ATTACHABLE ACOUSTIC PANELS AND METHOD OF MAKING SAME

A propulsion assembly (10) includes a fan (18) and a fan case system (20) disposed about the fan (18). The fan case system (20) includes at least one perforated portion (48) including a plurality of holes (50). The propulsion assembly (10) further includes at least one acoustic panel (24) mounted to the exterior surface (44) of the fan case system (20) coincident with the at least one perforated portion (48). The at least one acoustic panel (24) includes a core (26) including a plurality of cells (28) extending between a first side (30) of the core (26) and a second side (32) of the core (26). The at least one acoustic panel (24) further includes a back skin (34) attached to the second side (32) of the core (26). The first side (30) of the core (26) is in contact with the exterior surface (44) of the fan case system (20) to form a plurality of resonant cavities (52) defined by the plurality of holes (50), the plurality of cells (28), and the back skin (34).