As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE AND CLIMB DUCT PRESSURE SPLIT OF 30 PSI L/12PSI R/46 PSI ON DESCENT R/35PSI L/8PSI CABIN VSI ON PRESSURIZATION PANEL FLUCTUATED FROM 0 CLIMB TO 1000 FT PER MIN T/S REF AMM 36-10 FOUND A/C TO BE OK. RAN LEFT ENGINE AND ALL PRESSURE GOOD SEE L/P 8912767.