What happened
On April 7, 2019, a Tecnam P92 Echo Classic, registration LV-S026, was conducting a local flight departing from the Puan aerodrome in Buenos Aires. The aircraft was carrying a pilot and one passenger. After approximately 40 minutes of flight at 2,000 feet, the pilot began a descent to 1,500 feet to mitigate turbulence. During this descent, the pilot reduced power to idle, at which point the engine ceased operation.
Following several unsuccessful attempts to restart the engine, the pilot executed an emergency landing on Provincial Route 76. During the descent, the aircraft struck medium-voltage power lines crossing the highway. The impact caused the left wing fuel tank to rupture and damaged the fuselage, landing gear, and propeller. The aircraft subsequently came to rest in a nearby field. There were no fatalities and no injuries to the crew or passenger, though the impact caused a fire in the adjacent field due to damaged electrical lines.
The investigation
The investigation examined the engine's performance, the fuel used, and the regulatory environment regarding automotive fuel in Argentina. Investigators analyzed the engine components and the fuel specifications. It was noted that the aircraft was operating with automotive gasoline (nafta súper) containing 12% ethanol. The investigation also reviewed the discrepancies in flight hour logs and the pilot's flight records.
Findings
- The engine failure was most likely caused by vapor lock, where fuel vaporization in the fuel lines interrupted the flow to the engine.
- The aircraft was using automotive gasoline with a 12% ethanol content, which exceeds the 10% maximum limit permitted by the Rotax engine manufacturer.
- While the Tecnam flight manual suggested automotive fuel could be used without limitation, the engine manufacturer's constraints were not aligned with this instruction.
- Argentine civil aviation regulations (ANAC) prohibit the use of automotive fuels in aircraft due to bioethanol content.
- The investigation identified secondary safety concerns, including the lack of flight hour records for the pilot and the unauthorized movement of wreckage prior to official notification.