What was found
DURING FLIGHT HYDRAULIC SYSTEM NR 1 QUANTITY DROPPED TO 0 PERCENT. PSI REMAINED AT 3000 PSI. RETURNED TO SLC. FOUND NR 1 HYDRAULIC QUANTITY AT 15 PERCENT, SERVICED IAW 12-12-29. RAN NR 1 ENGINE, NO LEAKS NOTED AT ENGINE HYDRAULIC PUMP. OPERATED NR 1 ELECTRIC HYDRAULIC PUMP, FLUID LEVEL GOOD, TEMPERATURE OK. HYDRAULIC LEAK LEFT ENGINE. REPLACED LEFT ENGINE HYDRAULIC PUMP IAW 31-00-03. OPS AND LEAK CHECKS GOOD. S/N OFF MX6066207.