The Lycoming LIO-320 is a horizontally opposed, air-cooled, four-cylinder aircraft engine produced by Lycoming Engines. It is part of the Lycoming O-320 series, which is widely used in general aviation aircraft. The "LIO" designation indicates that this engine is specifically designed for use in helicopters, though it is also used in fixed-wing aircraft.

• Engine Type: Horizontally opposed (flat-four) configuration, air-cooled
• Displacement: 320 cubic inches (5.24 liters)
• Power Output: 150 to 160 horsepower (HP), depending on model and configuration
• Fuel Type: Aviation gasoline (avgas), typically 100LL (low lead)
• Weight: 240 to 260 pounds (109 to 118 kg), depending on model and accessories
• Applications: Primarily used in light helicopters and some fixed-wing aircraft
• Reliability: Known for durability and reliability, popular for training and general aviation
• Maintenance: Requires regular maintenance including oil changes, spark plug replacements, and inspections

• LIO-320-B1A: Common variant used in helicopters
• LIO-320-C1A: Variant with slight differences in configuration and power output

The LIO-320 is often used in light helicopters, including:

• Robinson R22: Popular two-seat training helicopter
• Schweizer 300: Light helicopter used for training and agricultural purposes