What happened
On 9 January 2017, a Piper PA46-310P (registration N46U) was preparing for a private flight from Birrfeld Airport (LSZF) to Straubing Wallmühle (EDMS). The flight was intended to begin under visual flight rules before transitioning to instrument flight rules. The weather conditions were cold, with temperatures at -1°C and the runway surface partially covered in snow.
During the takeoff roll on runway 26, the engine initially performed normally. However, as the pilot lifted the nose landing gear at approximately 80 knots, the aircraft experienced a sudden and marked loss of power. The pilot immediately aborted the takeoff, steering the aircraft toward a north-westerly direction to avoid a nearby main road. The aircraft overshot the end of the runway by roughly 40 meters, coming to a stop in a snow-covered meadow. The two occupants sustained minor injuries, and the aircraft suffered a bent nose landing gear fork.
The investigation
Investigators examined the aircraft's Continental TSIO 550Cl4B engine and fuel system. A static engine test performed shortly after the incident showed no mechanical abnormalities, and the engine functioned correctly through its entire operating range. Subsequent inspections of the air filter and engine bay pipes also revealed no issues. The nose landing gear fork was replaced, and follow-up inspections of the engine and fuel system yielded no further faults. The aircraft successfully completed its intended flight to Germany several weeks later.
Laboratory analysis was conducted on fuel samples taken from the fuel filter sump and both wing collector tanks. While the fuel met AVGAS 100LL specifications, the tests revealed significant variations in water content across the different samples.
Findings
- The fuel sample from the left collector tank contained a high water content of 430 mg/kg and approximately 0.5 ml of free water.
- The formation of ice crystals in the fuel system likely restricted the fuel supply to the engine during the takeoff phase.
- The high water content in the fuel, combined with sub-freezing temperatures, allowed ice crystals to form and float within the fuel, potentially causing a temporary blockage in the fuel system.