N375HA accident at Seattle, WA

The loss of control of the left-hand engine and the subsequent thermal damage to the left wing on landing during engine reverse operation was due to a blockage of the variable stator vane torque motor filter that resulted in the engine’s electronic engine control to improper schedule maximum fuel flow resulting in flames out the engine’s exhaust tailpipe that impinged the wing. Contributing to the event were: - The presence of water containing dissolved aluminum sulfate (alum) in the airplane fuel system that initiated a sudden blockage of the engine VSV TM SP filter. - The maintenance provider omitted to sump the fuel tanks during the 10-day period of inactivity of the airplane. - While the engine was in an internally stalled condition during the reverse and post-reverse thrust operation, the electronic engine control logic allowed the fuel metering unit to supply maximum fuel flow despite the throttle at idle speed.