What happened
On February 9, 2013, a Scheibe SF-28 A powered glider, registration F-CFJL, was conducting a local training flight near Ploërmel Loyat, France. The flight was operated by the Planeurs de Brocéliande club and carried an instructor in the rear seat and a student pilot.
During the final stages of the landing approach, at an estimated altitude of five meters, the aircraft passed below the established approach slope. As the instructor attempted a nose-up input to execute the flare, the rear control stick detached from its housing. This sudden loss of pitch control caused the aircraft to pitch down abruptly. The propeller and the forward section of the fuselage struck the grass runway, causing the glider to slide approximately 150 meters before coming to a halt. The aircraft sustained severe damage to the landing gear and fuselage.
The investigation
The investigation focused on the mechanical integrity of the rear seat control stick system. On this specific model, the rear stick is designed to be removable to prevent accidental inputs by passengers during boarding; it is secured by pushing the stick 40 mm into a tube and tightening a wing nut.
Investigators examined the maintenance history of F-CFJL, which had completed 13 flight hours and 28 cycles since its last major inspection in August 2012. While the tightness of the wing nut had been verified during that August inspection, the stick had not been removed or reinstalled since that time. The instructor reported that he had performed the required elevator control checks prior to takeoff and observed no unusual play or positioning in the stick. He noted that while he made frequent, though limited, pitch inputs during the flight to demonstrate maneuvers to the student, he did not realize the stick was dislodging until the impact occurred.
Findings
- The primary cause of the accident was the lack of tightness of the rear seat stick wing nut.
- The separation of the stick during the flare maneuver led to an unrecoverable nose-down attitude.
- There were no recorded similar occurrences of this nature in the databases of the BEA, DGAC, BFU, or the aircraft manufacturer, suggesting this was an isolated event.