The FAA’s official list of Supplemental Type Certificates lives inside the Dynamic Regulatory System at drs.faa.gov, and you can search it by STC number, aircraft make and model, certificate holder name, or type certificate number. It is the authoritative public record of every STC the FAA has issued, and it is free to use. What follows is how to reach it, how to search it efficiently, and how to read what you find so the record actually tells you whether a modification is approved for your aircraft.
Where the Official STC List Lives
Go directly to drs.faa.gov/browse/STC/doctypeDetails. You can also reach the same database from the FAA’s Supplemental Type Certificates information page at faa.gov, which links to DRS under the “Supplemental Type Certificates” heading.1Federal Aviation Administration. Supplemental Type Certificates
Bookmark the DRS page itself. Third-party STC listings show up in search results, and many of them carry outdated or incomplete records. Using them to make a compliance decision is a mistake that can leave an aircraft in a legally questionable airworthiness status. DRS pulls records from Aircraft Certification Offices nationwide and is the definitive source.
How to Search the STC Database
DRS gives you several entry points. Pick the one that matches what you already know.
- STC number. The fastest route. Every STC has a unique alphanumeric identifier (for example, SA00001SE). If you have it from maintenance records, a sales listing, or the STC holder, type it in for an exact match.
- Aircraft make and model. Use this when you want to see every approved modification available for your aircraft. This is the search most owners run when exploring avionics packages, engine conversions, or interior upgrades.
- STC holder name. Search by the company or individual who obtained the certificate. Useful when you know which shop or manufacturer developed a modification but do not have the number.
- Type Certificate number. Connects modifications to the underlying certified product design. Valuable for engines and propellers that appear across multiple airframes.
Be precise with make and model. A search for “Cessna 172” returns a different set of results than “Cessna 172S,” and an STC approved for one model series may not cover another. The database returns the certificate along with associated documentation, and the FAA notes the data is provided for informational purposes.
How to Read an STC Record
Finding the certificate is only half the job. Read it carefully before anyone touches the aircraft. Every record has a few components that together define what is approved, where, and under what conditions.
Approved Model List
The Approved Model List (AML) is where compliance begins. It specifies every aircraft make, model, and in some cases individual serial numbers to which the STC applies. If your aircraft is not on the AML, the STC cannot legally be used on it. This is where people trip up: they see an STC for a “Piper PA-28” and assume it covers all PA-28 variants, when the AML may list only the PA-28-180 and PA-28-235. Verify the exact designation before going further.2Federal Aviation Administration. AC 20-180 – Approved Model List Supplemental Type Certificate (AML-STC)
Limitations and Conditions
Every STC specifies limitations and conditions governing both installation and operation. These commonly include required companion equipment, weight and balance adjustments, operational restrictions such as speed or altitude limits, and mandatory changes to the Aircraft Flight Manual or its supplement. Ignoring a limitation is not a paperwork problem. It means the aircraft is operating outside its approved design.
Approved Data and Installation Instructions
The STC references FAA-approved engineering data: drawings, specifications, and step-by-step installation instructions. The work must be performed exactly according to this data. Small deviations take the installation outside the scope of the approval and leave the aircraft without a basis for its airworthiness in that area.
Instructions for Continued Airworthiness
The STC holder is responsible for providing instructions for continued airworthiness so owners and operators can maintain the modification properly over the life of the aircraft.3Federal Aviation Administration. FAA Order 8110.54A – Instructions for Continued Airworthiness Check the record for ICA references, because those obligations follow the aircraft.
Finding the STC in the List Is Not Permission to Install It
A detail that catches people off guard: you cannot download an STC from DRS and start installing. The STC holder who allows someone to use the certificate to alter an aircraft must provide that person with written permission acceptable to the FAA.4eCFR. 14 CFR 21.120 – Responsibility of Supplemental Type Certificate Holders The holder owns the proprietary design data, and the installer needs the full engineering package to do the work correctly.
In practice, that means contacting the STC holder or an authorized distributor and purchasing a license or kit that includes the approved data package and written authorization. Costs vary widely. Some holders sell kits that bundle hardware, data, and permission; others license the data separately. Having the STC number from DRS without this permission is not enough to proceed legally.
When an STC Is Actually Required
Any major change to a product’s type design that does not warrant a completely new type certificate requires either an STC or an amendment to the original TC. If you do not hold the original type certificate, an STC is your only option.5eCFR. 14 CFR 21.113 – Requirement for Supplemental Type Certificate
The word “major” carries a specific regulatory meaning. Major airframe alterations include changes to wings, tail surfaces, fuselage, engine mounts, control systems, landing gear, and other structural elements. Changes to the basic design of fuel, electrical, hydraulic, de-icing, or pressurization systems also qualify, as do modifications that shift empty weight or center of gravity beyond certificated limits. Powerplant major alterations include engine conversions, installation of unapproved accessories, and fuel-grade changes. Propeller major alterations cover blade and hub redesigns, governor changes, and de-icing installations.6Legal Information Institute. 14 CFR Appendix A to Part 43 – Major Alterations, Major Repairs, and Preventive Maintenance
Minor alterations do not need an STC. The FAA also will not issue an STC solely to approve minor changes or identical replacement parts, unless installing those parts itself constitutes a major design change.7Federal Aviation Administration. Supplemental Type Certificate Process – Application to Issuance
Field Approvals for One-Off Alterations
For a one-time major alteration where a formal STC is impractical, a field approval through an FAA Aviation Safety Inspector at your local Flight Standards District Office may be an option. The applicant prepares a data package with drawings, engineering substantiation, and supporting documentation, then submits it for review. If the inspector finds the data acceptable, they sign off on the Form 337 for that specific aircraft. A field approval covers a single aircraft and a single installation; an STC can be used repeatedly on every aircraft in its AML.
Using the STC List When Buying an Aircraft
An STC-based modification becomes part of the aircraft’s type design once it is installed and documented on FAA Form 337. When the aircraft changes hands, the new owner inherits both the benefits and the obligations of any installed STCs. During pre-purchase inspection, verify each of these:
- Every STC number listed in the logs appears in DRS as an active, issued certificate.
- The aircraft’s specific make, model, and serial number falls within the AML for each STC.
- An FAA Form 337 exists in the aircraft’s records for each major alteration.8Legal Information Institute. 14 CFR Appendix B to Part 43 – Recording of Major Repairs and Major Alterations
- Maintenance logbooks reflect ongoing compliance with any ICA requirements tied to the modification.
The holder’s obligation to provide written permission under 14 CFR 21.120 runs to the person performing the alteration, not to subsequent owners.4eCFR. 14 CFR 21.120 – Responsibility of Supplemental Type Certificate Holders Once the modification is properly installed and documented, a new owner does not have to re-obtain permission from the STC holder simply because ownership changed. If the new owner wants to modify or update the installation, that goes back to the holder for current data and authorization.
A logbook that references an STC number the DRS does not recognize, or an aircraft serial number that sits outside the AML, is a red flag worth resolving before closing. The database is the check that catches both problems.