As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOTH DUCT PSI IN DESCENT ONLY 10 PSI. POSSIBLE HI STAGE VLV ISSUE. RAN BOTH ENGINES WITH NO PACKS ON 10 PSI, WITH RT ENGINE ONLY WITH PACKS 5 PSI. WITH LT ENGINE PACKS 12 PSI. REPLACED PILOT REG AND HI STAGE SHUTOFF VALVE PER MM, OP'S CHECK GOOD.