B757 CREW HAD AN ENG FAILURE.

Narrative

PROB AROSE AT CRUISE; FL350; LIGHT ICING/LIGHT TURB ASSOCIATED WITH CUMULO NIMBUS. L ENG INDICATED N1 VIBRATIONS IN 'AMBER' RANGE; APPROX 3.8. INITIAL INDICATION WAS VIA EICAS. CAPT REDUCED L THROTTLE TO IDLE; N1 VIBES REDUCED TO NORMAL RANGE. INCREASED PWR TO CRUISE N1; VIBRATIONS INCREASED TO 5.0 (STILL IN 'AMBER' RANGE). ADVANCED THROTTLES TO CLB PWR (IN ATTEMPT TO CLB ABOVE ICE/TURB); N1 VIBRATION STAYED AT 5.0 AND L ENG EXPERIENCED 2 SIGNIFICANT (ROLLED/YAWED ACFT) COMPRESSOR STALLS. ALSO PLTS DETECTED AN ODOR SIMILAR TO BURNING ELECTRICAL INSULATION. CAPT ELECTED TO PERFORM PRECAUTIONARY ENG SHUTDOWN USING ENG FAILURE/SHUTDOWN CHKLIST AND DIVERT TO MSP (NEAREST SUITABLE FIELD). LNDG/RECOVERY ROUTING; UNEVENTFUL. HUMAN FACTORS: CREW ATTRIBUTED VIBRATIONS TO ICING CONDITIONS UNTIL 'ELECTRICAL SMOKE' ODOR AND COMPRESSOR STALLS CONVINCED PLTS TO SHUT DOWN ENG. MAY HAVE BEEN A TENDENCY TO DENY ANY MECHANICAL PROB EXISTED. CREW ALSO RATIONALIZED THAT 'ELECTRICAL SMOKE' ODOR WAS ASSOCIATED WITH OZONE AND ST ELMO'S FIRE ACTIVITY. FIXATION ON METEOROLOGICAL CONDITIONS PROBABLY WORKED AGAINST ULTIMATE DECISION TO SHUT DOWN ENG. EMER PROCS; RECENTLY PRACTICED IN SINGLE VISIT TRAINING SIMULATOR SESSION; RAN FLAWLESSLY. FLT ATTENDANTS PERFORMED PROFESSIONALLY.