What was found
IAH - FLIGHT 2990, THE CREW REPORTED A SMOKE DETECTION WARNING DURING TAXI. THE AIRCRAFT RETURNED TO THE GATE WITHOUT INCIDENT WHERE MAINTENANCE PLACED THE NUMBER ONE PACK ON MEL 21-50-01 CONTROL NUMBER 004868, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE. THE AIRCRAFT RETURNED TO IAH ON FLIGHT 3556 ON 01/23/01 WHERE MAINTENANCE REMOVED AND REPLACED THE AVIONICS VENT FAN RELAY, REMOVE MEL 21-50-01 CONTROL NR 004868, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.