Supplemental Type Certificate
STCSection 03: Certification & Approval Types
Definition
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.
Where This Shows Up
STCs are one of the most common forms of design approval in aviation. They enable third parties (not the original manufacturer) to develop modifications such as avionics upgrades, engine conversions, interior reconfigurations, structural repairs, and performance enhancements. The STC certification basis includes the regulations applicable to the changed portion of the product and any areas affected by the change.
Primary Sources
Artifacts Produced
The complete set of design data, drawings, installation instructions, and compliance documentation associated with an STC.
Maintenance and inspection instructions that the STC holder must provide for the modification.
Across Jurisdictions
14 CFR Part 21, Subpart E (§ 21.111-21.120)
The FAA issues STCs and maintains a public database of all issued STCs (STC repository).
Part 21, 21.A.112A through 21.A.118A
EASA issues STCs. A DOA holder may have privileges to approve certain STCs. EASA STCs are published in a searchable database.
CAR 521 — Supplemental Type Certificates
TCCA issues STCs under the Canadian Aviation Regulations with procedural requirements in CAR 521.
Related Terms
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