14 CFR § 151.129 - Payments.

(a) The United States' share of advance planning costs is paid in two installments unless the advance planning grant agreement provides otherwise. Upon request by sponsor, the first payment may be made in an amount not more than 50 percent of the maximum obligation of the United States stipulated in the advance planning grant agreement upon certification by sponsor that 50 percent or more of the proposed work has been completed. The final payment is made upon the sponsor's request after—

(1) The conditions of the advance planning grant agreement have been met;

(2) Evidence of cost of each item has been submitted; and

(3) Audit of submitted evidence or audit of sponsor's records, if considered desirable by FAA, has been made.

(b) When the advance planning proposal relates to the selection of an airport site, the advance planning grant agreement provides that Federal funds are paid to the sponsor only after the site is selected and the Administrator is satisfied that the site selected for the airport is reasonably consistent with existing plans of public agencies for development of the area in which the site is located, and will contribute to the accomplishment of the purposes of the Federal-aid Airport Program.