What happened
On April 14, 2013, at approximately 11:55 UTC, a MÁRA – WING M 21 motorized hang glider, registration OK-IZN 02, crashed in the village of Valeč, Czech Republic. The pilot had taken off from Žatec/Macerka airport and performed a landing on a field approximately 1.5 km east of Valeč. After taking off again from the field, the pilot flew over the northern part of the village at an altitude of approximately 50 m AGL.
Witnesses observed that while the aircraft was flying over the town center, the engine RPM suddenly increased and the aircraft began to pitch and bank to the left. The aircraft then entered a steep climb, at which point the wing structure collapsed upward. This was followed by a vertical descent in a left rotation, and the aircraft impacted the ground on its left side. The pilot sustained fatal injuries at the scene.
The investigation
The ÚZPLN investigation focused on the structural integrity of the aircraft and the pilot's pre-flight procedures. Investigators examined the wreckage and found that the landing gear attachment to the wing had become disconnected. Specifically, a 10 mm transverse load-bearing pin was missing from the assembly. The investigation also revealed that the parallel safety suspension, which consisted of climbing rope, was improperly installed and failed to prevent the gear from shifting.
Technically, the aircraft had undergone unauthorized modifications, including a new engine installation and changes to the fuel system, which had not been inspected or approved by the LAA ČR technical inspector. Additionally, the aircraft's technical certificate had expired in November 2012.
Findings
- The primary cause of the accident was the disconnection of the wing-to-landing gear attachment caused by the loss of the transverse load-bearing pin during flight.
- The loss of the pin was preceded by the loosening of an unsecured M10 nut.
- The parallel safety rope was improperly installed, allowing the gear to shift under load.
- The pilot failed to perform a thorough pre-flight inspection of the landing gear attachment.
- The aircraft was operating with an expired technical certificate and contained unapproved structural and engine modifications.
- The flight was conducted at an altitude lower than permitted by regulations for flying over populated areas.