Accident Flight
On August 10, 1996, a pilot who had received a glider certification on July 24, 1996, was flying a Let L-13 glider solo for the first time. The pilot had logged approximately 2.1 hours in the same type of glider prior to the accident flight. The flight plan involved being towed to traffic pattern altitude, releasing the glider, entering the traffic pattern, and landing.
Sequence of Events
The glider was released approximately 3 miles southwest of the airport at an altitude of 1,850 feet. The airport elevation is 269 feet. Witnesses reported that the glider entered a right spin about 5 to 10 seconds after release and continued spinning until it impacted the ground.
Weight and Balance Information
To prevent the center of gravity from exceeding the aft limit, a placard in the cockpit indicated that the minimum front seat solo weight was 150 pounds. The pilot’s weight was between 128 and 135 pounds, and a single 25-pound ballast bag was found in the wreckage. However, after the glider had been repainted and modified with a non-standard tailwheel, revised weight and balance data showed that the current minimum front seat solo weight was 181 pounds. Based on this data, which was kept in the operator’s maintenance shop, the glider’s center of gravity was computed to be 1.4 inches behind the aft limit. The pilot’s personal copy of the Let L-13 operating manual did not contain the revised weight and balance data. Copies of the glider’s operating manual were being sold to renters without this updated information.