As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: APPROXIMATELY 2 HOURS INTO FLIGHT A BURNING RUBBER / ELECTRICAL ODOR WAS SMELLED THROUGHOUT THE ENTIRE AIRCRAFT FOR APPROXIMATELY 5 MINUTES THEN THE ODOR DISSIPATED. MAINTENANCE FOUND THE LEFT PACK BELLOWS BETWEEN THE CONDENSOR (10HM2) AND CHECK VALVE (15MH) WAS SEPERATING FROM THE FLANGE. MAINTENANCE REPLACED THE BELLOWS AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK.