CFR›Title 14›Chapter I›Part 38 ContainsSubpart A; Appendix A; Subpart BCorpusDaily eCFRDisplayed edition2026-04-15Last updated2026-04-15 PART 38—AIRPLANE FUEL EFFICIENCY CERTIFICATION Contents A Subpart A—General Sections 38.1–38.9 Appendix A to Part 38 Appendix A to Part 38—Determination of Airplane Fuel Efficiency Metric Value B Subpart B—Determining Fuel Efficiency for Subsonic Airplanes Sections 38.11–38.23 Authority42 U.S.C. 4321 et seq., 7572; 49 U.S.C. 106(g), 40113, 44701-44702, 44704; 49 CFR 1.83(c)SourceDocket No. FAA-2022-0241, Amdt. No. 21-107, 89 FR 12654, Feb. 16, 2024, unless otherwise noted. Previous 36 Part 36—Noise Standards: Aircraft Type and Airworthiness Certification Next 39 Part 39—Airworthiness Directives