The Ultrasport 331 is a growth version of the Ultrasport 254 designed to meet the FAA FAR Part 21.191 (g) Amateur Built Aircraft Kit category. Like the Ultrasport 254, the 331 has a structural composite airframe, composite main and shrouded tail rotor blades, but the 331 comes with some added creature comforts , such as an electric start system, bigger fuel tank and fully enclosed cockpit with removable doors as standard equipment. It has a cruise speed of 65 mph (105 kmph) and a empty weight of 330 lbs. (150 kgs). Optional features such as floats may also be installed for added safety. The 331 is designed to meet the worldwide microlight helicopter category and is marketed and sold in the U.S. as an amateur built helicopter kit and in other countries where microlight helicopter category is regulated.