As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TROUBLESHOOTING FOR THE LT PACK TRIP. ACFT GROUNDED . FOUND THE SENSE LINE ON THE LT ACM FOR THE STANBY TEMP CONTROL VALVE LOOSE. REMOVED THE LT ACM IAW AMM 21-51-04. FOUND THE FAN IMPELLER DAMAGED AND ACM SEIZED. NO FOD DAMAGE NOTED IN THE COOLING AIR EXHAUST PATH. VISUALLY INSPECTED THE HEAT EXCHANGERS. NO DEFECTS. INSTALLED NEW LT ACM IAW AMM 21-51-04-400-802-002. ACM INSTALLATION TEST PASSED. LEAK AND OPS CHECKED GOOD.