As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB OUR LT DUCT PRESSURE BELOW 20 PSI DROP TO 18 PSI ON CLIMB AT CRUISE LT DUCT 30 PSI RT 38 PSI. GROUNDED - YES. PERFORMED FIM 36-10 TASK 801 DUCT PRESSURE LOW, THE ENGINE IS THE BLEED SOURCE. FOUND PRSOV AND HIGH STAGE REGULATOR NOT IN LIMITS. REPLACED PRSOV PER AMM TASK 36-11-04-400-801, REPLACED HIGH STAGE REGULATOR PER AMM TASK 36-11-07-400-801. REPERFORMED FIM 36-10 TASK 801. NO FAULTS FOUND.