14 CFR § 21.613 - Duration.

---
identifier: "/us/cfr/t14/s21.613"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 21.613 - Duration."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "21.613"
section_name: "Duration."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "C"
subchapter_name: "AIRCRAFT"
part_number: "21"
part_name: "CERTIFICATION PROCEDURES FOR PRODUCTS AND ARTICLES"
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. 7572; 49 U.S.C. 106(f), 40105, 40113, 44701-44702, 44704, 44707, 44709, 44711, 44713, 44715, 45303."
cfr_part: "21"
---


# 21.613 Duration.

(a) A TSO authorization or letter of TSO design approval is effective until surrendered, withdrawn, or otherwise terminated by the FAA.

(b) If a TSO is revised or canceled, the holder of an affected FAA letter of acceptance of a statement of conformance, TSO authorization, or letter of TSO design approval may continue to manufacture articles that meet the original TSO without obtaining a new acceptance, authorization, or approval but must comply with the requirements of this chapter.