Falcon 50 crew lost cabin pressurization at FL430, and did an emergency descent to 10000 ft.

Attributes
ACN	637037
Time
Date	200411
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 43000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	general aviation : personal
Make Model Name	Falcon 50
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company other
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 120 flight time total : 5800 flight time type : 2600
ASRS Report	637037
Person 2
Affiliation	company other
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : cabin differential press other flight crewa other flight crewb
Resolutory Action	controller : provided flight assist controller : issued new clearance flight crew : diverted to another airport flight crew : declared emergency other
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

We had been cruising at FL430 for about 45 mins when we suddenly lost aircraft pressurization. The cabin light and cabin horn came on simultaneously. I immediately did an emergency descent. During the emergency descent I discovered I could not talk to center with my oxygen mask on. The first officer realized I could not communicate with center, then he got in touch with center and declared an emergency as we were descending below FL400. The first officer proceeded with the checklist as center cleared us down to 10000 ft. Center gave us vectors to ZZZ where we made an uneventful landing. During the emergency descent I noticed our cabin psi had dropped to 0 psi and our cabin altitude had increased to 14000 ft. When we noticed all the above we tried to manually pressurize the airplane. The manual pressurization mode did not work, maybe because our power was at flight idle while doing the descent, I don't know. I contacted center and tower and asked if any reports needed to be filled out and both said no. Callback conversation with reporter revealed the following information: maintenance went over the aircraft with a fine tooth comb. All door seals were inspected. All electronics checked normal. Maintenance replaced the cabin pressurization controller, as a precaution. Nothing was found positively. The aircraft has been restr to overland rtes. The aircraft, over the past 6 weeks was normal.

Original NASA ASRS Text

Title: FALCON 50 CREW LOST CABIN PRESSURIZATION AT FL430, AND DID AN EMER DSCNT TO 10000 FT.

Narrative: WE HAD BEEN CRUISING AT FL430 FOR ABOUT 45 MINS WHEN WE SUDDENLY LOST ACFT PRESSURIZATION. THE CABIN LIGHT AND CABIN HORN CAME ON SIMULTANEOUSLY. I IMMEDIATELY DID AN EMER DSCNT. DURING THE EMER DSCNT I DISCOVERED I COULD NOT TALK TO CTR WITH MY OXYGEN MASK ON. THE FO REALIZED I COULD NOT COMMUNICATE WITH CTR, THEN HE GOT IN TOUCH WITH CTR AND DECLARED AN EMER AS WE WERE DSNDING BELOW FL400. THE FO PROCEEDED WITH THE CHKLIST AS CTR CLRED US DOWN TO 10000 FT. CTR GAVE US VECTORS TO ZZZ WHERE WE MADE AN UNEVENTFUL LNDG. DURING THE EMER DSCNT I NOTICED OUR CABIN PSI HAD DROPPED TO 0 PSI AND OUR CABIN ALT HAD INCREASED TO 14000 FT. WHEN WE NOTICED ALL THE ABOVE WE TRIED TO MANUALLY PRESSURIZE THE AIRPLANE. THE MANUAL PRESSURIZATION MODE DID NOT WORK, MAYBE BECAUSE OUR PWR WAS AT FLT IDLE WHILE DOING THE DSCNT, I DON'T KNOW. I CONTACTED CTR AND TWR AND ASKED IF ANY RPTS NEEDED TO BE FILLED OUT AND BOTH SAID NO. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: MAINT WENT OVER THE ACFT WITH A FINE TOOTH COMB. ALL DOOR SEALS WERE INSPECTED. ALL ELECTRONICS CHKED NORMAL. MAINT REPLACED THE CABIN PRESSURIZATION CTLR, AS A PRECAUTION. NOTHING WAS FOUND POSITIVELY. THE ACFT HAS BEEN RESTR TO OVERLAND RTES. THE ACFT, OVER THE PAST 6 WKS WAS NORMAL.

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.