Incident Overview
On 19 July 2015, a SZD-50-3 Puchacz glider, operated by an unnamed entity, was involved in a tow incident at EPBC. The pilot, a glider pilot, was flying the glider as part of a tow team behind an airplane. The flight proceeded normally up to an altitude of 700 meters, the prescribed altitude for the towed flight. At that point, the pilot attempted to release the tow rope by pulling the release handle multiple times, but the glider did not separate from the tow plane.
Sequence of Events
As the towing airplane began its descent, a jerk occurred and the glider was simultaneously released. The release happened because the tow rope came untied from a larger link. Specifically, the release trigger cable had torn at the point where it is common for both release knobs, preventing normal operation of the release mechanism. After the release, the remainder of the flight was uneventful, and the glider landed without further consequence.
Investigation Findings
The investigation, conducted by the user (operator) under the supervision of Andrzej Pussak, determined that the cause of the incident was the tearing of the release trigger cable at the location where it is shared by both release knobs. No safety recommendations were formulated by the commission. However, the incident was discussed with other flying personnel, and an inspection of release cables on other gliders was performed, which found no similar damage. It was recommended to inspect the cables every three months.
Damage and Injuries
No injuries were reported among the occupants. The aircraft did not sustain any damage.
Conclusion
The incident was resolved without any adverse outcome beyond the failure of the release mechanism. The causal factor identified was a defective release trigger cable.