What was found
INSPECTION TYPE: N/A, SUPPLEMENTAL SDR, ATB, EMERGENCY DECLARED. LANDED MANUALLY, MET BY CFR VEHICLES & TOWED. SHORTLY AFTER TAKEOFF LT HYD QTY & ENGINE PUMP EICAS MESSAGES DISPLAYED FOLLOWED BY LT HYD SYSTEM PRESS MESSAGE LIGHT. ALTERNATE GEAR & FLAP EXTENSION WERE REQUIRED. LT EDP CASE DRAIN FILTER BOWL CROSS THREADED, AMM 29-11-17-401. REMOVED AND REPLACED LT EDP DRAIN CASE FILTER MODULE, REF 757 MM CHAP 29-11-17-404. SERVICED LEFT HYD SYSTEM PERFORMED LEAK AND OPERATIONS CHECK OF LT HYD SYSTEM EDP FILTER MODULE, SYSTEM CHECKS OK.