What was found
ON APPROACH MAX NP WENT TO 114% ON LT ENGINE. NP WAS 114% TO 95% ALL THE WAY DOWN THE APPROACH. ON LANDING, LT ENGINE NP WENT TO 21% & STAYED THAT WAY TO THE GATE. NO CONTROL ISSUES. RAN QRH. AT NO TIME DID IT FEEL LIKE THE PROP FEATHERED. AT NO TIME DID THE NP STABILIZE UNTIL AFTER LANDING. FLT#5452 REPLACED LT ENGINE PCU IAW AMM, PN 782490-46, SN ON 980711, SN OFF 920763.