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.