As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JFK 0 FLT 187 - AFTER TAKEOFF, OUTFLOW VALVE REMAINED OPEN. AIRCRAFT WOULD NOT PRESSURIZE. RETURND TO JFK. PLACARDED AUTO CABIN PRESSURIZATION CONTROL INOP PER MEL. CHECK C 4-17-97 MCI. REPLACED THE OUTFLOW VALVE ACT WHICH HAD FAILED IN THE OPEN POSITION CAUSING THE CIRCUIT BREAKER TO POP. (M)