Abstract: A flap door in the floor of an aircraft cabin has a mechanism for locking and unlocking the flap door from either side. A bearing block with a bellcrank lever pivoted to the block is attached to the flap door that hinges upwardly into the passenger cabin. The bellcrank lever is one-armed and has a lateral roller that engages into a lateral guide groove. Further, a locking member is provided on the one-armed bellcrank lever, which catches behind a spring biased stop member on the bearing block in the closed position of the flap door. A handle recessed in the upwardly facing surface of the flap door is connected through a flexible pull member for withdrawing the stop member out of its locking position to open the door from above.

Abstract: A flap door for closing a hatch through a floor separating an upper and lower deck, e.g. in an aircraft, is equipped with a locking and unlocking mechanism in which a locking roller can be moved out of a locking position prior to any force applied to the door in an upward opening direction. For this purpose a bearing block is secured to the body of the flap door and a bell crank lever is journalled in the mounting block. One lever arm of the bell crank lever is constructed as a handle, while the other substantially shorter arm of the bell crank lever carries at its free end the locking roller. In its locking position the locking roller engages a spring biased locking claw. When the flap door is to be opened, the initial angular movement of the handle lever caused the roller to first disengage from the claw and then roll along a guide rail. When the unlocking is completed, the handle lever is in a substantially vertical position enabling the operator to apply an upwardly directed force to the flap door.

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.