What happened
On April 12, 2004, a Jurca MJ-77 "Gnatsum"—a homebuilt replica of the P-51 Mustang—was conducting flight testing near Brienne-le-Château, France. The pilot, who was also the aircraft's builder, was performing a series of test flights to obtain a specific permit for high-powered aircraft. After departing Brienne-le-Château at approximately 10:30 AM, the pilot completed several low-altitude circuits before heading toward Saint-Léger-sous-Brienne.
While flying over a field at an altitude of approximately 500 feet, a witness observed the engine experiencing successive misfires and shutdowns. The aircraft began a left-hand turn and descended toward a forest, passing over power lines at an altitude of roughly 200 feet. The aircraft subsequently struck the ground in a steep nose-down attitude with a left bank. The impact destroyed the aircraft, and the pilot was killed.
The investigation
The investigation focused on the aircraft's fuel state and the flight conditions at the time of the accident. Investigators found that the landing gear was extended at the time of impact and that the aircraft had not struck any obstacles in flight. Although no fire occurred, the wing tanks were ruptured and empty, and the central auxiliary tank was also found to be dry. Only a very small amount of fuel remained in the rear tank.
Records indicated that the aircraft had been refueled three times in the preceding months, with varying amounts of fuel added. However, the exact fuel consumption rate during ground tests or the recent flight tests could not be precisely determined. The investigation also noted that the aircraft's center of gravity was positioned toward the rear and that the aircraft lacked a stall warning device.
Findings
- The primary cause of the accident was inadequate monitoring of fuel consumption, which led to an engine failure due to fuel exhaustion.
- The pilot's decision to operate at low altitudes significantly reduced the margin of maneuver for an emergency landing or parachute deployment.
- The aircraft's lack of a stall warning device may have contributed to the loss of control during the turn.
- The pilot's tendency to fly at low altitudes, combined with the aircraft's low glide ratio, left little opportunity for recovery once the engine failed.