What happened
On August 28, 2004, a Nicollier HN 700 "Ménestrel 2" ultralight aircraft, registered F-PDMC, departed from the Loupiac microlight airfield for a local flight toward Lacave. Shortly after takeoff, the aircraft's Limbach L 2000 E engine lost power and subsequently stopped.
Upon realizing the engine failure, the pilot attempted to restart the engine after reopening the forward fuel tank valve. These efforts were unsuccessful, forcing the pilot to perform an emergency landing in the surrounding countryside. During the descent, the left wing struck a tree located at the edge of a wooded area approximately two kilometers from the runway. The impact caused the aircraft to pitch forward and strike the ground at an angle of roughly sixty degrees. The pilot sustained injuries, and the aircraft was destroyed.
The investigation
The investigation focused on the sequence of events leading to the engine shutdown and the pilot's actions during the pre-flight phase. Investigators examined the fuel system configuration and the functionality of the cockpit instrumentation. It was noted that the fuel gauge for the forward tank provided inverted readings—indicating "empty" when full and vice versa—likely due to an electrical polarity reversal. While this error was present, the pilot, who was the sole operator of the aircraft, was accustomed to this malfunction and did not attribute the accident to the gauge.
Findings
- The primary cause of the engine failure was that the pilot closed the forward fuel tank valve prior to takeoff.
- The pilot was distracted while performing the pre-flight checklist, leading to the mechanical error.
- The engine failure occurred during the initial climb phase of the flight.