What was found
DURING DESCENT REDUCED POWER LEVERS TO IDLE, RT ENG WOULD NOT DECREASE BELOW 80 PERCENT N1, 500 PDS TORQUE, NORMAL SETTINGS 63 PERCENT & 100 PDS. INFORMED TOWER THAT WE HAD AN ENG ABNORMALITY & MAY NEED TO SHUT DOWN ON THE RUNWAY BUT DIDN'T NEED OTHER ASSISTANCE. PILOT FEATHERED RT PROP, LANDED WITH NO ISSUES & TAXIED BACK TO RAMP. WE BOARDED THE ACFT & HAD THE PILOT RUN THE ENG UP & WITNESSED THE SAME ISSUE WAS STILL PRESENT BUT N1 HAD DECREASED TO 70 PERCENT N1. THE ACFT WAS SHUT DOWN & WE INSPECTED THE FUEL CONTROL LINKAGE & COULD NOT FIND ANY ISSUES WITH THE LINKAGE OR RIGGING. WE STARTED & RAN THE ACFT AGAIN ON THE RAMP & THE RT ENG WAS OPERATING NORMALLY WITH NO ISSUES. CALLED THE FUEL CONTROL OVERHAUL SHOP & CAME TO THE CONCLUSION THAT IT WAS A DECELERATION ISSUE & REPLACED THE FUEL CONTROL WITH AN OVERHAULED FUEL CONTROL. WE WILL SEND THIS FUEL CONTROL IN FOR EVALUATION TO TRY & DETERMINE THE CAUSE.