A return land in a B727 mandated by loss of cabin pressure.

Attributes
ACN	316234
Time
Date	199509
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ape
State Reference	OH
Altitude	msl bound lower : 5000 msl bound upper : 23000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude other other
Route In Use	enroute : on vectors enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 239 flight time total : 6041 flight time type : 100
ASRS Report	316234
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Climbing out of cvg at approximately 5000 ft a very loud pack rumble began actually shaking the aircraft. The packs were isolated to determine which one was malfunctioning. The right pack was turned off first, the rumble continued and the cabin altitude began to increase rapidly. The right pack was reinstated and the left pack was secured. The rumble stopped and the pressurization returned to normal, although the cabin altitude was now between 2500-3000 ft. Climb out was continued and leveloff at FL230 was normal. A PA was made to advise the passenger that we had an air-conditioning problem, and that was what caused the noise and vibration. A radio call was then made to operations, maintenance and flight control to give them a heads up prior to our arrival in cle. While so was talking with maintenance, the cabin altitude started to rise slowly (800-1000 FPM). We requested a lower altitude from center and were given a descent to FL210. We advised center we had a pressurization problem but did not need to declare an emergency. We were first told there was no traffic below us but were then given a step down to FL200 and we saw an aircraft in front of and below us on TCASII. The cabin then began an off scale climb on the cabin altitude, we declared an emergency, center vectored, the traffic got out of the way, and the loss of pressurization and emergency descent checklists were performed. Center cleared us down to 10000 ft, but before we could get down, the cabin altitude warning horn sounded, and shortly thereafter, the passenger oxygen masks automatically deployed. This occurred just north of the appleton VOR, and since we no longer have maintenance in cle, the captain decided to return to cvg. Level off at 10000 ft was normal and we terminated the emergency. We still could not regain control of the pressurization. The cabin altitude and rate of descent followed that of the aircraft, we did a slow 700-800 FPM descent into cvg requesting a long downwind leg to minimize passenger discomfort.

Original NASA ASRS Text

Title: A RETURN LAND IN A B727 MANDATED BY LOSS OF CABIN PRESSURE.

Narrative: CLBING OUT OF CVG AT APPROX 5000 FT A VERY LOUD PACK RUMBLE BEGAN ACTUALLY SHAKING THE ACFT. THE PACKS WERE ISOLATED TO DETERMINE WHICH ONE WAS MALFUNCTIONING. THE R PACK WAS TURNED OFF FIRST, THE RUMBLE CONTINUED AND THE CABIN ALT BEGAN TO INCREASE RAPIDLY. THE R PACK WAS REINSTATED AND THE L PACK WAS SECURED. THE RUMBLE STOPPED AND THE PRESSURIZATION RETURNED TO NORMAL, ALTHOUGH THE CABIN ALT WAS NOW BTWN 2500-3000 FT. CLBOUT WAS CONTINUED AND LEVELOFF AT FL230 WAS NORMAL. A PA WAS MADE TO ADVISE THE PAX THAT WE HAD AN AIR-CONDITIONING PROB, AND THAT WAS WHAT CAUSED THE NOISE AND VIBRATION. A RADIO CALL WAS THEN MADE TO OPS, MAINT AND FLT CTL TO GIVE THEM A HEADS UP PRIOR TO OUR ARR IN CLE. WHILE SO WAS TALKING WITH MAINT, THE CABIN ALT STARTED TO RISE SLOWLY (800-1000 FPM). WE REQUESTED A LOWER ALT FROM CTR AND WERE GIVEN A DSCNT TO FL210. WE ADVISED CTR WE HAD A PRESSURIZATION PROB BUT DID NOT NEED TO DECLARE AN EMER. WE WERE FIRST TOLD THERE WAS NO TFC BELOW US BUT WERE THEN GIVEN A STEP DOWN TO FL200 AND WE SAW AN ACFT IN FRONT OF AND BELOW US ON TCASII. THE CABIN THEN BEGAN AN OFF SCALE CLB ON THE CABIN ALT, WE DECLARED AN EMER, CTR VECTORED, THE TFC GOT OUT OF THE WAY, AND THE LOSS OF PRESSURIZATION AND EMER DSCNT CHKLISTS WERE PERFORMED. CTR CLRED US DOWN TO 10000 FT, BUT BEFORE WE COULD GET DOWN, THE CABIN ALT WARNING HORN SOUNDED, AND SHORTLY THEREAFTER, THE PAX OXYGEN MASKS AUTOMATICALLY DEPLOYED. THIS OCCURRED JUST N OF THE APPLETON VOR, AND SINCE WE NO LONGER HAVE MAINT IN CLE, THE CAPT DECIDED TO RETURN TO CVG. LEVEL OFF AT 10000 FT WAS NORMAL AND WE TERMINATED THE EMER. WE STILL COULD NOT REGAIN CTL OF THE PRESSURIZATION. THE CABIN ALT AND RATE OF DSCNT FOLLOWED THAT OF THE ACFT, WE DID A SLOW 700-800 FPM DSCNT INTO CVG REQUESTING A LONG DOWNWIND LEG TO MINIMIZE PAX DISCOMFORT.

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.