On June 6, 1999, about 1449 hours Pacific daylight time, a homebuilt experimental Blanco Sea Hawker amphibian, N2485, operated by the owner/builder/pilot, was destroyed after colliding with terrain near Yucca Valley, California. The private pilot, the sole occupant, was fatally injured. Visual meteorological conditions prevailed for the personal cross-country flight operating under 14 CFR Part 91 and no flight plan was filed. The flight originated at Hemet, California, about 1417, and was destined for Park City, Utah. According to a sheriff's helicopter pilot, about 32 minutes after departure from Hemet, witnesses reported seeing the airplane flying from south to north along a ridgeline just southwest of the "saddle" separating Morongo Valley from Yucca Valley. The airplane was then observed to make a sudden tight turn to the left, and then angle into the ground. The pilot reported that the air above 100 feet agl was "very turbulent, very rough" that afternoon. A deputy coroner investigator reported the accident location as: 116 degrees 29 minutes 29.6 seconds north latitude by 34 degrees 06 minutes 20.1 seconds west longitude. The site elevation was reported as 3,207 feet msl and the density altitude was 6,180 feet msl. A Federal Aviation Administration (FAA) inspector from the Riverside Flight Standards District Office conducted an accident site examination. He reported that a postaccident fire had consumed the airframe structure and all engine accessories. A Lycoming engine investigator, under the supervision of the FAA inspector, conducted a detailed engine examination. The inspector reported that there was no evidence found of mechanical failure or malfunction of the engine. One of four carbon fiber propeller blades was found separated from the propeller hub and free of impact damage. The other three were still attached to the propeller hub and fire damaged. No pilot or airplane logbooks were recovered.