What happened
On 30 September 2012, a Quik GT450 microlight, registration G-GTEE, was performing a landing approach at Carrickbrack airfield in County Donegal. After a short flight originating from Buncrana, the pilot attempted to land on Runway 26. During the final approach, at an altitude of approximately 350 feet, the pilot heard a loud noise and experienced a sudden loss of control as the wing's structural integrity failed. The aircraft entered a rapid spiral descent and struck a wet agricultural field with significant force. The pilot, who was the sole occupant, sustained serious injuries.
The investigation
The AAIU examined the wreckage and the condition of the aircraft's sail. Investigators found that the sail had split from the starboard trailing edge toward the nose. A failure in the shift cable grommet prevented the structure from limiting the extent of the tear, causing the sail to rip across more than half of its axis. Post-accident testing revealed that both the polyester sailcloth and the aramid reinforcement band had lost sufficient strength to meet required safety standards.
Meteorological data indicated that the flight occurred during blustery conditions, with surface winds gusting between 25 and 30 knots. The investigation also noted that the aircraft's pitch trim was set to 'full fast,' a setting that maximizes control response but also increases the impact of gust loads. Additionally, while the pilot was secured by a lap strap, the shoulder restraint was not in use during the flight.
Findings
- The primary cause of the accident was the in-flight failure of the sail, which led to a significant loss of lift on the starboard side.
- The strength of the sail material had degraded due to prolonged exposure to UV radiation, leaving it unable to withstand operational loads.
- The aircraft was likely operating in wind conditions exceeding the 20-knot limit specified in the operator's manual.
- High gust loads, exacerbated by the 'full fast' pitch trim setting, contributed to the structural failure of the weakened fabric.