Method and avionics device for controlling the pitch angle of a fan or propeller of an aircraft powertrain

A method for controlling and limiting a pitch angle of the blades of a fan or propeller of a powertrain of an aircraft, the method being carried out in an avionics device of said aircraft, the avionics device being housed on board the aircraft, being independent of the powertrain and being connected to a control device for controlling said powertrain driving said fan or said propeller, the control device being contained within the powertrain, the method comprising:

• obtaining first items of information representative of flight conditions of said aircraft in relation to its external environment, supplied by at least one avionics computer of the aircraft independent of the powertrain, these first items of information comprising at least an altitude and an airspeed of the aircraft,
• determining a threshold value for the pitch angle of the blades of said fan or propeller, based on said first items of information, so as to limit the risks of undesirable aerodynamic effects affecting the flight of the aircraft when the aircraft is flying at said altitude at said airspeed,
• obtaining an item of information representative of a current pitch angle of the blades of said fan or propeller, and then
• sending, to said control device for controlling the powertrain, a control signal when said item of information representative of said current pitch angle of the blades is less than said threshold value, for the purpose of locking the pitch angle of the blades of the fan or propeller, under control by the control device of the powertrain.