40 CFR § 1031.40 - Turboprop engines.

---
identifier: "/us/cfr/t40/s1031.40"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 1031.40 - Turboprop engines."
title_number: 40
title_name: "Protection of Environment"
section_number: "1031.40"
section_name: "Turboprop engines."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "U"
subchapter_name: "AIR POLLUTION CONTROLS"
part_number: "1031"
part_name: "CONTROL OF AIR POLLUTION FROM AIRCRAFT ENGINES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "87 FR 72351, Nov. 23, 2022, unless otherwise noted."
cfr_part: "1031"
---


# 1031.40 Turboprop engines.

The following standards apply to turboprop engines with rated output at or above 1,000 kW:

(a) *Smoke.* Engines of a type or model for which the date of manufacture of the individual engine is on or after January 1, 1984, may not have a characteristic level for smoke number exceeding the following value:

SN = 187·rO<sub>−</sub>
<sup>0.168</sup>

(b) [Reserved]