S.C. Code Ann. § 54-3-1010

As a means of raising the funds needed from time to time in the acquisition, construction, equipment, maintenance and operation of any facility, building structure, terminal railroad or any other matter or thing which the Authority is herein authorized to acquire, construct, equip, maintain or operate, all or any of them, the Authority may issue bonds, payable both as to principal and interest from the revenues to be derived from the operation of all or any part of its properties and facilities, and the powers and authority granted to counties, cities, school districts and other political subdivisions of the State are hereby extended to and made available to the Authority. All revenue bonds issued by the Authority to obtain funds for the acquisition, construction, equipment, maintenance and operation of its properties and facilities shall be issued in accordance with the provisions of Sections 6-21-10 to 6-21-570 and all conditions, restrictions and limitations imposed by said Sections 6-21-10 to 6-21-570 as amended, shall be observed by the Authority in the issuance of such bonds, except as follows: (1) A pledge of the net revenues derived from the operation of its properties and facilities, all or any of them, rather than its gross revenues, may be made; and (2) Free service may, in the discretion of the Authority, be afforded to the United States of America, or any agency, department, corporation or instrumentality thereof, by any property or facility of the Authority to acquire, construct, equip, maintain and operate which funds were obtained from the revenue bonds purchased and held by a Federal agency, provided such free service is with the consent and at the request of the Federal agency then holding the whole of such revenue bonds.