On October 17, 1999, at 0920 hours Pacific daylight time, an amateur-built Mintz Vari-eze, N86KM, landed in the desert short of runway 2L at the Jean, Nevada, airport, following a pilot reported rough running engine. The aircraft, constructed, owned, and operated by the pilot under 14 CFR Part 91, sustained substantial damage. The private pilot and one passenger, the sole occupants, were not injured. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The personal flight originated at the Jean airport about 0900 for a local area personal flight. According to Federal Aviation Administration (FAA) inspectors from the Las Vegas, Nevada, Flight Standards District Office, the pilot was giving rides as part of an Experimental Aircraft Association Discover Aviation program. The pilot departed runway 2L and was on a downwind departure when the engine began to run rough. The pilot turned toward the runway but had insufficient altitude and power to make the airport. The aircraft landed short of the runway in desert terrain. In his statement, the pilot said the cylinder head on the Rotorway RW-100 engine failed and opened a hole over one of the cylinders. The FAA inspector who examined the airplane on-scene reported that the hole had the appearance of a "burn through." The inspection could not determine the underlying reason for the cylinder head failure.