What happened
On August 4, 2016, a SZD-51-1 Junior glider, registration SP-3508, was performing a landing at the EPLU aerodrome. During the landing sequence, the aircraft touched down at an excessive speed, estimated by the pilot to be between 100 and 110 km/h, while the aerodynamic brakes remained partially closed. The aircraft initially landed with a slight left wing low.
Upon touchdown, the main wheel bounced, causing the glider to lose its windward direction and veer to the left. Due to the lack of lateral stability, the tip of the left wing struck some tall grass growing on the otherwise mown airfield surface. This contact initiated a dynamic left-hand ground loop. During the maneuver, the tail lifted, and the aircraft pivoted on the nose area near the bungee launch hook. The glider eventually came to a halt approximately 50 meters from the initial touchdown point, having rotated roughly 200 degrees from its original landing heading.
The investigation
The investigation examined the aircraft's condition, the pilot's flight parameters, and the environmental conditions at the time of the accident. The weather was reported as having winds from 230°-270° at approximately 6 m/s, with 3/8 Cu clouds at 1500m and 4/8 As coverage. The investigation also reviewed the aircraft's maintenance status, noting that the SZD-51-1 Junior was within its valid airworthiness period and had sufficient hours remaining before its next scheduled maintenance.
Structural damage to the aircraft was significant, including a broken canopy support cable, damage to the leading edge of the right wing approximately 75cm from the root, localized fuselage skin damage behind the wings, and internal structural damage to the ribs. Additionally, the leading edge and spar of the vertical stabilizer were broken, and the skin had detached from the spar.
Findings
- The primary cause of the accident was pilot error, specifically landing at an excessive speed with the aerodynamic brakes partially closed.
- The pilot failed to maintain lateral stability during the landing roll.
- The contact between the left wingtip and tall grass on the runway surface triggered the ground loop.