Experimental Airworthiness Certificate: Purposes, Phase I, and Limits

An experimental airworthiness certificate is an FAA authorization that lets an aircraft outside standard certification fly legally in U.S. airspace for one of nine specific purposes, from flight-testing a new design to operating a homebuilt airplane. Every certificate carries operating limitations that restrict where, when, and how the aircraft can be flown, and the aircraft must be used only for the purpose the certificate was issued under. Using it for anything else is itself a violation.

The Nine Purposes the FAA Will Issue One For

Federal regulations list nine separate purposes under which the FAA will issue an experimental airworthiness certificate. Each locks the aircraft into a specific type of activity.¹

Research and development: testing new design concepts, equipment, engine installations, operating techniques, or new uses.
Showing compliance with regulations: flight tests to demonstrate a design meets federal airworthiness standards, including work toward type certificates, supplemental type certificates, and major design changes.
Crew training: training the certificate applicant’s own flight crews on a specific aircraft.
Exhibition: displaying an aircraft’s flight capabilities at air shows and in film and television, plus proficiency flying and travel to and from those events.
Air racing: competing, practicing, and traveling to and from races.
Market surveys: sales demonstrations and customer crew training for prospective buyers.
Operating amateur-built aircraft: flying an aircraft the builder personally completed more than 50 percent of, solely for education or recreation.
Operating primary kit-built aircraft: flying a primary-category aircraft assembled from a kit without the kit manufacturer’s direct supervision or quality control.
Operating light-sport aircraft: flying certain light-sport aircraft, typically kit-built and assembled to the manufacturer’s instructions and an applicable consensus standard.

The amateur-built category is by far the most common path. It comes with the well-known “51 percent rule,” which requires the individual or group to have personally completed more than half of the fabrication and assembly tasks. A quick-build kit that does 70 percent of the work will disqualify the project.

How Long the Certificate Stays Valid

Duration depends on the purpose. Certificates issued for research and development, showing compliance, crew training, or market surveys last three years from the date of issue or renewal, unless the FAA sets a shorter period.²

Certificates for exhibition, air racing, amateur-built, primary kit-built, and light-sport aircraft have no expiration date. They stay valid as long as the aircraft remains registered in the United States and the owner keeps meeting the operating limitations and annual inspection requirements.² The FAA can still suspend or revoke any airworthiness certificate, and when it does, the certificate must be surrendered on request.

Phase I Flight Testing

Every newly certificated experimental aircraft starts in a restricted flight-testing period pilots call Phase I. Flight is confined to a geographic test area the FAA assigns, and the aircraft cannot leave that area until it has been shown to be controllable throughout its speed range and free of hazardous characteristics.³

The minimum hours depend on the powerplant setup:

25 hours with an unaltered, type-certificated engine and propeller combination.
40 hours if the engine or propeller is not type-certificated, or if a type-certificated engine or propeller has been modified from its approved design.
10 hours plus at least five takeoffs and landings for gliders, balloons, and airships.
5 hours after any major change to a previously certificated aircraft.

These figures come from FAA Order 8130.2, which guides the inspectors who write your operating limitations.⁴ Homebuilders using automotive conversions or experimental engines usually face the 40-hour minimum, and choosing the wrong engine at the design stage can nearly double the test period.

During Phase I, the FAA can restrict who rides in the aircraft, up to barring passengers entirely. Your specific operating limitations spell out what is allowed. Read them before the first flight.

What You Can and Cannot Do After Phase I

After completing Phase I and logging the results, the geographic restriction lifts. You can carry passengers after telling them the aircraft is experimental. Several limitations stay with the certificate for the life of the aircraft.

You cannot carry passengers or property for compensation or hire in operations that would require an air carrier or commercial operator certificate. No charter, no paid sightseeing rides, no freight for money. You cannot fly over densely populated areas or through congested airways unless the FAA grants a special authorization in your operating limitations.³

Three requirements apply on every flight:

Advise every person on board that the aircraft is experimental.
Operate under visual flight rules during the day, unless the FAA has specifically authorized otherwise.
Notify air traffic control of the aircraft’s experimental status when using ATC services.

These are regulatory obligations, not suggestions.³ Violating an operating limitation can bring suspension or revocation of the airworthiness certificate, civil penalties, or both.

Night and IFR Flight Require Extra Authorization

The default is day VFR only. You cannot fly at night or under instrument flight rules unless the FAA specifically authorizes it in your operating limitations.³ Builders who install a full glass panel with GPS, weather overlay, and synthetic vision sometimes learn only afterward that they are legally stuck in clear daylight until they apply for and receive that authorization.

Night VFR authorization generally requires standard night equipment: position lights, anti-collision lights, a landing light, and adequate instrument-panel and cockpit lighting. IFR authorization sets a higher bar, and the FAA will look for appropriate navigation instruments, communication equipment, and an electrical system that can power everything for the duration of the flight. The authorization must appear in your operating limitations before any such flight is legal.

Annual Condition Inspection

An experimental certificate doesn’t exempt the aircraft from maintenance oversight. Your operating limitations will require a condition inspection at least once every 12 calendar months. The aircraft cannot fly after that period lapses until the inspection is completed and the aircraft found safe for operation.⁵

Three categories of people can perform the inspection on an amateur-built aircraft:

The builder, if they hold an FAA repairman certificate (experimental aircraft builder) for that specific aircraft.
An FAA-certificated mechanic with airframe and powerplant ratings.
An appropriately rated repair station.

To qualify for the repairman certificate, you must be at least 18, be the primary builder, show the FAA you have the skill to judge whether the aircraft is safe, and be a U.S. citizen or lawful permanent resident.⁶ The certificate is tied to the specific aircraft you built and does not follow the airframe to a new owner.

Every condition inspection must be recorded in the aircraft’s maintenance records with a signed statement showing the inspection date, the aircraft’s total time in service, and the inspector’s certificate information.⁵

If You Buy an Existing Experimental Aircraft

The experimental airworthiness certificate transfers with the aircraft. The new owner does not apply for a new certificate, but they do need to keep it current and stay within its operating limitations. What does not transfer is the original builder’s repairman certificate. If the previous owner had been signing off their own condition inspections, budget for an A&P mechanic or repair station to do them going forward.

A Note on Light-Sport Experimental Certificates

If you’re looking at a kit-built light-sport aircraft, the ground has shifted. As of October 22, 2025, the FAA stopped issuing new experimental certificates for kit-built light-sport aircraft under the old rules and for aircraft transitioning from a light-sport category certificate. New certification categories now cover kit-built light-sport and former light-sport category aircraft. A further round of changes takes effect July 24, 2026, when the FAA removes the old “light-sport aircraft” definition and puts revised airworthiness certification requirements and operating limitations in place.⁷

MOSAIC also broadens what qualifies for light-sport category certification. Manufacturers can now build rotorcraft and powered-lift designs, the prescriptive weight limits are gone, and maximum stall speeds have increased. An existing experimental light-sport certificate issued before October 2025 will need revised operating limitations before a light-sport repairman can perform your annual condition inspection.⁷

1
eCFR. 14 CFR 21.191 – Issue of Experimental Airworthiness Certificates
2
eCFR. 14 CFR 21.181 – Duration
3
eCFR. 14 CFR 91.319 – Aircraft Having Experimental Certificates: Operating Limitations
4
Federal Aviation Administration. FAA Order 8130.2L – Airworthiness Certification of Aircraft
5
Federal Aviation Administration. Advisory Circular 65-23A – Certification of a Repairman (Experimental Aircraft Builders)
6
eCFR. 14 CFR Part 65 Subpart E – Repairmen
7
Federal Aviation Administration. Modernization of Special Airworthiness Certification (MOSAIC) Fact Sheet