MKC83FA113

The builder/plt purchased the basic airframe & rotor kit from bensen, but purchased the eng from another source. The eng was not modified iaw bensen instructions. Reportedly, the plt was only going to conduct taxi & ground runs when he started at aprx 1100 CDT. However, after a number of taxi & hi speed runs, the gyrocopter was observed to takeoff at aprx 1800 CDT. After takeoff, the plt turned to a downwind, then a base leg. A witness reported seeing something fall from the acft before it descended from his view. Subsequently, the acft crashed aprx 1500 ft from the apch end of the rwy in a 50 to 55 deg bank. A 6 gal fuel can was found aprx 90 ft from the acft. The can had been attached with 2 elastic shock cords, which was not iaw bensen instructions. Paint & scrape marks on the rotor blades & the fuel can matched one another. The plt was not certificated & no evidence was found that he had previous flt experience. The word 'ultralight' was found painted on the mast of the gyrocopter.