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.

Display Status This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Object Details
Date Circa 1960s Country of Origin United States of America Type PROPULSION-Reciprocating & Rotary Manufacturer Lycoming (Williamsport, Pennsylvania) Physical Description Type: Reciprocating, 6 cylinders, Horizontally opposed, Air-cooled Power rating: 186 kW (250 hp) at 2,575 rpm Displacement: 8.9 L (542 cu in.) Bore and Stroke: 130 mm (5.1 in.) x 111 mm (4.4 in.) Weight: 180.1 kg (397 lb) Dimensions Height 62.4 cm (24.56 in.), Width 84.8 cm (33.38 in.), Depth 94.5 cm (37.19 in.)
Materials Aluminum
Synthetic Fabric
Copper Alloy
Cadmium Plating
Phenolic Resin
Inventory Number A19870201000 Credit Line Transferred from the U.S. Marine Corps, Marine Corps Air-Ground Museum and Museums Branch Activities, Quantico, Virginia Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
For more information, visit the Smithsonians Terms of Use.