Apparatus and methods for aircraft propeller control

A method of monitoring an operating condition of an aircraft propeller rotatable about a longitudinal axis and having an adjustable blade angle, the method comprising:

• measuring a distance between position markers on a feedback device mounted for rotation with said propeller, said position markers diverging in a longitudinal direction and said feedback device mounted for longitudinal movement along with adjustment of said blade angle, wherein said measured distance is representative of a longitudinal position of said feedback device;
• comparing a value representative of said longitudinal position with at least one reference value;
• and
• outputting a signal representative of said longitudinal position.

An aircraft engine comprising:

• a propeller rotatable about a longitudinal axis, said propeller having blades with adjustable blade angle;
• a feedback ring mounted for rotation with said propeller, and for movement along said longitudinal axis along with adjustment of said blade angle, said feedback ring comprising a plurality of position markers spaced around its circumference such that a circumferential distance between at least some adjacent ones of said position markers varies along said longitudinal axis;
• a propeller shaft extending from a gearbox for driving said propeller;
• a sensor fixedly mounted to said gearbox proximate said feedback ring, said sensor operable to produce a signal when passed by a feedback marker, such that an interval between ones of said signals is indicative of a circumferential distance between adjacent ones of said position markers;
• and
• a controller in communication with said sensor to measure an interval between consecutive ones of said signal on engine startup and compute a corresponding longitudinal position of said feedback ring, said controller configured to produce a warning signal if said longitudinal position is outside a threshold range.