Final Report: Ice crystals caused Beechjet engine flameouts
Hawker Beechcraft Beechjet 400A, Norfolk, Va., June 14, 2006–The NTSB said the probable cause of the dual engine flameout was the accretion of high-altitude ice crystals on the compressor vanes and their ingestion into the engine high-pressure compressor when the pilots pulled back the power levers. This caused compressor surges and the flameouts of both engines. Contributing factors were the lack of training on the hazards of high-altitude ice crystals to gas turbine engines and guidance to the pilots to activate the engine anti-ice system in conditions where high-altitude ice crystals might exist.
The Beechjet was at FL380 when the engines flamed out. The pilots stated that they maintained FL380 until the airplane had slowed to 180 knots before they began to descend. During the descent, they maintained between 220 to 250 knots, with both engines showing rotation. The pilots stated that the left engine restarted on its own at about FL300 and the right engine started on its own at about FL240.