[4] A variety of air-cooled radial engines, including the Wright Whirlwind, Pratt & Whitney Wasp and Pratt & Whitney Wasp Junior of varying horsepowers, could be installed depending on customer preferences.

[5] The fuselage was built up from steel tubes and normally fabric covered; however, later versions were provided with aluminum monocoque structures.

[6] During the development of the design, a six-inch stretch was made by moving the rudder post aft.

An enclosed cockpit version of the NA-16 was submitted to the United States Army Air Corps for performance tests as a basic trainer on 27 May 1935.

[12] The Army accepted the trainer for production but with some detail changes, including a larger engine and faired landing gear modifications.

The U.S. Army Air Corps ordered 42 BT-9s, equipped with the Wright R-975 Whirlwind engine, and 40 BT-9As, which could be armed with .30 cal.

[1]: 73 The Commonwealth Aircraft Corporation produced 755 units of a modified version of the NA-16-2K (NA-33) known there as the Wirraway between 1939 and 1946.

[16] The resulting aircraft owed little to the NA-16, however Allied Intelligence saw so few examples that the error was not corrected and some drawings show a modified NA-16.