Accident Details
On the day of the accident, the pilot departed Worland, Wyoming, at approximately 0950 Mountain Standard Time, aiming to resume an aerial pipeline patrol route toward Cody, Wyoming. Before departure, both wing fuel tanks had been filled to capacity with 50 gallons of usable fuel each. After an estimated 20 minutes of flight, the aircraft struck terrain in an area characterized by uneven, sage-covered ground.
Wreckage Examination
Post-crash examination revealed the flaps were extended to 8 degrees. The ignition switch was found in the 'LEFT' position. Evidence indicated the pilot had reduced the aircraft's speed before impact. No evidence suggested the engine was developing power at the time of impact; the propeller exhibited aft bending with minimal abrasion and chordwise scratching. Extensive hydraulic effect was observed on both main fuel tanks and on one of the brass floats within the carburetor float chamber.
Engine and Systems Testing
A teardown of the engine disclosed no pre-impact mechanical malfunction. The aircraft's fuel, air, and ignition systems were examined and no anomalies were found. Additionally, post-crash testing of the auxiliary fuel system revealed no mechanical malfunction.
Weather Conditions
The temperature and dew point at Worland were 54°F and 32°F, respectively. According to icing probability charts, these conditions were conducive to the formation of carburetor ice. However, the presence of carburetor icing was not verified during the investigation.