Aircraft equipment problem malfunction mandates an emergency descent after loss of cabin pressure.

Attributes
ACN	267544
Time
Date	199403
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : fwa
State Reference	IN
Altitude	msl bound lower : 10000 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau tower : mia
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Navigation In Use	Other
Flight Phase	cruise other 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 : 200 flight time total : 12000 flight time type : 2400
ASRS Report	267544
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
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 flight crew : exited adverse environment other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

We had been level at FL260 for about 10 mins when we noticed a 50 FPM rate of climb on the cabin vsi. We attempted to correct this by moving the packs up to the next highest setting. This gave us a rate of descent on the cabin altitude. One of the packs, however, overheated. We asked ZAU for FL240 to meet an aircraft limitation with 1 pack inoperative. During the delay between the request and the clearance to FL240, we switched to manual pressurization. We suspected an outflow valve as the cause of the cabin's inability to hold altitude. When we received our clearance to FL240, I began the descent. The cabin 'blew.' I noticed the cabin vsi pegged at 2000 FPM and the passenger oxygen light on, indicating the masks had dropped. I performed the 'rapid depressurization' memory items. We told ZAU we needed lower, now! They step descended us to 10000 ft. We performed an emergency descent. After leveling at 10000 ft, I requested a clearance to fwa. The aircraft was stable and there was no evidence of structural damage. I decided to return to cincinnati. After landing, maintenance discovered a 3 inch section of the cargo door seal had blown out. My crew performed a textbook example of how this situation should be handled. The passenger, who had been told they would not get any peanuts if they didn't listen to the flight attendant's predep safety briefing, performed as they were supposed to.

Original NASA ASRS Text

Title: ACFT EQUIP PROB MALFUNCTION MANDATES AN EMER DSCNT AFTER LOSS OF CABIN PRESSURE.

Narrative: WE HAD BEEN LEVEL AT FL260 FOR ABOUT 10 MINS WHEN WE NOTICED A 50 FPM RATE OF CLB ON THE CABIN VSI. WE ATTEMPTED TO CORRECT THIS BY MOVING THE PACKS UP TO THE NEXT HIGHEST SETTING. THIS GAVE US A RATE OF DSCNT ON THE CABIN ALT. ONE OF THE PACKS, HOWEVER, OVERHEATED. WE ASKED ZAU FOR FL240 TO MEET AN ACFT LIMITATION WITH 1 PACK INOP. DURING THE DELAY BTWN THE REQUEST AND THE CLRNC TO FL240, WE SWITCHED TO MANUAL PRESSURIZATION. WE SUSPECTED AN OUTFLOW VALVE AS THE CAUSE OF THE CABIN'S INABILITY TO HOLD ALT. WHEN WE RECEIVED OUR CLRNC TO FL240, I BEGAN THE DSCNT. THE CABIN 'BLEW.' I NOTICED THE CABIN VSI PEGGED AT 2000 FPM AND THE PAX OXYGEN LIGHT ON, INDICATING THE MASKS HAD DROPPED. I PERFORMED THE 'RAPID DEPRESSURIZATION' MEMORY ITEMS. WE TOLD ZAU WE NEEDED LOWER, NOW! THEY STEP DSNDED US TO 10000 FT. WE PERFORMED AN EMER DSCNT. AFTER LEVELING AT 10000 FT, I REQUESTED A CLRNC TO FWA. THE ACFT WAS STABLE AND THERE WAS NO EVIDENCE OF STRUCTURAL DAMAGE. I DECIDED TO RETURN TO CINCINNATI. AFTER LNDG, MAINT DISCOVERED A 3 INCH SECTION OF THE CARGO DOOR SEAL HAD BLOWN OUT. MY CREW PERFORMED A TEXTBOOK EXAMPLE OF HOW THIS SIT SHOULD BE HANDLED. THE PAX, WHO HAD BEEN TOLD THEY WOULD NOT GET ANY PEANUTS IF THEY DIDN'T LISTEN TO THE FLT ATTENDANT'S PREDEP SAFETY BRIEFING, PERFORMED AS THEY WERE SUPPOSED TO.

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.