As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VERY NOTICEABLE PRESSURIZATION SURGE AT ABOUT 600'. REPLACED SEAL ON CHECK VALVE RT PACK BEFORE DIST DUCT. LEAK AND OPS CK GOOD. WHILE TROUBLESHOOTING LOG 2, FOUND SECTION OF GASKET MISSING FROM FWD MATING SURFACE OF CONDITIONED AIR CHECK VALVE ATTACH POINT. REPLACED GASKET PER MM. OPS AND LEAK CHECKS OK. ALSO REPLACED ISOLATION VALVE PER MM AS A PRECAUTION. OPS AND LEAK CHECKS OKAY.