Narrative:

On climb out cruise aircraft unable to maintain depressurization. Flight from tpa to phl. Flight diverted to ZZZ prior to flight, a crack was detected on the #2 engine high pressure heat exchanger. After flight, the air pressure regulator valve failed, causing pressurization problems. Flight was rerted to ZZZ. Repair was made, aircraft was released for continued service. Callback conversation with reporter revealed the following information: the reporter stated the aircraft diverted into ZZZ with pressurization and #2 engine overheat problems. The reporter said the #2 engine pneumatic heat exchanger was found cracked causing the overheat and pressure problems. The reporter said the heat exchanger was replaced and the airplane released for service. The reporter stated the first flight out, the airplane returned to the gate with no pneumatic air from the #2 engine. The reporter aid the pneumatic pressure regulator and shutoff valve had failed closed. The reporter stated a pneumatic system performance test was not accomplished after the heat exchanger replacement.

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Original NASA ASRS Text

Title: A B737-400 WAS DISPATCHED IN NON COMPLIANCE WITH A FAILED #2 ENG PNEUMATIC PRESSURE REGULATOR VALVE. ACFT RETURNED WITH CABIN PRESSURE PROBS.

Narrative: ON CLBOUT CRUISE ACFT UNABLE TO MAINTAIN DEPRESSURIZATION. FLT FROM TPA TO PHL. FLT DIVERTED TO ZZZ PRIOR TO FLT, A CRACK WAS DETECTED ON THE #2 ENG HIGH PRESSURE HEAT EXCHANGER. AFTER FLT, THE AIR PRESSURE REGULATOR VALVE FAILED, CAUSING PRESSURIZATION PROBS. FLT WAS RERTED TO ZZZ. REPAIR WAS MADE, ACFT WAS RELEASED FOR CONTINUED SVC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT DIVERTED INTO ZZZ WITH PRESSURIZATION AND #2 ENG OVERHEAT PROBS. THE RPTR SAID THE #2 ENG PNEUMATIC HEAT EXCHANGER WAS FOUND CRACKED CAUSING THE OVERHEAT AND PRESSURE PROBS. THE RPTR SAID THE HEAT EXCHANGER WAS REPLACED AND THE AIRPLANE RELEASED FOR SVC. THE RPTR STATED THE FIRST FLT OUT, THE AIRPLANE RETURNED TO THE GATE WITH NO PNEUMATIC AIR FROM THE #2 ENG. THE RPTR AID THE PNEUMATIC PRESSURE REGULATOR AND SHUTOFF VALVE HAD FAILED CLOSED. THE RPTR STATED A PNEUMATIC SYS PERFORMANCE TEST WAS NOT ACCOMPLISHED AFTER THE HEAT EXCHANGER REPLACEMENT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.