As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON APPROACH INTO DTW SMELL IN COCKPIT. EMERGENCY DECLARED, A/C LANDED SAFELY. RAN BOTH ENGINES AND USED BLEEDS TO OPERATE PACKS, NO SMELL WAS NOTED. INSPECTED AFT BAY OIL LEVELS AND COCKPIT FOR BURNED OUT LIGHTS NONE FOUND. REMOVED AND REPLACED BOTH COALESCER BAGS.