System and method for electronic propeller blade angle position feedback

An aircraft propeller system comprising:

• a propeller having a plurality of blades each rotatable from a positive blade angle to a negative blade angle;
• an annular member comprising circumferentially-spaced first singularities each extending generally parallel and at least a second singularity extending non-parallel to the first singularities;
• a sensor adjacent the annular member and configured for detecting said singularities passing the sensor, the annular member and sensor slidingly mounted with respect to one another between first and second relative axial positions, one of the annular member and sensor mounted for rotation with the propeller and the other fixedly mounted to the engine;
• and
• a detection unit connected to the sensor and configured for computing, by a processor, a blade angle position based elapsed time between detected singularities.

A method for blade angle position feedback for an aircraft propeller, the propeller rotatable about an axis and comprising a plurality of blades each rotatable through a plurality of blade angles, the propeller having at least a first mode of operation where the plurality of blades are operated at a positive blade angle and a second mode of operation where the plurality of blades are operated at a negative blade angle, the method comprising:

• receiving a sensor signal from at least one sensor fixedly mounted adjacent an annular member operatively connected to rotate with the propeller, the annular member comprising at least two circumferentially-spaced first singularities extending substantially parallel to the axis and at least one second singularity extending non-parallel to the first singularities, the at least one sensor configured for successively detecting a passage of each one of the at least two first singularities and the at least one second singularity as the annular member is rotated and axially displaced and for generating a sensor signal accordingly, the annular member and at least one sensor configured for relative axial displacement between a first relative axial position and a second relative axial position, the first position corresponding to the first mode of operation and the second position corresponding to the second mode of operation;
• determining, by a processor, on the basis of the sensor signal a time interval elapsed between the passage of successive ones of the at least two first singularities and the at least one second singularity;
• and
• computing, by the processor, from the time interval a blade angle position for the plurality of blades.