What happened
While performing a series of circuits, the aircraft experienced a sudden loss of engine power as it climbed through approximately 505 feet above ground level. In response to the power loss, the pilot transitioned into a glide. Although the glide speed was slightly below the target, it remained close to the optimal speed for the aircraft's weight, providing near-peak glide performance.
Due to a lack of suitable landing sites within the aircraft's gliding range, the pilot attempted to land in an open area. However, the aircraft struck trees located along the southern boundary of the field, which caused the left wing to separate before the aircraft ultimately impacted the ground. The accident resulted in head injuries to the pilot.
The investigation
Investigators examined the wreckage, engine components, and recorded flight data to identify the cause of the power loss. Analysis of the engine and fuel systems revealed no evidence of icing, ignition issues, or induction problems. While the data confirmed a significant drop in fuel flow—falling from 113 l/h to 22 l/h—the fuel supply itself was sufficient, as both tanks contained enough fuel to power the engine.
Investigators explored whether the pilot might have accidentally moved the mixture control while adjusting the propeller. While the data showed the pilot successfully adjusted the RPM as intended, the fuel flow reduction was much larger than what would be expected from a minor mixture adjustment. Because the impact destroyed the engine control linkages, the exact position of the mixture lever prior to impact could not be confirmed. Ultimately, no mechanical defect in the fuel system was identified during the dismantling and testing of the components.
Additionally, the investigation looked into an incorrect engine variant installed on VH-CWK. A maintenance error had led to the installation of a K1A5 engine instead of the required K1G5 variant. While this was a deviation from the aircraft's flight manual, the differences between the two variants were minor and did not impact the aircraft's operation or contribute to the crash.
Findings
- A significant reduction in fuel flow caused the engine to lose power during the climb.
- The specific cause for the reduction in fuel flow could not be determined.
- The aircraft struck trees during a forced landing attempt, leading to the collision with terrain.