FAA Federal Aviation Regulations (FARS, 14 CFR)

Any person who alters a product by introducing a major change in type design, not great enough to require a new application for a type certificate under §21.19, shall apply to the Administrator for a supplemental type certificate, except that the holder of a type certificate for the product may apply for amendment of the original type certificate. The application must be made in a form and manner prescribed by the Administrator.