As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO FIELD DUE TO THE LEFT UPPER DUCT HEAT FAIL LIGHT ILLUMINATED. THROUGH TROUBLESHOOTING THE LEFT UPPER DUCT WAS DETERMINED TO BE THE PROBLEM. THE DUCT ASSEMBLY WAS REPLACED AND A FUNCTIONAL CHECK OF THE SYSTEM WAS PERFORMED WITH ALL INDICATIONS NORMAL. (Z)