What happened
On the evening of January 23, 2000, a Synairgie Skyranger ultralight, identified as 68ADW, was performing a local flight from the Châtelleredault Targé airfield. Shortly after takeoff, while the aircraft was in a climbing attitude at an altitude of approximately 60 meters, the engine suddenly ceased operation. Witnesses observed the aircraft banking to the left and pitching down before impacting the ground approximately 100 meters to the left of the runway threshold. The impact destroyed the aircraft and resulted in two fatalities, involving the pilot and one passenger.
The investigation
Investigators examined the wreckage and the engine, a Rotax 582 DCDI. While the cylinders showed no signs of seizure, endoscopic examination revealed traces of water within the rear cylinder. The propeller and cone showed that the engine was not producing power at the moment of impact.
An inspection of the fuel system revealed a significant amount of water within the fuel tank. The investigation focused on the fuel tank's venting system and the aircraft's storage conditions. It was noted that the aircraft had been stored for two and a half months in a hangar with a leaking roof. Furthermore, the vent cap, designed to prevent water ingress, had not been reinstalled during a recent maintenance operation. The fuel tank cap support had also been modified with two holes to drain stagnant water, which inadvertently allowed moisture to enter the tank.
Findings
- The primary cause of the engine failure was fuel contamination by water.
- The water entered the fuel tank through the large-diameter vent hole because the protective device had not been replaced following maintenance.
- The aircraft's storage in a poorly maintained hangar with a leaking roof contributed to the accumulation of moisture.
- Due to the specific geometry of the fuel tank and the location of the fuel outlet, the water remained at the bottom of the tank and did not manifest during ground testing, only reaching the engine during the high pitch angle of the climb.