As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW ADVISED OF "BURNING SMELL IN CABIN" AND THAT "SMOKE FUMES WERE SMELLED IN THE CABIN". AIRCRAFT DIVERTED BACK TO POINT OF DEPARTURE AT KBDL. SUSPECT SMELL TO BE FROM INSTALLATION OF "NEW" UPPER AND LOWER OZONE CONVERTERS INSTALLED PRIOR TO DEPARTURE TO COMPLY WITH 2500HR INSPECTION / RESTORATION REQUIREMENT. REMOVED AND INSPECTED OZONE CONVERTERS WITH NO DEFECTS NOTED. GROUND AND LEAK CHECKS PERFORMED SATISFACTORY WITH NO FURTHER SMELL NOTED IN CABIN OR COCKPIT. AIRCRAFT RETURNED TO SERVICE.