As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
YQB FLIGHT 2128 - THE CREW REPORTED PACK 2 PRODUCES SMOKE IN CABIN WHEN TURNED ON. THE AIRCRAFT RETURNED TO THE GATE WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED AND PERFORMED OPERATIONAL CHECKS OF THE PACK SYSTEM IN BOTH MANUAL AND AUTO USING THE APU AND ENGINE BLEED. NO SMOKE WAS DETECTED AND ALL OPERATIONAL CHECKS WERE GOOD. THE AIRCRAFT WAS RELEASED FOR SERVICE.