On August 30, 2007, approximately 0630 Pacific daylight time, an experimental Fitt Kitfox airplane, N96KL, sustained substantial damage after impacting terrain following a precautionary landing near Diamond Springs, California. The private pilot and his sole passenger sustained serious injuries. Visual meteorological conditions prevailed for the cross-country flight, which was being operated in accordance with 14 Code of Federal Regulations Part 91. A flight plan was not filed. The flight departed the Cameron Airpark (O61), Cameron Park, California, about 0620, and was en route to Homedale, Idaho. According to the pilot on initial climb "...the engine temps were slightly higher than normal and [I] shallowed the climb, continuing to monitor the instruments. After about 5 to 10 minutes I observed the oil pressure gauge drop to near zero, then to zero." The pilot stated that he thought his altitude at the time was close to 3,000 feet when he elected to make a precautionary landing, due to what he felt "...was the high probability of the engine quitting." The pilot reported that he located a large open area and began to circle to lose altitude; the landing site was located about 8 nautical miles east of the departure airport. The pilot stated that after committing to land, "...I found himself a bit too close to the edge of the clearing, so I attempted to put [the airplane] on the ground with a nose high, power on final descent." During the landing sequence the airplane sustained substantial damage to the fuselage, and both wings. The airplane came to rest in an upright position, and there was no fire. A post-accident examination of the airplane's engine revealed that upon disassembly of the oil tank, a foreign object composed of a plastic material was observed plugged in the pickup portion of the oil supply tube. An examination of the foreign object after its removal from the oil supply tube failed to reveal its identity or origin. The pilot reported that he had performed an engine oil change 5 days prior to the accident, and that during the oil change he disassembled and then reassembled the oil tank, but did not know what the foreign object was, or where it came from.