As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTO PRESSURIZATION WAS INOPERATIVE AND CABIN PRESSURIZATION COULD NOT BE CONTROLLED MANUALLY WITH ALL BLEEDS ON HIGH AND ALL CTC'S OPERATING. THE CREW DONNED OXYGEN MASKS AND DESCENDED TO FL 10. MAINTENANCE INSPECTED AND REMOVED A PIECE OF INSULATION FROM THE RIGHT SAFETY VALVE. OPERATION CHECKS WERE COMPLETED IAW DC-8 MM, AND THE AIRCRAFT WAS RETURNED TO SERVICE.