What happened
On April 29, 2022, an Ellipse Spirit (registration D–MKGE) was performing a takeoff from runway 26 at Frýdlant Airport. During the takeoff roll, the aircraft traveled approximately 250 meters at a speed of roughly 80 km/h without the pilot lifting the nose wheel. As the aircraft entered a soft, waterlogged section of the runway, the nose gear began to sink into the terrain. This sudden resistance caused the nose gear's locking brace to fail, leading to the retraction of the nose gear. The subsequent impact caused the propeller to strike the ground and resulted in damage to the engine cowling and the forward fuselage.
There were no injuries to the two occupants on board.
The investigation
The ÚZPLN investigation focused on the structural integrity of the nose gear and the runway conditions. At the time of the incident, a NOTAM was in effect for Frýdlant Airport, warning of reduced runway load-bearing capacity due to waterlogging and recommending that takeoffs and landings be performed on the northern edge of the runway.
Investigators analyzed data from a Kanardia Nesis flight recorder, which confirmed that the engine was operating normally and that the aircraft maintained a nearly constant longitudinal pitch of approximately -3° throughout the roll, indicating the nose wheel was not lifted. Calculations based on the recorded deceleration showed that the braking force exerted by the soft terrain reached approximately 4293 N, resulting in a load of 437.7 kg on the nose gear. This force exceeded both the operational limit (266.8 kg) and the design limit (400.2 kg) of the component.
Material testing was performed on samples taken from the broken locking brace. While one sample showed a strength of 570 MPa—roughly 15% lower than the required 669 MPa for the specified steel—other samples exceeded the standard. However, the investigation concluded that the structural reserve of the gear was sufficient to handle such a deviation, and the primary cause was the extreme load applied during the incident.
Findings
- The primary cause of the incident was improper piloting technique, specifically the failure to lift the nose wheel during the takeoff roll.
- The takeoff was performed on a section of the runway with reduced load-bearing capacity.
- The combination of the unlifted nose wheel and the soft runway surface created excessive forces that exceeded both the operational and design load limits of the nose gear assembly.