What happened
On May 6, 2011, a SZD-51-1 Junior glider, registration PH-957, was performing a winch launch at Teuge Airport. During the climb, the pilot noticed that moving the control stick had very little effect on the aircraft's pitch. Initially believing the winch speed was too low, the pilot attempted to signal for more power, but the aircraft failed to respond to pitch inputs.
After reaching an altitude of approximately 250 meters, the pilot disconnected from the winch cable. The aircraft immediately assumed a low nose attitude, stabilizing at a speed of about 150 km/h. Realizing that elevator control was non-functional, the pilot decided to return to the airfield immediately. Despite the lack of pitch control, the pilot managed a soft landing by utilizing ground effect and maintaining a full aft stick position. There were no injuries and no damage to the aircraft.
The investigation
The investigation focused on the assembly process of the aircraft earlier that day. The glider had been assembled by a group of three pilots, including a solo pilot and an inexperienced student. It was established that there was no designated person in charge of overseeing the assembly process. While experienced pilots performed the daily inspection (A-check), they failed to notice that the elevator connection was not properly secured.
Investigators found that during the assembly of the stabilizer, the solo pilot and the student pilot were responsible for the elevator connection. The person performing the task moved the locking sleeve upward but did not ensure that the locking pin had popped outward to confirm a secure lock. Furthermore, the pilot's cockpit check prior to the second flight did not include a visual verification of the elevator's movement.
Findings
- The primary cause of the control issues was the improper securing of the elevator connection during aircraft assembly.
- The connection likely became disconnected due to vibrations during the first flight of the day, ground transport, or the winch launch itself.
- The assembly process lacked clear leadership, with the critical task of securing the elevator left to inexperienced individuals.
- The daily inspection failed to identify the unsecured mechanism because the inspectors did not verify the position of the locking pin.
- The aircraft was not equipped with an automatic elevator connection, a feature available in later models of the SZD-51-1 Junior.
Safety action
- The investigation highlighted a lack of formal training regarding the assembly and disassembly of gliders within the flying club.
- There was a noted deficiency in the training and execution of the daily 'A-check' inspections, specifically regarding the verification of vital control surfaces.