As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: SOF EVENT. SMELL WAS REPORTED BY CABIN CREW AS BURNT RUBBER OR VERY HOT PLASTIC. MILD ODORS WERE NOTED FOLLOWING TAKEOFF BUT WERE NOT OBTRUSIVE OR IMPAIRING AND APPEARED TO DISSIPATE. THE ODOR RETURNED ON DECENT. MAINTENANCE REPLACED APU DE OIL SOLENOID VLV PACKING IAW AMM 49-91-49.