Lycoming traces its beginning to a mid-nineteenth century sewing machine manufacturer. Sold and restructured in 1907 as the Lycoming Foundry and Machine Company, it produced automobile engines, and later was a subsidiary of the Auburn Auto Company. Although its early aircraft engines were radials, Lycoming entered the light-aircraft engine field early in 1938 with the introduction of the air-cooled, four-cylinder, horizontally opposed O-145 engine.

The basic Lycoming O-540 powered many general aviation aircraft, including versions of the Piper Aztec, Comanche, Cherokee, Dakota, and Pawnee as well as the Maule M-5-235, Cessna Skylane RG, and Aero Commander 500. In a modified form, it also powered many U.S. and European aerobatic aircraft, such as the Extra 260 and Pitts S-2S.

This O-540-A3D5 engine powered the Piper U-11A (Piper PA-23 Aztec). In February 1960, 20 Piper Aztecs were purchased off-the-shelf by the U.S. Navy for use as utility transports. Delivered as UO-1s, they were later redesignated U-11As.