What was found
INSPECTION TYPE:N/A DIVERSION - AT FL300 THE C HYD QTY MESSAGE CAME ON EICAS. CENTER QUANTITY WAS AT 0 .48 AND DROPPING. DURING DIVERT TO KBIL QUANTITY AT 0.14 WE EXTENDED THE LANDING GEAR NORMALLY. WHEN FLAPS "ONE" WAS SELECTED, CENTER HYD PRESS WAS LOST, CREW DECLARED AN EMERGENCY.T/S AND FOUND RT STAB TRIM CONTROL MODULE LEAKING AT CONTROL AND ARMING VALVE ASSY RETAINER . REPLACED O-RING ON VALVE ASSY RETAINER. SERVICED CENTER HYD. SYSTEM TO FULL. PERFORMED LEAK CK. OPS AND LEAK CHECK GOOD MM 27-41-00-715-014