NTSB Identification: DEN04LA070.
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Accident occurred Friday, May 07, 2004 in Natrona, WY
Probable Cause Approval Date: 09/29/2004
Aircraft: Crimmins Smyth Sidewinder, registration: N92AC
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

After refueling to capacity, the pilot took off to ferry his newly-purchased airplane it to his home base. After 1 hour in cruise flight at 9,500 feet msl, the engine --- which had been producing 2,500 rpm --- began "surging" and started losing power. Carburetor heat was opened and the mixture was adjusted, but the engine continued to lose power. Cylinder head temperature, oil temperature, and oil pressure indicated normal parameters. As the airplane began losing altitude, the pilot decided to land in an open area. During the landing rollout, the nose and right main landing gears were torn off, and the left main landing gear folded underneath the airplane. The firewall was buckled and there was wing damage. Later examination of the fuel selector valve a considerable amount of fine grit inside the fuel screen. Similar grit was seen inside the fuel tank. The airplane was given a conditional inspection on May 6, 2004. Prior to that, the last conditional inspection was on August 1, 1996. Tachometer time between these two inspections was 178.9 hours. At the last inspection, the fuel tank was removed, cleaned by a radiator shop, and reinstalled in the airplane.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

fuel starvation due to contamination, resulting in the fuel selector valve becoming totally blocked. Contributing factors were the inadequate conditional inspection, and the lack of nsuitable terrain on which to make a forced landing.

Full narrative available

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