Loss of cabin pressurization results in emergency descent.

Attributes
ACN	145712
Time
Date	199005
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bvt
State Reference	IN
Altitude	msl bound lower : 28500 msl bound upper : 28500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 3750
ASRS Report	145712
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : declared emergency none taken : unable none taken : anomaly accepted
Consequence	faa : investigated
Supplementary
Primary Problem	Aircraft

Narrative:

Loss of pressurization occurred passing through FL285. It was first discovered because a popping sensation in the ears. Corrective actions were taken by leveling the aircraft, manually controling the outflow valves, and eventually making an emergency descent. My first thought was that the second officer had made an operational error. After scanning his panel and not finding that to be so, I ordered manual operation. When this procedure did not produce the desired results, an emergency descent was executed. Although the procedure was performed correctly, the experience level of the first and second officers did have an effect on the quality of the maneuver in that the time to execute the maneuver was lengthened. Upon landing and FAA inspection of the aircraft, insulation was found wedged in the left-aft outflow valve. At this time I have not been informed as to whether the insulation actually belonged in the adjacent areas and therefore it is impossible for me to offer an opinion as to how to correct the problem.

Original NASA ASRS Text

Title: LOSS OF CABIN PRESSURIZATION RESULTS IN EMERGENCY DESCENT.

Narrative: LOSS OF PRESSURIZATION OCCURRED PASSING THROUGH FL285. IT WAS FIRST DISCOVERED BECAUSE A POPPING SENSATION IN THE EARS. CORRECTIVE ACTIONS WERE TAKEN BY LEVELING THE ACFT, MANUALLY CTLING THE OUTFLOW VALVES, AND EVENTUALLY MAKING AN EMER DSNT. MY FIRST THOUGHT WAS THAT THE S/O HAD MADE AN OPERATIONAL ERROR. AFTER SCANNING HIS PANEL AND NOT FINDING THAT TO BE SO, I ORDERED MANUAL OPERATION. WHEN THIS PROC DID NOT PRODUCE THE DESIRED RESULTS, AN EMER DSNT WAS EXECUTED. ALTHOUGH THE PROC WAS PERFORMED CORRECTLY, THE EXPERIENCE LEVEL OF THE FIRST AND SECOND OFFICERS DID HAVE AN EFFECT ON THE QUALITY OF THE MANEUVER IN THAT THE TIME TO EXECUTE THE MANEUVER WAS LENGTHENED. UPON LNDG AND FAA INSPECTION OF THE ACFT, INSULATION WAS FOUND WEDGED IN THE LEFT-AFT OUTFLOW VALVE. AT THIS TIME I HAVE NOT BEEN INFORMED AS TO WHETHER THE INSULATION ACTUALLY BELONGED IN THE ADJACENT AREAS AND THEREFORE IT IS IMPOSSIBLE FOR ME TO OFFER AN OPINION AS TO HOW TO CORRECT THE PROBLEM.

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.