What was found
AFTER T/O, NR 2 ENG OIL TEMP RISING, WENT THRU CHECKLIST. CLOSED BYPASS DOORS. TEMP ABOVE 107 DEGREES ABOUT 20 MINS & ABOVE 115 DEGREES ABOUT 10 MINS, PEAKED AT 122 DEGREES, STARTED COOLING AGAIN. ON DESCENT BACK, BY LANDING, TEMP NORMAL. MX CKD CDS, OIL TEMP IN AREA B IAW Q400 TASK 05-53-00-210-814. INSPECTION OF ENG IAW SUBTASK 05-53-080-002. NO DEBRIS FOUND IN FILLERS. PERFORMED FIY TASK FOR HIGH OIL TEMP OPS IAW 79-00-00-810-805. DETERMINED OIL COOLER DOOR ACT FAILED. REPLACED ACT IAW 79-21-31-000-801 & 79-21-31-400-801. OPS CHK OF DOOR ACT GOOD AND LEAK CHECK OF FILTERS GOOD. REPLACED NR 1 ENG OIL COOLER BYPASS VLV IAW 79-22-01-000-801 & 79-22-01-401-801. OPS & LEAK CHK GOOD. OIL TEMP NORMAL. A/C RTS.