As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT & RT DUCT PRESSURE SPLIT DURING CRUISE, WITH ENGINES RUNNING. LT & RT ISOLATION VALVES CLOSED & BLEED SWITCH ON. LT PRESSURE 35 PSI & RT PRESSURE 20 PSI, CRUISE FL 370 LEPR 1.17 REPAIR 1.22. PERFORMED AIR SUPPLY DISTRIBUTION SYSTEM TEST PER AMM 36-11-00-501. BLEED PRESSURES AND BLEED SHIFT POINTS NORMAL. SYSTEM TEST ACCOMPLISHED.