What was found
FLIGHT 3007-CMH-CLT - A FEW MOMENTS AFTER TAKEOFF, DURING CLIMB FROM CMH, LAVATORY SMOKE DETECTOR WENT OFF. THIN LAYER OF SMOKE AND SMELL OF SMOKE IN TOP OF CABIN. DECIDED TO RETURN TO AIRPORT. DURING DESCENT, THE SMOKE CLEARED AND LAVATORY SMOKE DETECTOR STOPPED ALARMING. CHECKED LAVATORY, NO SMOKE, NO VISIBLE FIRE. LANDED WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED NR 2 ENGINE IAW JC CE720001. PERFORMED ENGINE RUN AND OPS CHECK, ALL CHECKS GOOD.