A port-door release assembly includes a door and a linkage coupled to the door to support the door during movement between open and closed positions. The port-door release assembly includes a drive shaft coupled to the linkage to drive movement of the linkage. The port-door release assembly includes a motor configured to rotate the drive shaft which moves the linkage and the door to the open and/or closed positions. The port-door release assembly includes a back-up release assembly movable relative to the linkage to disconnect the drive shaft from the linkage which allows the door to move to the open position without actuation of the motor. A door assembly includes the port-door release assembly as described above and a housing defining a port in which the door is movable relative to the housing between the open position that uncovers the port and the closed position that covers the port.