As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER STARTING APU DUCT PRESS NEVER ROSE ABOVE 10 PSI WITH PACKS OFF. SHUT DOWN AND RESTARTED WITH NO SUCCESS. REPLACED TOTAL PRESSURE SENSOR, NO HELP. APU EGT AT 522 DEG C. IN DUCT PRESSURIZATION MODE. PER FIM AND APU SHOP 500 DEG C MAX NEEDS APU. REMOVED APU PN 3800298-1-5 SN P-1706 PER MM. INSTALLED APU PER MM 49-11-01. NO HELP. REPLACED ECU NO HELP. REINSTALLED ORIGINAL REPLACED SURGE VALVE CHECKS GOOD MCO AND PLAC REMOVED MFG P/N 979806-12.