Protection for a circuit for controlling the orientation of propeller blades of an aircraft engine

A hydraulic control circuit for actuating a double-acting steering actuator for orienting the blades of an aircraft engine pusher propeller, the double-acting actuator comprising a first and a second chamber, the circuit comprising:

• a high-pressure line and a low-pressure line;
• a distributing valve for connecting the first chamber to the high-pressure line and the second chamber to the low-pressure line or vice versa, or for isolating the two chambers from the high-pressure and low-pressure lines;
• a first protection valve being able to assume a deactivated position or an activation position that places the first chamber in communication with the high-pressure line;
• a second protection valve being able to assume a deactivated position or an activation position that places the second chamber in communication with the low-pressure line;
• the protection valves include an activation hydraulic inlet and a deactivation hydraulic inlet that can be connected to the high-pressure line or to the low-pressure line to place them in the deactivation or activation position;
• an amplification valve being able to assume a deactivated position or an activation position that connects the high-pressure line to each activation inlet and the low-pressure line to each deactivation inlet to activate the protection valves;
• the amplification valve including a hydraulic control inlet for placing the amplification valve in the activation position when the control inlet is connected to the low-pressure line and for placing the amplification valve in the deactivated position when the control inlet is connected to the high-pressure line;
• and a protection solenoid valve being able to assume a deactivation position or an activation position wherein the protection solenoid valve connects the control inlet of the amplification valve to the low-pressure line in order to activate the amplification valve.