What happened
The pilot, who was not instrument-rated, was operating a flight from Farmington, New Mexico, to El Cajon, California. The journey included a stop at Borrego Springs, California, where a passenger deplaned. Before departing Farmington, the pilot received a weather briefing for the entire trip but only filed a flight plan for the first leg after being advised of adverse weather conditions along the second leg.
Upon arriving at Borrego Springs, the pilot discovered that aviation fuel was not available. Concerned about having sufficient fuel to complete the remainder of the flight, he purchased and used 2-1/2 gallons of Supreme unleaded automotive fuel. During the subsequent leg of the flight, the aircraft crashed in mountainous terrain.
A witness reported hearing the engine sputter before seeing the aircraft emerge from clouds at a steep 65-degree angle. The witness estimated the cloud base was between 400 and 500 feet above ground level. Weather conditions were described as rainy and heavy at times, with low ceilings and breaks in the overcast.
The investigation
A teardown of the engine revealed no evidence of a pre-impact mechanical failure. However, the aircraft was too badly damaged to determine the amount of fuel remaining in the tanks prior to impact. The crash site elevation was approximately 3900 feet.
Findings
The use of automotive fuel in an aircraft engine designed for aviation gasoline likely contributed to the loss of power. The pilot's decision to continue the flight in adverse weather conditions, combined with the lack of available aviation fuel at the stopover, created a critical situation. The non-instrument rated status of the pilot may have limited his ability to navigate safely through the reported low ceilings and rain.
Safety message
Pilots should ensure that only approved aviation fuels are used in their aircraft. Automotive fuel can cause severe engine damage and failure. Additionally, pilots must carefully plan for fuel availability at all stops, especially in remote areas, and avoid flying into known adverse weather without appropriate qualifications and equipment.