As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT ENGINE HPSOV EICAS IN DESCENT, TURNED OFF LT BLEED VALVE PER QRH. ACCOMPLISHED HEALTH CHECK OF NR 1 ENGINE PNEUMATIC SYSTEM PER MM. PRESSURE REGULATING VALVE FAILED CHECK. REPLACED PRV PER MM. OPS AND LEAK CHECKED GOOD. PNEUMATIC HEALTH CHECK WAS ACCOMPLISHED ON HPSOV AND PRV SYSTEM ONLY. FITTING ON PRV VALVE WAS LEAKING WHICH CAUSED TABLE LIMITS TO BE LOW. REPLACED NR 1 ENG PRV.