It must have a maximum stall speed of 45 knots in landing configuration; a maximum of two seats; there is no limit on maximum speed unless it is a glider, which is limited to Vne 135 kn CAS; fixed undercarriage (except for amphibious aircraft, which may have repositionable gear, and gliders, which may have retractable gear); an unpressurized cabin; and a single non-turbine engine driving a propeller if it is a powered aircraft.