Concrete Municipal Airport: Concrete, Washington

Airport is located 1 mile south of Concrete, Washington.

For 7 years, the pilot had performed maintenance, which included 100-hour and annual inspections of his airplane's engine. On an undetermined date, a rope-like material had been placed between the exhaust's heater shroud and muffler. At an undetermined date/time, this material became separated from its installed location. During takeoff on the accident flight, the rope-like material became lodged in the carburetor's air intake. This resulted in restricting the flow of air into the carburetor, and the engine lost power. It was a dark night, and the airplane collided with trees during the ensuing forced landing. Toxicology results were consistent with the relatively recent use of diphenhydramine, an over-the-counter antihistamine with sedative and impairing effects, and propoxyphene, a prescription narcotic medication with impairing effects. The levels detected on toxicology evaluation were not consistent with impairment at the time of the accident. The
pilot had indicated to the FAA a history of diabetes and kidney stones, but not the use of diphenhydramine or propoxyphene, and it could not be determined whether medical conditions or the use of medication may have played a role in his decision to insert the rope-like material in the engine compartment.
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After performing a series of takeoffs and landings, the pilot landed and spent 30 to 45 minutes on the ground before taking off for the accident flight. The pilot reported that during the flight, he flew low and slow, and the engine experienced a power failure. Thereafter, the airplane impacted a river and nosed over in 4 feet of water. The engine, including the carburetor, was examined. The engine was torn down, and no evidence of a preimpact anomaly was observed. The carburetor was bench tested and performed within the manufacturer's specifications.