What was found
PRESSURIZATION CANNOT KEEP THE CORRECT CABIN PRESSURE AT FL340 DIFF PRESSURE ONLY6.5 CABIN ALT TO 10K FT OUTFLOW APPEA REDFULLCLS PERFORMED PRESSURIZATION SYSTEM GROUND TEST REF AMM 21-31-00 ON PRESSURE CONTROLLER #1 AND #2. BOTH SYSTEMS BITE TEST OK. THREE EXISTING FAULTS OBSERVED: LO INFL / HI LEAKG ; CAB ALT 10000 FT ; MANUAL SWITCH. PER FLT CREW DEBRIEF - FL340 ON ''AUTO'' MODE F/O NOTICED DIFF PRE SS IND AT 6.5, CREW SAID SHOULD BE AT @ 8.0. THERE WERE NO WARN, MSTR CAUTION, CABIN ALT OR PRESS AUTO FAIL LIGHT ILLUM & NO AUR AL. ON DESCENT, CREW SEL ''ALTN'' MODE, STATED NO CHANGE ON DIFF P FOUND FLEXIBLE DUCT BETWEEN THE RIGHT PACK ACM AND THE HPWS CONDENSER RUPTURED. ALSO FOUND LEFT PACK FLEXIBLE DUCT BETWEEN THE ACM AND THE HPWS CONDENSER HAS A INCH AND A HALF SPLIT IN IT. WHILE INSPECTING THE TORN FLEXIBLE HOSES, ON RIGHT PACK SIDE FOUND HEAT EXCHANGER CONDENSER HAS CRACKS ON UNDERSIDE/BELLY. SEE ATTACHED PICS. RESS IND, THEN SEL ''MAN'' MODE. WHILE DESCENDING TO FL10, CABIN A LT LIGHT ILLUM, CREW THEN MANUALLY DEPLOYED PASS OXY. CREW STATE D - PRESSURIZATION, PNEUMATICS & PACKS WERE ALL NORMAL. REPLACED LEFT PACK FLEXIBLE DUCT BETWEEN THE ACM AND THE HPWS CONDENSER PER AMM 21-51-00. NEEDS TO BE LEAK CHECKED. PARTS USED: 19-4700-3-0012,QTY :1 C/W PACK OPERATION CONFIDENCE CHECK PER AMM 21-00-05-780-801 GRND OPS CHK AND SYSTEM CHK NORMAL OK TO CONTINUE.