Force application device for control stick in a power failure situation

A force application device for a control stick of an aircraft, the control stick comprising a shaft and a control lever configured to drive the shaft in rotation around a first axis, the force application device comprising:

• a magnetic brake including:
• a braking part configured to be connected to the shaft,
• a volume containing a rheological fluid in contact with the braking part, resistance to shear of the rheological fluid being variable as a function of a magnetic field applied to the rheological fluid,
• a force feedback motor configured to exert a resistive force opposing the rotation of the shaft around the first axis,
• a power source of the force feedback motor,
• a movable magnetic element having a position close to the magnetic brake and a position distant from the magnetic brake, the movable magnetic element emitting a magnetic field in the volume in the close position, the movable magnetic element being biased toward
• the close position, and
• separating means configured to retain the movable magnetic element in the distant position when the separating means are supplied with electrical power by the power source, and configured not to retain the movable magnetic element in the distant position when the separating means are not powered.