Abstract: The invention concerns an apparatus for producing a rapid air pressure equalisation between regions of an aircraft fuselage which are separated from each other by an aircraft fuselage structure and which have an air pressure difference relative to each other, in an aircraft, in particular a passenger aircraft, comprising at least one through-flow opening in the aircraft fuselage structure, a decompression flap (62) which at least partially closes the through-flow opening, and an unlocking mechanism which when a critical air pressure difference is exceeded unlocks the decompression flap (62) from its closed position so that the decompression flap (62) can be moved into an open position in which the through-flow opening is substantially opened. In accordance with the invention the decompression flap (62) comprises a plurality of portions which are hingedly connected together.