What was found
APPROX 1 HR INTO FLIGHT AT FL290, NOTICED NR 3 ENG OIL QTY INDICATING 0. INITIALLY OIL PRESS & TEMP MATCHED THE OTHER TWO ENGS. OVER NEXT 45 MINUTES, OIL PRESS DROPPED TO 15 PSI, PERFORMED PRECAUTIONARY SHUTDOWN. INSPECTED NR 3 ENG, LOWER HALF OF THRUST REVERSER COWLING IS WET. OPENED FAN COWL & THRUST REVERSER COWL IAW AMM71-10-00-2 FOUND OIL PRESS TRANSMITTER HAS CRACK. REPLACED NR 3 ENG OIL TRANSMITTER IAW MM 79-33-01-4-1 & SERVICED ENG OIL FOR PROPER LEVEL IAW MM 12-12-01-3-1. RAN NR 3 ENG & COMPLIED WITH WIND MILLING INSPECTION IAW MM 71-00-00-5-1 & ALSO 80% N2 ABOUT 5 MINUTES, FOUND NO OIL LEAK FROM AROUND OF OIL TRANSMITTER IAW JRH. ACFT OK FOR SERVICE.