As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WAITING FOR PUSHBACK, HEARD LOUD GRINDING NOISE FROM BELOW COCKPIT AND A STRONG BURNING ODOR DETECTED. FOUND THE NR 3 AVIONICS FAN HAD A BEARING FAILURE AND THE BLADES CONTACTED THE CASE CAUSING THE GRINDING NOISE, THE FAN IMPELLER ALSO STOPPED TURNING AFTER CONTACT. INSTALLED A NEW FAN AND OPS CHECKED IAW AMM 21-26-02-4. OPS CHECKED GOOD.