What was found
IN-FLIGHT, MAIN CARGO SMOKE DETECTION ILLUMINATED. DEPARTED (CVG), UNSCHEDULED LANDING AT HARRISBURG, PENNSYLVANIA (MDT), CONTINUED TO PHILADELPHIA (PHL). GENERATED BY PILOT REPORT. COMPLETED OPERATIONAL CHECK. OPERATION CHECK GOOD. INSPECTION OF AFT CABIN FOUND MOISTURE TO CAUSE FALSE INDIICATION. OPERATION CHECK GOOD IAW MM 26-00. (X)