{"data":{"id":"us/14-cfr-38.13","jurisdiction":"us","citation":"14 CFR 38.13","heading":"Specific air range.","body":"(a) For each airplane subject to this part, the SAR of an airplane must be determined by either:\n(1) Direct flight test measurements; or\n(2) Using a performance model that is:\n(i) Validated by actual SAR flight test data; and\n(ii) Approved by the FAA before any SAR calculations are submitted.\n(b) For the airplane model, establish a 1/SAR value at each of the following reference airplane masses:\n(1) High gross mass: 92 percent MTOM.\n(2) Low gross mass: (0.45 * MTOM) + (0.63 * (MTOM^0.924)).\n(3) Mid gross mass: simple arithmetic average of high gross mass and low gross mass.\n(c) To obtain (1/SAR)avg as required to determine the fuel efficiency metric value described in § 38.11, calculate the average of the three 1/SAR values described in paragraph (b) of this section. Do not include auxiliary power units in any 1/SAR calculation.\n(d) All determinations made under this section must be made in accordance with the procedures applicable to SAR as described in appendix A to this part.","path":["Title 14—Aeronautics and Space","CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER C—AIRCRAFT","PART 38—AIRPLANE FUEL EFFICIENCY CERTIFICATION","Subpart B—Determining Fuel Efficiency for Subsonic Airplanes"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-14.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:24:20Z","sha256":"b9102f7a152c5f725b354119f4e744d241a9b6ab0de409f859bebb58330ac2ab","source_id":"us-cfr","stale":true,"prev":"us/14-cfr-38.11","next":"us/14-cfr-38.15"},"notice":"GroundRules: Original legal text. Not legal advice."}