; 130 Stat. 641) is amended by striking 2018 and inserting 2023 . 556. Regions and centers (a) In general Section 44507 of title 49, United States Code, is amended— (1) by striking the section heading and inserting Regions and centers ; (2) by striking The Civil Aeromedical Institute and inserting the following: (a) Civil Aeromedical Institute The Civil Aeromedical Institute ; and (3) by adding at the end the following: (b) William J. Hughes Technical Center The Secretary of Transportation shall define the roles and responsibilities of the William J. Hughes Technical Center in a manner that is consistent with the defined roles and responsibilities of the Civil Aeromedical Institute under subsection (a). . (b) Clerical amendment The analysis for chapter 445 of title 49, United States Code, is amended by striking the item relating to section 44507 and inserting the following: 44507. Regions and centers. . 557. Study on airport revenue diversion (a) Study Not later than 180 days after the date of enactment of this Act, the Comptroller General of the United States shall initiate a study of— (1) the legal and financial challenges related to repealing the exception in section 47107(b)(2) of title 49, United States Code, for those airports the Federal Aviation Administration has identified are covered by the exception; and (2) measures that may be taken to mitigate the impact of repealing the exception. (b) Contents The study required under subsection (a) shall address— (1) the level of revenue diversion at the airports covered by the exception described in subsection (a)(1) and the uses of the diverted revenue; (2) the terms of any bonds or financial covenants an airport owner has issued relying on diverted airport revenue; (3) applicable local laws or ordinances requiring use of airport revenue for non-airport purposes; (4) whether repealing the exception would improve the long-term financial performance of impacted airports