Understanding FAA Supplemental Type Certificates (STC)

What is a Supplemental Type Certificate (STC)?

A Supplemental Type Certificate (STC) from the FAA is the official approval for any major modification or repair to a type-certified aircraft, engine, or propeller. It serves as a formal amendment to the product’s original design, ensuring the altered configuration meets all required safety and airworthiness standards.

An STC differs from a Type Certificate (TC). While a TC is the original certification for a manufacturer’s new aircraft design, an STC is typically pursued by a third party to modify that existing, approved design, making it a key driver of innovation and upgrades across the industry.

STCs are essential for modernizing the global aviation fleet. They provide a clear regulatory pathway for significant upgrades—like installing advanced avionics, boosting engine performance, or reconfiguring an aircraft’s interior—without the need for a complete and costly re-certification. This process allows operators to keep their fleets equipped with the latest technology and capabilities.

The approval process is handled by an FAA Aircraft Certification Office (ACO) or a Designated Alteration Station (DAS). These authorities review the proposed modification, its impact on the original design, and all supporting data to confirm its safety. Once granted, the STC becomes a permanent part of the aircraft’s official records.

How to Access the Supplemental Type Certificate Database

Finding the right STC for a specific aircraft modification is a critical step for compliance and safety. The primary official source is the FAA’s Dynamic Regulatory System (DRS), which serves as the central repository for all regulatory data.

For a more user-friendly experience, several third-party online databases offer comprehensive access to STC information. One example is the Aviation Database, which holds records for over 81,000 STCs. These platforms enable searches using various criteria—like the STC number, TC number, holder’s name, or aircraft model—making it simpler to confirm if an STC exists for a modification and to locate the holder’s contact details.

Additionally, many manufacturers and major aviation service providers maintain their own dedicated STC databases. Companies like Collins Aerospace and Duncan Aviation, for instance, offer online portals to look up STCs specific to their products. These specialized databases are useful when you’re considering an upgrade from a particular company, as they provide direct access to relevant approval documents and technical details.

The Application-to-Issuance Process for STCs

Securing an STC is a detailed, FAA-overseen process designed to ensure any major modification upholds the strictest safety standards. The process begins when an applicant submits a proposal to the relevant FAA Aircraft Certification Office (ACO). This package must detail the intended modification and establish its ‘certification basis‘—the specific airworthiness regulations the change is required to meet.

Upon receiving the application, the ACO begins a detailed review. FAA engineers and inspectors examine the design data, assessing its impact on the aircraft’s structural integrity, performance, and safety. To validate the change, the FAA may require compliance demonstrations—such as ground inspections, flight tests, or engineering analyses—where the applicant must prove the modification performs as intended. Once the applicant successfully demonstrates full compliance, the FAA issues the STC.

Responsibilities of STC Holders

Receiving an FAA STC isn’t the final step; it’s the beginning of an ongoing obligation. The holder is now responsible for the continued airworthiness of every aircraft modified under their certificate—a duty essential for both maintaining the STC’s validity and upholding aviation safety.

A primary duty is to maintain all approved design data, from the engineering drawings to the test results that supported the STC application. The holder must also provide operators with comprehensive Instructions for Continued Airworthiness (ICA), which detail the required procedures for inspection, maintenance, and repair to keep the modification safe over its entire service life.

Additionally, the STC holder must provide ongoing technical support to operators and maintenance personnel, addressing inquiries and distributing service bulletins as needed. Should any issues arise, the holder is responsible for developing and managing FAA-approved repairs or modifications to ensure every installation remains in conformity with the approved design.

Uses of STC Data in Aviation

For aircraft owners, operators, maintenance technicians, and engineers, STC data is a vital resource. Accessing this information is essential for ensuring compliance, planning upgrades, and maintaining airworthiness. The ability to quickly search and verify STC details supports a wide range of daily operations and strategic decisions across the industry.

The demand for STC data stems from three primary uses:

• Verifying a modification: To confirm that an alteration on an aircraft is legal and properly certified, especially during pre-purchase inspections.

• Finding upgrade solutions: To discover approved pathways for modernizing an aircraft with upgrades like new avionics or enhanced engines.

• Obtaining support and documentation: To access essential installation data, Instructions for Continued Airworthiness (ICA), and ongoing technical support directly from the STC holder.

Understanding FAA’s Dynamic Regulatory System (DRS)

While several third-party databases offer STC information, the FAA’s definitive source is the Dynamic Regulatory System (DRS). This integrated digital platform is the central repository for a large volume of regulatory data, including every approved STC. It’s the primary tool FAA offices and authorized personnel use to efficiently track, review, and maintain certification records, ensuring data integrity across the agency.

For the public, however, accessing the DRS directly is a challenge. The system wasn’t designed for public-facing searches, with a specialized interface and strict access protocols. Gaining entry typically requires official FAA credentials or direct coordination with the agency, making it an internal resource rather than a public search engine.

The restricted nature of the DRS underscores its core mission: supporting the FAA’s critical oversight of aircraft modifications. By maintaining a centralized, up-to-date database, the system gives regulators immediate access to the accurate information needed for safety assessments and compliance checks. This data management is essential for upholding airworthiness standards for every single aircraft modified under an STC.