Narrative:

Crew arrived at aircraft at scheduled time and were met by mechanic and told all of what had been done in regards to the discrepancies from a previous flight on 10/thurs/04 involving an air turn back. After reviewing log book and waiting for last minute cargo offload, we pushed back and completed engine starts and taxi out for an uneventful takeoff on runway 33R. On climb out an erratic temperature flux was noted on #1 acm gauge by selecting #3 temperature indicated steady. Before top of climb got zone one over temperature with temperature controller in automatic with maximum cold selected, since zone one trim valve indicated full heat selected manual temperature control and drove trim valve toward cool. Since zone one temperature remained high went to trim master off procedures selected zone two as master because #1 had seemed erratic. The acm temperature on #1 pack still erratic with fluctuations to higher temperatures, #1 pack tripped as temperature fluctuated up to 185 degrees. Was able to reset first time, unable to reset on subsequent attempt, doors not positioning properly. Made attempt in manual but could not gain control. Because of previous history with this aircraft and extended over water flight planned made attempt to contact company for guidance with no luck, checked our position and elected to divert to ZZZZ1,first officer. We jettisoned 60000 pounds of fuel and made a normal 585000 pound landing at ZZZZ1,first officer. Due to one pack operation, aircraft depressurized in the descent at about 6000 ft altitude when differential decreased to zero. Callback conversation with reporter revealed the following information: the reporter was the flight engineer on this B747-100 that was involved in a previous diversion and fuel dump incident caused by the #3 pack air cycle machine failure. After repairs were made, the airplane was again dispatched over water and at top of climb, the #1 pack air cycle machine displayed erratic temperatures, the zone 1 control tripped for over temperature and then the #1 pack tripped off. Now operating with one pack on extended over water flight, it was decided to divert. Fuel was dumped and the diversion station advised but landing was delayed. After a short wait, an uneventful landing was made. Maintenance replaced the #1 air cycle machine and the zone one trim air valve due to found failed open. Also replaced were several #1 pack sensors. While the above work was being done it was discovered the auxiliary power unit pneumatic ducting was cracked and the auxiliary power unit pneumatic check valve was found failed. These units were also replaced.

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Original NASA ASRS Text

Title: A B747-100 ON CLB DIVERTED AND DUMPED FUEL DUE TO #1 PACK AIR CYCLE MACHINE ERRATIC, ZONE ONE TEMP HIGH AND #1 PACK TRIPPED OFF OVER TEMP.

Narrative: CREW ARRIVED AT ACFT AT SCHEDULED TIME AND WERE MET BY MECHANIC AND TOLD ALL OF WHAT HAD BEEN DONE IN REGARDS TO THE DISCREPANCIES FROM A PREVIOUS FLT ON 10/THURS/04 INVOLVING AN AIR TURN BACK. AFTER REVIEWING LOG BOOK AND WAITING FOR LAST MINUTE CARGO OFFLOAD, WE PUSHED BACK AND COMPLETED ENG STARTS AND TAXI OUT FOR AN UNEVENTFUL TKOF ON RWY 33R. ON CLB OUT AN ERRATIC TEMP FLUX WAS NOTED ON #1 ACM GAUGE BY SELECTING #3 TEMP INDICATED STEADY. BEFORE TOP OF CLB GOT ZONE ONE OVER TEMP WITH TEMP CTLR IN AUTO WITH MAX COLD SELECTED, SINCE ZONE ONE TRIM VALVE INDICATED FULL HEAT SELECTED MANUAL TEMP CTL AND DROVE TRIM VALVE TOWARD COOL. SINCE ZONE ONE TEMP REMAINED HIGH WENT TO TRIM MASTER OFF PROCS SELECTED ZONE TWO AS MASTER BECAUSE #1 HAD SEEMED ERRATIC. THE ACM TEMP ON #1 PACK STILL ERRATIC WITH FLUCTUATIONS TO HIGHER TEMPS, #1 PACK TRIPPED AS TEMP FLUCTUATED UP TO 185 DEGS. WAS ABLE TO RESET FIRST TIME, UNABLE TO RESET ON SUBSEQUENT ATTEMPT, DOORS NOT POSITIONING PROPERLY. MADE ATTEMPT IN MANUAL BUT COULD NOT GAIN CTL. BECAUSE OF PREVIOUS HISTORY WITH THIS ACFT AND EXTENDED OVER WATER FLT PLANNED MADE ATTEMPT TO CONTACT COMPANY FOR GUIDANCE WITH NO LUCK, CHKED OUR POSITION AND ELECTED TO DIVERT TO ZZZZ1,FO. WE JETTISONED 60000 LBS OF FUEL AND MADE A NORMAL 585000 LB LNDG AT ZZZZ1,FO. DUE TO ONE PACK OPERATION, ACFT DEPRESSURIZED IN THE DSCNT AT ABOUT 6000 FT ALT WHEN DIFFERENTIAL DECREASED TO ZERO. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS THE FLT ENGINEER ON THIS B747-100 THAT WAS INVOLVED IN A PREVIOUS DIVERSION AND FUEL DUMP INCIDENT CAUSED BY THE #3 PACK AIR CYCLE MACHINE FAILURE. AFTER REPAIRS WERE MADE, THE AIRPLANE WAS AGAIN DISPATCHED OVER WATER AND AT TOP OF CLB, THE #1 PACK AIR CYCLE MACHINE DISPLAYED ERRATIC TEMPS, THE ZONE 1 CTL TRIPPED FOR OVER TEMP AND THEN THE #1 PACK TRIPPED OFF. NOW OPERATING WITH ONE PACK ON EXTENDED OVER WATER FLT, IT WAS DECIDED TO DIVERT. FUEL WAS DUMPED AND THE DIVERSION STATION ADVISED BUT LNDG WAS DELAYED. AFTER A SHORT WAIT, AN UNEVENTFUL LNDG WAS MADE. MAINT REPLACED THE #1 AIR CYCLE MACHINE AND THE ZONE ONE TRIM AIR VALVE DUE TO FOUND FAILED OPEN. ALSO REPLACED WERE SEVERAL #1 PACK SENSORS. WHILE THE ABOVE WORK WAS BEING DONE IT WAS DISCOVERED THE AUXILIARY POWER UNIT PNEUMATIC DUCTING WAS CRACKED AND THE AUXILIARY POWER UNIT PNEUMATIC CHECK VALVE WAS FOUND FAILED. THESE UNITS WERE ALSO REPLACED.

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.