What was found
AFTER ENG START C HYD QTY EICAS ILLUMINATED AND THE HYD QTY DECREASED TO .11 ON CENTER SYSTEM. AIRCRAFT BACK TO BLOCK AND GROUNDED BY MAINTENANCE. MAINTENANCE FOUND #10 SPOILER PCA FILTER HOUSING O-RING BLOWN, REMOVED AND REPLACED FILTER HOUSING O-RINGS IAW B767 AMM 27-61-02-434-060. LEAK CHECK GOOD CODE 600-4-D OPS CHECKS GOOD CENTER HYD SERVICED TO FULL IAW B767 MM 12-12-01. AIRCRAFT RETURNED TO SERVICE.