As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTS ON DESCENT PASSING 8000 FT WE NOTICED A STRONG PETROCHEMICAL ODOR. APU WASN’T SELECTED ON UNTIL 5000 FT. NOXIOUS FUMES WAS EVIDENT IN ENTIRE AIRCRAFT (NOTE: NO PAX ONBOARD, PIC/SIC DONNED O2 MASKS). OPEN ERTS 12/19 AT THIS TIME. SUSPECT APU SEAL, TBD.