What was found
ON DESCENT INTO BIL NR 1 PEC CAUTION ILLUMINATED AND POWERPLANT MESSAGE APPEARED ON ED. NP WAS 1060. PERFORMED PRECAUTIONARY SHUTDOWN. F/O HAD 18% TORQUE ON BOTH ENGINES AND HAD JUST REDUCED POWER TO FLIGHT IDLE WHEN CAUTION LIGHT ILLUMINATED. ALL INDICATIONS HAPPENED SIMULTANEOUSLY. CONDITION LEVERS WERE AT MIN 850. UNABLE TO REDUCE PROP RPM WITH REDUCTION IN POWER LEVER. (ALREADY AT FLIGHT IDLE). LANDING UNEVENTFUL. IDENTIFIED NR 1 PROPELLER BUSS BAR (1EA) BROKEN. REPLACED DAMAGED BUSS BAR IAW AMM TASK 61-10-06-000-804 AND 61-10-06-400-804. VARIFIED INTEGRITY OF NR 1 DUAL PULSE PROBE (MPU) ASSY IAW AMM TASK 61-20-06-760-801 - CHECKED GOOD. PERFORMED T/C 6710007 PROPELLER / PEC INSTALLATION RUNS AND T/C 6710005 ENGINE POWER ASSURANCE CHECK (NR 2). ALL OPS CHECK GOOD. OVERSPEED CONDITION WITHIN LIMITS IAW AMM TASK 05-11-00-992-802. RETURNED TO SERVICE.