History of Flight
On May 9, 2008, at 1645 Pacific daylight time, an experimental Thorp T-18, N8613A, collided with a residence following a loss of engine power during initial takeoff from Crest Airpark in Kent, Washington. The pilot, who was also the registered owner, operated the airplane under 14 CFR Part 91. The airline transport pilot, the sole occupant, was killed. The sole occupant of the residence was not injured. The airplane sustained substantial damage. Visual meteorological conditions prevailed, and no flight plan was filed.
A witness, whose home is located about three-quarters of the way down runway 33, reported stepping out of his back door and hearing the airplane depart. Initially, the engine sound was smooth. As it continued, he heard the engine running rough. When the airplane flew past his hangar at about 300 feet above the runway, the witness observed two puffs of white smoke. The airplane appeared to have adequate airspeed and was still climbing, although the engine was cutting out. The engine then cut out completely, and the airplane continued straight ahead for about 1 second. It then entered a slow turn to the right. When it had turned approximately 160 degrees, the right wing stalled, and the airplane rolled into a spin. The airplane went out of view of the witness in a nose-down attitude of approximately 70 degrees.
A friend of the pilot, who had known him for 40 years, stated that he had flown the accident airplane many times and considered it a good airplane. The airplane had not flown since August 2007. The pilot had the carburetor overhauled and recently installed a new air inlet on the cowling. This was the first flight since the new items were installed. Prior to the flight, the pilot drained all old fuel from the airplane and refueled. The friend stated that the pilot ran up the airplane before departure, and no problems were identified. The engine had a supplemental type certificate (STC) for auto fuel, and the pilot tested his fuel to ensure no alcohol was present.
The pilot's friend, who also had an airplane based at the airpark, indicated that when taking off on runway 33, there are limited options for emergency landings. To the west of the airport there are houses; straight ahead of the runway there are trees; to the east (the direction the pilot was flying) there is a road and a couple of small fields. The friend said there was no suitable landing area available when a loss of power occurred at a low altitude.
Personnel Information
The pilot, age 69, held an airline transport certificate for multi-engine airplanes and a commercial pilot certificate for single-engine airplanes, as well as certified flight instructor (multi-engine and instrument), ground, aviation maintenance technician-powerplant, flight engineer, and aircraft dispatcher certificates. His most recent medical certificate, a second class issued in March 2008, had the limitation that the pilot must wear corrective lenses. The pilot reported approximately 8,400 hours of flight time on his last medical application.
Aircraft Information
The Thorp T-18 was manufactured in 1969. The last condition inspection was completed on October 16, 2007, at a tachometer time of 257.9 hours. There were no airframe hours listed for that logbook entry, but the previous condition inspection in August 2006 showed a total airframe time of 3,302.5 hours.
Medical Information
The King County Medical Examiner performed an autopsy on the pilot and attributed the cause of death to impact injuries sustained in the accident. The FAA Forensic Toxicology lab conducted toxicological testing. Results were negative for carbon monoxide, cyanide, and volatiles. The results were positive for diphenhydramine (0.101 ug/ml, ug/g) in the blood, and diphenhydramine was also detected in the urine.
Tests and Research
Federal Aviation Administration inspectors reported that the airplane impacted a residence located east of the airpark. All control surfaces remained attached, and the wreckage was confined to the impact area. The fuselage was consumed in a post-impact fire.
Investigators examined the wreckage after recovery. Examination of the airframe revealed no control system anomalies. The fuel system was traced from the fuel tank to the engine. The fuel valve was in the closed position.
The airplane was powered by a Textron Lycoming O-320-E2D engine. The crankshaft was rotated by hand using the propeller hub. Thumb compression was observed in proper firing order on cylinders 1, 3, and 4; thumb compression on cylinder number 2 was weaker compared to the others. Mechanical continuity was obtained, and there was no evidence of foreign object ingestion or detonation. Removal of cylinder number 2 showed no visible cracks on the cylinder head, and the combustion chamber was undamaged. Each piston ring was secure, and the valves were undamaged. The magnetos were removed and produced spark at all plug leads during hand rotation. The spark plugs were removed, and the electrodes displayed coloration consistent with normal operation when compared with the Champion Spark Plugs "Check-A-Plug" chart AV-27.
The bottom portion of the carburetor was displaced from the engine; the top portion remained attached at the mounting pad. The float assembly was displaced from its mount and crushed. The fuel filter screen was free of visible contaminants. The air box, portions of the exhaust system, the starter, and the alternator were also displaced from the engine.
There was no evidence of pre-impact mechanical malfunctions observed.