As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HIGH STAGE REGULATOR ON THE NR 1 ENGINE FAILED A HEALTH CHECK. REVERSE FLOW DIAPHRAM FAILED. ACFT GROUNDED. REMOVED & REPLACED THE NR 1 HIGH STAGE REGULATOR IAW AMM 36-11-07. ACCOMPLISHED ENGINE BLEED AIR CROSSOVER TEST IAW AMM 36-11-00-710-801. OPS TESTED GOOD. ALL INDICATIONS WITHIN GIVEN PARAMETERS.