Narrative:

Flight departed late; scheduled XA42; to ZZZ. The delay was for a broken bolt right engine pylon. Once departed; aircraft tail number could not get engines to start. APU bleed pressure on command start switch went to 30 psi; start activated on right engine. At 7.5% N1 bleed air stopped. Engine rolled back. Same occurrence left engine. Flight attendant called to report noise in back of aircraft. Maintenance completed a placard of APU bleed air. Ground start accomplished; all indications normal. During departure; cabin rate of climb went to 1450 FPM. No faults or system switching. Selected system #2; same result. Coordination with ARTCC for divert to ZZZ. Cabin stopped climbing once descent reached 14000 ft MSL. Cabin started to descend. Normal schedule by landing. Maintenance officials stated that with no system switching or fault lights that air was escaping through the cabin at a rate that the system could not keep up with. Pack output normal. Cooling normal. Xbleed start normal. Maintenance started procedure to find cabin leak possibly associated with APU plumbing. Maintenance indicated that a break in APU bleed air duct would be faulted by gas wire length of tube; unless wire broken or inoperative; crew does not have test capability of bleed leak detectors. Callback conversation with reporter revealed the following information: reporter stated that he has not heard from maintenance what caused this event. He did learn that as long as the pressure controllers are functioning normally a system fault will not be indicated. In this case since both controllers were unsuccessfully attempting to control the cabin no fault would be indicated because the failure was not in the controllers but in some other component. A high rate of cabin climb was indicated on the ECAM but because the return to land was initiated with the cabin at about 7000 ft the cabin altitude warning did not illuminate. The reporter also stated that if a reverse air flow valve had failed and air was escaping through an APU duct; there is no detection system to indicate that type of failure. Additionally; if a fire/overheat warning line is broken or missing; the system will not indicate the lack of detection capability and obviously also cannot indicate a fire/overheat caused by duct bleed air leak.

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Original NASA ASRS Text

Title: AN A300 CABIN WOULD NOT COMPLETELY PRESSURIZE AFTER DEP. THE ACFT WAS RETURNED TO THE DEP ARPT.

Narrative: FLT DEPARTED LATE; SCHEDULED XA42; TO ZZZ. THE DELAY WAS FOR A BROKEN BOLT R ENG PYLON. ONCE DEPARTED; ACFT TAIL NUMBER COULD NOT GET ENGS TO START. APU BLEED PRESSURE ON COMMAND START SWITCH WENT TO 30 PSI; START ACTIVATED ON R ENG. AT 7.5% N1 BLEED AIR STOPPED. ENG ROLLED BACK. SAME OCCURRENCE L ENG. FLT ATTENDANT CALLED TO RPT NOISE IN BACK OF ACFT. MAINT COMPLETED A PLACARD OF APU BLEED AIR. GND START ACCOMPLISHED; ALL INDICATIONS NORMAL. DURING DEP; CABIN RATE OF CLB WENT TO 1450 FPM. NO FAULTS OR SYS SWITCHING. SELECTED SYS #2; SAME RESULT. COORD WITH ARTCC FOR DIVERT TO ZZZ. CABIN STOPPED CLBING ONCE DSCNT REACHED 14000 FT MSL. CABIN STARTED TO DSND. NORMAL SCHEDULE BY LNDG. MAINT OFFICIALS STATED THAT WITH NO SYS SWITCHING OR FAULT LIGHTS THAT AIR WAS ESCAPING THROUGH THE CABIN AT A RATE THAT THE SYS COULD NOT KEEP UP WITH. PACK OUTPUT NORMAL. COOLING NORMAL. XBLEED START NORMAL. MAINT STARTED PROC TO FIND CABIN LEAK POSSIBLY ASSOCIATED WITH APU PLUMBING. MAINT INDICATED THAT A BREAK IN APU BLEED AIR DUCT WOULD BE FAULTED BY GAS WIRE LENGTH OF TUBE; UNLESS WIRE BROKEN OR INOP; CREW DOES NOT HAVE TEST CAPABILITY OF BLEED LEAK DETECTORS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE HAS NOT HEARD FROM MAINT WHAT CAUSED THIS EVENT. HE DID LEARN THAT AS LONG AS THE PRESSURE CONTROLLERS ARE FUNCTIONING NORMALLY A SYS FAULT WILL NOT BE INDICATED. IN THIS CASE SINCE BOTH CONTROLLERS WERE UNSUCCESSFULLY ATTEMPTING TO CTL THE CABIN NO FAULT WOULD BE INDICATED BECAUSE THE FAILURE WAS NOT IN THE CONTROLLERS BUT IN SOME OTHER COMPONENT. A HIGH RATE OF CABIN CLB WAS INDICATED ON THE ECAM BUT BECAUSE THE RETURN TO LAND WAS INITIATED WITH THE CABIN AT ABOUT 7000 FT THE CABIN ALT WARNING DID NOT ILLUMINATE. THE RPTR ALSO STATED THAT IF A REVERSE AIR FLOW VALVE HAD FAILED AND AIR WAS ESCAPING THROUGH AN APU DUCT; THERE IS NO DETECTION SYS TO INDICATE THAT TYPE OF FAILURE. ADDITIONALLY; IF A FIRE/OVERHEAT WARNING LINE IS BROKEN OR MISSING; THE SYS WILL NOT INDICATE THE LACK OF DETECTION CAPABILITY AND OBVIOUSLY ALSO CANNOT INDICATE A FIRE/OVERHEAT CAUSED BY DUCT BLEED AIR LEAK.

Data retrieved from NASA's ASRS site as of January 2009 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.