As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION TYPE:N/A AT FLT LVL 320 LTN PACK OFF GOT EICAS MSG CAB ALT WARN. RAN CHECKLIST, LT PACK TO ON, MESSAGE GO AWAY. DEFERRED AS PER MEL 21-51-1. **SUPPLEMENTAL SDR** CREW DECLARED EMERGENCY - DONNED O2 MASKS AND DESCENDED TO FL100. MX INSPECTED RT ECS BAY FOUND DUCT PN AS1505-28A0032 REF IPC 21-51-15-01 DISCONNECTED. INSTALLED AND LEAK CK OK. C/W RT PACK BITE CK OK AMM 21-51-00-745-159. PLACARD REMOVED DEFERRAL CLEARED.