Patent Description:
In aircraft engines, continuous inlet air is compressed, mixed with fuel in an inflammable proportion, and exposed to an ignition source to ignite the mixture which then continues to burn to produce combustion products. The combustion of the air-fuel mixture can be used to power various mechanical components, which in turn can be used to produce thrust or other mechanical force.

Certain aircraft engines are mechanically coupled to propellers, which produce thrust to propel the aircraft. A propeller control unit provided for use with the propeller serves to effect control of the operation of the propeller, including to control pitch angles of the blades of the propeller, and to control the rotational speed of the propeller. The propeller control unit is actuated by way of a hydraulic fluid, which is supplied under pressure by a pump and distributed at a variable pressure to achieve target values of propeller speed and blade pitch angle.

While existing propeller control systems are suitable for their purposes, improvements remain desirable.

<CIT> discloses a propeller control system comprising a feedback ring and a controller configured to produce a warning signal if the measured longitudinal position of the feedback ring is outside a threshold range. Other prior art methods and systems for aircraft propeller control are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

In one aspect, there is provided a method for validating a propeller control unit associated with a propeller having blades, in accordance with claim <NUM>.

In an embodiment, the comparing of the one of the actual pitch angle of the blades and the actual rotational speed of the propeller to the corresponding one of the pitch angle threshold and the rotational speed threshold comprises comparing the actual pitch angle of the blades to one of the commanded pitch angle, a value based on the commanded pitch angle, and a range of values based on the commanded pitch angle.

In an embodiment according to any of the previous embodiments, the comparing of the one of the actual pitch angle of the blades and the actual rotational speed of the propeller to the corresponding one of the pitch angle threshold and the rotational speed threshold comprises comparing the actual rotational speed of the propeller to one of a commanded rotational speed based on the commanded pitch angle, a value based on the commanded rotational speed, and a range of values based on the commanded rotational speed.

In an embodiment according to any of the previous embodiments, the commanding of the actuation of the control valve is performed in response to obtaining a request to perform a start sequence for an engine associated with the propeller.

In an embodiment according to any of the previous embodiments, the method comprises determining, at the controller, at least one of an engine speed of the engine and a propeller speed of the propeller, and performing the commanding of the actuation of the control valve in response to determining that the at least one of the engine speed and the propeller speed is above a speed threshold during the start sequence.

In an embodiment according to any of the previous embodiments, the method comprises obtaining, at the controller and subsequent to the issuing of the warning signal, a request to revalidate the propeller control unit, in response to the obtaining of the request to revalidate the propeller control unit, commanding, by the controller, a subsequent actuation of the control valve to alter the pitch angle of the blades, determining, at the controller, one of a subsequent pitch angle of the blades and a subsequent rotational speed of the propeller after the predetermined time delay has elapsed from the commanding of the subsequent actuation of the control valve, comparing, at the controller, the one of the subsequent pitch angle of the blades and the subsequent rotational speed of the propeller to the corresponding one of the pitch angle threshold and the rotational speed threshold, and issuing, by the controller, a subsequent warning signal in response to determining one of the subsequent pitch angle failing to meet the pitch angle threshold and the subsequent rotational speed failing to meet the rotational speed threshold.

In an embodiment according to any of the previous embodiments, the method comprise issuing, by the controller, a validation signal in response to determining one of the subsequent pitch angle meeting the pitch angle threshold and the subsequent rotational speed meeting the rotational speed threshold.

In an embodiment according to any of the previous embodiments, the issuing of the warning signal comprises providing an indication of a recommended operating time of the propeller prior to issuing the request to revalidate the propeller control unit.

In an embodiment according to any of the previous embodiments, the issuing of the subsequent warning signal comprises providing an indication of a maintenance action to be performed on the propeller control unit.

In an embodiment according to any of the previous embodiments, the method comprises preventing, by the controller, operation of a component of an aircraft associated with the propeller in at least one operating regime in response to the determining of the one of the actual pitch angle failing to meet the pitch angle threshold and the actual rotational speed failing to meet the rotational speed threshold.

In an embodiment according to any of the previous embodiments, the preventing of the operation of the component of the aircraft associated with the propeller in the at least one operating regime comprises preventing operation of an engine of the aircraft in the at least one operating regime.

In an embodiment according to any of the previous embodiments, the method comprises issuing, by the controller, a validation signal in response to determining one of the actual pitch angle meeting the pitch angle threshold and the actual rotational speed meeting the rotational speed threshold.

In another aspect, there is provided a system for validating a propeller control unit associated with a propeller having blades, in accordance with claim <NUM>.

In an embodiment according to any of the previous embodiments, the instructions are executable for determining at least one of an engine speed of the engine and a propeller speed of the propeller, and performing commanding of the actuation of the control valve in response to determining that the at least one of the engine speed and the propeller speed is above a speed threshold during the start sequence.

In an embodiment according to any of the previous embodiments, the instructions are executable for obtaining, subsequent to the issuing of the warning signal, a request to revalidate the propeller control unit, in response to the obtaining of the request to revalidate the propeller control unit, commanding a subsequent actuation of the control valve to alter the pitch angle of the blades, determining one of a subsequent pitch angle of the blades and a subsequent rotational speed of the propeller after the predetermined time delay has elapsed from the commanding of the subsequent actuation of the control valve, comparing the one of the subsequent pitch angle of the blades and the subsequent rotational speed of the propeller to the corresponding one of the pitch angle threshold and the rotational speed threshold, and issuing a subsequent warning signal in response to determining one of the subsequent pitch angle failing to meet the pitch angle threshold and the subsequent rotational speed failing to meet the rotational speed threshold.

In an embodiment according to any of the previous embodiments, the instructions are executable for preventing operation of a component of an aircraft associated with the propeller in at least one operating regime in response to the determining of the one of the actual pitch angle failing to meet the pitch angle threshold and the actual rotational speed failing to meet the rotational speed threshold.

In an embodiment according to any of the previous embodiments, the instructions are executable for issuing a validation signal in response to determining one of the actual pitch angle meeting the pitch angle threshold and the actual rotational speed meeting the rotational speed threshold.

<FIG> illustrates a gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a compressor section <NUM> for pressurizing ambient 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. A low pressure (LP) turbine <NUM> drives, via a reduction gear box (RGB), a propeller <NUM> having propeller blades <NUM> for providing thrust to the aircraft. Although referred to herein as the propeller <NUM>, it should be understood that the propeller <NUM> may be a broader propeller system, and may include various components related to the propeller itself, including components which assist in regulating the operation of the propeller <NUM>. An oil system <NUM> is provided for the gas turbine engine <NUM>, and provides lubrication for the rotating components of the gas turbine engine <NUM>, which include bearings for the rotating turbomachinery (e.g. the compressors, turbines, shafts, and gears), the RGB and the propeller control systems, etc..

<FIG> illustrates the engine <NUM> as a gas turbine engine of an aircraft. It should, however, be understood that the engine <NUM> may include any other suitable type of engine comprising a propeller <NUM>, such as a piston engine, a turboshaft engine, a rotary engine, for instance a Wankel engine, any other suitable type of combustion engine, and the like. In addition, although the various embodiments and examples provided in the present disclosure relate primarily to flight applications in which an engine (e.g., the engine <NUM>) drives a propeller (e.g., the propeller <NUM>), it should be understood that other fields of application, including in industrial settings, power generation settings (e.g. wind turbines), and the like, are also considered.

As illustrated in <FIG>, an engine controller <NUM> is coupled to the engine <NUM> for controlling operation of the engine <NUM>. Similarly, a propeller controller <NUM> is coupled to the propeller <NUM> for controlling operation of the propeller <NUM>. The engine controller <NUM> and the propeller controller <NUM> may be communicatively coupled to one another via any suitable wired and/or wireless means, and may exchange signals, information, and the like to collaboratively operate the engine <NUM> and the propeller <NUM>. In some embodiments, the engine controller <NUM> and the propeller <NUM> are communicatively coupled via one or more electrical, optical, and/or electromagnetic communication channels. In some other embodiments, the engine controller <NUM> and the propeller <NUM> may be communicatively coupled via one or more hydraulic and/or mechanical communication channels. In some further embodiments, the coupling between the engine controller <NUM> and the propeller <NUM> is effected by any suitable combination of the above. For example, one or more electrical wires, cables, or the like couple the engine controller <NUM> to the propeller controller <NUM>. The operational control exerted by the engine controller <NUM> and the propeller controller <NUM> may include controlling the operation of the oil system <NUM>.

With reference to <FIG>, a schematic representation of the engine <NUM> and the propeller <NUM> is illustrated. As noted hereinabove, the engine controller <NUM> and the propeller controller <NUM> are coupled to one another. In addition, the engine controller <NUM>, and in some embodiments the propeller controller <NUM>, may be connected to an external system, which may be an avionics system <NUM>, in applications in which the engine <NUM> forms part of an aircraft, or a different external system in other applications.

The propeller controller <NUM> forms part of and assists in operating a propeller control unit (PCU), illustrated here at <NUM>. The PCU <NUM> includes a valve <NUM> which is controlled by the propeller controller <NUM>. In some embodiments, the valve <NUM> is an electrohydraulic servo valve (EHSV). The valve <NUM> modulates a flow of a fluid, for instance oil, which flows to the propeller <NUM> from a reservoir <NUM> via a conduit <NUM>. Put differently, the valve <NUM> controls the rate at which oil flows from the reservoir <NUM> to the propeller <NUM>. The flow of oil through the conduit <NUM> governs the operation of the propeller <NUM>, including modifying the pitch angle of the propeller blades <NUM> (sometimes referred to as the beta angle) and the rotational speed of the propeller <NUM>. The particular response of the propeller <NUM> to increasing or decreasing the oil flow to the propeller <NUM>, by increasing or decreasing the degree to which the valve <NUM> is open (which increases or decreases the oil pressure delivered to the propeller <NUM>), may vary from one application to the next. For example, increasing the oil flow to the propeller <NUM> causes the propeller blades <NUM> to transfer to a lower pitch angle, such that, when the propeller <NUM> is operating in a forward (i.e., positive) range of pitch angles, the propeller <NUM> experiences acceleration (i.e., an increase in rotational speed). By way of another example, decreasing the oil flow to the propeller <NUM> causes the propeller blades <NUM> to transfer to a higher pitch angle, so that, when the propeller <NUM> is operating in a forward (i.e., positive) range of pitch angles, the propeller <NUM> experiences deceleration (i.e., a decrease in rotational speed). Other examples and implementations are also considered.

In some cases, it may be desirable to validate whether the PCU <NUM> is functioning properly. In some cases, deterioration of the valve <NUM> may occur, which results in poor response times when a change in the pitch angle of the propeller blades <NUM> is commanded. In some other cases, the valve <NUM> may malfunction, for instance due to wear, contamination, the presence of debris, or the like, causing requests to change in the pitch angle of the propeller blades <NUM> to fail. Other issues resulting from faulty behaviour of the valve <NUM> include governing speed drift, propeller speed overshoots, and the like, which in turn can trigger accommodation systems of the aircraft. It should also be noted that the viscosity of the fluid (e.g. oil) which flows from the reservoir <NUM> to the propeller <NUM> may affect the overall response time of the PCU <NUM>, independently from the operation of the valve <NUM>. The present disclosure provides, inter alia, methods and systems for validating PCUs, including validating the response time and/or operation of the valve <NUM>.

Validation of the PCU <NUM> may be performed at any suitable time, and at any suitable frequency. In some embodiments, the flight phases during which validation of the PCU <NUM> is performed, and frequency of validation, are selected to achieve a particular testing outcome. For example, validation of the PCU <NUM> is performed during a start sequence of the engine <NUM>. In some cases, validation of the PCU <NUM> being performed during the start sequence may allow for verification of the functionality of the PCU <NUM> after exposure to various ambient and environmental conditions, which may affect the functionality of the PCU <NUM>. For instance, the viscosity of the fluid flowing through the conduit <NUM> to the propeller <NUM> may vary due to ambient and environmental conditions. Additionally, operability of the valve <NUM>, or other valves of the PCU <NUM>, may be validated before a flight mission in situations in which the engine <NUM> and/or an associated aircraft have not been operated for a certain period of time. In some embodiments, the engine start sequence for the engine <NUM> is composed of a plurality of operations, including validation of the PCU <NUM>, which are performed in a particular order following an engine start request from an operator of the engine <NUM> and/or of an aircraft of which the engine <NUM> forms part. Thus, validation of the PCU <NUM> may be performed in response to the operator issuing the engine start request, for example to the engine controller <NUM>. Performing validation of the PCU <NUM> during the engine start sequence may serve to detect failure of the PCU <NUM> prior to a period of extended operation which would be hindered by malfunction of the PCU <NUM>. By way of another example, validation of the PCU <NUM> is performed as part of a routine maintenance procedure. Other uses cases are also considered.

In some other embodiments, validation of the PCU <NUM> is performed in response to receiving a PCU validation request from the operator, which may be received, for instance, at the propeller controller <NUM>. A manufacturer, designer, regulator, or other relevant authority may specify that PCU validation should be performed at certain predetermined engine parameters, and the operator of the engine <NUM> may be trained to request PCU validation only when the predetermined engine parameters are satisfied. For example, the engine parameters for PCU validation may specify a particular engine temperature, engine power output, engine speed (e.g., a rotational speed of an output shaft of the engine <NUM>), propeller rotational speed, etc., or any suitable combination thereof. In some embodiments, the engine controller <NUM> may prompt the operator to perform the PCU validation when the engine controller <NUM> determines that the predetermined engine parameters are satisfied. For instance, the engine controller <NUM> may issue an alert to the operator via the avionics system <NUM>, which may cause a message to appear on a display, a visual indicator to be illuminated or otherwise activated, or the like. The operator may then issue the request to perform the PCU validation, which is provided to the engine controller <NUM>.

In some further embodiments, the engine controller <NUM> may be configured for automatically performing the PCU validation, for instance as part of the engine start sequence, after determining that the predetermined engine parameters are satisfied. For example, the engine controller <NUM> and/or the propeller controller <NUM> may be configured for maintaining the predetermined engine parameters for the duration of the PCU validation. In this example, the predetermined engine parameters may correspond to particular steady-state conditions for the engine <NUM> and/or for the propeller <NUM>, which may be determined by the manufacturer, designer, regulator, or other relevant authority, for instance on the basis of analytical and/or experimental data.

Other approaches are also considered. By way of an example, validation of the PCU <NUM> in the context of a wind turbine (in which there is no engine <NUM>) may be prompted, or automatically be performed, once the propeller <NUM> has been active for a predetermined amount of time, or when a temperature of the oil flowing through conduit <NUM> reaches a predetermined temperature.

In some embodiments, validation of the PCU <NUM> is performed by commanding the valve <NUM> to achieve a predetermined state, that is to say, a predetermined degree of openness or closedness. For example, the propeller controller <NUM> commands the valve <NUM> to achieve a state of being open to a maximum or minimum amount, to <NUM>% of a maximum amount, <NUM>% of a maximum amount, <NUM>% of a maximum amount, or the like. The predetermined degree of openness or closedness may correspond to a predetermined position of the valve <NUM> which, when achieved, results in a predetermined oil pressure being delivered to the propeller <NUM>, which in turn causes the blades <NUM> to achieve a commanded pitch angle. By way of another example, the propeller controller <NUM> commands the valve <NUM> to achieve the predetermined position of the valve <NUM> which, when achieved, results in the predetermined oil pressure causing the propeller <NUM> to achieve a commanded rotational speed (which may be associated with the commanded pitch angle, for instance based on the relationship between the rotational speed of the propeller <NUM> and the pitch angle of the blades <NUM>). Validation of the PCU <NUM> is performed by comparing the actual pitch angle of the blades <NUM> to a pitch angle threshold and/or the actual rotational speed of the propeller <NUM> to a rotational speed threshold, as appropriate. The pitch angle threshold can be the commanded pitch angle, or a value based thereon; similarly, the rotational speed threshold, which may be determined by one or more known relationships between the pitch angle of the blades <NUM> and the rotational speed of the propeller <NUM>, may be a commanded rotational speed (i.e., associated with the commanded pitch angle), or a value based thereon. It should be noted that the engine <NUM> may be operating in a steady-state while the validation of the PCU <NUM> is ongoing, or may be in transition from one state to another, for instance accelerating or decelerating in any suitable fashion.

The propeller controller <NUM> may issue the command as an analog signal, for instance a voltage level applied to the valve <NUM>, or as a digital signal transmitted to a controller associated with the valve <NUM>. The particular predetermined state which the propeller controller <NUM> commands for the valve <NUM> may be established by a manufacturer, designer, regulator, or other relevant authority. For instance, the manufacturer of the propeller <NUM> and/or of the engine <NUM> may establish the parameters by which the validation of the PCU <NUM> is performed, including the predetermined state commanded for the valve <NUM>.

Commanding the valve <NUM> to achieve the predetermined state causes a change in the flow of fluid to the propeller <NUM>, which in turn alters the pitch angle of the blades <NUM> of the propeller <NUM> (and, by extension, the rotational speed of the propeller <NUM>). The expected time required for the valve <NUM> to achieve the predetermined state, and thus for the blades <NUM> to achieve an associated predetermined pitch angle, may be known. For instance, a manufacturer, designer, regulator, or other relevant authority, may perform various testing tasks to determine the expected time. The expected time for the blades <NUM> to achieve the predetermined pitch angle may be provided to the propeller controller <NUM> and/or to the engine controller <NUM>, for instance being stored in a memory or other data repository.

After a predetermined time delay has elapsed-commensurate with the expected time required for the valve <NUM> to achieve the predetermined state-the actual pitch angle of the blades <NUM> and/or the actual rotational speed of the propeller <NUM> is determined. The engine <NUM> and the propeller <NUM> are provided with a sensing system capable of determining the pitch angle of the blades <NUM> and the rotational speed of the propeller <NUM>. For instance, the sensing system makes use of a feedback ring which rotates with the propeller <NUM> and moves axially in response to changes in the pitch angle of the blades <NUM>. The sensing system can be used to determine the actual pitch angle of the blades <NUM> and the actual rotational speed of the propeller <NUM>.

The propeller controller <NUM> and/or the engine controller <NUM> may, after the time delay has elapsed, compare the actual pitch angle of the blades <NUM> to the pitch angle threshold, and/or compare the actual rotational speed of the propeller <NUM> to the rotational speed threshold. The pitch angle threshold and the rotational speed threshold are representative of expected values for the pitch angle of the blades <NUM> and the rotational speed of the propeller <NUM> when the valve <NUM> is in the predetermined state. When the actual pitch angle (and/or actual rotational speed) fails to meet the pitch angle threshold (and/or the rotational speed threshold), it can be concluded that the valve <NUM> did not reach the predetermined state, and thus that the PCU <NUM> is not operating as expected. Conversely, when the actual pitch angle (and/or actual rotational speed) meets the pitch angle threshold (and/or the rotational speed threshold), it can be concluded that the valve <NUM> did reach the predetermined state, and thus that the PCU <NUM> is operating as expected.

The comparison of the actual pitch angle to the pitch angle threshold may include comparing the actual pitch angle to the commanded pitch angle itself, to a value based thereon (e.g., <NUM>% of the commanded pitch angle), a range of values including the commanded pitch angle, and the like. Similarly, the comparison of the actual rotational speed to the rotational speed threshold may include comparing the actual rotational speed to the commanded rotational speed itself, to a value based thereon (e.g., <NUM>% of the commanded rotational speed), a range of values including the commanded rotational speed, and the like. It should be noted that the actual pitch angle may be considered to meet the pitch angle threshold when a difference between the actual pitch angle and the pitch angle threshold is below a predetermined amount, or when the actual pitch angle and the pitch angle threshold are within a particular range, or the like. Similarly, the actual rotational speed may be considered to meet the rotational speed threshold when a difference between the actual rotational speed and the rotational speed threshold is below a predetermined amount, or when the actual rotational speed and the rotational speed threshold are within a particular range, or the like. The comparison of the actual pitch angle of the blades <NUM> to the pitch angle threshold (and/or of the actual rotational speed of the propeller <NUM> to the rotational speed threshold) can be performed by the engine controller <NUM>, the propeller controller <NUM>, a unified controller which combines the functionality of the engine controller <NUM> and the propeller controller <NUM>, or any other suitable control device, as appropriate.

When the comparison of the actual pitch angle (and/or actual rotational speed) to the pitch angle threshold (and/or rotational speed threshold) indicates that the PCU <NUM> is validated (i.e., that the response time of the valve <NUM> is adequate), the engine controller <NUM> and/or the propeller controller <NUM> can issue a signal indicating that the PCU <NUM> has been validated. The validation signal may be issued to the avionics system <NUM>, which in turn may cause a message to appear on a display, a visual indicator to be illuminated or otherwise activated, or the like. The signal can indicate that the validation of the PCU <NUM> was successful, a response time of the valve <NUM>, or any other suitable information. In some embodiments, a record of the validation may be stored, for instance in a database of any suitable type, along with relevant metadata or other information, as an indication that the PCU validation was performed and validated the PCU <NUM>. In embodiments in which the PCU validation is performed as part of a start sequence for the engine <NUM> or another system of which the engine <NUM> is an element, the validation of the PCU <NUM> may be the trigger for continuing with the start sequence, or for operating the engine <NUM> (or the broader system) in a different operating regime. For example, validation of the PCU <NUM> may be a prerequisite for operating the engine <NUM> in a pre-takeoff or takeoff regime. The engine controller <NUM> may indicate to the operator that the engine <NUM> cannot be transitioned to the pre-takeoff or takeoff regime, for instance from a ground idle regime, until the PCU <NUM> is validated. Once the PCU <NUM> is validated and the avionics system <NUM> receives the relevant signal, the avionics system <NUM> may indicate to the operator that the engine <NUM> may be transitioned to the pre-takeoff or takeoff regime.

When the comparison of the actual pitch angle (and/or actual rotational speed) to the pitch angle threshold (and/or rotational speed threshold) indicates that the PCU <NUM> is not validated (i.e., that the response time of the valve <NUM> is not adequate), the engine controller <NUM>, the propeller controller <NUM>, and/or the avionics system <NUM> may, separately or collaboratively, enact one or more countermeasures to accommodate for the invalidated PCU <NUM>. In some embodiments, the engine controller <NUM> and/or the propeller controller <NUM> issues a warning signal which indicates the failed validation of the PCU <NUM>. The warning signal may be sent to an operator of the propeller <NUM> (and therefore of the engine <NUM>). For example, in cases in which the engine <NUM> forms part of an aircraft, the warning signal may be sent to an operator of the aircraft, which may be a pilot, a maintenance worker, or the like, and may be communicated to the operator via the avionics system <NUM>. For instance, the warning signal may be presented to the operator via a display, which may include one or more screens, one or more warning lights, one or more audio messages, or the like.

The warning signal may include various information for presentation to the operator. By way of an example, the warning signal may indicate that the PCU <NUM> was not validated by the validation procedure performed. By way of another example, the warning signal may indicate a degree of failure, that is to say, an indication of the difference between the actual pitch angle of the blades <NUM> (and/or actual rotational speed of the propeller <NUM>) and the pitch angle threshold (and/or rotational speed threshold) after the predetermined time delay elapsed. For instance, the warning signal may indicate that the actual pitch angle reached only <NUM>% of the pitch angle threshold. The degree of failure may be indicative of additional countermeasures which may be implemented manually by the operator.

By way of a further example, the warning signal may indicate whether or not failure of validation of the PCU <NUM> is likely to be remedied under different operating conditions for the propeller <NUM> and/or the engine <NUM>. For instance, the response of the propeller <NUM> to the operation of the valve <NUM> may also be based on properties of the fluid flowing through the conduit <NUM>, including the viscosity of the fluid. Thus, in some cases, the warning signal may indicate a likelihood of a subsequent validation of the PCU <NUM> succeeding, and/or a recommended operating time of the propeller <NUM> and/or the engine <NUM> prior to issuing the request to revalidate the PCU <NUM>. In some embodiments, the avionics system <NUM> may prompt the operator to request that the subsequent validation of the PCU <NUM> be performed, or may automatically request the subsequent validation after the recommended operating time has elapsed.

In some embodiments, the warning signal being issued to the avionics system <NUM> causes the avionics system <NUM> to enact various countermeasures. As noted hereinabove, validation of the PCU <NUM> may be performed as part of a start sequence of the engine <NUM> and/or for the propeller <NUM>. When the avionics system <NUM> obtains the warning signal, the avionics system <NUM> may prevent the engine <NUM> and/or the propeller <NUM> from operating in one or more operating regimes. For example, during the start sequence of the engine <NUM>, the engine <NUM> is operated in an idle mode, a pre-takeoff mode, or the like. When the warning signal is received by the avionics system <NUM>, the avionics system <NUM> may thereafter prevent the engine <NUM> from being operated in a different regime, such as a takeoff regime, or the like. Alternatively, or in addition, upon determining that the PCU <NUM> is not validated, the engine controller <NUM> and/or the propeller controller <NUM> can request that the avionics system <NUM> prevent the engine <NUM> from being operated in a different regime.

After determining that the PCU <NUM> is not validated, and after issuing the warning signal, in some embodiments attempts to subsequently validate the PCU <NUM> are performed. Subsequent attempts at validation of the PCU <NUM> may be performed in similar fashion to the initial PCU validation described hereinabove: subsequent actuation of the valve <NUM> is commanded, and a subsequent blade angle of the blades <NUM> (and/or a subsequent rotational speed of the propeller <NUM>) is determined after the predetermined time delay has elapsed from the commanding of the subsequent actuation of the valve <NUM>. The subsequent blade angle (and/or subsequent rotational speed) is compared to the blade angle threshold (and/or rotational speed threshold), and when the subsequent blade angle (and/or subsequent rotational speed) meets the blade angle threshold (and/or rotational speed threshold), the PCU <NUM> is validated. When the subsequent blade angle (and/or the subsequent rotational speed) fails to meet the blade angle threshold (and/or rotational speed threshold), a subsequent warning signal is issued to the operator, for instance via the avionics system <NUM>. The blade angle threshold (and/or the rotational speed threshold) used as part of the subsequent validation attempt may be the same as the original blade angle threshold (and/or original rotational speed threshold), or may differ therefrom in any suitable fashion.

In some cases, multiple attempts to revalidate the PCU <NUM> are permissible, whereas in some other cases, validation of the PCU <NUM> may only be attempted a predetermined number of times. Attempts to revalidate the PCU <NUM> may be requested by the operator, for instance via the avionics system <NUM>, which commands the engine controller <NUM> and/or the propeller controller <NUM> to attempt to revalidate the PCU <NUM>, or may be performed automatically. By way of an example, in response to receiving the warning signal, the avionics system <NUM> may command the engine controller <NUM> and/or the propeller controller <NUM> to attempt to revalidate the PCU <NUM>. The command may be sent a predetermined time delay after receiving the warning signal, or after a time delay included as part of the warning signal. By way of another example, upon determining that the PCU <NUM> is not validated, the engine controller <NUM> and/or the propeller controller <NUM> may attempt to revalidate the PCU <NUM> after issuing the warning signal. Other approaches are also considered.

When a subsequent validation attempt for the PCU <NUM> results in the PCU <NUM> being validated, the engine controller <NUM> and/or the propeller controller <NUM> may issue a signal, for instance to the avionics system <NUM>, that the PCU <NUM> was subsequently validated. Subsequent validation attempts for the PCU <NUM> which result in failure to validate the PCU <NUM> lead to subsequent warning signals being issued. The subsequent warning signals may be substantially similar to the warning signal described hereinabove, or may be different in any suitable fashion. In some embodiments, when a final validation attempt for the PCU <NUM> fails, the subsequent warning signal may indicate that no further validation attempts are permitted. The subsequent validation signal(s) may also provide other information, such as a proposed maintenance action to be performed on the PCU <NUM> and/or the propeller <NUM> more generally.

In other embodiments, the PCU <NUM> may be validated using other approaches. For instance, after commanding the valve <NUM> to achieve a predetermined state, the engine controller <NUM> and/or the propeller controller <NUM> may continually monitor the actual pitch angle of the blades <NUM>, and/or actual rotational speed of the propeller <NUM>, until the pitch angle threshold (and/or rotational speed threshold) associated with the predetermined state of the valve <NUM> is achieved. The actual time delay required for the actual pitch angle of the blades <NUM> to reach the pitch angle threshold (and/or actual rotational speed of the propeller <NUM> to reach the rotational speed threshold) may be measured and compared to an expected time delay. When the engine controller <NUM> and/or the propeller controller <NUM> determine that the actual time delay is beyond the expected time delay (or beyond a value based on the expected time delay, outside of a range including the expected time delay, etc.), the warning signal can be issued to the operator to indicate that the PCU <NUM> is not operating as expected (i.e., that the response time of the valve <NUM> is slower than expected). Other approaches are also considered.

In some embodiments, the predetermined time delay is a fixed value which remains constant for all validations of the PCU <NUM>. The predetermined time delay can be altered by a maintenance crew or other responsible entity, but otherwise remains constant, as established by the manufacturer, designer, regulator, or other relevant authority. In some other embodiments, the predetermined time delay may be periodically updated. By way of an example, the predetermined time delay may be updated over the lifespan of the valve <NUM> to account for expected wear and tear and degradation of the valve <NUM>. The predetermined time delay could increase, for instance to allow for slower response times of the valve <NUM> as the valve <NUM> ages, but would nevertheless allow the engine controller <NUM> and/or the propeller controller <NUM> to detect failure or malfunction of the valve <NUM>. By way of another example, the predetermined time delay may be periodically updated based on the result of the validations of the PCU <NUM>. For instance, the predetermined time delay can be based on, or adjusted based on, an average response time for a previous number of validations, a rolling average response time for a previous number of validations, or the like. In this fashion, anticipated gradual deterioration of the valve <NUM> may be taken into account when validating the PCU <NUM>, while allowing the engine controller <NUM> and/or the propeller controller <NUM> to detect failure or malfunction of the valve <NUM>. Other approaches for modifying the predetermined time delay are also considered. In some cases, the evolution of the response time of the valve <NUM> may be tracked over time, and may be used to predict eventual failure of the valve <NUM> and/or to recommend preventative maintenance for the PCU <NUM>.

Although the present disclosure focuses primarily on systems in which the PCU <NUM> controls operation of the propeller <NUM> via a hydraulic system, it should be understood that the techniques described herein may also be used to validate PCUs which operate on different principles. For instance, an alternative embodiment of the PCU <NUM> may control the operation of the propeller <NUM> via one or more electrical actuators, via one or more pneumatic actuators, or the like, and the methods and systems escribed herein may be used to validate the alternative embodiment of the PCU <NUM>.

With reference to <FIG>, an example of a computing device <NUM> is illustrated. For simplicity, only one computing device <NUM> is shown; it should nevertheless be understood that multiple computing devices <NUM> operable to exchange data may be employed, as appropriate. The computing devices <NUM> may be the same or different types of devices. The engine controller <NUM>, the propeller controller <NUM>, and/or the avionics system <NUM> may be implemented, in whole or in part, using one or more computing devices <NUM>. The engine controller <NUM> and/or the propeller controller <NUM> may be implemented as part of a full-authority digital engine controller (FADEC) or other similar device, including an electronic engine controller (EEC), engine control unit (ECU), propeller electronic controller (PEC), propeller control unit, and the like. In some embodiments, the engine controller <NUM> and/or the propeller controller <NUM> are implemented as a Flight Data Acquisition Storage and Transmission system, such as a FASTTM system. The engine controller <NUM> and/or the propeller controller <NUM> may be implemented in part in the FASTTM system and in part in the FADEC, EEC, or other similar device. The engine controller <NUM> and/or the propeller controller <NUM> may be implemented using physical controllers, distributed controllers, virtual controllers (i.e., implemented within one or more virtual machines), or any suitable combination thereof.

In some embodiments, the EEC, the PEC, and/or any other control devices may be operated or provided in a single-channel configuration, or may be operated or provided in a dual- or multiple-channel configuration. Depending on the configuration of the control device(s), validation of the PCU <NUM> may be performed via a single channel, or via multiple channels. For instance, a determination of failure of the PCU <NUM> based on a validation performed on a first channel may be confirmed via a similar determination performed on a second channel. Other embodiments may also apply.

The processing unit <NUM> may comprise any suitable devices configured to implement the functionality described herein, including the various methods described hereinbelow, such that instructions <NUM>, when executed by the computing device <NUM> or other programmable apparatus, may cause the functions/acts/steps described herein to be executed.

With reference to <FIG>, there is illustrated a method <NUM> for validating a propeller control unit, for instance the PCU <NUM>. The PCU <NUM> is associated with a propeller having blades, for instance the propeller <NUM> having blades <NUM>, and in some case may form part of an engine, for instance the engine <NUM>. In some other cases, the PCU <NUM> and the associated propeller may be associated with another system, for instance a wind turbine, or the like. In some embodiments, the method <NUM> is performed, in whole or in part, as part of a start sequence for the engine <NUM>, or for another system of which the propeller <NUM> forms part. For example, a request to perform validation of the PCU <NUM> is obtained as part of an engine start sequence, following which one or more of the steps of the method <NUM> are performed. Part or all of the method <NUM> may be performed by the engine controller <NUM>, the propeller controller <NUM>, and/or the avionics system <NUM>, which may collaborate to perform the steps of the method <NUM> in any suitable fashion. Reference in the following paragraphs to a "controller" may thus refer to any suitable combination of the engine controller <NUM>, the propeller controller <NUM>, and/or the avionics system <NUM>.

At step <NUM>, in some embodiments the method <NUM> comprises determining, at the controller, at least one of an engine speed of the engine <NUM> and a propeller speed of the propeller <NUM>. In embodiments in which the propeller <NUM> associated with the PCU <NUM> forms part of an engine system, for instance the engine <NUM>, the engine speed (e.g. the speed of the LP turbine <NUM>) may be determined in addition to, or instead of, the propeller speed. In other embodiments, the propeller speed may be determined. The terms "propeller speed" and "engine speed" may refer to the rotational speed of one or more elements of the propeller <NUM> and engine <NUM>, respectively.

At step <NUM>, the method <NUM> comprises commanding, by the controller, actuation of a control valve of the propeller control unit, for instance the valve <NUM> of the PCU <NUM>. The actuation of the valve <NUM> results in altering a pitch angle of the blades <NUM> of the propeller <NUM>, which in turn may alter a rotational speed of the propeller <NUM>. In some embodiments, the actuation of the valve <NUM> is performed in response to obtaining a request to perform validation of the PCU <NUM>, for instance from an operator associated with the propeller <NUM> (e. g, an operator of the engine <NUM>, or of another broader system of which the propeller <NUM> forms part). In some embodiments, actuation of the valve <NUM> is performed after detecting that the engine speed and/or the propeller speed, determined at step <NUM>, are found to be above or at a particular speed threshold. For example, when performed as part of the start sequence for the engine <NUM>, the method <NUM> step <NUM> is performed after detecting, at step <NUM>, that the engine speed is above or at a speed threshold of the engine <NUM>.

At step <NUM>, the method <NUM> comprises determining, at the controller, one of an actual pitch angle of the blades <NUM> and an actual rotational speed of the propeller <NUM> after a predetermined time delay has elapsed from the commanding of the actuation of the control valve <NUM>. The predetermined time delay may be based on an expected delay required for the valve <NUM> to reach a particular state, resulting in the pitch angle of the blades <NUM> reaching a pitch angle threshold, or in the rotational speed of the propeller <NUM> reaching a rotational speed threshold, based on the commanding performed at step <NUM>. The predetermined time delay may be established by a manufacturer, designer, regulator, or other relevant authority. The actual pitch angle of the blades <NUM> and the actual rotational speed of the propeller <NUM> can be determined in any suitable fashion, for instance using a feedback system which employs a feedback device which rotates with the propeller <NUM> and moves axially in response to changes in the pitch angle of the blades <NUM>.

At step <NUM>, the method <NUM> comprises comparing, at the controller, the one of the actual pitch angle of the blades and the actual rotational speed of the propeller to a corresponding one of the pitch angle threshold and the rotational speed threshold (the rotational speed threshold associated with the pitch angle threshold). The actuation of the valve <NUM> at step <NUM> commands the valve <NUM> to achieve a particular state (i.e., a degree of openness or closedness), which in turn corresponds to a commanded pitch angle for the blades <NUM>, on which the pitch angle threshold is based, and an associated commanded rotational speed of the propeller <NUM>, on which the rotational speed threshold is based. The comparison of the actual pitch angle to the pitch angle threshold may be made between the actual pitch angle and the commanded pitch angle, with a value based on the commanded pitch angle, with a range of values including the commanded pitch angle, or the like (or for similar combinations involving the actual rotational speed and the rotational speed threshold). The comparison between the actual pitch angle or the actual rotational speed and the pitch angle threshold or the rotational speed threshold may be performed in any suitable fashion.

At decision step <NUM>, a determination is made regarding whether the actual pitch angle meets the pitch angle threshold, or whether the actual rotational speed meets the rotational speed threshold. Step <NUM> may include determining whether the actual pitch angle meets the commanded pitch angle, a value based thereon, a range of values including the commanded pitch angle, or the like. Step <NUM> may also include determining whether the actual rotational speed meets the commanded rotational speed, a value based thereon, a range of values including the commanded rotational speed, or the like. In response to determining that the actual pitch angle (and/or actual rotational speed) fails to meet the pitch angle threshold (and/or rotational speed threshold), the method <NUM> moves to step <NUM>. In response to determining that the actual pitch angle (and/or actual rotational speed) does meet the pitch angle threshold (and/or rotational speed threshold), the method <NUM> moves to step <NUM>.

At step <NUM>, the method <NUM> comprises issuing, by the controller, a warning signal to the operator of the propeller <NUM>. The warning signal may include an indication that the PCU <NUM> was not validated, of a degree of failure of the PCU <NUM>, of a recommended time delay before attempting revalidation of the PCU <NUM>, or any other suitable information. The warning signal may be presented to the operator via a display, which may include a screen, a warning light, an audio device, or the like, and which may form part of the avionics system <NUM>. In some embodiments, at step <NUM>, the method <NUM> comprises preventing operation of a system associated with the propeller <NUM> in at least one operating regime. In embodiments in which the propeller <NUM> is part of the engine <NUM> and/or of a larger system, such as an aircraft, step <NUM> may include preventing a component of the aircraft from operating in a different operating regime, for instance preventing the engine <NUM> from entering a takeoff operating regime, or the like.

In response to determining that the actual pitch angle (and/or actual rotational speed) does meet the pitch angle threshold (and/or rotational speed threshold), the method <NUM> moves to step <NUM>. It should be noted that meeting the pitch angle threshold (and/or rotational speed threshold) may also includes surpassing the pitch angle threshold (and/or rotational speed threshold) or being sufficiently similar to pitch angle threshold (and/or rotational speed threshold). At step <NUM>, the method <NUM> comprises issuing, by the controller, a validation signal to the operator. The validation may be presented to the operator via a display, which may include a screen, a warning light, an audio device, or the like, and may include any information which may be relevant for the operator.

In some embodiments, subsequent attempts to validate the PCU <NUM> may be performed, for instance by repeating one or more of the steps of the method <NUM>. The method <NUM> may thus return to a previous step, for instance step <NUM>, from step <NUM> or step <NUM>. A subsequent actuation of the valve <NUM> is commanded and a subsequent pitch angle of the blades <NUM> (and/or subsequent rotational speed of the propeller <NUM>) is determined. The subsequent blade angle (and/or subsequent rotational speed) is compared to the pitch angle threshold (and/or rotational speed threshold) to determine whether the PCU <NUM> is validated. When the subsequent blade angle (and/or subsequent rotational speed) fails to meet the pitch angle threshold (and/or rotational speed threshold), a subsequent warning signal may be issued, which may, for instance, include a recommended maintenance action for the PCU <NUM>. When the subsequent blade angle (and/or subsequent rotational speed) does meet the pitch angle threshold (and/or rotational speed threshold), the PCU <NUM> is validated, and a validation signal is issued, for instance for presentation to the operator.

The methods and systems for validating a propeller control unit described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device <NUM>. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems described herein may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems described herein may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit <NUM> of the computing device <NUM>, to operate in a specific and predefined manner to perform the functions described herein, for example those described in the method <NUM>.

Claim 1:
A method for validating a propeller control unit (<NUM>) associated with a propeller (<NUM>) having blades (<NUM>), the method comprising:
commanding, by a controller (<NUM>, <NUM>), actuation of a control valve (<NUM>) of the propeller control unit (<NUM>) to achieve a predetermined degree of openness or closedness of the control valve (<NUM>) in order to cause a change in a flow of fluid to the propeller (<NUM>) to alter a pitch angle of the blades (<NUM>) to a commanded pitch angle and to control a rotational speed of the propeller (<NUM>) to a commanded rotational speed;
determining, at the controller (<NUM>, <NUM>) and via a sensing system at the propeller (<NUM>), one of an actual pitch angle of the blades (<NUM>) and an actual rotational speed of the propeller (<NUM>) after a predetermined time delay has elapsed from the commanding of the actuation of the control valve (<NUM>), the predetermined time delay commensurate with an expected time required for the control valve (<NUM>) to achieve the predetermined degree of openness or closedness;
comparing, at the controller (<NUM>, <NUM>), the one of the actual pitch angle of the blades (<NUM>) and the actual rotational speed of the propeller (<NUM>) to a corresponding one of a pitch angle threshold and a rotational speed threshold, the pitch angle threshold and the rotational speed threshold based on the commanded pitch angle; and
issuing, by the controller (<NUM>, <NUM>), a warning signal in response to determining one of the actual pitch angle failing to meet the pitch angle threshold and the actual rotational speed failing to meet the rotational speed threshold.