The BT-12 production line inside the Fleetwings plant showing ships #9 thru #14 of a 24 ship order with serials 42-3684 to 3707 allocated. Serials 42-3708 thru 3883, which would have brought the order up to 200, were cancelled when the military decided they preferred the Vultee BT-13. Construction involved the extensive use of stainless steel, including for skin panels. The fuselage structure was made from carbon steel tube with stainless skin panels attached using "Shake-proof Fasteners" (probably what is known as quarter-turn fasteners today). The novelty of the design probably put the military off as being too different for maintenance to cope with.

The Fleetwings Model 23 was a two-seat basic trainer designated BT-12 by the military. It was powered by a P&W R-985 engine of 450 hp and utilized much stainless steel for construction. This prototype was flown from the Fleetwings plant at Bristol/PA to Wright Field, Dayton/OH on 12 January 1941, with acceptance tests commencing on 21 April 1941. In this photo it is up on an acceptance flight with Fleetwings chief project test pilot William H. Engle in the front and Doug Mason in the rear seat. On 21 February 1944 it was tagged as CL-26 (Ground maintenance trainer) and last known of at the Walter Soplata Collection, Newbury, OH. Collection holder William Engle is the son of Fleetwings test pilot William H. Engle.

The BT-12 was built of steel sheeting on a tubular frame. Fleetwings argued that spot-welding steel was quicker than riveting aluminium and easier to maintain and, at the same time, that the use of steel saved aluminium. This airframe wears no readable serial but it can only be the XBT-12 prototype, first flown in 1939, which Rudy Arnold also photographed on the ground on 1 May 1941 at Wright Field. It took the company until 1942 to build one more aircraft against an order for 176. 23 were completed in 1943 before the project was cancelled. Not everything got done fast during WWII! Photo by: Rudy Arnold / Smithsonian Institution