What was found
BLEED 1 LEAK DURING DEPARTURE, RAN QRH, MESSAGE DID NOT EXTINGUISH AND RETURNED TO DEPARTURE. EMERGENCY DECLARED. PERFORMED OPC OF E1 BLEED AIR SYSTEM AS PER EMB145 AMM 36-00-00. OPS CHECKED GOOD. PERFORMED LEAKAGE TEST OF LT AIR BLEED SYSTEM DUCTS IAW AMM 36-00-00. LEAK CHECKED GOOD. PERFORMED AN OPS CHECK IAW AMM 36-11-05, OPS CHECKED GOOD. PERFORMED OPS CHECK OF BLEED 1 TEMP SENSOR IAW AMM 36-11-05, OPS CHECKED GOOD. INSTALLED BLEED DUCT AT JOINT 17 IAW AMM 36-11-10. REPLACED BLEED DUCT CLAMP ON ENGINE 1 BLEED VALVE IAW AMM 36-11-05. REPOSITIONED CLAMPS AND DUCTS BETWEEN PRECOOLER AND Y-DUCT IN THE LT PYLON IAW AMM 36-11-09. OPS AND LEAK CHECKED GOOD. REMOVED AND REPLACED LT PYLON HARNESS W421 IAW SWPM 20-50-00 AND SWPM 20-13-02, OPS CHECKED GOOD IAW AMM 36-20-02. REMOVED AND REPLACED CHECK VALVE GASKET AND OPS CHECKED GOOD IAW AMM 36-11-01.