Method for controlling a rotorcraft, associated rotorcraft and computer program

A method for controlling a rotorcraft, the rotorcraft comprising at least two combustion engines, at least one regulation system and one transmission system, the at least two engines being mechanically connected to the transmission system respectively by at least two couplings,

• wherein the control method comprises at least the following steps:
• identifying at least one engine referred to as an N2-regulated engine from among the at least two engines, the at least one N2-regulated engine being identified as an engine supplied with fuel with a fuel flow rate regulated as a function of the speed of rotation N2 of at least one first output shaft of the at least one N2-regulated engine and supplied by at least one first fuel metering valve controlled as a function of a flow rate setpoint transmitted by at least one first regulation system depending on the speed of rotation N2 of the at least one first output shaft;
• identifying an engine referred to as a non-N2′-regulated engine from among the at least two engines, the non-N2′-regulated engine being identified as an engine supplied with fuel with a fuel flow rate that is not regulated as a function of the speed of rotation N2′ of a second output shaft and supplied by a second fuel metering valve being that is either not regulated, or is controlled as a function of a flow rate setpoint transmitted by at least one second regulation system irrespective of the speed of rotation N2′ of the second output shaft;
• determining at least one first permissible input torque limit for at least one first coupling of the transmission system connected to the at least one first output shaft;
• determining a second permissible input torque limit for a second coupling of the transmission system connected to the second output shaft;
• determining a first current operating torque transmitted by the second output shaft to the second coupling of the transmission system;
• determining at least one permissible residual combined torque limit for at least one member of a mixing unit of the transmission system, the at least one residual combined torque limit being calculated according to the following formula:
• CR1=Cadm−(C1*Z)
• where Cadm is a permissible combined torque limit for the at least one member of the mixing unit;
• C1 is the first current operating torque transmitted by the second output shaft to the second coupling of the transmission system;
• and
• Z is a reduction coefficient between a speed of rotation of the second coupling and a speed of rotation of the at least one member of the mixing unit;
• identifying a critical torque limit as being the lowest of the values from among the at least one first input torque limit, second input torque limit and at least one residual combined torque limit;
• and
• generation of a control setpoint limit of the at least one first regulation system, the control setpoint limit being generated as a function of the critical torque limit.