What happened
On July 20, 1964, a Jodel DR-1051, registered as HB-EBZ, was preparing for a VFR flight from Bordeaux-Mérignac to Arcachon. The aircraft, operated by Aéro-club de Genève, was cleared for takeoff from runway 05 at 16:26 TU. After takeoff, the pilot requested a right turn to establish a direct heading toward the destination.
As the aircraft reached an altitude of approximately 30 meters while initiating the right turn, the engine suddenly ceased operation. To maintain airspeed and prevent a stall, the pilot leveled the aircraft and entered a dive, turning left to return to the runway. The aircraft struck the runway surface approximately 200 meters from the end of the strip. The impact caused the aircraft to veer and undergo a ground loop, eventually coming to a halt near the left edge of the runway. There were no fatalities or injuries among the pilot or the two passengers, but the aircraft sustained significant damage to the landing gear and the right wing.
The investigation
The investigation focused on the sudden loss of power and the subsequent sequence of maneuvers. Investigators examined the engine's performance and the environmental conditions prior to departure. It was noted that the aircraft had been parked on a concrete apron for over an hour in high temperatures, with ambient temperatures reaching 31°C.
Before takeoff, the pilot encountered difficulties starting the engine with the starter; after 30 minutes of attempts, the engine had to be hand-started. Following the restart, the aircraft remained at idle for five minutes immediately before the takeoff roll. Post-accident inspections of the engine showed that while it initially failed to start via the starter, it could be restarted by hand and functioned normally during subsequent testing by experts.
Findings
- The direct cause of the accident was an engine failure during the takeoff climb.
- The loss of power was likely caused by fuel vapor lock (gasification of fuel) occurring between the carburetor and the forward fuel tank, a phenomenon exacerbated by the aircraft sitting on hot concrete.
- The severity of the structural damage was contributed to by the pilot's aggressive recovery maneuver; the high-sink-rate impact with the runway caused the landing gear to collapse and triggered the ground loop that damaged the right wing.