As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, F/A REPORTED A LOUD VIBRATION NOISE BETWEEN ROWS 1 AND 4. NOISE COULD NOT BE HEARD IN COCKPIT. CAPTAIN MADE DECISION TO DIVERT AND DECLARED AN EMERGENCY. LANDED WITHOUT INCIDENT. MX FOUND THE RT AIR DUCT B WAS DELAMINATED AND THE RAM AIR DUCT C HAD A BROKEN FLANGE. MX REPLACED THE NACA BOOT AND DUCT IAW AMM AND OPS CHECKED GOOD.