As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR RETURN DUE TO SMOKE EVENT. CREW ISOLATED TO VENT EXTRACT FAN PER SMOKE EVENT FORM. EMERGENCY DECLARED. FOUND EXTRACT FAN 18HQ FAULT IN MCDU.ALSO CB AE2 POPPED. REMOVED AND REPLACED EXTRACTOR FAN 18HQ IAW AMM 21-26-51-000-001 -A AND 21-26-51-400-001A. PEFORM OPERATIONAL TEST IAW AMM 21-26- 00-710-001-A. SYSTEM CHECKS GOOD.