As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PNEUMATIC DUCT SPLIT DURING CLIMB AND CRUISE IN EXCESS OF 20 PSI. LEFT DUCT INDICATES 20 PSI, RIGHT IS 40-45 PSI. ACFT GROUNDED. RAN NR 1 ENG ON GROUND AND VERIFIED LOW LT DUCT PRESS WITH PACKS ON. R & R LT PRSOV IAW AMM 36-11-04 AND BAR IAW AMM 36-11-03. ALSO, REPLACED PRSOV CONTROL AIR FLEX LINE. SYS GROUND FUNCTIONAL TEST GOOD IAW AMM AND 36-11-00-710-801 BLEED AIR CROSSOVER TEST.