As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK DUCT PRESSURE 5 PSI. RIGHT PACK DUCT PRESSURE 45 PSI. ACFT GROUNDED. FOUND THE NR 1 ENGINE PRECOOLER CONTROL VALVE SUPPLY PRESSURE SENSE LINE BROKEN. REMOVED AND REPLACED THE SENSE LINE IAW AMM 36-12-400-801, STEP 3. F. (9), AND (10). ACCOMPLISHED INSTALLATION TEST IAW AMM 36-12-02-400-801 3. G THROUGH H (2). OPS AND LEAK CHECKED GOOD. BOTH LEFT AND RIGHT PACK DUCT PRESSURE ARE NORMAL.