PZL-104 Wilga 35A Fuel Exhaustion Incident Near Połaniec (SP-ZOO)

Incident Overview and Flight Details On 13 October 2018, a PZL-104 Wilga 35A was involved in an incident near Ossala, close to Połaniec, Poland. The aircraft was operated by a professional pilot for a ferry flight from the EPSY airfield to Mieliec (EPML). The flight was planned for 2 hours and 55 minutes, and the aircraft was fueled to capacity with 195 liters. Departure occurred at 13:25. After reaching 1,500 feet, the pilot set the engine parameters to 680 manifold pressure and 1,750 rpm. ## Sequence of Events The aircraft reached Wyszogród (EPMO Q) around 14:20, where the pilot contacted FIS Warsaw and received a direct course to EPML. At 15:20, the pilot contacted FIS Kraków and began a gradual descent near Łagów. At that time, the GPS indicated 25 minutes remaining to EPML, while the fuel gauges showed approximately 40 liters of fuel remaining. After contacting EPML and agreeing to land on runway 09, the engine began to run unevenly and subsequently shut down. The pilot informed EPML of the situation, selected a suitable area, and landed in a meadow in uncontrolled terrain. The pilot was not injured, and the aircraft sustained no damage. After the flight, 1.5 liters of fuel were drained from the aircraft. ## Investigation and Technical Findings On 29 October 2018, a check flight was conducted to determine the average fuel consumption under comparable conditions. The flight lasted 1 hour and 3 minutes, with a total engine running time of 73 minutes, including ground operations. Fuel consumption was 93 liters. Calculations showed the following average hourly fuel consumption: - From all flights in the current year: 56 liters/hour - On 13 October 2018: 69 liters/hour - During the check flight on 29 October 2018: 76 liters/hour During the check flight, cylinder head temperatures were observed to remain in the lower range (130°C), and there was no engine response when the altitude corrector lever was moved. These findings indicated that the engine was running on a rich mixture, which caused the cylinders to be cooled by fuel and resulted in lower cylinder head temperatures. The rich mixture significantly increased fuel consumption, and the symptoms pointed to improper carburetor operation. ## Probable Cause and Safety Actions The engine shutdown was caused by fuel exhaustion, resulting from a significant increase in fuel consumption during the incident flight compared to normal and average consumption during previous operations, due to improper carburetor operation. The investigating entity conducted refresher training for flight personnel on flight planning and monitoring procedures, particularly regarding fuel consumption. The Commission did not formulate any safety recommendations or comments.