(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]