Amateur-built Smyth Sidewinder accident near Natrona, Wyoming, May 7, 2004
On May 7, 2004 at about 6:30 pm local time, a amateur-built Smyth Sidewinder, registered N92AC, was substantially damaged in an accident near Natrona, Wyoming. It was a ferry flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 7, 2004 · about 6:30 pm local time
- Place
- Natrona, Wyoming · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built Smyth Sidewinder
- Registration
- N92AC · registry record · serial 212380
- Damage
- Substantial damage
- Flight
- Ferry flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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 complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 750 hours in all; 6 in this make and model; 30 in the last 90 days; 10 in the last 30 days; 600 as pilot in command; 300 on instruments
- Last flight review: September 12, 2003
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 601 hours
- Last inspection: annual inspection, May 6, 2004; 4 hours since
- Maximum gross weight: 1,413 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-290-G-D (piston); 0 hours total
The flight
- Departed from: THP Thermopolis WY at 5:30 pm
- Destination: CPR Casper WY
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 240° at 18 knots, gusting 24
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 21°F (-6°C)
- Altimeter: 30.03 inHg
- Observation at 6:53 pm from CPR, 22 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The docket at the NTSB holds the report as a PDF and the investigation's photographs and documents. This site never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number DEN04LA070.