Patent Description:
Propeller powered aircraft, small and large, require propeller balancing at some point in time. Some require balancing more often than others.

Many systems require the aircraft to be on the ground to perform engine runs in order to collect the data needed for propeller balancing. This is not an effective solution as the ground data is not truly representative of inflight conditions. Other systems will collect data inflight and provide it to a ground station post-flight for analysis. However, such systems are programmed to gather data at specific points in time, which again does not consider specific operational conditions of the flight.

Therefore, there is room for improvement.

<CIT> discloses propeller balancing using inflight data.

In one aspect, there is provided a method for propeller balancing of an aircraft as set forth in claim <NUM>.

In another aspect, there is provided a system for propeller balancing of an aircraft as set forth in claim <NUM>.

There is described herein systems and methods for propeller balancing on propeller-powered aircraft. The aircraft is equipped with an engine, such as a turboprop engine having a propeller. <FIG> illustrates an exemplary gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication an inlet <NUM> through which ambient air is propelled, a compressor section <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases. The turbine section <NUM> illustratively comprises a compressor turbine <NUM>, which drives the compressor assembly and accessories, and at least one power or free turbine <NUM>, which is independent from the compressor turbine <NUM> and drives the rotor shaft <NUM> through a reduction gearbox (RGB) <NUM>. Hot gases may then be evacuated through exhaust stubs <NUM>. Other configurations for a free turbine turboprop engine <NUM> may also apply.

A propeller <NUM> through which ambient air is propelled, is composed of a propeller hub <NUM> and blades <NUM>. The propeller <NUM> converts rotary motion from the engine <NUM> to provide propulsive force to the aircraft.

<FIG> illustrates an example aircraft <NUM>, which may be any type of propeller-driven aircraft <NUM>. At least one sensor <NUM> is provided per engine (reference <NUM> in <FIG>) of the aircraft <NUM>, for collecting measurement data from the propeller <NUM> while the aircraft is in flight. The sensor(s) <NUM> may comprise, but are not limited to, at least one accelerometer, at least one phase angle sensor, at least one torque sensor, and/or at least one altitude meter. The measurement data collected by the sensor(s) <NUM> may be referred to as "full-flight data". As used herein, the term "full-flight data" refers to data (aircraft and engine operational data parameters) which is collected in real-time, throughout the duration of a flight of the aircraft <NUM>, to provide a complete indication of engine performance during flight, as opposed to snapshot data, which is collected at one point in time during flight and not in real-time. In one embodiment, the measurement data corresponds to the acceleration of the front of the engine <NUM> in a direction normal to the propeller shaft. When the propeller <NUM> is out of balance, as the center of mass rotates around the axis of rotation, the resulting centripetal force tries to pull the propeller <NUM> towards the center of mass. This rotating imbalance force acts on the mass of the engine <NUM> and propeller <NUM> and accelerates it. This acceleration is measured by the sensor(s) <NUM>.

The sensor(s) <NUM> may be mounted directly on the engine <NUM>, proximate to the propeller <NUM>, in order to measure the acceleration of the propeller <NUM> as well as the phase angle of the propeller shaft. The installation may be permanent or temporary. A permanent mount may be performed during manufacture of the engine <NUM>. When the aircraft <NUM> is assembled, the sensor(s) <NUM> may be connected to an existing aircraft harness (not shown). One or more additional cables, adapters, connectors, and/or harnesses may be added in order to connect the sensor(s) <NUM> to the existing aircraft harness. A temporary mount may be performed after manufacture of the engine <NUM> and/or after aircraft assembly, such as during aircraft maintenance.

The measurement data collected by the sensor(s) <NUM> may be transmitted to an aircraft-mounted electronic device (referred to herein as a "data acquisition and transmission unit" <NUM>), via the existing aircraft harness and/or additional cables, adapters, connectors, and/or harnesses. Alternatively, transmission of the data collected by the sensor(s) <NUM> is performed wirelessly. Therefore, the sensor(s) <NUM> may be configured for providing the measurement data to the data acquisition and transmission unit <NUM> via any suitable wired or wireless communication path, including RS-<NUM>, USB, USB <NUM>, USB <NUM>, USB-C, SATA, e-SATA, ThunderboltTM, Ethernet, Wi-Fi, ZigbeeTM, BluetoothTM, and the like.

The data acquisition and transmission unit <NUM> may take various forms, such as a Flight-data Acquisition, Storage, and Transmission (FASTTM) box, as manufactured by Pratt & Whitney Canada, or any other computer-controlled unit that receives data from various aircraft and engine systems and sensors. In one embodiment, the data acquisition and transmission unit <NUM> transmits the received data off-aircraft to one (or more) data processing device(s) as in <NUM> adapted to communicate with a plurality of client devices <NUM> via a network <NUM>, such as the Internet, a cellular network, Wi-Fi, or others known to those skilled in the art. As will be discussed further below, the data processing device <NUM> is configured to determine a propeller balancing solution for the aircraft <NUM> and output the propeller balancing solution as determined to the device(s) <NUM>.

In some embodiments, the data acquisition and transmission unit <NUM> may be configured to store the data received from the aircraft systems and sensors in memory prior to transmitting the received data to the data processing device(s) <NUM>, which in turn computes the propeller balancing solution. In yet another embodiment, the data acquisition and transmission unit <NUM> may be configured to store the received data and compute the propeller balancing solution on-board.

The data acquisition and transmission unit <NUM> may comprise one or more antenna, one or more processors, and a memory (none shown). The one or more antenna enable establishment of a connection (e.g., wireless) with the data processing device <NUM>. The processor(s) may be coupled to a data bus of the aircraft <NUM> for receiving the measurement data and any other data from the aircraft and engine systems and sensors (e.g., from the sensor(s) <NUM>). In some embodiments, the measurement data is transmitted to and received at the data acquisition and transmission unit <NUM> using the Aeronautical Radio Inc. (ARINC) <NUM> data transfer standard for aircraft avionics. Other data standards may also be used, such as ARINC <NUM>, ARINC <NUM>, and MIL-STD-<NUM>. It should be understood that, while <FIG> illustrates (for clarity purposes) a single data acquisition and transmission unit <NUM> having both data acquisition and data transmission functionalities, more than one unit as in <NUM> may be provided. For example, the aircraft <NUM> may comprise a data acquisition unit separate from the data transmission unit.

The illustrated data acquisition and transmission unit <NUM> is configured to process the measurement data received from the sensor(s) <NUM> in order to obtain vibration data for the engine <NUM> and/or the propeller <NUM>. In one embodiment, the vibration data comprises propeller speed as well as phase angle and magnitude (or level) of engine vibration. Speed may be denoted as a Rotation Per Minute (RPM) of the propeller <NUM>. The sensor(s) <NUM> may act as a tachometer to measure the RPM of the propeller <NUM>. One or more additional sensors may also be provided for this purpose. Magnitude may be denoted as a peak velocity in units of Inches Per Second (IPS). The phase angle (denoted in degrees) is found by detecting when one particular propeller blade passes the sensor(s) <NUM>, and corresponds to the relationship between the waveform of the vibration magnitude signal to the angular position of the propeller <NUM>. In one embodiment, the data acquisition and transmission unit <NUM> may be configured to digitize the measurement data if received in analog form, and to determine the vibration data from the digitized data.

In some embodiments, a dedicated device (referred to herein as a "Propeller Balance Monitoring System" or PBMS, not shown) may be provided to pre-condition the propeller vibration and phase angle data for live streaming to the data acquisition and transmission unit <NUM>. In particular, the PBMS may be configured to perform conversion of the measurement data from an analog form to a digitized form. The sensor(s) <NUM> are illustratively connected to the PBMS via a suitable harness. The PBMS may be integrated with the data acquisition and transmission unit <NUM> or provided separately therefrom.

In one embodiment, the data acquisition and transmission unit <NUM> also receives data from an engine computer <NUM> and/or an aircraft computer <NUM>. This data will be collectively referred to as aircraft data, and denote engine and/or aircraft performance parameters. The aircraft computer <NUM> may be an aircraft management controller (AMC), a flight management system (FMS), an aircraft digital computer system, or any other device used for computing inside an aircraft <NUM>. The engine computer <NUM> may be any type of computing unit of an engine <NUM>, such as an engine control unit (ECU), an engine electronic controller (EEC), an engine electronic control system, and a Full Authority Digital Engine Controller (FADEC). Data transmitted from the engine computer <NUM> and/or the aircraft computer <NUM> to the data acquisition and transmission unit <NUM> may be provided over a dedicated communication bus or any other existing communication system of the aircraft <NUM>. Example data provided by the aircraft computer <NUM> comprises airspeed, altitude, stability, and position of the aircraft <NUM> at any point in time during a flight. Example data provided by the engine computer <NUM> comprises torque, speed, rating, torque stability, propeller speed stability, and compressor speed stability of the engine <NUM> at any point in time during engine operation.

For purposes of computing a propeller balancing solution, the data acquisition and transmission unit <NUM> is configured to transmit the vibration data to the data processing device <NUM> via a communication link <NUM>. In one embodiment, the communication link <NUM> is wireless. The wireless communication may be established upon engine start up with the aircraft <NUM> parked, after completion of a flight mission of the aircraft <NUM>, or after engine shutdown. In other embodiments, the communication link <NUM> may be wired (e.g., USB, Ethernet, or the like). The vibration data is then used for propeller balancing, as will be described further herein.

In some embodiments, the vibration data is transmitted to the data processing device <NUM> in real-time or at regular intervals during a flight mission of the aircraft <NUM>, based on specific operational conditions. In other embodiments, the vibration data is transmitted to the data processing device <NUM> at the end of at least one flight mission of the aircraft <NUM>. The vibration data may be transmitted to the data processing device <NUM> (for determining the balancing solution) at the end of every flight mission, after every other flight mission, or after any suitable number of flight missions of the aircraft <NUM>, depending on the number of flight missions required to obtain full-flight data for the aircraft <NUM>. For example, for an aircraft <NUM> that requires data to be collected over five (<NUM>) hours in order to perform propeller balancing, if a given flight mission of the aircraft <NUM> lasts three (<NUM>) hours only, the vibration data needs to be collected and transmitted over two (<NUM>) flight missions of the aircraft <NUM>. Conversely, if the aircraft's flight mission lasts seven (<NUM>) hours, the vibration data needs only be collected and transmitted over one (<NUM>) flight mission for propeller balancing purposes.

As used herein, the term "mission" refers to a flight to perform a specific task. The mission may be defined by various parameters, such as duration, destination, cargo, and any flying parameters to be used during the mission, such as propeller speed or maximum altitude. For example, operator X may have aircraft A and B fly at a propeller speed of <NUM> RPM wile aircraft C flies at a propeller speed of <NUM> RPM. The value associated for the flight criteria "propeller speed" may therefore differ between aircraft A and B and aircraft C. In some embodiments, operator X may define a unique set of flight criteria and associated values for each flight of an aircraft as a function of the specific flight parameters of a given flight, such as propeller speeds, cruising altitudes, etc..

The data processing device <NUM> may comprise a series of servers corresponding, but not limited, to a microserver, a web server, an application server, and a database server. In one embodiment, the data processing device <NUM> is a server provided on the ground (referred to herein as a "ground server"). It should however be understood that the methods and systems described herein may use cloud computing, such that the data processing device <NUM> may be a cloud server. Indeed, the systems and methods described herein may support Internet of Things (IoT) connectivity with a cloud data analytics platform. Distributed computing may also apply, such that the data processing device <NUM> may comprise a set of two or more servers. Any other suitable data processing device may apply. These servers are all represented by data processing device <NUM> in <FIG>. In addition, it should be understood that, while the data processing device <NUM> is illustrated as being remote from the aircraft <NUM>, the balancing solution may, in some embodiments, be determined on the aircraft <NUM>, such that the data processing device <NUM> may be provided on-board the aircraft <NUM> (e.g., as part of the data acquisition and transmission unit <NUM>) as described elsewhere.

The data processing device <NUM> illustratively comprises a vibration data processing unit <NUM>, a propeller balancing unit <NUM>, and a portal creation unit <NUM>. It should be understood that the propeller balancing unit <NUM> and the portal creation unit <NUM> may be provided directly on the data processing device <NUM>, as illustrated, or separately therefrom.

As shown in <FIG>, in one embodiment, the propeller balancing unit <NUM> illustratively comprises a vibration data extraction unit <NUM>, a vibration average magnitude computation unit <NUM>, and a vibration average phase angle computation unit <NUM>. The vibration data processing unit <NUM> is configured to process the vibration data received from the data acquisition and transmission unit <NUM>. In particular, after at least one flight mission, the vibration data processing unit <NUM> is configured to extract the phase angle and magnitude of engine vibration from the received vibration data (using the vibration data extraction unit <NUM>) and to compute an average vibration magnitude (using the average vibration magnitude computation unit <NUM>) and an average vibration phase angle (using the average vibration phase angle computation unit <NUM>).

In one embodiment, the average vibration magnitude and the average vibration phase angle are computed at units <NUM> and <NUM>, respectively, for at least one selected flight condition (i.e. for at least one selected flight segment or phase and/or at least one selected time period or duration) of a given flight mission. Indeed, average propeller vibration characteristics are illustratively computed for several engine and/or aircraft operational conditions, for trend monitoring and balancing purposes. The selected flight condition(s) may vary from one flight mission to the next and may comprise any suitable flight segment(s) and any suitable number of flight hours. The duration over which the vibration magnitude and the vibration phase angle are average may depend on the natural flight to flight variability observed in the recorded full-flight data. The duration may be configurable and hence tuneable per aircraft and/or engine application in order to obtain the most accurate and consistent operational trend.

In one embodiment, the selected flight condition may be provided as an input to the data processing device <NUM>, e.g. via the client device(s) <NUM>. A user (e.g., an operator of the aircraft <NUM>) may indeed provide an indication of flight segment(s) and/or flight duration(s) for which propeller balancing is to be performed. In another embodiment, the vibration data processing unit <NUM> may be configured to automatically identify, from the vibration data received from the data acquisition and transmission unit <NUM>, one or more flight condition(s) during which propeller imbalance is most affected and accordingly identify the selected flight segment(s) and/or the selected flight duration(s). For this purpose, the vibration data processing unit <NUM> (e.g., the vibration data extraction unit <NUM>) may compare the vibration data to a predetermined threshold, determine one or more flight segment(s) during which vibration is above the threshold (meaning that propeller imbalance is most affected), and determine for how long the aircraft <NUM> has been operating at the excessive vibration level in order to determine the flight duration(s). The vibration magnitude and the vibration phase angle are then averaged for the flight segment(s) and/or the flight duration(s) as determined.

The threshold may be determined by an operator of the aircraft <NUM>. The user may indeed provide an indication, e.g. via their client device <NUM>, of the threshold at which propeller balancing is to be performed. The average vibration magnitude and the average vibration phase angle may then be computed at units <NUM> and <NUM> once the user-defined threshold is reached. The threshold may also be set according to regional and/or other types of aircraft regulations or as a function of the aircraft's mission or of a number of aircraft parameters (e.g., aircraft size, engine type, etc.). It should however be understood that, in other embodiments, the propeller balancing solution may be computed for any level of vibration, thus alleviating the need for comparison of the vibration magnitude to a threshold.

In one embodiment, the selected flight condition corresponds to a stable cruise condition or constant climb phases of flight. Other suitable flight conditions (e.g., ground operation) may apply. As understood by those skilled in the art, a constant climb phase of flight corresponds to a flight phase during which the aircraft <NUM> climbs to a given altitude at a constant climb rate. A stable cruise condition corresponds to an operating condition of the aircraft <NUM> during which certain flight criteria, which may correspond to engine parameters and/or aircraft parameters, are attained. Stable cruise condition may be operator-specific. Example aircraft parameters are minimum altitude, stability duration, minimum calibrated air speed, altitude stability, and calibrated airspeed stability. Example engine parameters are propeller rotational speed, engine torque, engine rating, engine torque stability, engine propeller speed (Np) stability, and engine compressor speed (Nh) stability.

The average vibration magnitude and the average vibration phase angle computed by the vibration data processing unit <NUM> are then provided to the propeller balancing unit <NUM> for further processing. As will be discussed further below, the propeller balancing unit <NUM> determines a propeller balancing solution (or updates a previously computed balancing solution) based on the average vibration magnitude, the average vibration phase angle, and propeller calibration data (e.g., influence coefficients) retrieved from memory. In one embodiment, determining the propeller balancing solution comprises determining a value and a placement location for at least one weight (or mass) to be added to (or removed from) the propeller <NUM> (i.e. placed on or removed from a propeller balance rim) to correct propeller imbalance (i.e. reduce vibration).

The balancing solution may be determined using at least one balance equation (e.g., provided by the engine manufacturer), based on the average vibration magnitude and the average vibration phase angle computed, from the full-flight vibration data, for the selected flight condition(s). The balancing solution is also illustratively determined based on customized influence coefficients that are specific to the propeller <NUM> and aircraft <NUM>, as will be discussed further below. The balancing solution may further be determined based on the values and locations of the weights currently installed on the propeller <NUM>.

As understood by those skilled in the art, the propeller balance rim (not shown) is a ring that is coupled to the propeller <NUM> and which provides a number of balance weight locations each configured to receive therein a balancing weight (selected as part of the balancing solution) for correcting propeller imbalance. Pre-classified weights can indeed be mounted directly on the propeller balance rim in order to achieve an optimum propeller assembly balanced state. In one embodiment, each balance weight location is numbered in a counter-clockwise direction beginning with location <NUM> and ending with location <NUM>. As also understood by those skilled in the art, influence coefficients may be stored in memory (e.g., as a lookup table or other suitable format) to provide an indication as to which corrective balancing weight(s) will have the most impact on correcting propeller imbalance. The memory may be associated with the data acquisition and transmission unit <NUM> and/or with the data processing device <NUM>. For example, the influence coefficients may be stored in a data warehouse <NUM> communicatively coupled to the data processing device <NUM>. Alternatively or in addition, the influence coefficients may be stored in a memory of the data acquisition and transmission unit <NUM>.

In one embodiment, the influence coefficients are designed for an entire fleet of aircraft and the propeller balancing unit <NUM> is configured to fine-tune these influence coefficients according to the propeller configuration (i.e. the physical state of the propeller <NUM>) and/or operational characteristics (which may be retrieved from a memory associated with the data acquisition and transmission unit <NUM> or with the data processing device <NUM>), such that the propeller balancing parameters (i.e. the influence coefficients) are customized for the propeller <NUM> (i.e. specific to the propeller hardware and therefore unique per propeller configuration and aircraft operational conditions). The propeller configuration data illustratively comprises identifying data for the propeller <NUM> (e.g., propeller part number, propeller serial number) and propeller weight characteristics (e.g., values and locations of counterweights currently installed on the propeller <NUM>). The operational characteristics illustratively relate to information about the unique operational behaviour (e.g., loading of the propeller <NUM>) associated with the manner in which the aircraft <NUM> is flown.

The propeller balancing unit <NUM> is illustratively configured to monitor the propeller configuration and/or operational behaviours over time (e.g., over the course of several days, weeks, or months) and monitor the impact of the differences in propeller configuration and/or operational behaviours on the vibration level of the aircraft <NUM> (and accordingly on the propeller imbalance) in order to tune the influence coefficients. For example, monitoring of the propeller configuration and operational characteristics over two (<NUM>) months may indicate that installing a weight of <NUM> grams on a given blade of the propeller <NUM> consistently results in a decrease in propeller vibration by a magnitude of <NUM> IPS. Generic influence coefficients can be adjusted or tuned (to obtain customized influence coefficients) in the propeller balancing unit <NUM> to differentiate specific balance solutions dependent on selected propeller configurations and/or aircraft flight segment(s). As such, influence coefficients, which are unique per propeller configuration and aircraft operational conditions, are used by the propeller balancing unit <NUM> to select the appropriate balancing weights to be used as part of the balancing solution.

The data processing device <NUM> may then optionally send the propeller balancing solution determined by the propeller balance unit <NUM> to the data warehouse <NUM>, which maintains a history of propeller balancing solutions over time. In other embodiments, the propeller balancing solution may be stored in a memory (not shown) associated with the data acquisition and transmission unit <NUM>. In one embodiment, the data warehouse <NUM> stores counterweight mass values and locations associated with each propeller balancing solution determined by the propeller balancing unit <NUM>. The data warehouse <NUM> further stores the existing propeller configuration (based on information obtained from the diagnostic system of the aircraft <NUM>, not shown) as well as the propeller calibration data (i.e. the influence coefficients), along with the newly determined propeller balancing solution. The propeller balancing solution is then made available to one or more client devices <NUM> over a network <NUM>, such that the balancing solution can be readily installed by maintenance personnel. In one embodiment, the provided information comprises a weight and location for installation on the propeller balance rim.

It should be understood that, in some embodiments (e.g., where the data processing device <NUM> is provided on-board the aircraft <NUM>), the propeller balancing solution may be made available to the client device(s) <NUM> planeside. For example, the propeller balancing solution may be rendered on the client device <NUM> planeside, using any suitable secure wireless connection (and, e.g., IoT connectivity technology). Alternatively, upon landing of the aircraft <NUM>, the user may connect their client device <NUM> to the aircraft <NUM> using any suitable wired connection (e.g. USB, Ethernet, or the like) for the purpose of manually retrieving the balancing solution determined by the propeller balancing unit <NUM> and downloading the propeller balancing solution onto their client device <NUM>. In some embodiments, a portable electronic device, such as a USB flash drive or other suitable data storage device, that is associated with the client device <NUM> may be connected to a communication port of the aircraft <NUM> for downloading the propeller balancing solution.

The data warehouse <NUM> described herein may be provided as collections of data or information organized for rapid search and retrieval by a computer. It is structured to facilitate storage, retrieval, modification, and deletion of data in conjunction with various data-processing operations. The data warehouse <NUM> may consist of a file or sets of files that can be broken down into records, each of which consists of one or more fields. Database information may be retrieved through queries using keywords and sorting commands, in order to rapidly search, rearrange, group, and select the field. The data warehouse <NUM> may be any organization of data on a data storage medium, such as one or more servers. It should be understood that the data warehouse <NUM> may also be provided in a cloud-based server-less environment.

The client devices <NUM> comprise any portable or handheld communication device, such as a smartphone, a desktop computer, a portable computer, a tablet, or the like, adapted to communicate over at least one network. The network <NUM> is capable of carrying data and can involve wired connections, wireless connections, or a combination thereof. The network <NUM> may involve different network communication technologies, standards and protocols, for example. The network <NUM> may include, but is not limited to, the Internet, Ethernet, plain old telephone service (POTS) line, public switch telephone network (PSTN), integrated services digital network (ISDN), digital subscriber line (DSL), coaxial cable, fiber optics, satellite, mobile, wireless (e.g. Wi-Fi, WiMAX), SS7 signaling network, fixed line, local area network, wide area network, and any combination thereof.

The portal creation unit <NUM> is configured to create a portal remotely accessible by the one or more client devices <NUM> over the network <NUM>, and to display the balancing solution (retrieved from the data warehouse <NUM> or received directly from the propeller balancing unit <NUM>) within a graphical user interface of the web portal. As used herein, the term "portal" refers to a specially designed website that renders (i.e. visually displays) the balancing solution and related information for viewing by the client device(s) <NUM>. In one embodiment, the portal is web-based and the portal (and associated graphical user interface) is illustratively displayed to users in a web browser, over the network <NUM>. As will be discussed further below, in one embodiment, the portal creation unit <NUM> is configured to generate an intuitive representation of the balancing solution that can be used by maintenance personnel to perform a propeller balance maintenance action. The representation of the balancing solution can also be used to enable the analysis of how the balancing solution is trending, as well as to enable the analysis of reliability of the balancing solution based on data quality and scatter. The portal creation unit <NUM> is indeed configured to create a representation of the balancing solution that comprises trending and visualization of propeller vibration and balancing characteristics over time, including the magnitude and location of imbalance. In one embodiment, the web-based portal may be subscription-based and may have different service levels associated therewith, including the ability to proactively schedule propeller balance maintenance actions. The web-based portal may also include automated customer alerting functions based on pre-configured threshold detections and/or anomaly signatures.

It should be understood that the data processing device <NUM> may be configured to provide the balancing solution (e.g., to the client device(s) <NUM>) in any suitable fashion other than through a web portal, using any suitable communication means. For example, the propeller balancing solution may be provided in a text format (e.g. stored as an Extensible Markup Language (XML) file in the data warehouse <NUM>) indicative of the values and locations of balancing weights that are to be installed on (or removed from) the propeller rim. The balancing solution may then be transmitted to the client device(s) <NUM> using text messaging or the like.

<FIG> is a screenshot of a web portal interface <NUM> presenting a trend line overview of propeller vibration for two engines over time, in accordance with one embodiment. In the example of <FIG>, a first trend plot <NUM> is presented for a first engine and a second trend plot <NUM> is presented for a second engine. The trend plot representation is rendered (i.e. displayed) in the remote web portal to enable maintenance personnel to identify engines with high levels of vibration. Maintenance personnel is then able to view details of propeller vibration by selecting (e.g., clicking on) an individual data point through the graphical user interface, using any suitable input device (e.g., a mouse and/or keyboard) of the client device (reference <NUM> in <FIG>) on which the web portal interface is rendered. This is shown in <FIG>, which is a screenshot of a web portal interface presenting a plot <NUM> of propeller vibration for one engine, at a given point in time. As can be seen in <FIG>, by selecting an individual data point on a given trend line (<NUM> or <NUM>) of <FIG>, a user can view propeller vibration details. In one embodiment, the propeller vibration details are provided in a polar coordinate chart scaled to the level of vibration normally experienced by the propeller <NUM>. For the given data point, both the magnitude (e.g., <NUM> IPS) and phase angle (e.g., <NUM> degrees) of propeller vibration imbalance are represented on the polar chart, as shown in <FIG>. This representation may enable the user to intuitively assess the reliability of the propeller balancing solution calculation over time as the user can readily visualize whether a calculated propeller balance solution varies widely or is fairly consistent over time.

The web portal may also be used to represent the existing propeller configuration (i.e. counterweight locations) and the propeller calibration data (e.g., influence coefficients) along with the propeller balancing solution. These may be retrieved from the data warehouse (reference <NUM> in <FIG>). In this manner, maintenance personnel may no longer need to use ground supporting equipment and physically inspect the propeller hardware to conduct a propeller balancing maintenance action. The visualization of the locations of weights around the propeller balance rim may facilitate understanding of new weight locations proposed in the balancing solution. This is illustrated in <FIG>, which is a screenshot of a web portal interface <NUM> showing weights <NUM> that are currently installed on a propeller balance rim, in accordance with one embodiment. The current vibration magnitude and phase angle (<NUM> IPS at -<NUM> degrees) are also indicated at the center of the plot presented on the web portal interface <NUM>.

<FIG> is a screenshot of a web portal interface <NUM> presenting a propeller balancing solution, in accordance with one embodiment. The propeller balancing solution is illustratively computed by the propeller balancing unit <NUM> (based on the propeller vibration trend and current propeller configuration settings, as described herein above) and rendered on the web portal by the portal creation unit <NUM>. If any of the weights presented in the web portal interface <NUM> are incorrect, the user may change these weights by adjusting the counterweight locations around the propeller balance rim and/or editing the values of the counterweights (using any suitable input device of the client device <NUM>). In this manner, maintenance personnel is provided with the flexibility to work with counterweights that are at their disposal, rather than needing to strictly adhere to the prescribed counterweights calculated by the data processing device <NUM>.

In the example of <FIG>, counterweights <NUM> are selected by the user for modification. The revised propeller configuration (i.e. the adjusted weight configuration) is then received at the portal creation unit <NUM> of the data processing device <NUM>. The revised propeller configuration is then sent to the propeller balancing unit <NUM>, which re-computes the balancing solution accordingly. In particular, the propeller balancing unit <NUM> calculates the expected vibration magnitude if the counterweights as modified by the user were to be installed on the propeller. The propeller balancing unit <NUM> then outputs a new balancing solution, which is then presented to the user in an updated web portal interface <NUM>, as shown in <FIG>.

In some embodiments, the vibration data processing unit <NUM>, the propeller balancing unit <NUM>, and/or the portal creation unit <NUM> may be implemented in hardware, using analog and/or digital circuit components. For example, the vibration data processing unit <NUM>, the propeller balancing unit <NUM>, and/or the portal creation unit <NUM> may each be provided as an application-specific integrated circuit (ASIC) or a field programmable gate array (FPGA). In some embodiments, the vibration data processing unit <NUM>, the propeller balancing unit <NUM>, and/or the portal creation unit <NUM> are each provided as a non-transitory computer readable medium having stored thereon program code executable by a processor for carrying out the instructions of the program code.

In other embodiments, the vibration data processing unit <NUM>, the propeller balancing unit <NUM>, and/or the portal creation unit <NUM> are each implemented using a combination of hardware and software components, as illustrated in <FIG>. In particular, <FIG> is an example embodiment of a computing device <NUM> that may be used for implementing the vibration data processing unit <NUM>, the propeller balancing unit <NUM>, and/or the portal creation unit <NUM>. As depicted, the computing device <NUM> includes at least one processing unit <NUM> and memory <NUM>. The memory <NUM> has stored therein computer-executable instructions <NUM>.

The memory <NUM> may include a suitable combination of any type of computer memory that is located either internally or externally to computing device <NUM>, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like.

The instructions <NUM> may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the vibration data processing unit <NUM>, the propeller balancing unit <NUM>, and/or the portal creation unit <NUM>. Alternatively, the instructions <NUM> may be implemented in assembly or machine language. The language may be a compiled or interpreted language. The instructions <NUM> may be readable by a general or special-purpose programmable computer.

Referring now to <FIG>, there is illustrated a flowchart for an example embodiment of a method <NUM> for propeller balancing, as performed by the instructions <NUM> when executed by the processing unit <NUM> of the computing device <NUM> (e.g., as performed at the data processing device <NUM>). The method <NUM> comprises, at step <NUM>, propeller full-flight vibration data is received in the manner described herein above. The full-flight propeller vibration data is data collected in real-time, during operation of the propeller in-flight. The next step <NUM> is to compute an average vibration magnitude and phase angle based on the vibration data received at step <NUM>. As described herein above, the average vibration magnitude and phase angle are computed after at least one flight mission. In one embodiment, the average vibration magnitude and phase angle are computed for at least one selected flight condition (i.e. flight segment(s) and/or flight duration(s)) for which the propeller vibration exceeds a predetermined threshold.

A propeller balancing solution is then determined at step <NUM>, based on the average vibration magnitude and phase angle computed at step <NUM> and on propeller calibration data (i.e. influence coefficient(s) customized for the propeller and aircraft), using at least one balance equation. The balancing solution may then be optionally stored to memory (e.g., sent to a data warehouse) at step <NUM> in order to maintain a history of propeller balance solutions over time. At step <NUM>, a balancing need is then signalled by outputting the balancing solution determined at step <NUM>, for maintenance action purposes. The balancing need may be signaled by rendering the balancing solution on a web portal accessible to one or more client devices over a network, such as the Internet. As discussed herein above, a graphical user interface of the web portal may be used to allow users to correct the propeller balance solution determined at step <NUM>. The web portal may also be used to render a current configuration of the propeller, as well as propeller vibration trend overviews.

In one embodiment, using the systems and methods described herein may alleviate the need for performing engine ground runs to verify vibration levels before and after a propeller balance maintenance action is performed. In one embodiment, using the systems and methods described herein, may also alleviate the need for connecting expensive ground support equipment to the aircraft <NUM> at the time of performing a propeller balance maintenance action. In one embodiment, using the systems and methods described herein, may further alleviate the need for changing the sensor(s) used to support propeller balancing. In some embodiments, using the systems and methods described herein, it may become possible to conduct propeller balancing without having to physically look at the propeller hardware to identify the current propeller configuration (e.g. counterweight masses and locations). In some embodiments, using the systems and methods described herein may also enable the calculation of a propeller balancing solution before the aircraft returns to the hangar, and may allow to feed the balancing solution to maintenance personnel in order to prepare for proactive maintenance actions. The systems and methods described herein may also allow to fine tune propeller calibration data (e.g. influence coefficients) to a specific set of hardware, rather than assuming that the balancing parameters are the same for an aircraft entire fleet.

Claim 1:
A method for propeller balancing of an aircraft (<NUM>), the method comprising:
operating a propeller (<NUM>) in-flight;
receiving propeller vibration data during operation of the propeller (<NUM>) in-flight;
computing, after at least one flight of the aircraft (<NUM>), an average vibration magnitude and an average vibration phase angle based on the propeller vibration data;
retrieving propeller configuration data from memory;
retrieving, from memory, propeller calibration data comprising at least one influence coefficient indicative of an impact of at least one balancing weight on correcting an imbalance of the propeller (<NUM>);
tuning the at least one influence coefficient according to one of the propeller configuration data and a flight condition of the aircraft (<NUM>);
determining a propeller balancing solution by identifying, using at least one balance equation and based on the average vibration magnitude, the average vibration phase angle, and the at least one influence coefficient, a value for the at least one balancing weight and a placement location for the at least one balancing weight for correcting the imbalance of the propeller (<NUM>); and
generating a balancing need indication by outputting the propeller balancing solution.