What was found
DEN - FLT 780 - FLIGHT CREW REPORTED NR 1 ENGINE WAS SHUT DOWN DUE TO LOW OIL QTY AND AN EMERGENCY WAS DECLARED. MAINTENANCE REPLACED O-RING ON FUEL CARBON SEAL IN STL. DURING FLT NR 217 STL TO DEN, NR 1 ENGINE OIL QTY DECREASED AND AIRCRAFT DIVERTED TO MCI AS PRECAUTIONARY MAINTENANCE. REPLACED NR 1 ENGINE N2 GEARBOX, PERFORMED A TEST FLT AND SYSTEM CHECKED OK. (M)