What happened
On July 20, 2016, a Nicollier HN700 microlight, identified as 46-DX, departed from the private Lacave airfield in France for a private flight. Shortly after takeoff from runway 31, witnesses reported hearing the engine sputter. The aircraft failed to maintain altitude and eventually struck the ground in a cleared area approximately 350 meters to the left of the runway end. The impact was characterized by a high nose-down attitude and a significant vertical descent rate. The pilot was killed, and the aircraft was destroyed.
The investigation
Investigators examined the wreckage and the airfield environment. The investigation noted that the pilot had not flown the aircraft for approximately four years and had recently been performing maintenance work on the engine. Meteorological conditions at the time included a 10-knot wind from 2/40 and CAVOK visibility.
Technical analysis of the engine revealed that while the engine block and fuel, lubrication, and cooling systems were intact, the propeller had stopped before impact. On this engine type, even during a power loss, the propeller should continue to rotate due to the relative wind. Furthermore, investigators identified a significant electrical defect: the crimping of the magneto capacitor terminal featured an excessively large exposed wire area. This defect could have caused the ignition system to fail if the exposed wire contacted the magneto casing. Additionally, a previously noted error in the fuel level transmitter installation was discovered, which could have caused the pilot to misinterpret fuel readings.
Findings
- The engine suffered a power loss during the initial climb.
- An electrical fault in the ignition system likely caused the engine to stop.
- During the attempt to reach a clear landing area, the pilot failed to maintain the minimum flying speed, leading to an aerodynamic stall.
- The pilot's lack of recent flight experience contributed to the inability to manage the engine failure effectively during the critical takeoff phase.