What happened
On July 11, 2006, an EV-97 Eurostar ultralight aircraft, registration OH-U432, was conducting a flight from Kemi-Tornio toward Kuortane. After a scheduled stop at Ranu for refueling, the aircraft proceeded to Haapavesi aerodrome. During the refueling process, 18 liters of gasoline were transferred from a plastic canister located in the passenger footwell to the aircraft's fuel tank.
During the subsequent takeoff from runway 30, the aircraft climbed at a very steep angle but at an insufficient airspeed. Witnesses observed the aircraft drifting to the right approximately 100 meters after takeoff while at an altitude of only 4 meters. As the pilot attempted to correct the direction, the left wing struck the runway surface, causing damage to the wingtip profile and aileron. The aircraft continued to climb with poor controllability, oscillating between left and right turns. Due to the unstable flight conditions, the pilot decided to terminate the climb and perform a forced landing in a nearby field. The aircraft flew under a power line and crossed four ditches, resulting in significant damage to the landing gear, fuselage, and wings.
The investigation
The investigation examined the aircraft's configuration, the pilot's actions, and the impact of the recent refueling. Investigators found that the pilot had bypassed the standard pre-flight inspection due to haste. Furthermore, the investigation focused on the shift in the aircraft's center of gravity following the transfer of 13.5 kg of fuel from the cabin to the fuel tank. The investigation also reviewed the safety implications of the pyrotechnic-activated parachute system installed in the aircraft.
Findings
- The pilot failed to perform the required pre-flight inspection before departure.
- The aircraft was improperly trimmed for the new weight distribution; the pilot had maintained the trim settings used for cruise flight rather than readjusting for the shifted mass.
- The transfer of 18 liters of fuel from the cabin to the tank caused a shift in the center of gravity, leaving the aircraft in a tail-heavy configuration.
- The pilot failed to monitor the airspeed during the takeoff roll, focusing instead on the RPM gauge and the aircraft's erratic handling.
- The transport of loose fuel in a plastic canister within the cockpit was in violation of safety regulations.
- The aircraft's high-efficiency trim system meant that even small changes in mass caused significant aerodynamic deviations.