A thermal management system for transferring heat from a heat load, the thermal management system comprising: at least one composite structural member that supports a heat load source that generates the heat load; a heat transfer member in thermal contact with the at least one composite structural member and in thermal contact with a heat sink; and a thermally conductive first fastener, in thermal contact with the heat transfer member, that couples the heat load source to the at least one composite structural member and conducts heat from the heat load source into the heat transfer member, wherein: the heat transfer member conducts heat from the thermally conductive first fastener to the heat sink; the at least one composite structural member is included in a composite wing spar; the at least one composite structural member comprises a first composite structural member, comprising a base, a cap, and a web portion and a second composite structural member, comprising a base, a cap, and a web portion; the web portion of the first composite structural member is positioned adjacent and spaced apart from the web portion of the second composite structural member to define a central cavity between the first composite structural member and the second composite structural member; and the heat transfer member is a thermally conductive material, positioned in at least a portion of the central cavity and extending to cover at least a portion of the base and the cap of the first composite structural member and at least a portion of the base and the cap of the second composite structural member. at least one composite structural member that supports a heat load source that generates the heat load; a heat transfer member in thermal contact with the at least one composite structural member and in thermal contact with a heat sink; and a thermally conductive first fastener, in thermal contact with the heat transfer member, that couples the heat load source to the at least one composite structural member and conducts heat from the heat load source into the heat transfer member, wherein: the heat transfer member conducts heat from the thermally conductive first fastener to the heat sink; the at least one composite structural member is included in a composite wing spar; the at least one composite structural member comprises a first composite structural member, comprising a base, a cap, and a web portion and a second composite structural member, comprising a base, a cap, and a web portion; the web portion of the first composite structural member is positioned adjacent and spaced apart from the web portion of the second composite structural member to define a central cavity between the first composite structural member and the second composite structural member; and the heat transfer member is a thermally conductive material, positioned in at least a portion of the central cavity and extending to cover at least a portion of the base and the cap of the first composite structural member and at least a portion of the base and the cap of the second composite structural member. the heat transfer member conducts heat from the thermally conductive first fastener to the heat sink; the at least one composite structural member is included in a composite wing spar; the at least one composite structural member comprises a first composite structural member, comprising a base, a cap, and a web portion and a second composite structural member, comprising a base, a cap, and a web portion; the web portion of the first composite structural member is positioned adjacent and spaced apart from the web portion of the second composite structural member to define a central cavity between the first composite structural member and the second composite structural member; and the heat transfer member is a thermally conductive material, positioned in at least a portion of the central cavity and extending to cover at least a portion of the base and the cap of the first composite structural member and at least a portion of the base and the cap of the second composite structural member.