S.C. Code Ann. § 55-11-360

All revenues derived by the commission from the operation of any revenue-producing facility which may not be required to operate, maintain, enlarge and improve its airport facilities, or to pay obligations incurred in the issuance of any revenue bonds sold pursuant to the authorizations of item (19), Section 55-11-340, shall be paid over to the State Treasurer, and held by him for the payment of interest and principal of general obligation bonds of the district.