For major alterations on a US certificated aircraft, which is NOT considered approved data?

• A. Airworthiness Directives
• B. Supplemental Type Certificates
• C. Advisory Circulars
• D. AC 43.13-2A

Answer: (D)

The key idea is what counts as approved data to authorize a major alteration. Approved data are FAA-approved sources that authorize the alteration or the means to comply with airworthiness requirements. Airworthiness Directives are issued by the FAA to correct unsafe conditions and are binding; Supplemental Type Certificates provide FAA-approved design changes. Advisory Circulars, including AC 43.13-2A, are guidance documents that describe acceptable methods and practices but are not themselves FAA-approved data used to authorize a specific alteration. They help explain how to perform work, but completing an alteration requires data that the FAA has formally approved for that change. Therefore, Advisory Circulars are not considered approved data for major alterations.