What was found
(CAN) IN FLIGHT SHUTDOWN OF THE NR 1 ENGINE DUE TO AN OVERSPEED, PAN-PAN DECLARED. THE CREW REPORTED THEY WERE APPROX FL140 WHEN THEY RECEIVED THE NR 1 PEC CAUTION LIGHT WITH NR 1 PROPELLER SPEED INCREASED ABOVE 1020 RPM (RECORDED EXCEEDENCE WAS 1081 RPM OR 105.9 PERCENT), QRH SHUTDOWN WAS ACTIONED. THE F/O LANDED ACFT WITHOUT INCIDENT. ENGINEERING CONFIRMED THAT ACFT HAS NOW RETURNED TO SERVICE. THE NR1 ENGINE MPU WAS REPLACED DUE TO PINS A AND B WERE FOUND TO BE BREAKING DOWN TO THE CONNECTOR BACKSHELL IAW AMM 61-20-06-760-801 ITEM 3.