What happened
On May 11, 2018, at approximately 19:30, a Rutan VariEze, registration F-PRIQ, departed from Nancy-Essey aerodrome for a local flight. The aircraft was occupied by a pilot and one passenger. Shortly after takeoff, while the aircraft was in a crosswind component, a section of the right wing extremity—including the vertical stabilizer and right rudder—separated from the airframe. This structural failure caused the aircraft to enter an immediate spin. The aircraft struck the ground approximately four kilometers from the runway end, followed by a post-impact fire that destroyed the wreckage. The accident resulted in two fatalities.
The investigation
The BEA examined the wreckage and identified that most damage was consistent with the ground impact and subsequent fire, with the exception of the right wing extremity, which was found in two separate pieces near the main wreckage. Laboratory testing revealed that the expanded polystyrene (Styrofoam) foam used as the internal structural core of the wing had undergone significant degradation. This degradation was found to be consistent with exposure to AVGAS 100 LL fuel.
The investigation also reviewed the aircraft's maintenance history and regulatory framework. The aircraft operated under a restricted certificate (CNRA). While the owners had performed periodic inspections for certificate renewal, these inspections did not involve disassembly. Furthermore, the maintenance program used by the owners did not include specific "tapping" techniques to check for internal foam integrity, despite historical warnings from the original designer regarding fuel-related foam decay.