Incident Overview
During a pleasure flight, the pilot's last transmission indicated an intention to explore the glider's capabilities beyond straight-and-level flight. Witnesses in the area reported hearing a loud pop and observing the glider descending vertically without its left wing. The aircraft subsequently collided with terrain.
Wing Spar Examination
Post-accident examination revealed that the wing spar had fractured two feet from the root. A metallurgical test determined that the spar failed in a positive (up) overload condition.
Weight and Placard Information
The aircraft was placarded with a maximum pilot weight of 166 pounds. The pilot involved in the incident weighed 210 pounds, exceeding the placard limit.
Aerobatic Restrictions
A Schweizer service bulletin restricts the sailplane from performing aerobatic maneuvers. The pilot's intent to explore performance beyond straight-and-level flight may have involved maneuvers prohibited by this restriction.