49 U.S.C. § 47109

(a) General .— Except as otherwise provided in this section, the United States Government’s share of allowable project costs is— (1) 75 percent for a project at a medium or large hub airport; (2) not more than 90 percent for a project funded by a grant issued to and administered by a State under section 47128, relating to the State block grant program; (3) 90 percent for a project at any other airport; (4) 70 percent for a project funded by the Administrator from the discretionary fund under section 47115 at an airport receiving an exemption under section 47134; and (5) 95 percent for a project that— (A) the Administrator determines is a successive phase of a multiphase construction project for which the sponsor received a grant in fiscal year 2011; and (B) for which the United States Government’s share of allowable project costs would otherwise be capped at 90 percent under paragraph (2) or (3). (b) Increased Government Share .— If, under subsection (a) of this section, the Government’s share of allowable costs of a project in a State containing unappropriated and unreserved public lands and nontaxable Indian lands (individual and tribal) of more than 5 percent of the total area of all lands in the State, is less than the share applied on June 30, 1975 , under section 17(b) of the Airport and Airway Development Act of 1970, the Government’s share under subsection (a) of this section shall be increased by the lesser of— (1) 25 percent; (2) one-half of the percentage that the area of unappropriated and unreserved public lands and nontaxable Indian lands in the State is of the total area of the State; or (3) the percentage necessary to increase the Government’s share to the percentage that applied on June 30, 1975 , under section 17(b) of the Act. (c) Grandfather Rule.— (1) In general .— In the case of any project approved after September 30, 2003 , at a small hub airport or nonhub airport that is located in a State containing unappropriated and unreserved public lands and nontaxable Indian lands (individual and tribal) of more than 5 percent of the total area of all lands in the State, the Government’s share of allowable costs of the project shall be increased by the same ratio as the basic share of allowable costs of a project divided into the increased (Public Lands States) share of allowable costs of a project as shown on documents of the Federal Aviation Administration dated August 3, 1979 , at airports for which the general share was 80 percent on August 3, 1979 . This subsection shall apply only if— (A) the State contained unappropriated and unreserved public lands and nontaxable Indian lands of more than 5 percent of the total area of all lands in the State on August 3, 1979 ; and (B) the application under subsection (b), does not increase the Government’s share of allowable costs of the project. (2) The Government’s share of allowable project costs determined under this subsection shall not exceed the lesser of 93.75 percent or the highest percentage Government share applicable to any project in any State under subsection (b), except that at a primary non-hub and non-primary commercial service airport located in a State as set forth in paragraph (1) of this subsection that is within 15 miles of another State as set forth in paragraph (1) of this subsection, the Government’s share shall be an average of the Government share applicable to any project in each of the States. (d) Special Rule for Privately Owned Reliever Airports .— If a privately owned reliever airport contributes any lands, easements, or rights-of-way to carry out a project under this subchapter, the current fair market value of such lands, easements, or rights-of-way shall be credited toward the non-Federal share of allowable project costs. (e) Special Rule for Transition From Small Hub to Medium Hub Status .— If the status of a small hub airport changes to a medium hub airport, the Government’s share of allowable project costs for the airport may not exceed 90 percent for the first 2 fiscal years after such change in hub status. (f) Special Rule for Economically Distressed Communities .— The Government’s share of allowable project costs shall be 95 percent for a project at an airport that— (1) is receiving essential air service for which compensation was provided to an air carrier under subchapter II of chapter 417; and (2) is located in an area that meets one or more of the criteria established in section 301(a) of the Public Works and Economic Development Act of 1965 ( 42 U.S.C. 3161(a) ), as determined by the Secretary of Commerce. (g) Special Rule for Covered Equipment.— (1) In general .— The Government’s share of allowable project costs for covered equipment and its installation shall be 100 percent. (2) Definition of covered equipment .— For purposes of this subsection, the term “covered equipment” means aqueous film forming foam input-based testing equipment that is eligible for Airport Improvement Program funding based on Federal Aviation Administration PGL 21–01, titled “Extension of Eligibility for stand-alone acquisition of input-based testing equipment and truck modification”, dated October 5, 2021 (or any other successor program guidance letter). (3) Sunset .— The higher cost share authority established in this subsection shall terminate on the earlier of— (A) 180 days after the date on which the eligibility of covered equipment for Airport Improvement Program funding under the authority described in paragraph (2) terminates or is discontinued by the Administrator; or (B) 5 years after the date of enactment of this subsection. (h) Special Rule for Fiscal Years 2025 and 2026.— Notwithstanding subsection (a), the Government’s share of allowable project costs for a grant made to a nonhub or nonprimary airport in each of fiscal years 2025 and 2026 shall be 95 percent. (i) Special Rule for Sound Insulation Repair and Replacement .— With respect to a project to carry out sound insulation that is granted a waiver under section 47110(j), the allowable project cost for such project shall be calculated without consideration of any costs that were previously paid by the Government.