A turbine section of a gas turbine engine , comprising: an engine casing ; a rotor blade disposed radially inward of the engine casing with respect to a centerline axis of the gas turbine engine ; and a blade outer air seal comprising a wall extending between a forward hook and an aft hook , wherein the forward and aft hooks are adapted to mount the blade outer air seal to a casing of a gas turbine engine, and the wall includes at least a cored passage extending along at least a portion thereof, characterised in that the at least a cored passage comprises at least a crossover passage that extends radially and axially along a portion of the aft hook to communicate with one or more apertures along a trailing edge of the aft hook, the one or more apertures communicating with a plenum at least partially defined by a stator vane and a casing adjacent the trailing edge of the aft hook, wherein the forward and aft hooks are adapted to mount the blade outer air seal to the engine casing to dispose the wall between the engine casing and the rotor blade , and wherein the at least a cored passage extends substantially an entire length of the wall from adjacent the forward hook to adjacent the aft hook ; wherein the stator vane is disposed axially aft of the rotor blade ; and one or more conformal seals disposed between the trailing edge of the blade outer air seal and the stator vane, and wherein the one or more apertures that communicate with the cored passage are disposed radially outward of the conformal seals with respect to the centerline axis of the gas turbine engine, and wherein the crossover passage is configured to allow cooling air flow to be transported around conformal seal . an engine casing ; a rotor blade disposed radially inward of the engine casing with respect to a centerline axis of the gas turbine engine ; and a blade outer air seal comprising a wall extending between a forward hook and an aft hook , wherein the forward and aft hooks are adapted to mount the blade outer air seal to a casing of a gas turbine engine, and the wall includes at least a cored passage extending along at least a portion thereof, characterised in that the at least a cored passage comprises at least a crossover passage that extends radially and axially along a portion of the aft hook to communicate with one or more apertures along a trailing edge of the aft hook, the one or more apertures communicating with a plenum at least partially defined by a stator vane and a casing adjacent the trailing edge of the aft hook, wherein the forward and aft hooks are adapted to mount the blade outer air seal to the engine casing to dispose the wall between the engine casing and the rotor blade , and wherein the at least a cored passage extends substantially an entire length of the wall from adjacent the forward hook to adjacent the aft hook ; wherein the stator vane is disposed axially aft of the rotor blade ; and one or more conformal seals disposed between the trailing edge of the blade outer air seal and the stator vane, and wherein the one or more apertures that communicate with the cored passage are disposed radially outward of the conformal seals with respect to the centerline axis of the gas turbine engine, and wherein the crossover passage is configured to allow cooling air flow to be transported around conformal seal . <EOS>