A BAE3100 IN CRUISE AT 9000 FT DECLARED AN EMER AND DIVERTED DUE TO LOSS OF ENG CTL CAUSED BY A FAILED ENG TORQUE TRANSDUCER.

Narrative

APPROX 35 MINS INTO THE FLT AFTER LEVELING OFF AT OUR CRUISING ALT AND SETTING CRUISE PWR; WE BEGAN TO EXPERIENCE PROBS WITH THE L ENG. THE L ENG BEGAN A SLOW ACCELERATION TO 100% TORQUE AND 100% RPM. I REDUCED THE PWR LEVER FOR THE ENG. THIS SEEMED TO RELIEVE THE PROB. AFTER AN ADDITIONAL 5 MINS THE ENG AGAIN ACCELERATED TO 100% TORQUE AND 100% RPM. AT THIS TIME WE DECIDED TO RETURN TO REPUBLIC ARPT AND REQUESTED VECTORS TO REPUBLIC. OUR L ENG PWR LEVER WAS AT FLT IDLE YET WE WERE STILL GETTING 100% PWR. DUE TO WX CONSIDERATIONS; I DECIDED TO MATCH THE PWR AND CONTINUED TO OBSERVE THE L ENG WHILE RETURNING TO REPUBLIC ARPT. WHEN WE WERE WITHIN 10 NM OF REPUBLIC ARPT; I REQUESTED THAT THE EQUIP BE IN PLACE IN THE EVENT WE WOULD NEED ASSISTANCE. SHORTLY AFTER REQUESTING THE EQUIP BE CALLED; THE OIL PRESSURE ON THE L ENG BEGAN TO FLUCTUATE AND I OBSERVED THE GOVERNOR'S CTLING THE PWR ON THE L ENG AS PWR AND OIL PRESSURE BEGAN TO RISE AND FALL. AT THIS TIME; I DECIDED THAT ONCE ESTABLISHED ON THE ILS TO RWY 14 WE WOULD PERFORM A PRECAUTIONARY SHUTDOWN AS I COULD NO LONGER PREDICT THE PWR SETTINGS FOR THE L ENG. WE CONTINUED THE ILS TO RWY 14 WITH NO INCIDENT AND PERFORMED A NORMAL SINGLE ENG LNDG. AT NO TIME WERE MY PAX ALARMED OR CONCERNED FOR THEIR SAFETY. WE LATER CHANGED ACFT TO ABC AND CONTINUED THE CHARTER FLT. AT NO TIME DID I CONSIDER THE FLT TO BE IN SIGNIFICANT DANGER AS TO REQUIRE AN IMMEDIATE LNDG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE LOSS OF ENG CTL WAS A FAILED ENG TORQUE TRANSDUCER. THE RPTR SAID MAINT WAS ABLE TO PROVE THE FIX WITH AN ENG RUN AFTER THE TRANSDUCER WAS REPLACED.