14 CFR Part 21 (Certification Procedures)

The FAA regulation that prescribes procedural requirements for the issuance of type certificates, production approvals, airworthiness certificates, and related approvals for aircraft, aircraft engines, propellers, and articles. Part 21 defines who may apply for certification, what must be shown, and how approvals are issued, amended, and maintained. It is the procedural backbone of the FAA certification system.

The EASA Implementing Rule (Commission Regulation (EU) No 748/2012, Annex I) that establishes the certification procedures for aircraft, engines, propellers, parts, and appliances, as well as the requirements for design and production organisations. EASA Part 21 is functionally analogous to FAA 14 CFR Part 21 but differs in structure and process, particularly in its reliance on Design Organisation Approval (DOA) and Production Organisation Approval (POA) as the primary approval mechanisms.

The regulatory framework that governs the certification of aircraft, engines, propellers, and articles (parts and appliances), including procedures for type certificates, supplemental type certificates, production approvals, airworthiness certificates, and export airworthiness approvals. Part 21 is the foundational regulation that defines how a product progresses from design approval to production and operational service.

A formal approval issued by the certifying authority that confirms a product's type design complies with the applicable airworthiness requirements. A TC is issued for aircraft, aircraft engines, and propellers upon successful completion of the type certification process, which involves demonstrating compliance with every applicable regulation in the certification basis through analysis, test, and inspection. The TC defines the approved type design, operating limitations, applicable regulations, and conditions and limitations.

A modification to an existing Type Certificate that reflects a major change in the type design. An Amended TC is sought when the TC holder (or a person with proper licensing agreements) proposes changes that are significant enough to be classified as a major change but do not warrant a new, separate TC. The certification basis for an ATC typically includes the original TC certification basis plus any additional requirements triggered by the nature and extent of the change, as determined by the authority.

A design approval issued to an applicant who is not the TC holder, authorizing a major modification to an existing type-certificated product. An STC grants the holder the right to modify the product as described in the STC design data and to produce the modification components (or have them produced). The STC holder becomes responsible for the continued airworthiness of the modification, including providing ICAs, addressing unsafe conditions related to the modification, and ensuring compatibility with the underlying TC.

A Supplemental Type Certificate that includes an Approved Model List, which specifies multiple aircraft models on which the modification may be installed. An AML STC enables a single design approval to cover installation of a modification (typically avionics equipment or interior modifications) across many different aircraft types, rather than requiring separate STCs for each aircraft model. The STC holder demonstrates compatibility with each aircraft model listed on the AML.

A minimum performance standard for specified articles (materials, parts, processes, appliances, or components) issued by the FAA under 14 CFR Part 21, Subpart O. A TSO defines the minimum performance criteria that an article must meet, typically by referencing industry standards (such as RTCA DO- documents or SAE standards). A TSO Authorization (TSOA) is issued to a manufacturer who demonstrates that their article meets the applicable TSO standard, authorizing them to produce and mark the article as TSO-approved.

A combined design and production approval issued by the FAA under 14 CFR Part 21, Subpart K, that authorizes a manufacturer to produce and sell replacement or modification parts for installation on type-certificated products. A PMA holder must demonstrate that the part meets the applicable airworthiness requirements (design approval) and that the manufacturing quality system can consistently produce conforming parts (production approval). PMA parts are approved for installation as alternatives to original equipment manufacturer (OEM) parts.

An FAA approval issued under 14 CFR Part 21, Subpart F, that authorizes a manufacturer to produce duplicate products (aircraft, engines, propellers) under an approved type design without the FAA performing individual article conformity inspections. A PC holder must maintain a quality system that ensures each product conforms to the approved type design and is in a condition for safe operation. The PC is the FAA's primary production approval for complete products.

The classification of a change to a type design as either major or minor, which determines the approval process and regulatory path. A major change is one that has an appreciable effect on the weight and balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting the airworthiness of the product, or that is not done according to accepted practices or cannot be done by elementary operations. A minor change is one that does not meet the criteria for major. Major changes require more extensive compliance demonstration and authority involvement.

The formal authorization to perform a specific repair on a type-certificated product. Repairs are classified as major or minor, with major repairs requiring approved data from an authorized source before the work can be performed. Sources of approved repair data include the TC/STC holder's repair documentation, DER-approved repair designs, FAA-approved repair data, and repair data in the manufacturer's structural repair manual (SRM). The repair must restore the product to at least its original or properly altered condition.

The person or organization that applies to the certifying authority for a design approval (Type Certificate, STC, TSOA, or other approval). The applicant bears the responsibility for demonstrating compliance with all applicable airworthiness requirements and for providing the authority with the data, test results, and analyses necessary to support findings of compliance. The applicant must have the technical capability and resources to complete the certification program.

The government agency or body responsible for evaluating and approving (or rejecting) an applicant's compliance showing and issuing the certification approval. The certifying authority is typically the civil aviation authority of the State of Design. The authority establishes the certification basis, agrees on means of compliance, evaluates compliance data, conducts audits and inspections, makes findings of compliance, and ultimately issues or denies the requested approval.

The standard FAA form used to certify that a new or repaired/overhauled article (part, component, appliance) has been manufactured, inspected, tested, or maintained in accordance with approved data and is approved for return to service. An 8130-3 is issued by entities authorized by the FAA, including Production Certificate holders, PMA holders, TSO Authorization holders, repair stations, and FAA designees. It serves as both an airworthiness approval tag and an export airworthiness approval when used for international trade.

The standard EASA form used to certify that a new, repaired, or overhauled article has been manufactured or maintained in accordance with approved data and is released for service. EASA Form 1 is issued by organisations approved under EASA Part 21 (POA holders for new production) or EASA Part 145 (maintenance organisations for maintained articles). It serves as the primary airworthiness release document in the European system and is recognized internationally under bilateral agreements.

The standard Transport Canada form used to certify that an article has been manufactured, repaired, or overhauled in accordance with approved Canadian data and is released for service. TCCA Form One is issued by approved organisations under the Canadian regulatory framework and serves the same function as the FAA Form 8130-3 and EASA Form 1 in their respective jurisdictions.