On June 27, 2000, approximately 1106 Pacific daylight time, a Davis/Crouch Avid Mark IV experimental-category amateur-built airplane, N518DC, was substantially damaged in a forced landing following a loss of engine power approximately 3 nautical miles north of Concrete, Washington. The commercial pilot-in-command, listed on the FAA aircraft registry as a co-builder and co-owner of the aircraft, and a passenger were seriously injured in the crash. Visual meteorological conditions prevailed and no flight plan had been filed for the local 14 CFR 91 personal flight from Concrete. The pilot reported that he departed the Concrete, Washington, airport (WA13) about 1030 with 15 gallons of automotive fuel on board. He stated that he flew north over Baker Lake and Shannon Lake. He reported that during the return flight to the Concrete airport, while over Shannon Lake, the engine sputtered and quit, and would not restart. The pilot reported he then attempted an emergency landing in a rugged logging area west of Lake Shannon and north of Lake Tyee. He stated he was unable to make it to a logging road, and crashed into trees and bushes along the side of the road. The occupants facilitated their own rescue by dialing 911 on a cellular telephone and reporting the accident. An FAA inspector who responded to the accident scene reported that witnesses stated they heard a loud noise and saw a puff of smoke from the aircraft as it was flying, and that the aircraft then began to lose altitude before they lost sight of it. The FAA inspector reported that in a post-accident examination of the aircraft, he observed a hole in the engine crankcase, and that the #1 connecting rod had gone through the crankcase at the location of this hole. The engine was a Subaru automotive engine modified for use in experimental aircraft by Stratus, Inc. Stratus, Inc.'s owner reported to the NTSB that he and another individual with Stratus examined the aircraft wreckage with the FAA's permission following the accident. He reported that during their examination, the overheat sensors mounted on the cylinder heads were observed to be melted, indicative of the engine having experienced an overheat condition. Stratus, Inc.'s owner also reported that other indications of engine overheat within the engine were observed, such as oil baked onto the oil filler cap and the inside of a valve cover. The Stratus owner stated that his company has told customers that if an engine is overheated, it needs to be taken apart to check for damage. The FAA aircraft registry indicated that the airplane received an experimental-category airworthiness certificate on May 3, 1996. According to the aircraft owner, the airplane and engine had 309.3 hours total time and 5.1 flight hours since the aircraft's last condition inspection, which the pilot/owner signed off one week prior to the accident.