GRANT AGREEMENTS.

SEC. 19. GRANT AGREEMENTS.Upon approving a project application for airport development, the Secretary, on behalf of the United States, shall transmit to the sponsor or sponsors of the project application an offer to make a grant for the United States share of allowable project costs. An offer shall be made upon such terms and conditions as the Secretary considers necessary to meet the requirements of this part and the regulations prescribed thereunder. Each offer shall state a definite amount as the maximum obligation of the United States payable from funds authorized by this part, and shall stipulate the obligations to be assumed by the sponsor or sponsors. If and when an offer is accepted in writing by the sponsor, the offer and acceptance shall comprise an agreement constituting an obligation of the United States and of the sponsor. Thereafter, the amount stated in the accepted offer as the maximum obligation of the United States may not be increased by more than 10 per centum. Unless and until an agreement has been executed, the United States may not pay, nor be obligated to pay, any portion of the costs which have been or may be incurred.