During 1937, production licences for the type were obtained from North American Aviation along with an accompanying arrangement to domestically produce the Wirraway's Wasp engine from Pratt & Whitney. Additionally, a pair of NA-16s were purchased directly from North American to act as prototypes. The first of these two aircraft was the fixed undercarriage NA-16-1A (similar in design to the BT-9); the second was the retractable undercarriage NA-16-2K (similar to the BC-1). These two aircraft were also known by their NAA project accounting codes (NA-32 for the NA-16-1A and NA-33 for the NA-16-2K) sometimes leading to confusion; these accounting codes (or "charge" codes) were used internally by NAA to track their projects and were not the actual aircraft model numbers. During August 1937, the NA-16-1A arrived in Australia and, following its re-assembly, flew for the first time at Laverton on 3 September of that year, exactly two years before war was declared on Nazi Germany by the United Kingdom and France. During September 1937, the NA-16-2K arrived in Australia and likewise flew shortly afterwards. These aircraft were given the RAAF serials A20-1 and A20-2 within that organisation's numbering system.