As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT THERE WAS SMOKE IN THE CABIN AND COCKPIT DURING TAKEOFF. THE CREW ABORTED TAKEOFF AND RETURNED TO THE GATE WITHOUT INCIDENT. MAINTENANCE PERFORMED THE FAULT ISOLATION MANUAL TASK WITH NO DEFECTS NOTED. THE CREW THEN REPORTED A BURNING SMELL IN THE AIRCRAFT DURING PASSENGER BOARDING COMING FROM PACK NUMBER 1. THE PACK WAS DEFERRED. THE DEFERRAL WAS CLEARED ON 3/2/2012 WHEN MAINTENANCE REPLACED THE PACK NUMBER 1 AIR CYCLE MACHINE. OPERATIONAL CHECKS WERE GOOD WITH NO FURTHER DEFECTS NOTED.