Use of operational revenue

All revenue derived from the operation of the airport or flying field, after paying the operating expenses and maintenance, shall be set aside and used for additional improvements on the airport or for the retirement of bonds and interest thereon issued or advancement made for the purchase and improvement of the airport or flying field. Acts 1949, No. 53, § 9; A.S.A. 1947, § 74-509. All revenue derived from the operation of the airport or flying field, after paying the operating expenses and maintenance, shall be set aside and used for additional improvements on the airport or for the retirement of bonds and interest thereon issued or advancement made for the purchase and improvement of the airport or flying field. Acts 1949, No. 53, § 9; A.S.A. 1947, § 74-509.