As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FINAL APPROACH, AFTER GEAR EXTENSION, GOT MASTER CAUTION WITH BL SYS LO PRES INDICATION. FOLLOWED QRH/ECAM PROCEDURE. DECLARED EMERGENCY. MAINTENANCE TROUBLESHOT. REPLACED O-RING ON PLUG FOR BLUE HIGH PRESSURE MANIFOLD. LEAK CHECKS GOOD. CLEANED APU INLET AND COMPARTMENT.