As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OBSERVED DUCT PRESSURE (RT ENGINE LESS THAN 18PSI THRU 50% N1) WHILE PERFORMING BLEED AIR CROSSOVER TEST. LEFT ENGINE OK. ACFT GROUNDED. HIGH STAGE REGULATOR FAILED BLEED AIR HEALTH CHECK T/C NG-36WC-0001. REPLACED HIGH STAGE REGULATOR IAW AMM 36-11-07. OPS CK GOOD. ETOPS REPAIR CONFIGURATION COMPLIED WITH.