As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOSS OF PRESSURIZATION AT FL 280. EMERGENCY DESCENT TO 10,000 FT. CABIN ALTITUDE GOT UP TO A MAX OF 11,000 FT. OUTFLOW VLV APPEARED FULL CLOSED WITH FLOW LIGHT ON AT CONTROLLER. CABIN CONTINUED TO CLIMB. BOTH PACKS OPERATING NORMAL. REMOVED INSULATION FROM OUTFLOW VALVE AND SECURED PROPERLY.