Integration of a fan flutter damper in an engine casing

An acoustic treatment panel intended to be disposed on at least one wall of a turbojet in contact with a fluid flow, the panel comprising a first sheet, a second sheet parallel to the first sheet and having a first face intended to be in contact with a fluid flow and a second face facing the first sheet, and acoustic treatment cells extending between the first and second sheets and each including an enclosure and a cavity delimited by the enclosure,

• the enclosure of each cell comprising two openings facing one another, at least one of the openings being coincident with an opening of the enclosure of an adjacent cell,
• wherein the second sheet comprises a non-porous portion covering at least one first acoustic treatment cell and at least one porous portion disposed facing the at least one second acoustic treatment cell and comprising at least one perforation passing through the thickness of the second sheet and allowing the sound waves to gain access to at least one second acoustic treatment cell and to said at least one first acoustic treatment cell via the openings.