U.S.A 0-1, was completed, despite the misgivings of Barnwell, who was not satisfied with some of the modifications made, particularly in the use of the Liberty L-12 engine. According to Bruce, misdirections attributed to Major E. J. Hall of the U.S. Signals Corps had led to roughly 1,400 production drawings produced by Curtiss being rendered obsolete. The reputation of the type was also tarnished by three early crashes, although one had been attributed to pilot error and the other two to faulty workmanship. Only 27 Only 27 O-1s were completed. Efforts to change the engine of American-built Bristol Fighters to the more suitable Liberty 8 or the Wright-Hisso came up against political as well as technical problems. By July 1918, the only specimen of the American-built Hispano-Suiza engine had been installed in a Fighter; the combination soon gained the favour of the U.S. Air Board, which suggested to Curtiss that all work on the 400 horsepower Liberty L-12 version of the aircraft be abandoned in favour of the Hispano-Suiza version. In spite of protests by Curtiss, the contracts for the U.S.A. 0-1 were terminated, leading to only a pair of prototypes and 25 production aircraft out of the planned 2,000 aircraft being constructed. W. C. Potter, Assistant Director of Aircraft Production, suggested that the original Bristol Fighter should be produced exactly as per Barnwell's original design, save for the use of either the Liberty 8 or Hispano-Suiza engine. Potter's proposal was overlooked; instead it was decided to produce eight aircraft, four being fitted with the Hispano-Suiza engine, as the Engineering Division USB-1A and four being powered by the Liberty L-8 engine, as the Engineering Division USB-1B; only one each were built. In 1918, the Dayton-Wright Company designed a modified version, designated as the B-1A or XB-1A which used a 330-hp Wright-Hispano engine in a "new fuselage of wood-veneer monocoque construction". A later version was designated as the XB-1B and was equipped with the same engine. The XB-1A was armed with a pair of Marlin machine guns at the pilot's position while the XB-1B was armed with a pair of Browning machine guns. These aircraft were reportedly intended for use as night observation aircraft. Three prototypes were built by the Engineering division at McCook Field, with a further 44 aircraft built by the Dayton-Wright Company. According to Bruce, despite substantial efforts to differentiate and modify the aircraft's design, none of the