As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 7839, IAD TO GSO. CREW REPORTED A BURNT RUBBER SMELL IN CABIN WITH NO VISIBLE SMOKE PRESENT. FLIGHT ATTENDANT REPORTED THAT SMELL DISSIPATED WHEN PACK 2 WAS DESELECTED. MAINTENANCE OPERATED BOTH PACKS OFF OF BOTH ENGINE BLEEDS AND COULD NOT DUPLICATE THE ODOR AND NO OTHER DEFECTS WERE NOTED.