(The repair station technician from the previous two reports provides a third--and important--heat defect description.)

“A heater core was received from the customer. Upon teardown I found the interior of the combustion head (P/N 51A45) severely worn from flame erosion. Previous inspections by this repair station have found small holes appearing in the wall of the combustion head. From the outside (of the unit), the combustion head appears to be good. Internally, this combustion head is not airworthy. By following the Beech and Janitrol maintenance manual, these conditions (a deteriorated combustion head) would have been found earlier. TBO time is every 500 hours of heater operation or every engine overhaul, whichever occurs first.” (Heater assembly P/N given as D83A28. It is obvious this submitter has a great deal of experience and understanding of these units. Please share your speculations of the mechanical chain of event possibilities. For example: a deteriorated gas stove burner might produce an uneven flame for cooking—a small consequence; but if the burner is producing yellow flames—a much larger consequence of temperature and incomplete combustion. Are these concerns the same for the heater’s combustion head, or is a misdirected flame the primary consequence? The SDRS data base has three additional entries for this combustion head part number.)

Part Total Time: (unknown).