The Lycoming O-235 is a family of four-cylinder, air-cooled, horizontally opposed, piston aircraft engines that produce 100 to 135 hp (75 to 101 kW), derived from the earlier O-233 engine.

[1][2] Well-known designs that use versions of the O-235 included the Cessna 152, Grumman American AA-1 series, Beechcraft Model 77 Skipper, Piper PA-38 Tomahawk, American Champion Citabria, Piper Clipper, and the Piper PA-22-108 Colt.

The engines are all carburetor-equipped, feature dual magneto ignition and have a displacement of 233 cubic inches (3.82 L).

[2] The O-235 was developed into the lighter-weight Lycoming IO-233 engine for light sport aircraft.

[3] Data from Operator's Manual, Textron Lycoming Aircraft Engines.