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Lycoming O-540-A3D5, Horizontally-Opposed 6 Engine
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.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Country of Origin
United States of America
PROPULSION-Reciprocating & Rotary
Lycoming (Williamsport, Pennsylvania)
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)
Height 62.4 cm (24.56 in.), Width 84.8 cm (33.38 in.), Depth 94.5 cm (37.19 in.)
Transferred from the U.S. Marine Corps, Marine Corps Air-Ground Museum and Museums Branch Activities, Quantico, Virginia
National Air and Space Museum
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