What happened
On April 1, 2005, an experimental HB 207 "Alfa" was conducting a test flight at Bitburg airfield to evaluate the operation of its retractable landing gear. The pilot, who had approximately 324 total flight hours, was performing several approaches on runway 06. During the final approach, the pilot decided to execute a go-around to complete another circuit.
During the go-around maneuver, at an altitude of approximately 50 meters, the aircraft began to lose speed. Witnesses reported hearing unusual engine stuttering and irregular running. The aircraft's nose lifted slightly before it suddenly stalled and banked sharply to the left. The pilot transmitted a brief distress message, stating, "There is something," before the aircraft struck the ground. The left wing made initial contact with the runway and broke off, after which the aircraft slid into the grass, causing the right wing to separate as well. The impact destroyed the aircraft and caused fatal injuries to the pilot.
The investigation
The BFU examined the wreckage and the engine components. Investigators found that the fuel pressure gauge was at the lower red line and the oil pressure indicated a level typical of oil starvation. Upon inspection of the dual carburetors, investigators discovered that two screw connections were missing on the right carburetor, and the float chambers were empty. Additionally, while the fuel tank selector was set to the left tank, the electric fuel pump was not activated, contrary to the flight manual instructions for go-around procedures.
Regarding the cockpit, the investigation revealed that the pilot was wearing a four-point harness. However, the attachment points for the shoulder straps failed during the impact, causing the pilot to strike the instrument panel and control column. The investigation also noted that the seatbelt mounting hardware had been installed by the builder without specific instructions from the manufacturer or the belt supplier.
Findings
- The primary cause of the accident was the aircraft entering an aerodynamic stall during the go-around maneuver due to a massive loss of engine power.
- A significant loss of engine performance was likely caused by an inadequate fuel supply to the right carburetor, exacerbated by the fact that the electric fuel pump was not switched on.
- The pilot's limited experience with this specific aircraft type (only 2 hours of flight time on the HB 207 "Alfa") contributed to the sequence of events.
- The fatal nature of the impact was intensified by the failure of the seatbelt attachment points, which allowed the pilot to strike the aircraft interior.