Section 21.113 - Requirement for supplemental type certificate(a) If a person holds the TC for a product and alters that product by introducing a major change in type design that does not require an application for a new TC under § 21.19 , that person must apply to the FAA either for an STC, or to amend the original type certificate under subpart D of this part.(b) If a person does not hold the TC for a product and alters that product by introducing a major change in type design that does not require an application for a new TC under § 21.19 , that person must apply to the FAA for an STC.(c) The application for an STC must be made in the form and manner prescribed by the FAA.Doc. No. FAA-2006-25877, Amdt. 21-92, 74 FR 53387, Oct. 16, 2009; Doc. No. FAA-2018-0119, Amdt. 21-101, 83 FR 9169, Mar. 5, 2018 Doc. No. FAA-2018-0119, Amdt. 21-101, 83 FR 9169, 3/5/2018