---
kind: "section"
citation: "14 C.F.R. § 34.31"
title: "14"
number: "34.31"
heading: "Standards for exhaust emissions."
url: "https://uscodex.org/cfr/14/34.31"
---

# §34.31. Standards for exhaust emissions.

- (a) Exhaust emissions of smoke from each in-use aircraft gas turbine engine of Class T8, beginning February 1, 1974, shall not exceed a smoke number (SN) of 30.
- (b) Exhaust emissions of smoke from each in-use aircraft gas turbine engine of Class TF and of rated output of 129 kN (29,000 lb) thrust or greater, beginning January l, 1976, shall not exceed
- (c) The standards set forth in paragraphs [(a)](#a) and [(b)](#b) of this section refer to exhaust smoke emission emitted during operation of the engine as specified in the applicable sections of [subpart G](/cfr/14/subpartG.md) of this part, and measured and calculated in accordance with the procedures set forth in subpart G.

## Notes

### Amendments

[Doc. No. FAA-2012-1333, 77 FR 76852, Dec. 31, 2012]

### Authority

Authority: 42 U.S.C. 4321 et seq., 7572; 49 U.S.C. 106(g), 40113, 44701-44702, 44704, 44714.

### Source

Source: Docket No. 25613, 55 FR 32861, Aug. 10, 1990, unless otherwise noted.

### Amendments

[Doc. No. FAA-2012-1333, 77 FR 76852, Dec. 31, 2012]