Definition
An aircraft assembled by an individual builder from a manufacturer-supplied kit of parts, components, and instructions, rather than purchased complete from a factory. In the United States, kit-built aircraft are typically certificated in the Experimental Amateur-Built category under 14 CFR Part 21, which requires the builder to construct the major portion of the aircraft (the '51% rule') for educational or recreational purposes.
Plain English
An aircraft that the owner builds at home from a packaged set of parts and plans supplied by the manufacturer, instead of buying it ready-made from a factory.
Context Anchor
Seen in light-sport aircraft discussions, aircraft paperwork, and preflight planning when checking what kind of aircraft may be flown under specific pilot privileges.
Derivation
The word 'kit' comes from the Middle Dutch 'kitte', meaning a container or set of items packaged together. Combined with 'built' (constructed), it describes an aircraft put together from a packaged set of supplied parts — much like a model kit, but full-scale and flyable.
Why Pilots Care
Determines purchase cost, required inspections, operating limitations, and the certification path the finished aircraft must follow.
Intuition Check
Do not assume “kit-built” means the aircraft is automatically light-sport, unsafe, or homemade from scratch. It only tells you the aircraft was assembled from a kit; the aircraft’s official approval tells you how it may be flown.
Example Sentence 1
Many Light-Sport Aircraft on the market today are available either as factory-complete airplanes or as kit-built aircraft assembled by the owner.
Example Sentence 2
After completing the kit, the owner scheduled the required inspection before the first flight.