As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT ATTENDANTS REPORTED VIBRATION IN FLOOR IN FRONT OF AFT ENTRY DOOR AND GRINDING NOISE. ON DESCENT PULLED POWER LEVERS TO IDLE CABIN STARTED TO CLIMB AND NOISE AND VIBRATION WENT AWAY, WHEN POWER LEVERS ADVANCED CABIN DESCENDED AND VIBRATION AND NOISE RETURNED INSPECTED AREA, FOUND CRACKED THRESHOLD. REMOVED AND REPLACED THRESHOLD AS PER SRM 51-10-1.