Engine Icing To Blame?
In its news release, the NTSB says an FAA engine icing specialist notes that thunderstorms blow a lot of ice crystals into the upper-airway altitudes. Pratt and Whitney did a study on the phenomenon and discovered that if pilots don't turn on the engine anti-icing gear when this is going on, ice can build up on the front inner compressor stator and cause a surge and/or a flameout. The NTSB wants the FAA to make sure pilots are aware of the potential problem and what to do to avoid it. The board is urgently recommending the FAA require that engine icing systems be activated whenever aircraft are operating at high altitude near convective activity or when there's visible moisture in the air. It's also suggesting that pilots be warned of the danger and that work begin on engine ice detector systems.