Keystone B-5A front left quarter 060421-F-1234P-017.jpg
Keystone B-5A
Role Light bomber
Manufacturer Keystone Aircraft
Primary user United States Army Air Corps
Number built 3 Y1B-5
27 B-5A
Developed from Keystone B-3

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.

Design and development

Three B-3A (LB-10A) were reengined with Wright R-1750-3 radial engines and were redesignated Y1B-5. 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. The Pratt & Whitney-powered aircraft were designated B-3A, and the Wright-powered aircraft became B-5A. They provided the backbone of the U.S. bomber force from then to 1934.

Operational history

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.


Designed as LB-10 with 575 hp (429 kW) Pratt & Whitney GR-1860 engines; three ordered, but redesigned with 525 hp (392 kW) Wright R-1750-3 engines and delivered as the Y1B-5.
Three pre-production aircraft redesignated from LB-14 before delivery.
Wright R-1750-3 version originally ordered as B-3A, 27 built


 United States

Specifications (B-5A)

General characteristics



See also

Related development

Related lists