What happened
On July 8, 2012, a two-person crew operating an L13 SE Vivat, registration OK-4602, was conducting a flight from Hořice v Podkrkonoší toward the area east of Hradec Králové. The flight was intended to observe forest damage caused by recent storms. While maintaining an altitude of 150–180 meters AGL, the pilot experienced a sudden engine failure without prior warning.
After several unsuccessful attempts to restart the engine, the pilot identified a suitable landing site. To avoid a field covered in tall crops, the pilot selected a green area, which was believed to be a grassy field. The pilot performed the landing with the landing gear extended and flaps retracted. Upon touchdown, the aircraft struck an irrigation pipe system located within a carrot field. The impact caused a sudden deceleration, forcing the nose into the soft soil and causing the aircraft to flip onto its back. The two occupants escaped the aircraft with only minor abrasions.
The investigation
The ÚZPLN investigation focused on the cause of the engine failure and the circumstances of the landing. Technical inspections of the Mikron IIIB engine revealed that the ignition, oil, and fuel systems were functional. However, investigators discovered a 1.2 mm piece of silicone rubber debris lodged in the carburetor's main jet. This material, similar to silicone used for sealing the interface between the carburetor and the intake manifold, had blocked the fuel flow.
Regarding the landing, the investigation examined the terrain and the aircraft's configuration. The investigation established that the pilot likely discovered the irrigation pipes and the uneven, soft nature of the carrot field only moments before touchdown, leaving insufficient time to adjust the landing configuration. The use of a landing gear-down, flaps-up configuration—intended for a grass strip—resulted in a higher touchdown speed and increased kinetic energy, which contributed to the nose digging into the ground.