What happened
On the morning of 18 October 2015, a B&F Technik FK12 Comet took off from the EBAV airfield in Avernas-le-Bauduin for its second local flight of the day. Shortly after departure, witnesses observed the aircraft returning toward the airfield with visible flames emerging from the engine compartment and the left landing gear. One observer noted an abnormal engine sound during the approach.
As the aircraft flew over the airfield, it suddenly pitched downward and impacted a cultivated field located approximately 200 meters from the airfield barracks. The impact caused the aircraft to flip over, and a subsequent intense fire completely consumed the wreckage. The pilot, who was the owner of the aircraft, sustained one fatal injury.
The investigation
AAIU(Be) investigators examined the wreckage and the maintenance history of the aircraft. The investigation focused on the origin of the fire and the effectiveness of the pilot's emergency response. Investigators analyzed the condition of the engine'ert exhaust system and the recent maintenance performed on the fuel system. The inquiry also reviewed the flight manual's emergency procedures and the operational status of the fuel shut-off valve.
Findings
Investigators could not definitively pinpoint the exact spark for the fire, but identified two primary scenarios: a failure in the exhaust pipe releasing hot gases into the engine bay, or a fuel leak at the right-hand carburetor connection following recent maintenance. Several contributing factors were identified:
- The exhaust system featured non-original heat-resistant tape wrapping, which likely obscured cracks or damage from visual inspections.
- Recent maintenance on the exhaust system was performed without sufficient verification by qualified personnel.
- The fuel shut-off valve had not been regularly tested, meaning a potential internal leak or stuck valve could have gone undetected.
- The flight manual lacked specific emergency instructions for managing an engine fire while in flight, such as managing cabin ventilation or the electrical fuel pump.
Safety action
Following the investigation, the AAIU(Be) issued several recommendations to the Belgian Ultralight Federation. These include warnings regarding the use of heat-resistant tape on exhaust pipes, the promotion of regular testing for fuel shut-off valves, and a call for manufacturers to provide more comprehensive in-flight engine fire procedures in their flight manuals.