As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEPARTED SEA, PRESSURIZATION FAILED, WENT TO MANUAL PRESSURIZATION, STILL UNCONTROLLABLE. RETURNED TO SEA. CLEANED CABIN DOOR SEAL AND CHECKED CARGO DOOR SEAL. CHECKED OUTFLOW VALVES FOR OBSTRUCTIONS. PRESSURIZATION CHECKS GOOD DURING GROUND OPS IAW MM 21-30-00. COULD NOT DUPLICATE SQUAWK.