14 CFR § 21.191 - Experimental certificates.
Experimental certificates are issued for the following purposes:
(b) Showing compliance with regulations. Conducting flight tests and other operations to show compliance with the airworthiness regulations including flights to show compliance for issuance of type and supplemental type certificates, flights to substantiate major design changes, and flights to show compliance with the function and reliability requirements of the regulations.
(c) Crew training. Training of the applicant's flight crews.
(d) Exhibition. Exhibiting the aircraft's flight capabilities, performance, or unusual characteristics at air shows, motion picture, television, and similar productions, and the maintenance of exhibition flight proficiency, including (for persons exhibiting aircraft) flying to and from such air shows and productions.
(e) Air racing. Participating in air races, including (for such participants) practicing for such air races and flying to and from racing events.
(g) Operating amateur-built aircraft. Operating an aircraft the major portion of which has been fabricated and assembled by persons who undertook the construction project solely for their own education or recreation.
(h) Operating primary kit-built aircraft. Operating a primary category aircraft that meets the criteria of § 21.24(a)(1) that was assembled by a person from a kit manufactured by the holder of a production certificate for that kit, without the supervision and quality control of the production certificate holder under § 21.184(a).
(i) Operating light-sport aircraft. Operating a light-sport aircraft that -
(1) Has not been issued a U.S. or foreign airworthiness certificate and does not meet the provisions of § 103.1 of this chapter. An experimental certificate will not be issued under this paragraph for these aircraft after January 31, 2008;
(2) Has been assembled -
(ii) In accordance with manufacturer's assembly instructions that meet an applicable consensus standard; or
(3) Has been previously issued a special airworthiness certificate in the light-sport category under § 21.190.