A B727-200 flight departs msy with the left air conditioning pack MEL'ed. Plan was to fly at FL240 f...

Attributes
ACN	475480
Time
Date	200006
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : aex.airport
State Reference	LA
Altitude	msl single value : 22000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Route In Use	enroute airway : ns.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 300 flight time total : 13000 flight time type : 5000
ASRS Report	475480
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : instrument pilot : multi engine pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 5500 flight time type : 1500
ASRS Report	475771
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : improper documentation other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : cabin alt ind. other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to another airport flight crew : landed as precaution
Consequence	other other Other
Supplementary
Problem Areas	Aircraft Company Flight Crew Human Performance Maintenance Human Performance
Primary Problem	Aircraft

Narrative:

We were dispatched to FL240 due to the right air conditioning pack being inoperative for several maintenance carry-overs. We planned, with the dispatcher's approval, to try for FL240 and use a lower altitude if necessary, where the left air conditioning pack could maintain cabin pressure. From the previous flight, doubts existed concerning the capacity of the left air conditioning pack. Pushback, start, taxi and takeoff were normal. During climb out, passing FL220, it became apparent that the left pack would be unable to maintain cabin altitude below 10000 ft. We requested and received clearance in steps down to FL200, FL180, 16000 ft, 14000 ft, 12000 ft, 11000 ft, and finally 10000 ft where the cabin finally stabilized with the aircraft being virtually unpressurized. Both outflow valves were closed manually during the evolution, to no avail. Following a decision to divert to a close hub/maintenance base, an overweight landing was uneventfully accomplished, followed by an equipment swap and successful completion of the flight. Supplemental information from acn 475772: we were dispatched from msy to slc at FL240 due to the right pack being inoperative for several maintenance carry-overs. One of the maintenance carry-overs was detected en route to msy from atl, air mix valve inoperative. The procedure required that we turn the right pack off and continue to msy on a single pack. When this was attempted the cabin pressure started to climb slowly. Due to the fact that we were at altitude we elected to turn it back on and monitor it closely. The flight into msy was otherwise uneventful. After landing at msy the captain talked to the dispatcher and agreed that we could stop for fuel en route to ZLC if we were unable to maintain cabin pressure at FL240. Cabin altitude exceeded 10000 ft MSL for a short time and may have reached 11000 ft until we determined that we were not going to regain cabin pressure at all. All applicable procedures were followed. Oxygen masks were used and the cargo heat outflow valve and main outflow valves were manually closed. We diverted into dfw with concurrence of maintenance control and the dispatcher who came up with dfw WX and overweight landing data estimates.

Original NASA ASRS Text

Title: A B727-200 FLT DEPARTS MSY WITH THE L AIR CONDITIONING PACK MEL'ED. PLAN WAS TO FLY AT FL240 FOR DEST ARPT. FLT ENDS UP TOTALLY REPRESSURIZED AND DIVERTING TO DFW, TX.

Narrative: WE WERE DISPATCHED TO FL240 DUE TO THE R AIR CONDITIONING PACK BEING INOP FOR SEVERAL MAINT CARRY-OVERS. WE PLANNED, WITH THE DISPATCHER'S APPROVAL, TO TRY FOR FL240 AND USE A LOWER ALT IF NECESSARY, WHERE THE L AIR CONDITIONING PACK COULD MAINTAIN CABIN PRESSURE. FROM THE PREVIOUS FLT, DOUBTS EXISTED CONCERNING THE CAPACITY OF THE L AIR CONDITIONING PACK. PUSHBACK, START, TAXI AND TKOF WERE NORMAL. DURING CLBOUT, PASSING FL220, IT BECAME APPARENT THAT THE L PACK WOULD BE UNABLE TO MAINTAIN CABIN ALT BELOW 10000 FT. WE REQUESTED AND RECEIVED CLRNC IN STEPS DOWN TO FL200, FL180, 16000 FT, 14000 FT, 12000 FT, 11000 FT, AND FINALLY 10000 FT WHERE THE CABIN FINALLY STABILIZED WITH THE ACFT BEING VIRTUALLY UNPRESSURIZED. BOTH OUTFLOW VALVES WERE CLOSED MANUALLY DURING THE EVOLUTION, TO NO AVAIL. FOLLOWING A DECISION TO DIVERT TO A CLOSE HUB/MAINT BASE, AN OVERWT LNDG WAS UNEVENTFULLY ACCOMPLISHED, FOLLOWED BY AN EQUIP SWAP AND SUCCESSFUL COMPLETION OF THE FLT. SUPPLEMENTAL INFO FROM ACN 475772: WE WERE DISPATCHED FROM MSY TO SLC AT FL240 DUE TO THE R PACK BEING INOP FOR SEVERAL MAINT CARRY-OVERS. ONE OF THE MAINT CARRY-OVERS WAS DETECTED ENRTE TO MSY FROM ATL, AIR MIX VALVE INOP. THE PROC REQUIRED THAT WE TURN THE R PACK OFF AND CONTINUE TO MSY ON A SINGLE PACK. WHEN THIS WAS ATTEMPTED THE CABIN PRESSURE STARTED TO CLB SLOWLY. DUE TO THE FACT THAT WE WERE AT ALT WE ELECTED TO TURN IT BACK ON AND MONITOR IT CLOSELY. THE FLT INTO MSY WAS OTHERWISE UNEVENTFUL. AFTER LNDG AT MSY THE CAPT TALKED TO THE DISPATCHER AND AGREED THAT WE COULD STOP FOR FUEL ENRTE TO ZLC IF WE WERE UNABLE TO MAINTAIN CABIN PRESSURE AT FL240. CABIN ALT EXCEEDED 10000 FT MSL FOR A SHORT TIME AND MAY HAVE REACHED 11000 FT UNTIL WE DETERMINED THAT WE WERE NOT GOING TO REGAIN CABIN PRESSURE AT ALL. ALL APPLICABLE PROCS WERE FOLLOWED. OXYGEN MASKS WERE USED AND THE CARGO HEAT OUTFLOW VALVE AND MAIN OUTFLOW VALVES WERE MANUALLY CLOSED. WE DIVERTED INTO DFW WITH CONCURRENCE OF MAINT CTL AND THE DISPATCHER WHO CAME UP WITH DFW WX AND OVERWT LNDG DATA ESTIMATES.

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.

A B727-200 flight departs msy with the left air conditioning pack MEL'ed. Plan was to fly at FL240 for destination airport. Flight ends up totally repressurized and diverting to dfw, tx.