The Keystone B-5 is a light bomber made by the Keystone Aircraft company for the United States Army Air Corps in the early 1930s.

The B-5A was a Keystone B-3A with Wright Cyclone rather than Pratt & Whitney engines.

The Army Air Corps changed the design of the last 27 LB-10As on order, replacing the Pratt & Whitney R-1690 radial engines with the Wright R-1750-3.

B-5A were first line bombers of the United States for the period between 1930 and 1934.

Afterwards, they remained in service primarily as observation aircraft until the early 1940s.