As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RUBBER SMELL DESCENDING OUT OF 180. FOUND OIL SUBSTANCE IN CHECK VALVE AREA UPSTREAM OF LT RECIRC FAN. CLEANED AREA, REPLACED BOTH RT AND LT RECIRCULATION FILTERS PER MM. INSPECTED BOTH RT AND LT DUCTING UPSTREAM OF O-ZONE CONVERTERS, ALL DRY AND FREE FROM DEBRIS. INSPECTED MIX MANIFOLD, NO DESCREPANCIES NOTED. RAN BOTH PACKS FOR 2 HOURS, NO SMELL NOTICED.