What was found
DURING TAXI, CENTER HYD SYSTEM PRESSURE 1070 PSI WITH BOTH ENGINES RUNNING, A/C RETURNED TO GATE (BTB) AND MTX GROUNDED A/C. TROUBLE SHOT AND REMOVED AND REPLACED CENTER PRESSURE AND CASE DRAIN MODULE IAW B767 AMM 29-11-19, OPS TEST GOOD, NO LEAKS NOTED AT THIS TIME, PERFORMED TEST 3 OF LEFT AND RIGHT ENGINES 71-00-00, ALL PRESSURES ABOVE 3000 PSI AT THIS TIME.AND RETURNED A/C TO SERVICE.