FAR 21.1 — Certification Procedures
FAR 21.1 sets the scope of Part 21 and defines key certification terms like article, product, design approval, and production approval for pilots and applicants.
In Plain English
FAR 21.1 establishes what Part 21 covers and defines the vocabulary used throughout the certification rules. Part 21 lays out:
- Procedures for issuing and changing design approvals, production approvals, airworthiness certificates, and airworthiness approvals
- Rules for applicants and holders of those approvals or certificates
- Procedures for approval of articles
It then defines the building-block terms you'll see across Part 21:
- Airworthiness approval: an FAA document certifying an aircraft, engine, propeller, or article conforms to its approved design and is safe to operate.
- Article: a material, part, component, process, or appliance.
- Commercial part: an article on an FAA-approved Commercial Parts List in the design holder's ICA.
- Design approval: a type certificate (including amended/supplemental) or approved design under a PMA, TSO authorization, or letter of TSO design approval.
- Interface component: an article serving as a functional interface between aircraft, engines, and propellers.
- Product: an aircraft, aircraft engine, or propeller.
- Production approval: an FAA document allowing production per an approved design and quality system (production certificate, PMA, or TSO authorization).
- State of Design / State of Manufacture: the country with regulatory authority over design or production.
- Supplier: anyone in the supply chain providing a product, article, or service used in design, manufacture, or installation.
Why it matters: as a pilot, knowing these terms helps you read airworthiness paperwork, STCs, and PMA tags correctly when verifying an aircraft is legal to fly.
Regulation Text
14 CFR § 21.1§ 21.1 Applicability and definitions.
(a) This part prescribes—
(1) Procedural requirements for issuing and changing—
(i) Design approvals;
(ii) Production approvals;
(iii) Airworthiness certificates; and
(iv) Airworthiness approvals;
(2) Rules governing applicants for, and holders of, any approval or certificate specified in paragraph (a)(1) of this section; and
(3) Procedural requirements for the approval of articles.
(b) For the purposes of this part—
(1)means a document, issued by the FAA for an aircraft, aircraft engine, propeller, or article, which certifies that the aircraft, aircraft engine, propeller, or article conforms to its approved design and is in a condition for safe operation, unless otherwise specified;
(2)means a material, part, component, process, or appliance;
(3)means an article that is listed on an FAA-approved Commercial Parts List included in a design approval holder's Instructions for Continued Airworthiness required by § 21.50;
(4)means a type certificate (including amended and supplemental type certificates) or the approved design under a PMA, TSO authorization, letter of TSO design approval, or other approved design;
(5)means an article that serves as a functional interface between an aircraft and an aircraft engine, an aircraft engine and a propeller, or an aircraft and a propeller. An interface component is designated by the holder of the type certificate or the supplemental type certificate who controls the approved design data for that article;
(6)means an aircraft, aircraft engine, or propeller;
(7)means a document issued by the FAA to a person that allows the production of a product or article in accordance with its approved design and approved quality system, and can take the form of a production certificate, a PMA, or a TSO authorization;
(8)means the country or jurisdiction having regulatory authority over the organization responsible for the design and continued airworthiness of a civil aeronautical product or article;
(9)means the country or jurisdiction having regulatory authority over the organization responsible for the production and airworthiness of a civil aeronautical product or article.
(10)means a person at any tier in the supply chain who provides a product, article, or service that is used or consumed in the design or manufacture of, or installed on, a product or article.
[Doc. No. FAA-2006-25877, Amdt. 21-92, 74 FR 53384, Oct. 16, 2009; Doc. No. FAA-2013-0933, Amdt. 21-98, 80 FR 59031, Oct. 1, 2015; Amdt. 21-98A, 80 FR 59031, Dec. 17, 2015; Docket FAA-2015-0150, Amdt. 21-99, 81 FR 42207, June 28, 2016; Docket FAA-2018-1087, Amdt. 21-105, 86 FR 4381, Jan. 15, 2021]
Oral Exam Questions a DPE Might Ask
Q1Under FAR Part 21, what's the difference between a 'product' and an 'article'?
Per FAR 21.1, a **product** is an aircraft, aircraft engine, or propeller, while an **article** is a material, part, component, process, or appliance — basically anything that goes into or supports a product.
Q2What does 'design approval' include according to Part 21?
FAR 21.1 defines design approval as a type certificate (including amended and supplemental type certificates) or the approved design under a PMA, TSO authorization, letter of TSO design approval, or other approved design.
Q3What is an airworthiness approval and what does it certify?
Under FAR 21.1, an airworthiness approval is an FAA-issued document for an aircraft, engine, propeller, or article that certifies it conforms to its approved design and is in a condition for safe operation.
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Related Sections in Part 21