{"data":{"id":"us/40-cfr-1031.90","jurisdiction":"us","citation":"40 CFR 1031.90","heading":"Supersonic engines.","body":"The following standards apply to new engines installed in supersonic airplanes:\n(a) Smoke. Engines of a type or model for which the date of manufacture was on or after January 1, 1984, may not have a characteristic level for smoke number exceeding an emission standard that is the lesser of 50 or the following:\nSN = 83.6·rO− 0.274\n(b) [Reserved]\n(c) HC. Engines of a type or model for which the date of manufacture was on or after January 1, 1984, may not have a characteristic level for HC exceeding the following emission standard in g/kN rated output:\nHC = 140·0.92 rPR\n(d) CO. Engines of a type or model for which the date of manufacture was on or after July 18, 2012, may not have a characteristic level for CO exceeding the following emission standard in g/kN rated output:\nCO = 4550·rPR−1.03\n(e) NOX Engines of a type or model for which the date of manufacture was on or after July 18, 2012, may not have a characteristic level for NOX engines exceeding the following emission standard in g/kN rated output:\nNOX = 36+2.42·rPR","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER U—AIR POLLUTION CONTROLS","PART 1031—CONTROL OF AIR POLLUTION FROM AIRCRAFT ENGINES","Subpart B—Emission Standards and Measurement Procedures"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"37002bf68244f0f87a95f7d89fcc5c928320790e3a66e8c6e7f89c833a51c3fc","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-1031.60","next":"us/40-cfr-1031.130"},"notice":"GroundRules: Original legal text. Not legal advice."}