What happened
On January 2, 2013, a Pa-34-200 Seneca, registration OK-LFC, was performing a routine flight from Ostrava Mošnov to Vrchlabí. The flight was described by the pilot as calm and uneventful, with stable visibility and no turbulence. After landing on runway 29 at Vrchlabí, the pilot began taxiing toward a designated pickup point approximately 30 to 40 meters from the end of the runway.
As the aircraft was turning left, approximately two meters from the left edge of the runway, the nose gear suddenly collapsed. The impact caused the nose of the aircraft to strike the runway surface, leading to contact between the rotating propellers and the ground. This contact resulted in the immediate stoppage of both engines and damage to the propeller blades and engine cowlings. The pilot was uninjured and successfully executed emergency shutdown procedures, including cutting the electrical power and fuel supply.
The investigation
The ÚZPLN investigation examined the aircraft's technical condition and the runway environment. The runway surface was covered with 3.0 to 5.0 cm of moist snow over a frozen substrate, with various patches of frozen earth visible. Investigators identified a frozen lump of clay, approximately 10 cm in diameter, located in the path of the nose wheel.
Technical inspections of the Pa-3 and-200 Seneca did not reveal any pre-existing mechanical failures in the nose gear locking mechanism. However, the investigation noted that the manufacturer had previously issued service bulletins, such as SB 1123B, to address potential vulnerabilities in the nose gear's locking geometry. The investigation also considered the pilot's visibility, noting that the cockpit configuration and the mottled appearance of the snow-covered runway made it difficult to detect small surface irregularities.
Findings
- The pilot was properly qualified and the aircraft was airworthy at the time of the accident.
- The pilot could not effectively detect the frozen clay lump due to the visual characteristics of the runway surface and the aircraft's cockpit design.
- The nose gear collapsed due to an excessive shock load transmitted to the locking mechanism following a random impact between the nose wheel and a frozen obstacle.
- The impact of the nose gear collapse caused the nose section to strike the ground, resulting in damage to the composite nose cowl, the nose gear door mechanism, and both propellers.