A method of implementing a tactile signal warning device fitted to a human-operated flight control member of a rotorcraft, the flight control member forming part of a main control linkage for varying the pitch of blades of at least one main rotor of the rotorcraft having a drive axis that is substantially vertical and providing the rotorcraft essentially with its lift, the rotorcraft being provided with:
- a power plant providing mechanical power used at least for driving rotation of the main rotor, at least one auxiliary control linkage including an autopilot for generating flight control orders controlling the use of at least one anchorable motorized trim actuator arranged in parallel with the main control linkage;
- and
- a predictor unit that operates iteratively at a given frequency to calculate at least one power margin (MP1, MP2) relating to the power available from the power plant by taking the difference between a predicted power (PP) and a power limit (LP1, LP2) relating to power to be supplied by the power plant as predefined in application of a current regulation rating of the power plant,
- wherein the warning device comprises a first calculation member, referred to as a “warning unit”, a second calculation member formed by the predictor unit, a third calculation member, referred to as a “force management” unit, and at least one warning member for generating a tactile sensation perceptible by the human pilot by means of the flight control member, the at least one warning member comprising at least the trim actuator opposing a resisting force against the flight control member being moved by a human, such that:
- the force management unit generates command data relating to a human-originating request for lift to be supplied by the main rotor, the command data being a function of at least one item of data selected from the group comprising:
- position data supplied to the force management unit by a position sensor measuring a current position of the flight control member;
- and
- force data supplied to the force management unit by a force measurement device engaged with the main control linkage, the force data being representative of forces for moving the main control linkage under the effect of a human acting on the flight control member;
- the predictor unit calculating the predicted power (PP) by summing a current power (PC) of the power plant and a variation in the power to be supplied by the power plant as requested by a human acting on the flight control member and as deduced by the predictor unit from command data that is a function of at least one of the position data and the force data;
- and
- the warning unit collects at least one of the following items of data selected from the group comprising:
- the command data as a function of at least one of the position data supplied by the position sensor and the force data supplied by the force measurement device;
- at least a first said power margin (MP1) supplied by the predictor unit by taking the difference between the predicted power (PP) and a first said power limit (LP1);
- and
- state data relating to activation of at least any higher operating mode of the autopilot causing the main control linkage to be used to guide the rotorcraft along at least one travel axis including at least the gravity axis;
- wherein the warning unit generates an anchoring command for anchoring the trim actuator on the main control linkage, the anchoring command being generated on condition both of said first power margin (MP1) and of said command data that is a function of position data and/or of force data relating to a request to increase the lift to be supplied by the main rotor;
- wherein, as a result of the warning unit generating the command for anchoring the trim actuator, the predictor unit regulates activation of the motor of the trim actuator and consequently activates an anchoring command of the trim actuator on the main control linkage so as to vary the resisting force opposed by the trim actuator against human action on the flight control member;
- and
- wherein the warning unit ceases to generate the command for anchoring the trim actuator when the force management unit generates command data representative of a human request to reduce the lift to be supplied by the main rotor, the human exerting a drive force on the flight control member that opposes a resisting force of the trim actuator.