The Lycoming O-435 is a six-cylinder, horizontally opposed fixed-wing aircraft and helicopter engine made by Lycoming Engines.
Introduced in 1942, the O-435 was a six-cylinder version of the four-cylinder O-290. This engine was also developed as a light tank engine for the M-22 Locust during World War II.
This engine was used in the H-13 Souix helicopter, also known as he Bell-47 or M.A.S.H. Helicopter from the Korean War.