Abstract: Pressure equalization between the upper and lower compartments of an aircraft is provided through normally covered openings along the edges of the floor of the upper compartment. The covers each are comprised of a double-flap arrangement in which one flap is constructed as two hinged panels with locking features in order to hold the other flap in a clinging position. The space between the flaps participates in the air-conditioning circulation. In the case of a pressure drop in the lower compartment, the pressure differential tends to fold the winged panels, thereby releasing the locks so that air pressure can be equalized through uncovering of the openings.