Abstract: A device for actuating an aircraft undercarriage leg includes an electronic controller and an actuator. The actuator includes a three-phase electric motor connected to the electronic controller. The device is arranged to authorize gravity deployment of the aircraft undercarriage leg. The motor includes a stator having at least first and second star-coupled three-phase windings. The electronic controller includes a first control channel connected to the first three-phase winding, and a second control channel connected to the second three-phase winding. Each of the control channels includes a controller that generates a high-level control instruction, a driver that generates a low-level driver instruction from the high-level control instruction, and a braking circuit that brakes the motor during the gravity deployment of the leg by using energy produced by the motor. The device is arranged to use the control channels as a function of the availabilities of the components of each channel.