As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. ON THE DESCENT FORWARD FLIGHT ATTENDANT AND PILOTS HEARD A HIGH PITCH WHINE. FLIGHT ATTENDANT REPORTS FEELING A VIBRATION AN THE FLOOR AT DOOR R1. PILOTS POSSIBLY SMELLED SOMETHING LIKE HOT PLASTIC FOR A COUPLE OF MINUTES. FOUND EXTRACT FAN BAD. REMOVED AND REPLACED AVIONICS EXTRACT FAN, PER AMM 21-26-51-000-001-A.