As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOUD BANGING NOISE FROM LEFT PACK, MAIN DISTRIBUTION DUCT CAME LOOSE FROM CEILING AND WAS HANGING DOWN 4-6 INCHES BETWEEN ROWS 9-11. FOUND OVERHEAD DISTRIBUTION DUCT SEALANT SPLIT AT ROW 8 THROUGH 10. FOUND MISSING FASTENERS USED TO SECURE OVERHEAD DUCT TO CENTER OVERHEAD SLOT. REPLACED AIR DUCT AT ROW 8-10 PER MM21-23-01. CLEANED AIR NOZZLES AND RESTRICTOR PLATES AND INSTALLED. OPS CHECKD.