The Lycoming name comes from Williamsport, Pennsylvania, where an industrial works that traced its origins to the nineteenth century began building engines in the early 1900s. The company later produced automobile engines as well, but it is best known today as one of the two great American makers of piston aircraft engines, now part of the Textron group.

Lycoming engines are air-cooled, horizontally opposed four-, six- and eight-cylinder designs such as the O-320, O-360, IO-540 and their turbocharged variants. They power hundreds of thousands of aircraft, from trainers and light singles to twins, and are prized for predictable maintenance and a vast installed base supported by parts and documentation worldwide. The models documented in this collection cover much of today's trainer and light-aircraft fleet.

The manuals on this page provide factory-level documentation for Lycoming engines, including cylinder and valve service, crankshaft and bearing overhaul, fuel and induction systems, lubrication, ignition and electrical systems, torque specifications and inspection procedures. Overhaul and parts-catalog listings support both major work and routine scheduled maintenance. Because engine life is measured in operating hours rather than miles, the inspection limits and overhaul data in these manuals are especially important.

These documents are intended for aircraft owners, flight schools, aviation maintenance technicians and engine-overhaul shops. Following the manufacturer's procedures and specifications is essential to safety, reliability and the continued airworthiness of these engines.