A gas turbine engine comprising: a compressor section ; and an air-to-air heat exchanger (10; 400; 900) in fluid communication with the compressor section , comprising: a central manifold comprising an inlet portion (412; 912), a first outlet portion (414; 914), and a second outlet portion (416; 916); a plurality of tubes (20; 430) configured to receive air from the compressor section coupled to the central manifold ; a shroud at least partially encasing said plurality of tubes (20; 430); and a cooling air flow path (F) defined by at least one of the shroud , the plurality of tubes (20; 430), and an outer surface of the central manifold , wherein the cooling air flow path (F) is orthogonal to said plurality of tubes (20; 430), wherein, the air-to-air heat exchanger (10; 400; 900) is coupled to the gas turbine engine via an adjustable damper comprising: a first tube ; a second tube located at least partially within the first tube ; an adjusting member ; a moveable member ; and a spring member located between the adjusting member and the moveable member . a compressor section ; and an air-to-air heat exchanger (10; 400; 900) in fluid communication with the compressor section , comprising: a central manifold comprising an inlet portion (412; 912), a first outlet portion (414; 914), and a second outlet portion (416; 916); a plurality of tubes (20; 430) configured to receive air from the compressor section coupled to the central manifold ; a shroud at least partially encasing said plurality of tubes (20; 430); and a cooling air flow path (F) defined by at least one of the shroud , the plurality of tubes (20; 430), and an outer surface of the central manifold , wherein the cooling air flow path (F) is orthogonal to said plurality of tubes (20; 430), wherein, the air-to-air heat exchanger (10; 400; 900) is coupled to the gas turbine engine via an adjustable damper comprising: a first tube ; a second tube located at least partially within the first tube ; an adjusting member ; a moveable member ; and a spring member located between the adjusting member and the moveable member . a central manifold comprising an inlet portion (412; 912), a first outlet portion (414; 914), and a second outlet portion (416; 916); a plurality of tubes (20; 430) configured to receive air from the compressor section coupled to the central manifold ; a shroud at least partially encasing said plurality of tubes (20; 430); and a cooling air flow path (F) defined by at least one of the shroud , the plurality of tubes (20; 430), and an outer surface of the central manifold , wherein the cooling air flow path (F) is orthogonal to said plurality of tubes (20; 430), wherein, the air-to-air heat exchanger (10; 400; 900) is coupled to the gas turbine engine via an adjustable damper comprising: a first tube ; a second tube located at least partially within the first tube ; an adjusting member ; a moveable member ; and a spring member located between the adjusting member and the moveable member . a first tube ; a second tube located at least partially within the first tube ; an adjusting member ; a moveable member ; and a spring member located between the adjusting member and the moveable member . <EOS>