Changes requiring a new type certificate.
CFR · 2024-01-01 · US · Title 14
Each person who proposes to change a product must apply for a new type certificate if the FAA finds that the proposed change in design, power, thrust, or weight is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
official document · source cfr-2024 · id 14:§ 21.19