What happened
On August 28, 1999, a training flight involving a SZD-50-3 "Puchacz" glider resulted in an accident near Schönhagen. During a winch launch, the pilot experienced a momentary loss of tension in the tow rope at an altitude of approximately 40–50 meters, which then appeared to recover. However, at an altitude of 100–150 meters, the tension dropped again. This caused the airspeed to fall to approximately 60 km/h, leading the aircraft to bank sharply to the left and enter a spin.
Although the flight instructor provided radio instructions to release the tow rope and assist in recovering from the spin, the student pilot did not react. After several rotations in the spin, the glider impacted a pine forest approximately 100 meters from the runway. The impact resulted in one serious injury to the pilot and the total destruction of the aircraft, as well as damage to the surrounding forest.
The investigation
The BFU investigation focused on the mechanical state of the winch and the sequence of events leading to the loss of tension. Investigators examined a Hercules H 4 winch and found that the engine power had dropped suddenly during the third launch, despite the throttle being at full power.
Upon inspection, the investigation revealed that the lever used for the emergency engine shutdown was positioned toward the "off" position, and its wire security was open. Testing showed that when the lever was moved toward the "off" position, the engine experienced varying degrees of RPM drops. No technical defects were found on the SZD-50-3 "Puchacz" itself.
Findings
- The primary cause of the accident was a loss of winch tension caused by the accidental movement of the engine shutdown lever.
- The lever's wire security had been opened, likely through unintentional contact, allowing the lever to move toward the "off" position, possibly due to engine vibrations.
- The pilot failed to decide on an immediate launch abort during the initial loss of tension at low altitude.
- The pilot did not apply sufficient corrective input to prevent the aircraft from entering the critical flight state.