As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3824 -ATB/PRESS- RETURNED TO JFK DUE TO CABIN PRESSURE UNCONTROLLABLE. CORRECTIVE ACTION: FOUND GROUND AIR CHECK VALVE STUCK OPEN, REPLACED SAME. PERFORMED DPCP BITE CHECK. FOUND DCPC-1 FAULT CODE 30 'LO INFL/ HI LEAKG". REPLACED DCPC-1 PRECAUTIONARY. OPS CHECKS GOOD.