As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AIR SURGES WHILE TRYING TO OPERATE BOTH PACKS ON THE GROUND. VISUAL INSPECTION CARRIED OUT IN APU COMPARTMENT AREA. HOLE FOUND IN DUCT CONNECTED TO SURGE CONTROL VALVE. OLD BROKEN DUCT REMOVED AND NEW ONE FITTED. OPS CHECK GOOD. REF AMM 49-53-01-004-001.