As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT AT 5000 MSL POWER IDLE L A/C DUCT PRESS 13 PSI WHEN POWER INCREASED TO APPX 60 PERCENT N1 L&R DUCT PRESS NORMAL AND CLOSELY MATCHED. ACCOMPLISHED PNEUMATIC SYS TROUBLESHOOTING PER AMM 36 11 00 700 804. FOUND HI STAGE VALVE STIFF. ACCOMPLISHED LEAK CK OF ENG BLEED AIR SYS SENSE LINES PER AMM36 11 00 101. NO LEAKS NOTED. REPLACED HI STAGE VALVE PER AMM 36 11 06 400 801. PERFORMED IDLE RUN, OPS NORMAL.