What was found
PTU, P/N 4100310-6, S/N 461 WAS REMOVED FROM JAPAN AIRLINES MD-80 AIRPLANE DUE TO NOISY OPERATION AND HOT TEMPERATURE OF THE PTU BODY. THE PTU WAS DISASSEMBLED IN THE SHOP, WHICH REVEALED THE DRAIN PORT HOUSING, P/N 4102202-1 HAD CRACKED COMPLETELY AROUND THE CIRCUMFERENCE. SUBJECT HOUSING HAD ACCUMULATED 16,764 HOURS SINCE INSTALLATION IN ACCORDANCE WITH SB 4100310-29-0031 (AD 94-22-03). THE FAILED DRAIN PORT HOUSING WAS FORWARDED TO FRISBY AEROSPACE FOR A FAILURE INVESTIGATION.