---
kind: "unit"
title: "40"
title_heading: "Protection of Environment"
key: "chI/subchC/part51/subpartR"
level: "subpart"
label: "Subpart R"
heading: "Extensions"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/40/chI-subchC-part51-subpartR"
sections_count: 1
---

# Subpart R — Extensions

Title 40 C.F.R. — Protection of Environment › Chapter I — Environmental Protection Agency › Subchapter C — Air Programs › Part 51 — Requirements for Preparation, Adoption, and Submittal of Implementation Plans

## Sections

- [§51.341. Request for 18-month extension.](/cfr/40/51.341.md)