CFR > Title 40 > Chapter I > Subchapter U > Part 1033 > Subpart F CFR > Title 40 > Chapter I > Subchapter U > Part 1033 > Subpart F – Test Procedures Current as of: 2024 | Check for updates | Other versions § 1033.501 General provisions § 1033.505 Ambient conditions § 1033.510 Auxiliary power units § 1033.515 Discrete-mode steady-state emission tests of locomotives and locomotive engines § 1033.520 Alternative ramped modal cycles § 1033.525 Smoke opacity testing § 1033.530 Duty cycles and calculations § 1033.535 Adjusting emission levels to account for infrequently regenerating aftertreatment devices