As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED THAT DURING TAKEOFF, A BURNING ODOR WAS NOTED DURING TAKEOFF. THE ODOR SEEMED TO START AND STOP WITH THE OPERATION OF THE NR 1PACK. MAINTENANCE PERFORMED A GVI OF THE NR 1 PACK AND NO DEFECTS WERE NOTED. COULD NOT DUPLICATE. THE ACFT WAS RETURNED TO SERVICE.