Incident Overview
On 3 July 2022, a student and an instructor took off in a SZD-9 bis Bocian 1E glider (registration SP-4082) from Rybnik-Gotartowice airfield (EPRG) for an introductory flight. The launch was by winch. This was the 11th flight of that glider on the day of the incident. The takeoff, climb, cable release, and the first turn after release were normal. While on the downwind leg of the circuit, the student alerted the instructor to a sudden jam of the elevator and rudder. The instructor took control and confirmed that movement of both controls was severely restricted, though the glider remained controllable with full aileron authority. The instructor declared an emergency by radio and, using very small control inputs, continued the flight, merging the third and fourth turns. The glider landed safely on the airfield. No injuries occurred.
Investigation Findings
A post-flight inspection of the glider revealed that the trim plate of the elevator had become detached from its hinge pockets. Under aerodynamic pressure, the trim plate rotated on the control cable and became wedged between the elevator and the rudder. This condition significantly restricted the movement of both controls.
Cause
The cause of the incident was damage to the trim system that was not detected during the pre-flight inspection. No contributing circumstances were identified. The operator discussed the incident with flying and maintenance personnel, recommending more thorough pre-flight checks of control surface attachment and functionality, caution during hangaring and transport, and restricting access to equipment by unauthorized persons. No safety recommendations were issued by the commission.