Light-sport aircraft, or LSA, is a classification of aircraft specific to the United States.

The Federal Aviation Administration defines a light-sport aircraft as an aircraft with a maximum gross takeoff weight of less than 600 kilograms (1320 pounds) for aircraft designed to operate from land, 649 kilograms (1,430 pounds) for seaplanes, or 300 kilograms (660 pounds) for lighter-than-air craft; a maximum airspeed in level flight of 120 knots (222 km/h); either one or two seats; fixed undercarriage and fixed-pitch or ground adjustable propeller; and a single reciprocating engine, which includes diesel engines and Wankel engines.

LSA may be operated by holders of a Sport Pilot certificate, as opposed to a private, recreational, or higher pilot certificate, as do conventionally certificated aircraft. LSA also have less restrictive maintenance requirements and may be maintained and inspected by traditionally certificated Aircraft Maintenance Technicians, by individuals holding a Repairman: Light Sport certificate, and (in some cases) by their pilots and/or owners.

Several different kinds of aircraft may be certificated as LSA. Airplanes (both powered and gliders), rotorcraft (gyroplanes only, not true helicopters), powered parachutes, weight-shift control aircraft, and lighter-than-air craft (free balloons and airships) may all be certificated as LSA if they fall within the weight and other guidelines established by the FAA.

The U.S. definition of an LSA is similar to most other countries' definitition of "microlight" or "ultralight" aircraft. Except for the LSA's relatively generous MTOW of 600 kg, the other countries' microlight definitions are typically less restrictive, not limiting airspeed or the use of variable-pitch propellers.

By contrast, the U.S. FAA has a separate definition of ultralight aircraft defined in FAR 103. Aircraft falling within the U.S. ultralight specifications are extremely lightweight (less than 254 pounds if powered, or 155 pounds if unpowered), are intended for manned operation by a single occupant, have a fuel capacity of five U.S. gallons or less, a maximum calibrated airspeed of not more than 55 knots, and a maximum stall speed of not more than 24 knots. Ultralight aircraft in the U.S. do not require pilot licensing, medical certification, or aircraft registration.

Source: Wikipedia

Aircraft certificated as light-sport aircraft exceed the limitations defined for ultralight aircraft and require that the pilot possess, at a minimum, a Sport Pilot certificate. Among these aircraft we find those that were specifically designed to meet the LSA requirements, as well as overweight ultralights (commonly known as "fat ultralights") that previously were operated in technical violation of FAR 103.

In addition to aircraft specifically designed to meet the LSA requirements, certain certificated aircraft, such as the original Piper Cub, happen to fall within the definition of a light-sport aircraft and can be operated by individuals holding FAA Sport Pilot certificates. The aircraft can not be re-certificated as LSA, however; although Sport Pilots may operate conventionally certificated aircraft that fall within the definition of an LSA, the aircraft themselves continue to be certificated in their original categories.

Several designers and manufacturers of experimental aircraft kits are working to develop models that are compliant with the light-sport aircraft rules.

The Cessna Aircraft Company has recently unveiled a prototype of a new light-sport aircraft, the Cessna LSA Concept.

Source: Wikipedia