DOUBLE BOX COMPOSITE SEAL ASSEMBLY WITH INSERT FOR GAS TURBINE ENGINE, GAS TURBINE ENGINE AND METHOD

A seal assembly (176) for a gas turbine engine (20) according to an aspect of the present disclosure includes, among other things, a seal (69; 169; 269) including a main body (170) extending circumferentially between opposed mate faces (178; 278). The main body (170) has a sealing portion (177; 277) and an engagement portion (179; 279) extending outwardly from sealing portion (177; 277) along at least one of the mate faces (178; 278). The main body (170) has a core (192; 292) including one or more core plies having a first fiber construction comprising substantially continuous fibers and arranged to establish an internal cavity (184). An overwrap (194; 294) has one or more overwrap plies having a second fiber construction comprising substantially continuous fibers and are arranged to follow a perimeter of the one or more core plies to establish the engagement portion (179; 279) and the sealing portion (177; 277). The second fiber construction differs from the first fiber construction. A platform insert extends between portions of the core and the overwrap to establish the sealing portion. The platform insert (197; 297) has a construction that differs from the first and second fiber construction. A method of fabricating a seal (69; 169; 269) for a gas turbine engine (20) is also disclosed.