What happened
On September 10, 2009, during the Austrian National Aerobatic Gliding Championships at Spitzerberg Airfield, an LO-100 glider experienced a catastrophic structural failure. The pilot was performing a competitive aerobatic sequence via aero-tow. While transitioning from the first to the second figure of the routine, the pilot heard a loud bang from the starboard side. Upon inspection, the pilot observed the right wing exhibiting significant fluttering, though they initially believed the structure remained intact.
Shortly thereafter, the aircraft entered an unrecoverable spin. As the aircraft descended to approximately 500 meters, the pilot was forced to bail out using a rescue parachute. The pilot sustained one serious injury due to the sudden opening of the parachute. The LO-100 subsequently impacted agricultural land approximately 1 km west-southwest of runway 15/33 at Spitzerberg, resulting in the total destruction of the aircraft.
The investigation
The SUB investigation reconstructed the flight path using pilot statements, witness accounts, and data from a competition altitude transponder. The investigation focused on the physical condition of the wreckage, specifically examining the right wing, ailerons, and the leading edge. Technical analysis included laboratory testing of the wood and adhesive strength, specifically looking at the beech plywood spars and the integrity of the glue joints between the plywood and solid wood components. The investigation also reviewed the aircraft's maintenance history and the structural design of the single-spar wooden wing.
Findings
- The primary cause of the accident was the structural failure of the right wing, which resulted in a loss of control.
- The aircraft was performing high-load aerobatic maneuvers as part of a sanctioned competition.
- The impact of the aircraft with the ground led to the total destruction of the airframe.
- The pilot's survival was attributed to the successful deployment of the emergency parachute, though the rapid inflation caused physical injury.