As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE FL400 L BLEED PRESS FLUCTUATED DOWN 2 AROUND 24 PSI. THEN WENT DOWN AND STAYED AT 24 PSI MAINT TEXT: PER VERBAL FROM INBOARD CREW LT 24 PSI RT 42 PSI REMAINDER OF CRUISE FLT. REPLACED VALVE AND CONTROL PER MM 36-11-07 AND MM 36-11-08. ACCOMPLISHED NR 2 ENG PNEUMATIC SYSTEM CK ACCT HPSOV, PILOT VALVE AND DAMAGED SENSE LINE REPLACED. ACP RUN PER JRH WITH NO DEFECTS NOTED.