As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETUREND TO DEPARTURE AFTER TAKEOFF DUE TO FUMES DEVELOPED IN COCKPIT AND CABIN. FUMES WERE STRONG AND RUBBER-LIKE IN NATURE. FUMES CLEARED BEFORE LANDING. COMPLIED WITH FIM 21-21-00, & 21-22-00. NO ABNORMAL ODORS NOTED. OK FOR SERVICE. PERFORMED OF AIR CONDITIONING DISTRIBUTION SYS IAW AMM 21-51-00. OPS CHECKED GOOD.