System and method for detecting failure of a propeller feedback device

1. A method for detecting failure of a feedback device for detecting a parameter of a propeller driven by an engine, the method comprising:

at a computing device,

receiving at least one sensor signal from at least one sensor, the at least one sensor signal produced by the at least one sensor in response to relative movement between the feedback device and the at least one sensor, one of the feedback device and the at least one sensor moving along an axis with adjustment of a blade angle of the propeller, the at least one sensor signal indicative of a rotational speed and of the blade angle of the propeller;

determining, from the at least one sensor signal, whether the rotational speed of the propeller is within a predetermined range of a reference speed and an expected change in the blade angle of the propeller has occurred in response to a command to adjust the blade angle of the propeller to maintain the rotational speed of the propeller at the reference speed;

determining a period of time during which the rotational speed of the propeller has been within the predetermined range of the reference speed and the expected change in the blade angle of the propeller has failed to occur, comparing the period of time to a pre-determined duration, and determining that the movement of the one of the feedback device and the at least one sensor along the axis is inoperable response to determining that the period of time exceeds the pre-determined duration; and

in response to determining, from the at least one sensor signal, that the rotational speed of the propeller is within the predetermined range of the reference speed and the expected change in the blade angle of the propeller has failed to occur in response to the command, outputting an alert.

2. The method of claim 1 , further comprising outputting the command in order to cause a fluid to be exchanged between a blade angle actuator of the propeller and a source of the fluid to adjust the blade angle of the propeller.

3. The method of claim 2 , further comprising outputting the command in order to cause adjustment of a governing current that controls actuation of a valve operable to selectively fluidly connect the blade angle actuator with the source of the fluid.

4. The method of claim 1 , further comprising outputting the command to adjust the blade angle of the propeller in order to increase the rotational speed of the propeller towards the reference speed, and further wherein the determining, from the at least one sensor signal, whether the expected change in the blade angle of the propeller has occurred in response to the command comprises determining, from the at least one sensor signal, whether the blade angle of the propeller has decreased in response to the command.

5. The method of claim 1 , further comprising outputting the command to adjust the blade angle of the propeller in order to decrease the rotational speed of the propeller towards the reference speed, and further wherein the determining, from the at least one sensor signal, whether the expected change in the blade angle of the propeller has occurred in response to the command comprises determining, from the at least one sensor signal, whether the blade angle of the propeller has increased in response to the command.

6. The method of claim 3 , wherein the command is output to cause the governing current to be increased, and further wherein the determining, from the at least one sensor signal, whether the rotational speed of the propeller is within the predetermined range of the reference speed in response to the command comprises determining, from the at least one sensor signal, whether the rotational speed of the propeller has increased towards the reference speed in response to the command.

7. The method of claim 3 , wherein the command is output to cause the governing current to be decreased, and further wherein the determining, from the at least one sensor signal, whether the rotational speed of the propeller is within the predetermined range of the reference speed in response to the command comprises determining, from the at least one sensor signal, whether the rotational speed of the propeller has decreased towards the reference speed in response to the command.

8. The method of claim 1 , wherein the feedback device is operatively coupled to the propeller for rotation therewith, the determining that movement of the one of the feedback device and the at least one sensor along the axis is inoperable comprises determining that movement of the feedback device along the axis is inoperable, and wherein the movement of the feedback device along the axis being inoperable is determined in response to determining, on either of a first controller channel and a second controller channel, that the rotational speed of the propeller is within the predetermined range of the reference speed and that the expected change in the blade angle of the propeller has failed to occur.

9. The method of claim 1 , wherein the outputting the alert comprises generating a warning message indicative of the movement of the feedback device along the axis being inoperable and outputting the warning message for cockpit annunciation.

10. The method of claim 8 , further comprising, in response to determining that movement of the feedback device along the axis is inoperable, outputting a subsequent command to cause the propeller to feather.

11. The method of claim 8 , further comprising, in response to determining that movement of the feedback device along the axis is inoperable, outputting a subsequent command to cause the propeller to feather and to bring a power of the engine to idle.

12. The method of claim 3 , further comprising, in response to determining that movement of the one of the feedback device and the at least one sensor along the axis is inoperable, outputting a subsequent command to cause the governing current to be limited in order to restrict a volume of the fluid exchanged between the blade angle actuator and the source of the fluid and prevent the blade angle from being adjusted towards a reverse range.

13. A system for detecting failure of a feedback device in an engine system including an engine and a propeller driven by the engine to rotate about an axis, the system comprising:

a processing unit; and

a non-transitory computer readable medium having stored thereon program code executable by the processing unit for:

receiving at least one sensor signal from at least one sensor, the at least one sensor signal produced by the at least one sensor in response to relative movement between the feedback device and the at least one sensor, one of the feedback device and the at least one sensor moving along the axis with adjustment of a blade angle of the propeller, the at least one sensor signal indicative of a rotational speed and of the blade angle of the propeller;

determining, from the at least one sensor signal, whether the rotational speed of the propeller is within a predetermined range of a reference speed and an expected change in the blade angle of the propeller has occurred in response to a command to adjust the blade angle of the propeller to maintain the rotational speed of the propeller at the reference speed;

determining a period of time during which the rotational speed of the propeller has been within the predetermined range of the reference speed and the expected change in the bade angle of the propeller has failed to occur, comparing the period of time to a pre-determined duration, and determining that the movement of the one of the feedback device and the at least one sensor along the axis is inoperable in response to determining that the period of time exceeds the pre-determined duration; and

in response to determining, from the at least one sensor signal, that the rotational speed of the propeller is within the predetermined range of the reference speed and the expected change in the blade angle of the propeller has failed to occur in response to the command, outputting an alert.

14. The system of claim 13 , wherein the program code is executable by the processing unit for outputting the command comprising instructions to cause a fluid to be exchanged between a blade angle actuator of the propeller and a source of the fluid to adjust the blade angle of the propeller.

15. The system of claim 14 , wherein the program code is executable by the processing unit for one of:

outputting the command comprising instructions for adjusting the blade angle of the propeller in order to increase the rotational speed of the propeller towards the reference speed, and determining, from the at least one sensor signal, whether the expected change in the blade angle of the propeller has occurred in response to the command comprising determining whether the blade angle of the propeller has decreased in response to the command; and

outputting the command comprising instructions for adjusting the blade angle of the propeller in order to decrease the rotational speed of the propeller towards the reference speed, and determining, from the at least one sensor signal, whether the expected change in the blade angle of the propeller has occurred in response to the command comprising determining whether the blade angle of the propeller has increased in response to the command.

16. The system of claim 13 , wherein the program code is executable by the processing unit for determining, on either of a first controller channel and a second controller channel, that the rotational speed of the propeller is within the predetermined range of the reference speed and that the expected change in the blade angle of the propeller has failed to occur.

17. The system of claim 14 , wherein the program code is executable by the processing unit for outputting a subsequent command in response to determining that movement of the feedback device along the axis is inoperable, the subsequent command comprising instructions for one of:

causing the propeller to feather;

causing the propeller to feather and bringing a power of the engine to idle; and

causing the governing current to be limited in order to restrict a volume of the fluid exchanged between the blade angle actuator and the source of the fluid and prevent the blade angle from being adjusted towards a reverse range.

18. The system of claim 13 , wherein the feedback device is coupled to the propeller for rotation therewith about the axis and moves along the axis with adjustment of the blade angle of the propeller, the determining that movement of the one of the feedback device and the at least one sensor along the axis is inoperable comprising determining that movement of the feedback device along the axis is inoperable.