As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR CONTAMINATION, FUMES WERE NOTICED IN THE CABIN AFTER PROLONGED DECENT AND LEVEL OFF AT 4000' EVEN LASTED APPROX. 5MIN(PER F/A). PERFORMED 5 MINUTE IDLE RUN OF BOTH ENGINES USING ENGINE BLEED 1 & 2 TO SUPPLY PACKS. NO FUMES NOTED. PER AMM 21-53-00-710-802-A. AIRCRAFT OK FOR SVC.