As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FLT 530 - DFW-RIC, ON CLIMB-OUT ABOVE 1000 FEET HAD BURNING SMELL IN THE COCKPIT WITH MODERATE SMOKE THROUGHOUT THE CABIN. AIRCRAFT RETURNED AND LANDED DFW WITHOUT INCIDENT. INSPECTED ACM/PACK HEAT EXCHANGER DUCTING. NO DEFECTS NOTED. INSPECTED APU, FOUND OIL PRESENT IN THE APU PLENUM. REPLACED APU. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)