620 ILCS 45/19
The Board of Directors from time to time may execute and deliver bonds, notes or certificates of indebtedness in such form as may be approved by the Board of Directors, and payable at such place and subject to such terms as may be specified and in such denominations and amounts as the resolution authorizing the issuance thereof may provide. Any such bonds, notes or certificates of indebtedness shall mature within fifteen (15) years from the date thereof and shall be payable solely from revenue derived from the operation, management or use of the airport, landing field, airdrome, hangar, building, structure or other facility in accordance with the rules, regulations, contracts, leases or sub-leases of the Board of Directors. Such revenue obligations shall not be payable out of any funds derived by the Board of Directors from taxation or by funds derived from the sale of any property belonging to said airport, except notes or obligations incident to the purchase or acquisition of such personal property as may be purchased by the Board of Directors under a conditional sales contract, revenue from which personal property is pledged to secure payment of the balance due on the purchase price thereof, which is evidenced by any such notes or obligations. Any bond, note or certificate of indebtedness issued under this section shall recite in the body thereof that the same is payable solely from the revenue pledged to pay the same, and shall state the nature or source of such revenue, and shall state on its face that the same is not payable from taxation and that it is not a debt within the meaning of any statutory or constitutional limitation.
620 ILCS 45/19