What happened
On July 18, 2017, at approximately 12:44 LMT, a pilot operating an SZD-30C Pirat glider departed from the Piła (EPPI) aerodrome for a thermal flight. At approximately 17:15 LMT, while the aircraft was performing a turn at an altitude of roughly 500 meters and a speed of 110 km/h, the cockpit canopy opened unexpectedly. The aircraft was flying in conditions of significant turbulence at the time of the event.
Following the incident, the pilot managed to recover the aircraft to level flight and manually held the canopy closed. The pilot then successfully completed a landing at the departure aerodrome without further incident. While there were no injuries, the impact of the event resulted in the deformation of the canopy frame, rendering the canopy unable to be closed properly.
The investigation
The investigation, conducted by the operator's commission, focused on the mechanical failure of the canopy locking system. An examination of the hardware revealed that the tip of the canopy lock handle had broken off. The investigation established that the failure was caused by metal fatigue in the material from which the handle was constructed.
Findings
- The primary cause of the canopy opening was a fatigue crack in the tip of the cockpit lock handle.
- The structural integrity of the locking mechanism was compromised by material fatigue, leading to the detachment of the handle tip.
Safety action
Following the investigation, the following preventive measures were implemented:
- The incident was discussed with other glider pilots present at the airfield at the time of the departure.
- Glider pilots were notified of their obligation to inspect cockpit canopy handles for signs of material fatigue, including cracks, scratches, breaks, or bends.