What happened
On July 19, 2014, a Jodel D113V, registration F-PACK, was conducting a flight training session involving tailwheel (TW) maneuvers. The flight began at Les Mureaux aerodrome, proceeding to Chavenay for circuit training, and finally to Saint-Cyr aerodrome for takeoff-and-landing exercises.
Following a landing on runway 29L, the student pilot applied full power for a subsequent takeoff. During the initial climb, at an estimated altitude of 500 feet, the engine experienced misfires before spontaneously restarting and then losing all power. The instructor took control of the aircraft and performed a forced landing in a wheat field approximately 2 km from the runway, aligned with the runway axis. During the landing roll, the left landing gear collapsed, resulting in heavy damage to the aircraft.
The investigation
The investigation focused on the cause of the engine power loss. Investigators ruled out carburetor icing, as the ambient temperature was 25°C and the engine functioned normally during ground tests following the accident. Fuel availability was also confirmed, as the aircraft had approximately 30 liters of fuel remaining and the engine was successfully restarted on the ground by a mechanic.
Investigators examined the fuel system, noting that the aircraft was operating using only the main fuel tank. While the fuel selector position was verified and unlikely to have been moved accidentally, the investigation looked into the fuel delivery lines. It was noted that the fuel supply lines passed over the engine without significant thermal insulation.
Findings
- The exact cause of the power loss could not be definitively determined.
- A vapor lock phenomenon was identified as a possible contributing factor, as the uninsulated fuel lines passing over the engine could have caused fuel to vaporize, potentially interrupting the flow from the mechanical or electric pumps.
- The instructor's decision to land in the field aligned with the runway axis, rather than attempting a 180-degree turn, prevented injuries to the occupants.