As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU BLEED WILL NOT OPEN. APU BLEED OPERATED NORMAL FOR ABOUT 20 MINUTES (33-34PSI) THEN SURGE VALVE DUMPING AIR OVERBOARD. STARTED NR 2 ENGINE OK PRESSURE NORMAL TRIED TO START NR 1, PRESSURE DROPPED TO 9PSI THEN SLOW TO RISE TO 30 PSI. APU BLEED VALVE MUST REMAIN IN OFF POSITION. INSTALLED APU FLOW SENSING MODULE IAW AMM, OPERATIONS CHECKED NORMAL.