The Keystone B-3A was originally ordered as the LB-10A, but the U.S. Army dropped the Light Bomber (LB) designation in 1930 and renamed the LB-10A, LB-13 and LB-14 aircraft on order -- B-3A, Y1B-4 and Y1B-5A.
The B-3A, along with the very similar B-4, -5 and -6 series aircraft, were the last biplane bombers used by the U.S. Army. The B-3A was a conservative design and its performance was about the same as some bombers built 10 years earlier. A bomber design revolution that would make the Keystone aircraft completely obsolete was only a few years away. The all-metal monoplane bombers of the mid-1930s were so advanced, the newest bombers were actually faster than the pursuit planes in service with the Army.
The B-3A would remain in service until 1940. The 2nd Observation Squadron at Nichols Field, Philippines, was the last unit equipped with the B-3A.
TECHNICAL NOTES: Armament: Three Browning .30-cal. machine guns and 2,500 lbs. of bombs Engines: Two Pratt & Whitney R-1690-3 of 525 hp each Top speed: 114 mph at sea level Cruising speed: 98 mph Service ceiling: 12,700 ft. Range: 860 miles with full normal bomb load of 2,500 lbs. Span: 74 ft. 8 in. Length: 48 ft. 10 in. Height: 15 ft. 9 in. Weight: 12,952 lbs. gross Crew: Five Serial number: 30-281 to 30-343