What happened
On June 2, 2021, at approximately 10:58 UTC, a Schleicher ASW-19 B glider, registration OK-5235, was participating in a winch launch at Letkov Airport (LKPL). During the takeoff roll, the pilot attempted to maintain a level attitude by applying back pressure on the control column. However, the aircraft failed to respond to the input and instead entered a steep climb.
Upon realizing the malfunction, the pilot immediately released the tow cable. Without the continuous tension of the winch, the glider's speed dropped rapidly, leading to a steep descent. The aircraft reached a minimum altitude of approximately 15 meters before the nose of the fuselage struck the ground. The glider continued to slide along the terrain, eventually coming to rest in the field adjacent to runway 08L. The pilot sustained no injuries.
The investigation
The ÚZPLN investigation focused on the mechanical state of the aircraft following its assembly. The glider had been stored in a disassembled state in a trailer, a process that typically takes 15 to 20 minutes. Investigators examined the control linkages, specifically the L'Hotellier ball connector system used to connect the elevator control rod to the elevator surface. The investigation also reviewed the maintenance records, the pilot's flight experience, and the meteorological conditions at the time of the incident, which were characterized by light easterly winds and clear visibility.
Findings
- The pilot had sufficient flight experience and was fully qualified for the flight.
- The aircraft was airworthy and had a valid certificate of airworthiness.
- Following the assembly of the glider, the pilot failed to connect the control rod to the elevator.
- The pilot did not perform an adequate check to ensure the quick-release connector was properly engaged and secured.
- The loss of longitudinal control was caused by the disconnected elevator linkage, which allowed the elevator to move uncontrollably due to aerodynamic forces.
- The aircraft sustained significant structural damage to the forward fuselage, landing gear, and elevator surfaces due to the impact with the ground.