Every aircraft registered with the FAA (N-numbered) has an Airworthiness Certificate of some kind. The three types of Airworthiness certificates are Standard, Special, and Experimental.
Standard applies to factory-built aircraft like Cessnas and Boeings. They are built to an FAA-approved design with FAA oversight of the producer’s quality control system. No changes are allowed to the aircraft without manufacturer or FAA approval. These aircraft undergo millions of dollars worth of testing to earn their Standard Airworthiness Certificates. These aircraft can be rented and used commercially, carrying passengers and cargo for hire.
Special applies to factory-built aircraft in the Light Sport realm, that are produced to an FAA-accepted standard, but do not have direct FAA oversight of production and quality control. These aircraft can be rented but are not used to carry passengers and cargo for hire. They can be rented to a person for their flight training, but not used for point to point transportation like an airline.
Experimental is a broad category that applies to any aircraft that never earned a Standard or Special airworthiness certificate. It covers everything from home-built aircraft to huge warbirds and fighter jets. Many interesting aircraft on display and performing at airshows carry the Experimental airworthiness certificate. Sleek new innovative aircraft are typically Experimental as they are being developed and tested. After they are proven and have sufficient market demand, their manufacturer may put together a test program to earn Special or Standard airworthiness certificates.
Most older trikes are Experimental Light Sport Aircraft (ELSA). When the FAA started the Sport Pilot and Light Sport Aircraft regulations in 2006, they had a program to get these previously unregistered aircraft into the FAA N-number system. Large numbers of trikes and other light aircraft became registered with the FAA as Experimental Light Sport aircraft. The FAA issued them Airworthiness Certificates, Operating Limitations and N-numbers just like all other FAA-registered aircraft have.
Aircraft manufacturers register the new aircraft we build as Special Light Sport Aircraft (SLSA). To keep the Special Airworthiness Certificate, the aircraft must stay in its factory configuration and be professionally maintained. No changes or modifications are allowed without factory approval. An SLSA can be used for hire. An owner can rent the SLSA aircraft to other pilots. An instructor or flight school can rent the SLSA to their students. When used for hire, the SLSA aircraft must have a condition inspection every 100 flight hours, same as other aircraft used commercially.
Aircraft manufacturers can also produce new aircraft with Experimental Airworthiness Certificates. We produce the aircraft as an SLSA but then exchange the Special airworthiness certificate for an Experimental certificate. An ELSA aircraft can be modified and maintained by the owner but cannot be rented to others. If you want the flexibility of doing your own maintenance, adding accessories and modifications whenever you want without outside approval, choose the Experimental airworthiness certificate.