As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT, THE FLT ATTN REPORTED A BURNING PLASTIC SMELL IN THE AFT CABIN. FLT RETURNED TO ONT. CONTRACT MTC CHECKED THE CABIN INTERIOR LIGHTING SYSTEM AND BOTH AIR COND PACKS FOR PROPER OPERATION AND NO PROBLEMS FOUND. MTC AND FLT CREW TOOK A/C TO THE HI POWER AREA AND RAN BOTH ENGINES AT HI POWER WITH PACKS RUNNING, NO PROBLEMS FOUND.