An aircraft door actuator, including: a pneumatic cylinder for the opening of the door including a chamber into which a pressurized gas is injected via a first port, means for supplying the chamber of the cylinder with pressurized gas, via a supply pipe and said first port, means for setting the chamber to atmospheric pressure when the piston is in the position for opening the door, so as to allow said door to be moved into the closing position, including: a pressurized gas exhaust pipe a gate-valve means for guiding the opening of the gate-valve via the pressurized fluid located in the chamber when the door is in the opening position, so as to open the exhaust pipe in order to set said chamber of the cylinder to atmospheric pressure in a rapid manner once the door is open.