What happened
On August 4, 2022, a private pilot operating a Cessna 150B was conducting a flight between Aeródromo Puerto Sánchez and Aeródromo Teniente Vidal in the Aysel Region of Chile. After completing the first leg of the flight, the pilot prepared for the return journey with approximately 45 liters of fuel remaining.
During the return flight, the aircraft encountered severe turbulence at an altitude of 5,000 feet, which caused the engine to fluctuate in RPM and subsequently fail. Although the pilot successfully performed an in-flight restart, a second engine failure occurred approximately 10 nautical miles south of Coyhaique while at an altitude of 2,300 feet (roughly 700 feet AGL). Due to the low altitude and limited time, the pilot executed an emergency landing in an unprepared field. The pilot escaped the aircraft without injury, though the aircraft sustained significant damage, including a collapsed nose gear and structural deformation.
The investigation
DGAC Chile investigators examined the aircraft's maintenance records, fuel levels, and the pilot's flight planning. The investigation focused on why the engine failed twice during the same flight leg. Investigators analyzed the fuel remaining in the tanks and the impact of the meteorological conditions present at the time of the accident. The inquiry also reviewed the pilot's flight logs and the aircraft's operational history to determine if the fuel management or flight planning contributed to the event.
Findings
- The engine failure was caused by vapor lock within the fuel system. This occurred because the fuel level was so low that the severe turbulence caused air to enter the carburetor instead of liquid fuel.
- The pilot's flight planning failed to account for the 11.35 liters of unuseable fuel required by the aircraft's manual, which significantly reduced the actual flight autonomy.
- The pilot did not adjust the return flight plan to account for the higher fuel consumption and longer duration experienced during the initial leg of the flight.
- The aircraft was flying with fuel levels below the minimum usable threshold.
- The landing on irregular terrain caused extensive damage to the propeller, engine cowling, and landing gear.
Safety action
- The DGAC Chile recommends increasing awareness of the