As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3707 -ATB- RETURNED TO JFK DUE TO PRESSURIZATION ISSUES AND NO LT DUCT PRESSURE. CORRECTIVE ACTION: REPLACED LT PRSOV SENSE LINE AND LT HPV MUSCLE AIR LINE FOR LT ENGINE BLEED ISSUE. REPLACED RT BLEED AIR REGULATOR, RT SECONDARY HEAT EXCHANGER AND RT TCV SENSE LINE FOR RT BLEED SYSTEM ISSUES. OPS NORMAL.