Applicability.
§ 21.111
This subpart prescribes procedural requirements for the issue of supplemental type certificates.
CERTIFICATION PROCEDURES FOR PRODUCTS AND ARTICLES Subpart E—Supplemental Type Certificates
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Requirement for supplemental type certificate.
§ 21.113
(a) If a person holds the TC for a product and alters that product by introducing a major change in type design that does not require an application for a new TC under § 21.19, that person must apply to the FAA either for an STC, or to amend the original type certificate under subpart D of this part. (b) If a person does not hold the TC for a product and alters that product by introducing a major change in type design that does not require an application for a new TC under § 21.19, that person must apply to the FAA for an STC. (c) The application for an STC must be made in the form and manner prescribed by the FAA.
Applicable requirements.
§ 21.115
(a) Each applicant for a supplemental type certificate must show that the altered product meets applicable requirements specified in § 21.101 and— (1) In the case of an acoustical change described in § 21.93(b), show compliance with the applicable noise requirements of part 36 of this chapter; (2) In the case of an emissions change described in § 21.93(c), show compliance with the applicable fuel venting and exhaust emissions requirements of part 34 of this chapter; and (3) In the case of a fuel efficiency change described in § 21.93(d), show compliance with the applicable fuel efficiency requirements of part 38 of this chapter. (b) Each applicant for a supplemental type certificate must meet §§ 21.33 and 21.53 with respect to each change in the type design.
Issue of supplemental type certificates.
§ 21.117
(a) An applicant is entitled to a supplemental type certificate if the FAA finds that the applicant meets the requirements of §§ 21.113 and 21.115. (b) A supplemental type certificate consists of— (1) The approval by the FAA of a change in the type design of the product; and (2) The type certificate previously issued for the product.
Privileges.
§ 21.119
The holder of a supplemental type certificate may— (a) In the case of aircraft, obtain airworthiness certificates; (b) In the case of other products, obtain approval for installation on certificated aircraft; and (c) Obtain a production certificate in accordance with the requirements of subpart G of this part for the change in the type design approved by the supplemental type certificate.
Responsibility of supplemental type certificate holders to provide written permission for alterations.
§ 21.120
A supplemental type certificate holder who allows a person to use the supplemental type certificate to alter an aircraft, aircraft engine, or propeller must provide that person with written permission acceptable to the FAA.
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Compiled from an official source version. Later amendments or repeals may not be reflected; the official text prevails. Data as of 2026-03-24. Amendments after that date may not be reflected yet. Read the official text ↗
Source: United States Code / CFR (uscode.house.gov, govinfo.gov) — U.S. federal law, public domain (17 U.S.C. § 105).
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