engine health. <CIT> relates to health monitoring of gas turbine engines. <CIT> relates to an engine monitor for a multi-engine system.

Accordingly, it is desirable to provide methods for monitoring engine health of an aircraft having multiple engines for addressing one or more of the foregoing issues. Furthermore, other desirable features and characteristics of the various embodiments described herein will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.

The present invention relates to a method for monitoring engine health of an aircraft having a first engine and a second engine as defined in claim <NUM>.

The following Detailed Description is merely exemplary in nature and is not intended to limit the various embodiments or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

The present invention relates to methods for monitoring engine health of an aircraft having a first engine and a second engine as defined in the claims. In an exemplary embodiment, the first turbine gas temperature and the second turbine gas temperature are obtained during take-off of the aircraft from a runway. Advantageously, this provides a consistent engine state for obtaining the first turbine gas temperature and the second turbine gas temperature.

The first turbine gas temperature and the second turbine gas temperature are related to each other to define a first value. Relating the first and second turbine gas temperatures includes using the first set of ambient conditions to standardize the first turbine gas temperature and the second turbine gas temperature to define a first standardized turbine gas temperature and a second standardized turbine gas temperature, respectively. Next, a difference between the first standardized turbine gas temperature and the second standardized turbine gas temperature is determined to define the first value. The first value is compared to a data set for monitoring the engine health.

Advantageously, by relating the first turbine gas temperature and the second turbine gas temperature to each other to define a first value and comparing the first value to a data set, flight-to-flight variations in operating and/or ambient conditions are reduced and engine health can be monitored more accurately and effectively. Without being limited by theory, it is believed that this is because the first engine and the second engine are usually operated in a similar fashion prior to take-off, and thus the impact of each engine's operating conditions on turbine gas temperature is experienced substantially similarly by all of the aircraft's engines.

<FIG> illustrate a top view and a perspective view of an aircraft <NUM> that includes propulsion systems <NUM> and <NUM> that each include an engine <NUM>, <NUM> in accordance with an exemplary embodiment. As illustrated, the aircraft <NUM> is disposed on a runway <NUM>. Although the aircraft <NUM> is illustrated as having two engines <NUM> and <NUM>, it is to be understood that various alternate embodiments of the aircraft <NUM> may include the aircraft <NUM> having more than two engines and/or more than two propulsion systems. The aircraft <NUM> includes a fuselage <NUM> as the main body of the aircraft <NUM> that supports wings <NUM> and <NUM>. Depending on the design of the aircraft <NUM>, the engines <NUM> and <NUM> may be attached to the fuselage <NUM>, or alternatively, to the wings <NUM> and <NUM>. Landing gears <NUM> and <NUM> include a nose landing gear <NUM> with a wheel(s) <NUM> disposed under a nose section of the fuselage <NUM> and main landing gears <NUM> with wheels <NUM> and <NUM> disposed under the wings <NUM> and <NUM>, respectively, of the aircraft <NUM>.

As illustrated, the engines <NUM> and <NUM> are gas turbine engines. In some embodiments, the gas turbine engines may comprise turbojet engines or the like. In an exemplary embodiment, a turbojet engine operates by compressing air with an inlet fan and compressor blades that are rotating at operating speeds. Fuel is then mixed with the compressed air. The mixture of fuel and compressed air then moves into the turbojet's combustion chamber where it is ignited, increasing both its temperature and pressure. The hot, high-pressure mixture of air and combustion gases is then passed over a turbine (which drives the compressor blades) and then exits the turbojet engine. After exiting the turbojet engine, the high temperature, high pressure mixture is exhausted by the propulsion system through a nozzle at an aft end of the propulsion system to produce both thrust and a plume of exhaust gas (indicated by single headed arrows <NUM> and <NUM>).

The aircraft <NUM> includes an electronic system <NUM>. The electronic system <NUM> includes various control systems and devices including a flight management system, a memory storage device(s) <NUM>, an engine electronic controller system <NUM>, and other systems that include one or more processors such as a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform various aircraft functions. Moreover, the various systems of the electronic system <NUM> may include one or more displays that are in communication with a processor. The display may be any one of numerous known displays suitable for rendering textual, graphic, and/or iconic information in a format viewable by the pilot, crew member, and/or any other person authorized for such viewing. Further, the various systems of the electronic system <NUM> may be in communication with one or more of the other systems or operate autonomously from the other systems.

In an exemplary embodiment, the engine electronic controller system <NUM> includes a pair of engine electronic controllers <NUM>, each engine electronic controller <NUM> being in communication with a respective engine <NUM> or <NUM>. A throttle quadrant assembly (TQA) <NUM> and/or auto thrust controller <NUM> is in communication with the engine electronic controllers <NUM> to provide engine thrust commands <NUM> and <NUM>, respectively.

<FIG> illustrates an exemplary embodiment of an engine electronic controller <NUM> compatible for use with engines <NUM> and <NUM>. Engine electronic controller <NUM> includes blocks for performing Engine Electronic Controller (EEC) functions. The engine electronic controller <NUM> includes, for example, a processor <NUM>, an engine sensor input-output interface <NUM>, engine valve driver hardware <NUM>. The processor <NUM>, the engine sensor input-output interface <NUM>, the engine valve driver hardware <NUM> are used in performing the EEC functions.

The engine sensor input-output interface <NUM> receives data <NUM> from various engine sub-systems (not illustrated), and provides it to the various sensors <NUM> that may include, for example fluid flow sensors, temperature sensors, speed sensors, valve position sensors, etc. As will be discussed in further detail below, the temperature sensors include a first sensor <NUM> associated with the engine <NUM> and a second sensor <NUM> associated with the engine <NUM>. The sensors <NUM> generate sensor data output signals <NUM> that are provided to the processor <NUM>.

As part of the EEC functions, the processor <NUM> processes data <NUM> provided from various aircraft systems (e.g., including engine thrust commands <NUM> and <NUM> from the throttle quadrant assembly (TQA) <NUM> and/or the auto thrust controller <NUM>) and the sensor data output signals <NUM> to generate engine valve control signals <NUM> that are provided to the engine valve driver hardware <NUM> to control the corresponding engine <NUM>, <NUM> of the aircraft <NUM>. The processor <NUM> also provides data <NUM> to other aircraft systems including for example turbine gas temperature (TGT) of the engines <NUM>, <NUM> to the electronic system <NUM> as will be described in further detail below.

In particular and with reference to <FIG> and <FIG>, each of the engines <NUM>, <NUM> includes the corresponding sensor <NUM>, <NUM> that measures the turbine gas temperature (TGT) of the engine <NUM>, <NUM>. In an exemplary embodiment, the TGT of the engine <NUM>, <NUM> is the temperature of the exhaust gas stream <NUM>, <NUM> for that engine <NUM>, <NUM>, respectively. The sensors <NUM> and <NUM> are, for example, thermocouples or the like. In an exemplary embodiment, the aircraft <NUM> includes the memory storage device <NUM> that receives data corresponding to the TGTs from the sensors <NUM> and <NUM>, respectively.

The TGTs of the engines <NUM> and <NUM> are obtained from and/or during a flight (also referred to herein as "first flight"). As used herein, the term "flight" refers to any time from embarking to disembarking including taxi, take-off, mid-flight, and landing in which at least one of the engines <NUM> and <NUM> is running. The TGTs are obtained from the flight at a set of ambient conditions. The set of ambient conditions includes, for example, an ambient temperature and rotor speeds of the engines <NUM> and <NUM>. The ambient conditions refer to the conditions that are related to and/or impacted by the atmosphere surrounding the aircraft <NUM> at the time in which the TGTs are obtained. For example, the rotor speed of the engines <NUM> and <NUM> are impacted by the altitude at which the aircraft <NUM> takes off from the runway <NUM>. In an exemplary embodiment, the memory storage device <NUM> receives the data corresponding to the ambient conditions.

In an exemplary embodiment, the TGTs are obtained from the flight at about take-off of the aircraft <NUM> from the runway <NUM>. As used herein, the term "take-off' refers to the time at which the wheels <NUM> and <NUM> leave the runway <NUM> and/or the aircraft begins to ascend. As used herein, the term "about" is to be understood to encompass practical limits or tolerances for performing the specified task or event. In an exemplary embodiment, the set of ambient conditions are obtained from the flight at about or during take-off of the aircraft <NUM> from the runway <NUM>.

In an exemplary embodiment, obtaining the TGTs includes extracting data corresponding to the TGTs and the ambient conditions from the memory storage device <NUM> to an external memory storage device <NUM>. For example, the external memory storage device <NUM> may be located at the airport, remote facility, or the like and include one or more processors such as a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform various memory storage functions. The TGTs may be wirelessly communicated via path <NUM>, or alternatively, a communication pathway <NUM> that can be removably coupled to the aircraft, for example when the aircraft <NUM> is docked at the airport after a flight.

The TGTs are related to each other to define a value. In an exemplary embodiment, relating TGTs is performed by an electronic system <NUM>. The electronic system <NUM> is in communication with the external memory storage device <NUM> and includes one or more processors that is operative to use an algorithm to relate, compare, evaluate, and/or analyze the data. Relating the TGTs to each other includes using the set of ambient conditions to standardize the TGTs to define standardized TGTs. For example, the TGT of the engine <NUM> is standardized using the ambient temperature and the rotor speed of engine <NUM> and the TGT of the engine <NUM> is standardized using the ambient temperature and the rotor speed of engine <NUM>. This standardization includes mathematically adjusting the TGTs to what they would have been if they were calculated at a "standard temperature" (e.g., standard temperature of <NUM>) and a "standard rotor speed" (e.g., rotor speed at standard temperature of <NUM> and standard pressure of 1atm).

In an exemplary embodiment, the process of relating the TGTs to each other further includes taking a difference of the standardized TGTs to define the value. As used herein, the term "difference" refers to a mathematical difference between values. For example, taking a difference of <NUM> and <NUM> is <NUM> - <NUM> = -<NUM>, or, alternatively <NUM> - <NUM> = <NUM>.

In an exemplary embodiment, the process described above of obtaining and relating TGTs of the engines <NUM> and <NUM> is repeated for a plurality of flights, with each flight having its own set of ambient conditions. For example, TGTs of the engines <NUM> and <NUM> are obtained from another flight (also referred to herein as "second flight") at a set of ambient conditions. The TGTs of the second flight are related to each other to define a value. This includes using the set of ambient conditions from the second flight to standardize the TGTs and taking a difference of the standardized TGTs to define the corresponding value.

Referring to <FIG> and <FIG>, a data set <NUM> of standardized turbine gas temperatures for the engines <NUM> and <NUM> in accordance with an exemplary embodiment is shown. The data set <NUM> includes a plurality of values <NUM> and <NUM>. Each value <NUM>, <NUM> corresponds to a TGT obtained from one of the engines <NUM> or <NUM> from a specific flight at the set of ambient conditions for that flight. For example, line <NUM> includes standardized TGTs for the engine <NUM> from a plurality of flights in chronological order of flight. Similarly, line <NUM> includes standardized TGTs for the engine <NUM> from the same plurality of flights in chronological order of flight. As such, the plurality of values <NUM> and <NUM> represent the standardized TGTs obtained and related by the process described above for both engines <NUM> and <NUM>, respectively, from a plurality of flights, with each flight having its own set of ambient conditions.

Referring also to <FIG>, a data set <NUM> of a plurality of values <NUM> and a shifted, moving average <NUM> in accordance with an exemplary embodiment is shown. The plurality of values <NUM> correspond to the plurality of values <NUM> and <NUM>. This means that each of the values in the plurality of values <NUM> is defined by taking the difference between the standardized TGTs of the engines <NUM> and <NUM> for each of the flights in the plurality of flights. Line <NUM> includes the plurality of values <NUM> in chronological order of flight.

The plurality of values <NUM> are compared for monitoring engine health of the engines <NUM> and <NUM>. In an exemplary embodiment, comparing is performed by the electronic system <NUM>.

In an exemplary embodiment, comparing includes statistically analyzing at least two values in the plurality of values <NUM>. As used herein, the phrase "statistically analyzing" includes using one or more statistical methods to analyze the values being compared. In an exemplary embodiment, the process of statistically analyzing includes comparing the value from the most-recent flight to the other values in the plurality of values <NUM> of the data set <NUM>. At least one of the values from previous flights is used to produce an average, and the value from the most-recent flight is mathematically compared to the average. For example, if the three most-recent values in chronological order of flight are "<NUM>", "<NUM>", and "<NUM>", the average of (<NUM> + <NUM> + <NUM>)/<NUM> = <NUM> is mathematically compared to the value from the most-recent flight, which is <NUM>.

In an exemplary embodiment, the average is a moving average. For example, if the three most-recent values in chronological order of flight are "<NUM>", "<NUM>", and "<NUM>", a <NUM>-point moving average is (<NUM> + <NUM>)/<NUM> = <NUM>. This is mathematically compared to the value from the most-recent flight, which is <NUM>. If another value is collected and the four most-recent values in chronological order of flight are "<NUM>", "<NUM>", "<NUM>" and "<NUM>", a <NUM>-point moving average is (<NUM> + <NUM>)/<NUM> = <NUM>. This is mathematically compared to the value from the most-recent flight, which is <NUM>. As such, a moving average "moves" to more-recent values as values from new flights arrive in the data set <NUM>. A <NUM>-point moving average is an average of <NUM> values, a <NUM>-point moving average is an average of <NUM> values, and so on. In an exemplary embodiment, the average has a <NUM>-point moving average.

In an exemplary embodiment, the average is a shifted, moving average. For example, if the four most-recent values in chronological order of flight are "<NUM>", "<NUM>", "<NUM>" and "<NUM>", a <NUM>-point moving average with a <NUM>-point shift is (<NUM> + <NUM>)/<NUM> = <NUM>. This is mathematically compared to the value from the most-recent flight, which is <NUM>. The shift controls how recent the values are that are used in the average. A <NUM>-point moving average with no shift, for example, would be an average of the values from the two most-recent flights. Essentially, a shift pushes the calculation for the average back to less-recent data. In an exemplary embodiment, the average has a <NUM>-point shift.

In an exemplary embodiment, mathematically comparing includes taking a difference between the value from the most-recent flight and the average to define a deviation. In an exemplary embodiment, the deviation is a moving deviation sum. For example, if the five most-recent values in chronological order of flight are "<NUM>", "<NUM>", "<NUM>", "<NUM>", "<NUM>", and a <NUM>-point moving average with a <NUM>-point shift is (<NUM> + <NUM> + <NUM>)/<NUM> = <NUM>, then a <NUM>-point moving deviation sum is (<NUM>-<NUM>) + (<NUM>-<NUM>) + (<NUM>-<NUM>) = <NUM>. In an exemplary embodiment, the deviation is converted into sigma units. For example, a standard deviation is used to convert the deviation into sigma units. If the five most-recent values in chronological order of flight are "<NUM>", "<NUM>", "<NUM>", "<NUM>", "<NUM>" and the standard deviation (sigma) for the standardized TGTs of the engine is <NUM>, then a <NUM>-point moving average with a <NUM>-point shift is (<NUM> + <NUM> + <NUM>)/<NUM> = <NUM> and a <NUM>-point moving deviation sum is (<NUM>-<NUM>) + (<NUM>-<NUM>) + (<NUM>-<NUM>) = <NUM> = <NUM>/<NUM> sigma units = <NUM> sigma units. In an exemplary embodiment, the deviation is a <NUM>-point moving deviation sum.

In an exemplary embodiment, comparing includes comparing the deviation to a threshold value. For example, if the value of the deviation is greater than the threshold value, this predicts that there is an issue with engine health. If the value of the deviation is less than the threshold values, this predicts that there is not an issue with engine health. In an exemplary embodiment, the threshold value is <NUM> sigma units. In an exemplary embodiment, a communication relating to engine health is sent from the electronic system <NUM> to a user interface <NUM> in response to comparing the deviation to the threshold value. For example, an "alert", "warning", or "notice" is sent from the electronic system <NUM> to the user interface <NUM> in response to the value of the deviation being greater than the threshold value.

Referring to <FIG>, a method <NUM> for monitoring engine health of an aircraft having a first engine and a second engine in accordance with an exemplary embodiment is provided. The method <NUM> includes obtaining (STEP <NUM>) a first turbine gas temperature of the first engine and a second turbine gas temperature of the second engine from a first flight. The first turbine gas temperature and the second turbine gas temperature are related (STEP <NUM>) to each other to define a first value. The first value is compared (STEP <NUM>) to a data set for monitoring engine health.

Referring to <FIG>, a method <NUM> for monitoring engine health of an aircraft having a first engine and a second engine in accordance with an exemplary embodiment is provided. The method <NUM> includes obtaining (STEP <NUM>) a first turbine gas temperature of the first engine and a second turbine gas temperature of the second engine form a first flight. A third turbine gas temperature of the first engine and a fourth turbine gas temperature of the second engine from a second flight is obtained (STEP <NUM>). The first turbine gas temperature and the second turbine gas temperature are related (STEP <NUM>) to each other to define a first value. The third turbine gas temperature and the fourth turbine gas temperature are related (STEP <NUM>) to each other to define a second value. The method <NUM> further includes comparing (STEP <NUM>) the first value and the second value to monitor the engine health.

Claim 1:
A method for monitoring engine health of an aircraft (<NUM>) having a first gas turbine engine (<NUM>) and a second gas turbine engine (<NUM>), the method comprising the steps of:
obtaining a first turbine gas temperature of the first gas turbine engine (<NUM>) and a second turbine gas temperature of the second gas turbine engine (<NUM>) from a first flight;
relating the first turbine gas temperature and the second turbine gas temperature to each other to define a first value; and
comparing the first value to a data set for monitoring the engine health
wherein the obtaining step includes obtaining the first turbine gas temperature of the first gas turbine engine (<NUM>) and the second turbine gas temperature of the second gas turbine engine (<NUM>) from the first flight at a first set of ambient conditions, and
wherein the relating step includes using the first set of ambient conditions to standardize the first turbine gas temperature and the second turbine gas temperature to define a first standardized turbine gas temperature and a second standardized turbine gas temperature, respectively, wherein said standardization includes mathematically adjusting the turbine gas temperatures to what they would have been if they were calculated at a standard temperature and a standard rotor speed.