What happened
On October 15, 2021, a Piper PA-22-150, registration LV-FIU, departed from Florencio Varela for a low-level aerial advertising mission. Approximately 40 minutes into the flight, the pilot noticed a drop in engine RPM. Although the pilot initially managed to restore power by increasing the throttle, the engine subsequently lost power again and ceased functioning entirely.
To avoid a more serious incident, the pilot performed an emergency landing within the grounds of the Club Deportivo Pucará in Burzaco. During the landing roll, the aircraft struck wooden and metal bleachers and a wire fence, causing the nose gear to collapse and resulting in significant damage to the engine, propeller, wings, and forward fuselage. The pilot escaped the wreckage without injury.
The investigation
The investigation examined the engine, fuel samples, and the aircraft's maintenance state. While the flight controls were functional, the engine showed signs of significant wear, including worn crankshaft bearings and evidence of high temperatures on the cylinder fins. Investigators also discovered non-aviation grade aluminum rods installed in the engine and the use of automotive-grade fuel hoses.
Laboratory analysis of fuel samples taken from the tank and the engine filter revealed that the aircraft was using automotive gasoline. While the engine manufacturer, Lycoming, permits limited use of automotive fuel, the bioethanol content in Argentine automotive gasoline (approximately 12%) far exceeds the 1% limit specified by the manufacturer. Furthermore, the investigation noted that the pilot was conducting advertising flights over a densely populated area, which is prohibited for single-engine aircraft under local regulations.
Findings
- The engine shutdown likely resulted from vapor lock caused by the high bioethanol content in the automotive fuel, which increases volatility and interrupts fuel flow.
- The use of automotive gasoline violated both manufacturer specifications and Argentine civil aviation regulations (ANAC), which prohibit all types of automotive fuel in aircraft.
- The engine was in a degraded state, exhibiting significant wear and the presence of non-approved, non-aviation components.
- The flight operation took place in a restricted, densely populated area where single-engine aircraft operations are prohibited.
Safety action
- The investigation highlighted the necessity of using only manufacturer-approved fuels and components.
- There is a critical need to detect and prevent the use of unapproved parts in aviation engines and airframes.
- Authorities should implement stricter supervision of aerial work operations, particularly low-level advertising flights in populated zones.