What happened
On June 9, 1999, at 18:25, a Cessna TU 206 G Turbo, registration OO-MCP, was conducting a parachute jump flight near Bastia Airport. While climbing to 9,000 feet and executing a right-hand turn, the pilot noticed a decrease in engine RPM. Despite attempts to increase power via the throttle, the engine power continued to decline.
The pilot notified the control tower and descended to 5,000 feet to release the five passengers. The aircraft subsequently landed on runway 34 with the engine at idle. During the taxiing phase, the engine eventually stopped.
Upon inspection on the ground, fuel levels were found to be unevenly distributed: 35 liters remained in the left tank and 62 liters in the right tank. After verifying the fuel system and partially refilling the tanks with the remaining fuel, the engine was restarted and functioned normally.
The investigation
The investigation focused on the fuel delivery system and the pilot's fuel management. The pilot reported that the left tank had been selected for takeoff. However, when the power loss occurred during the turn, the pilot had not switched to the right tank.
Investigators reviewed the aircraft's flight manual, which contains a specific warning regarding fuel starvation. The manual notes that while the fuel system is designed to minimize unusable fuel, engine failure can occur if fuel levels are at or below one-quarter capacity during prolonged uncoordinated flight (such as slips or skids), which can uncover the fuel pickups.
Findings
- The pilot was performing a right-hand turn when the power loss occurred.
- The low level of fuel in the left tank caused the fuel to be displaced toward the wingtip during the maneuver.
- This movement caused the fuel pump to lose prime, leading to the engine power loss.
- The pilot failed to switch to the alternative fuel source during the period of power degradation.