The AC-12 was a high-wing cantilever monoplane with a fixed tailwheel landing gear. The enclosed cabin had a single seat forward for the pilot and a bench seat behind for two passengers. It was available fitted with a number of engines including the 950NaN0 Argus As 8 and 1200NaN0 de Havilland Gipsy III inline engines or a 1400NaN0 Armstrong Siddeley Lynx radial.