What was found
FLT 4503 - AFTER DEPARTING HTL ON FLAP RETRACTION, FLAP FAIL MESSAGE CAME ON EICAS. CREW LEVELED OFF AT 6,000 FEET AND PERFORMED AFTER TAKEOFF CHECK LIST. CREW THEN MAINTAINED 200 KNOTS, PERFORMED FLAP FAIL CHECK LIST AND CALLED MAINTENANCE CONTROL. CREW DECLARED AN EMERGENCY. FLIGHT RETURNED TO ATL AND SAFELY LANDED. MAINTENANCE REMOVED AND REPLACED LT BPSU. OPERATIONAL CHECKS WERE GOOD. AIRCRAFT RETURNED TO SERVICE. (X)