As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEX - FLT 3668 - AS THE CREW ENTERED THE AIRCRAFT, FOUND TEMP INSIDE CABIN TO BE HOT AND SMOKE THROUGHOUT THE CABIN. APU HAD BEEN STARTED BY GROUND CREW AND WAS RUNNING 30 PLUS MINUTES. SHUT OFF APU AND SMOKE DISSIPATED. MAINTENANCE RAN APU AND PACKS. NO SMOKE OR SOOT NOTED. RAN APU/PACKS FOR 1 HOUR IN ALL TEMP RANGES ALL CHECKS GOOD. (M)