An air intake unit for an engine of an aircraft; the intake unit comprises: a housing, inside which a plenum is defined, which can be connected to the engine of the aircraft; a main intake opening, which is obtained through a wall of the housing and through which the external air needed for the operation of the engine can be sucked into the plenum; at least one air filter, which is supported by the housing and engages the main intake opening so as to filter the external air flowing through said main intake opening; at least one bypass intake opening, which is obtained through a wall of the housing, is separate from and independent of the main intake opening and the air filter, and through which the external air needed for the operation of the engine can be sucked into the plenum; a shutter device, which is coupled to the bypass intake opening and is movable between a closed position, in which it closes the bypass intake opening, and an open position, in which it sets the passage through the bypass intake opening free; and an actuator, which moves the shutter device between the closed position and the open position; characterised in that the shutter device comprises two partitions (13, 14), which are mounted so as to rotate around respective rotation axes (15, 16) parallel to and spaced apart from one another and, in the closed position, are flush with the wall of the housing so as to seamlessly connect the two ends of the wall at the opposite sides of the bypass intake opening; wherein in the open position of the shutter device, an upper partition of said two partitions is arranged transversely to the wall of the housing and in a central area of the bypass intake opening; and in the open position of the shutter device, a lower partition of said two partitions is arranged parallel to the wall of the housing and overlaps said wall. a housing, inside which a plenum is defined, which can be connected to the engine of the aircraft; a main intake opening, which is obtained through a wall of the housing and through which the external air needed for the operation of the engine can be sucked into the plenum; at least one air filter, which is supported by the housing and engages the main intake opening so as to filter the external air flowing through said main intake opening; at least one bypass intake opening, which is obtained through a wall of the housing, is separate from and independent of the main intake opening and the air filter, and through which the external air needed for the operation of the engine can be sucked into the plenum; a shutter device, which is coupled to the bypass intake opening and is movable between a closed position, in which it closes the bypass intake opening, and an open position, in which it sets the passage through the bypass intake opening free; and an actuator, which moves the shutter device between the closed position and the open position; characterised in that the shutter device comprises two partitions (13, 14), which are mounted so as to rotate around respective rotation axes (15, 16) parallel to and spaced apart from one another and, in the closed position, are flush with the wall of the housing so as to seamlessly connect the two ends of the wall at the opposite sides of the bypass intake opening; wherein in the open position of the shutter device, an upper partition of said two partitions is arranged transversely to the wall of the housing and in a central area of the bypass intake opening; and in the open position of the shutter device, a lower partition of said two partitions is arranged parallel to the wall of the housing and overlaps said wall.