What happened
On September 17, 1996, a privately owned Rutan Long-Ez, registration N-17VN, was conducting a VFR flight from Ibiza, Spain, to Deventer, Netherlands. The pilot, flying solo, progressed along the coast of the Gulf of Lion, maintaining contact with approach controllers in Perpignan and Montpellier. During the flight, the pilot requested and received clearance to descend and climb between flight levels 75 and 95, confirming favorable VMC conditions.
At 11:15 UTC, the pilot's last communication was established with Montpellier approach. Shortly thereafter, at 11:30 UTC, the aircraft's radar echo suddenly disappeared while at an altitude of approximately 9,600 feet. No distress signal was transmitted. Following the loss of contact, search operations were initiated, and the wreckage was located at 17:40 UTC on the flank of a hill near Romiguières. The pilot was killed in the impact.
The investigation
The investigation focused on the wreckage distribution and the structural integrity of the airframe. The aircraft was found inverted, with the fuselage largely intact but the cockpit area destroyed. While the engine and propeller remained attached, the left wing was found to be severely fragmented. Large sections of the left wing, including the winglet and parts of the aileron, were recovered at distances of up to 1 km from the main wreckage.
Laboratory analysis of the left aileron control linkages revealed critical damage. Microscopic examination of four rod ends showed traces of molten metal and discoloration, indicating extreme heating. Furthermore, investigators found evidence of burnt foam within the left wing spar and several electrical arcs throughout the left wing structure. Because the aircraft's onboard electrical system was insufficient to cause such damage, investigators looked toward external atmospheric phenomena.
Findings
- The aircraft encountered rapidly deteriorating weather conditions characterized by intense thunderstorm activity and heavy rainfall.
- Satellite imagery confirmed the presence of massive cumulonimbus clouds with tops reaching 36,000 feet directly over the accident area.
- Lightning strikes were recorded in the immediate vicinity of the accident site during the timeframe of the disappearance.
- The primary cause of the accident was the in-flight disintegration of the left wing, likely triggered by a lightning strike.
- The extreme energy from the strike caused the left aileron control components to overheat and fail, potentially leading to structural failure through either an explosive effect on the composite structure or subsequent aeroelastic flutter.