Which document certifies modifications to an aircraft's type design approved by the FAA?

Which document certifies modifications to an aircraft's type design approved by the FAA?

• A. Manufacturers Service Bulletins
• B. Drawings
• C. Blueprints
• D. Supplemental Type Certificates (STC)

Answer: (D)

When an FAA-approved modification changes an aircraft’s type design, the authorization is documented in a Supplemental Type Certificate. This certificate is the official FAA approval that allows the modification to be incorporated into the aircraft’s design, covering the scope of the change, the engineering data, and the installation details. It ensures the modification meets safety standards and becomes part of the aircraft’s type design, so the altered aircraft remains airworthy under federal rules. Manufacturers Service Bulletins are internal notices about recommended or required maintenance or service, not FAA approvals of design changes. Drawings and blueprints are the design and fabrication documents used to build or modify the aircraft, but they themselves do not certify that a modification has been approved by the FAA.

When an FAA-approved modification changes an aircraft’s type design, the authorization is documented in a Supplemental Type Certificate. This certificate is the official FAA approval that allows the modification to be incorporated into the aircraft’s design, covering the scope of the change, the engineering data, and the installation details. It ensures the modification meets safety standards and becomes part of the aircraft’s type design, so the altered aircraft remains airworthy under federal rules.

Manufacturers Service Bulletins are internal notices about recommended or required maintenance or service, not FAA approvals of design changes. Drawings and blueprints are the design and fabrication documents used to build or modify the aircraft, but they themselves do not certify that a modification has been approved by the FAA.