other public authorities, and private sources, which shall be available for expenses incurred for research, engineering, and development. Grants-in-aid for airports (liquidation of contract authorization) (limitation on obligations) (airport and airway trust fund) (including transfer of funds) For liquidation of obligations incurred for grants-in-aid for airport planning and development, and noise compatibility planning and programs as authorized under subchapter I of chapter 471 and subchapter I of chapter 475 of title 49, United States Code, and under other law authorizing such obligations