LJ40 SUFFERS FAILURE OF LEFT ENGINE. DIVERTS TO NEAREST SUITABLE ARPT.

Narrative

DEPARTED FOR A FLT TO SYR. TKOF AND CLB PHASE OF FLT WERE NORMAL. WX WAS CLR WITH FEW CLOUD BUILD-UPS; NO TURB ENCOUNTERED. LEVELOFF AT FL410 WAS NORMAL; CRUISE CHKLIST COMPLETED; AND TREND MONITORING WAS COMPLETED. CRUISE PWR WAS SET AT 795 ITT AND NORMAL CREW MONITORING OF FLT CONTINUED. AT 1 HR INTO FLT A VERY NOTICEABLE (SUDDEN) SOUND CHANGE STARTED. A QUICK WALK TO REAR LAVATORY SECTION OF ACFT CONFIRMED SOUND APPEARED TO BE LOCATED IN TAIL AREA OF ACFT. MOVEMENT OF L AND R THRUST LEVERS CONFIRMED NOISE WAS ENG INDUCED AND IDENTED AS THE L (#1) ENG. A TIME SPAN OF ABOUT 5 MINS FROM WHEN NOISE STARTED; A NOTICEABLE ITT FLUCTUATION STARTED CAUSED BOTH AN INCREASE AND DECREASE; BUT MANLY A DECREASE IN ITT. A FLT LEVEL CHANGE WAS REQUESTED FROM FL410 TO FL310; AND PREPARATION WAS BEGUN FOR DIVERTING TO AN ALTERNATE ARPT; AND PRECAUTIONARY INFLT SHUTDOWN OF THE #1 ENG. WHEN PWR WAS REDUCED ON BOTH ENGS FOR START OF DSCNT; L ENG STABILIZED TO NORMAL INDICATION; SAME AS ENG #2. ENG NOISE FROM #1 ENG REDUCED TO A LEVEL THAT WAS NOT HEARD. DSCNT RATE WAS SET AT 1500 FPM; ALL INDICATIONS OF ENG NOW NORMAL. DSNDING AND PASSING FL370; L (#1) ENG ITT AGAIN BEGAN TO SWING; INCREASE TO DECREASE; BUT MORE TO DECREASE WHICH LASTED ABOUT 5-10 SECONDS; AT WHICH TIME ENG BEGAN TO ROLL BACK TO SHUTDOWN CONDITION. CTR WAS INFORMED OF THE PROB WE HAD AND AN EMER WAS DECLARED. VECTORS WERE GIVEN FOR ZZZ. FLT CREW PERFORMED CHKLIST AS APPROPRIATE FROM THE QRH; AND PREPARED THE ACFT FOR LNDG. LNDG WAS MADE ON RWY 5L AND WAS UNEVENTFUL. ACFT WAS TAXIED TO THE RAMP; INITIAL INSPECTION BY FLT CREW SHOWED NOTHING ABNORMAL AND NO OTHER INFO IS AVAILABLE AT THIS TIME.