As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT HP BLEED VALVE CYCLES ON AND OFF AT LOW POWER SETTINGS DUCT PRESS FLUCTUATES. INOPERATIVE LT HPSOV, COMPLIED WITH MEL REQUIREMENTS. REPLACED LT & RT ISOLATION BYPASS VALVES IAW MM. BITE AIR SUPPLY MODULE IAW MM. FOUND HPC FAULT. REPLACED HPC. RAN ENGINES, NO FLUCTUATIONS.