What happened
On September 3, 2022, at approximately 15:53 UTC, a Z-43 aircraft, registration OK-FOI, was taxiing from a refueling station toward the threshold of runway 13 at Skuteč Airport (LKSK). During the taxi, the pilot received information from the radio station regarding smoke emerging from the exhaust. Upon reducing power, the pilot was informed that flames were visible from the exhaust area. The pilot immediately shut down the engine and turned off the magnetos.
Following the engine shutdown, the pilot focused on the rapid evacuation of the three passengers on board. While the pilot successfully evacuated the occupants, the fire spread rapidly. Although the pilot did not perform all required emergency procedures for an engine or fuel system fire—specifically failing to close the fuel cock and failing to activate the engine fire extinguisher—the fire was eventually extinguished by the local fire department. The aircraft was destroyed by the fire.
The investigation
The ÚZPLN investigation involved analyzing witness statements, aircraft documentation, pilot records, and a technical report from LOM Praha s.p. based on the examination of wreckage. The investigation focused on identifying the source of the fire within the engine compartment, specifically evaluating the fuel system, the oil system, and the electrical system.
Investigators found no evidence of leaks or failures in the fuel or oil systems. The fuel system lines remained intact, and the oil system showed no signs of significant leakage or contamination that could have caused such an intense fire. The examination of the wreckage revealed that the most severe damage was concentrated around the battery area.
Findings
- The primary cause of the accident was likely a short circuit in the electrical system, with the focus of the fire located in the battery.
- The intensity and rapid spread of the fire were consistent with an electrical fire, and the initial smoke observed was grey, characteristic of burning plastic components.
- The pilot failed to follow all emergency procedures outlined in the Z-43 Flight Manual for an engine or fuel system fire on the ground, specifically neglecting to close the fuel valve.
- The aircraft was fully airworthy and had no reported mechanical issues during previous flights that day.