What happened
On May 30, 2014, a Zlín Z 381, registration OK-BSA, was performing a flight from Kroměříž to Pardubice as part of an aviation event. During the flight, the pilot noticed an increase in oil temperature and subsequently experienced engine power fluctuations. After attempting to stabilize the engine by switching to the fuel reserve, the engine eventually failed completely.
Due to the low altitude and the engine failure, the pilot was forced to perform an emergency landing. To avoid a muddy surface that might have caused the aircraft to flip, the pilot chose to land in a field of tall beets near the village of Nabočany. The aircraft struck the crops at a speed of approximately 70-80 km/h, resulting in damage to the fuselage and landing gear, but the pilot escaped without injury.
The investigation
The ÚZPLN investigation established that the engine failure was caused by the complete exhaustion of usable fuel. While the pilot had noted fuel dripping from the engine drainage lines prior to takeoff, this was later identified as a symptom of a faulty float in the carburetor.
Technical examination of the fuel system revealed that the fuel gauge was inaccurate, displaying approximately 8 to 10 liters more than was actually present in the tank. Furthermore, the investigation found that the carburetor had been incorrectly adjusted by a maintenance organization to specifications intended for a different carburetor model (W-45AK), which contributed to an incorrect fuel level in the float chamber.
Findings
- The primary cause of the incident was the exhaustion of usable fuel.
- The pilot did not initially recognize the engine irregularities as a sign of fuel depletion.
- The fuel gauge provided inaccurate readings, leading to insufficient fuel management.
- A leaking float in the carburetor caused excess fuel to drain into the engine drainage system.
- An incorrect carburetor adjustment by a maintenance organization contributed to the fuel system issues.
- The pilot's decision to land in the beet field prevented more severe damage to the aircraft that might have occurred on a muddy surface.