What was found
LGA - FLT 1129 - AFTER TAKEOFF LGA DURING CLIMB-OUT, SMOKE NOTED IN CABIN AND COCKPIT. AIRCRAFT RETURNED TO LGA AND LANDED OVERWEIGHT WITHOUT INCIDENT. REPLACED LT ENGINE. ACCOMPLISHED LEAK AND GROUND ENGINE RUN CHECK WITH NO DEFECTS FOUND. ACCOMPLISHED PACK BURNOUT PROCEDURE. ACCOMPLISHED OVERWEIGHT LANDING INSPECTION WITH NO DEFECTS FOUND. SYSTEM GROUND CHECKED NORMAL OPERATION WITH NO SMOKE NOTED IN CABIN OR COCKPIT. (M)