StacksVerified U.S. regulatory reference

40 CFR §1031.90

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
The following standards apply to new engines installed in supersonic airplanes:
  1. (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:
  2. (b)[Reserved]
  3. (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:
  4. (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:
  5. (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: