NTSB Probable Cause

PARTIAL FAILURE OF THE LEFT ENGINE FUEL PUMP, WHICH RESULTED IN A PARTIAL LOSS OF POWER IN THE LEFT ENGINE, BUT NOT ENOUGH OF A POWER LOSS TO TRIGGER AND/OR COMPLETE THE AUTOFEATHERING OPERATION OF THE LEFT PROPELLER, THUS ALLOWING INSUFFICIENT TIME FOR THE CREW TO MANUALLY FEATHER THE PROPELLER OR ATTAIN VMC (FOR THE AIRCRAFT CONFIGURED WITH AN UNFEATHERED PROPELLER).