THE ANTI-ICE AIR VALVE LIGHT ILLUMINATED ON AN SF34 DURING A CLB IN ICING CONDITIONS. WHEN THE FLC FOLLOWED ABNORMAL CHKLIST PROCS AND THEY REDUCED PWR; THEY NOTICED A PWR INTERRUPTION. THE ACFT WAS DSNDED OUT OF ICING CONDITIONS AND WHEN THE CREW ADDED PWR TO THE R ENG; THE OIL PRESSURE LIGHT CAME ON AND THE CREW FOLLOWED PROCS FOR AN ENG FAILURE. AN EMER WAS DECLARED AND THE FLT WAS DIVERTED.

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WE WERE ENRTE FROM BOS TO ROC ON A STEP-UP CLB. BEFORE ENTERING THE CLOUD LAYER WE TURNED ON THE ENG ANTI-ICE. SHORTLY AFTERWARDS THE R ANTI-ICE AIR VALVE LIGHT CAME ON. WE FOLLOWED THE ABNORMAL CHKLIST. FIRST WE RESET THE SWITCH WHICH DID NOT CORRECT THE PROB. THE CHKLIST THEN CALLS FOR A PWR REDUCTION TO A SPECIFIED ENG RPM; WHICH WE DID. WE THEN GOT A PWR INTERRUPTION (ROLLBACK) AND WE REQUESTED (FROM ATC) THE TOPS OF THE CLOUDS. AT THIS POINT WE HOPED TO CLB OUT OF THE ICING CONDITIONS. WE THEN GOT ANOTHER ROLLBACK AND REQUESTED A DSCNT TO CLR THE ICING CONDITIONS. WE DSNDED AND GOT CLR OF THE CLOUDS; THEN WE ADDED PWR TO THE R ENG. THE OIL PRESSURE LIGHT CAME ON; AND WE CONFIRMED THAT THE R ENG HAD FAILED;AND NOT RELIT. WE USED THE EMER ENG FAILURE CHKLIST AND THE ABNORMAL ONE ENG INOP CHKLIST; SECURED THE ENG; DECLARED AN EMER WITH MHT APCH; AND REQUESTED AN IMMEDIATE LNDG ON RWY 35 AT MANCHESTER. WE LANDED SUCCESSFULLY WITH NO FURTHER PROBS. I BELIEVE THAT THE ENG ANTI-ICE SYS ON THE SAAB 350 (GE) NEEDS IMPROVEMENT. ROLLBACKS ARE A TOO COMMON OCCURRENCE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS RPTR GLANCED AT THE FLT DATA RECORDER INFO WHEN IT WAS FIRST PULLED; AND THE PROB APPEARS TO INVOLVE A COMBINATION OF A STUCK P3 AIR VALVE; AND THE MALFUNCTION OF THE AUTOCOARSEN AND ANTI-ICE SYS. THE RPTR BELIEVES THAT THE AUTOCOARSEN SWITCH WAS NOT ARMED; BUT THERE IS EVIDENCE THAT THE PROP WAS FEATHERING WHEN THE FLC SHUT DOWN THE ENG. ALL OF THE PARAMETERS; EXCEPT SWITCH POS; FOR AUTOCOARSEN WERE MET WHEN THE FLC REDUCED PWR ACCORDING TO THE ABNORMAL CHKLIST PROCS FOR THE ILLUMINATION OF THE ANTI-ICE AIR VALVE LIGHT. THE AUTOCOARSEN SYS'S PARAMETERS INCLUDE ONE TORQUE ABOVE 50%; ONE TORQUE BELOW 50%; ONE P3 ABOVE 120; ONE P3 BELOW 120; AND BOTH PWR LEVER QUADRANT SWITCHES ABOVE 64%. REGARDLESS OF THE FINAL ANALYSIS OF THIS FLC'S EXPERIENCE; THIS RPTR DOES NOT FEEL COMFORTABLE WITH THE OVERLAP OF THE AUTOCOARSEN PARAMETERS AND THE ABNORMAL CHKLIST ANTI-ICE AIR VALVE PROCS. THE OUTCOME OF THIS COMBINATION OF THE ARMED AUTOCOARSEN SYS AND REDUCED PWR DURING A NON PRECISION APCH COULD SET A CREW UP FOR A LIKE EXPERIENCE CLOSE TO THE GND. FURTHER COMPLICATING FLC RESPONSE IS THE FACT THAT ONLY ONE ANNUNCIATOR ILLUMINATES FOR BOTH ENG OIL PRESSURE AND PROP OIL PRESSURE -- RPTR FEELS THAT THIS REQUIRES EXCESSIVE ATTN IN A CRITICAL SIT. SUPPLEMENTAL INFO FROM ACN 348349: ONCE LEAVING ICING CONDITIONS; (VISIBLE MOISTURE; OAT +10 DEGS C AND BELOW) I REINTRODUCED PWR TO THE R ENG. AT APPROX 60% TORQUE; THE R ENG FAILED. WE SECURED THE ENG USING THE ENG FAILURE CHKLIST. WE DECLARED AN EMER AND LANDED UNEVENTFULLY AT MHT ARPT. AFTER RUNNING UP THE ENG WITH A MECH; MR. X; ITT WAS OBSERVED (790 ITT). AFTER HE DID ADDITIONAL WORK WE RAN UP AGAIN WITH NORMAL INDICATIONS. WE THEN FERRIED ACFT TO PSM FOR MAINT. THIS ACFT HAD HAD A HISTORY OF PROBS IN THIS AREA WITH BOTH AIRFRAME AND ENG ICING EVENTS. I HAVE PERSONALLY BEEN INVOLVED WITH AN AIRFRAME ICING EVENT WITH THIS ACFT AND FILED A RPT IN THE PAST. IT IS MY BELIEF THAT A REVIEW OF THE ICING CERTIFICATION IS IN ORDER!