Homebuilt ‘51% Rule’ Clarified by FAA

Just what is a "homebuilt" is now clearer. A long-awaited FAA advisory circular (AC-20-27G) outlines the approval basis for an aircraft to be registered in the experimental/amateur-built category. At issue was how much of the building is done by the builder, as opposed to prefabricated kit parts and/or work performed by professionals at a builder-assistance center. Though the provisions of the FAA document are advisory in nature and not mandatory, they are considered guidelines for designated airworthiness representatives and FAA inspectors, whose signature is required for an aircraft to be registered in the experimental/amateur-built category.