What was found
FLIGHT 5295 CMH-STL, APPROX 700 FT AGL AFTER DEPARTURE ON RUNWAY 28L IN CMH FA REPORTED SMOKE IN CABIN AND A STRONG BURNING SMOKE ODOR WAS IN THE COCKPIT. A MINUTE OR SO LATER LAV SMOKE ON EICAS APPEARED. DECLARED AN EMERGENCY AND RETURNED TO FIELD. WHILE ON BASE LEG THE MESSAGE WENT AWAY, AND FA REPORTED SMOKE WAS CLEARING OUT. LANDED IN CMH ANYWAY AS A PRECAUTION. LANDED APPROX 2000 LBS OVER LANDING WEIGHT, THE VSI WAS APPROX 200 FPM DESCENT WHEN THE WHEELS TOUCHED THE RUNWAY. MAINTENANCE FOUND OIL IN THE NR 2 BLEED SYSTEM. REMOVED AND REPLACED NR 2 ENGINE IAW J/C CE720001. OPS CHECK AND LEAK CHECK GOOD. NO SMELL NOTED.