What was found
APU CT5ATP EGT HAS SHIFTED ABOVE THE 593 DEGREE THRESHOLD BUT REMAINS BELOW THE 605 THRESHOLD. GROUNDED - YES. ACCOMPLISHED B737-900 FIM 49-40 TASK 825. FOUND ECU INTERNAL FAILURE MAINT MSG 49-61153 ON MAINTENANCE HISTORY. FAULT HISTORY SHOWS DOOR NOT OPEN FAULT WITH MAINTENANCE MESSAGE 49-15003. DURING APU START UP ECU INTERNAL FAILURE IS LOGGED WITH CT5ATP TEMP FLUCTUATING 3 DEGREES C. REPLACED APU ECU REF B737-900 AMM 49-61-12-000-801. VERIFIED SOFTWARE 4918YUSA53-00 INSTALLED REF B737-900 IPC 49-61-12-01 FIG. 10. OPS CHECK NORMAL.