SEA05LA189

Just prior to the flight, the pilot, who was five hours into a ten hour experimental aircraft flight test regimen, readjusted the valve lash in the Subaru engine that powered the subject aircraft. At the beginning of the flight, he took off and climbed to about 1,000 feet above ground level (agl). After he rolled out on downwind, his ground crew contacted him on the aircraft radio to advise him that the aircraft's engine appeared to have been missing and running rough during the takeoff and initial climbout. About the time that the pilot received the radio transmission, the aircraft's engine quit producing power, and he decided to continue on around the pattern in order to execute a forced landing on the runway from which he had departed. As he turned from base to final, the pilot realized that he might not be able to stretch the glide to the end of the runway, but he elected to attempt to do so. When the aircraft descended to about 25 feet agl, its airspeed slowed to the point where it stall/mushed into the terrain about one-quarter of a mile off the end of the runway. In a post accident inspection, it was determined that the valve clearance in the engine had been set with a gap so small that when the internal engine temperature began to increase the exhaust valves in each cylinder did not completely close. Without the closure of the valves, sufficient compression was not created in the cylinders, and the engine stopped producing power.

On September 1, 2005, approximately 2030 mountain daylight time, an experimental Ballhagen/Shyrock Q-2, N12QJ, impacted the terrain during a no-power forced landing off the end of the runway at Flathead Skyranch, which is located about five miles southwest of Kalispell, Montana. The private pilot, who was the sole occupant, was not injured, but the aircraft, which is owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which originated at the same airport less than five minutes prior to the accident, was being operated in visual meteorological conditions. No flight plan had been filed. There was no report of an ELT activation.

According to the pilot, who was five hours into a ten hour experimental aircraft flight test regimen, just prior to this flight he had readjusted the valve lash in the Subaru engine that powered the subject aircraft. At the beginning of the flight, he took off on runway 16, and climbed to about 1,000 feet above ground level (agl). After he rolled out on downwind, his ground crew contacted him on the aircraft radio to advise him that the aircraft's engine appeared to have been missing and running rough during the takeoff and initial climbout. About the time that the pilot received the radio transmission, the aircraft's engine quit producing power, and he decided to continue on around the pattern in order to execute a forced landing on the runway from which he had departed. As he turned from base to final, the pilot realized that he might not be able to stretch the glide to the end of the runway, but he elected to attempt to do so. When the aircraft descended to about 25 feet agl, its airspeed slowed to the point where it stall/mushed into the terrain about one-quarter of a mile off the end of the runway. After impacting the terrain, the aircraft slid for about 75 feet before coming to a stop. During the impact with the ground, the front wing (canard) sustained substantial damage.

In a post accident inspection, both the pilot/owner and an FAA Airworthiness Inspector who responded to the scene determined that the valve clearance in the engine had been set with a gap so small that when the internal engine temperature began to increase, the exhaust valves in each cylinder did not completely close. Without the closure of the valves, sufficient compression would not be created in the cylinders, and the engine would stop producing power.