Cabin door or door seal failure on astra spx results in emergency descent and diversion.

Attributes
ACN	675485
Time
Date	200510
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : zzz.vor
State Reference	US
Altitude	msl single value : 43000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	general aviation : corporate
Make Model Name	Gulfstream 100 [G100] (IAI 1125 Astra)
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 8500 flight time type : 500
ASRS Report	675485
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : door warning light
Resolutory Action	flight crew : diverted to another airport flight crew : declared emergency
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

The aircraft was on autoplt at FL430. About 45 mins into the flight; the 'cabin door' caution light illuminated on the annunciator panel. The PNF read the checklist for that item. The checklist said to remain below FL390 if no pressurization problems were present. (None were at the time and the aircraft was holding pressurization with a cabin altitude of 7500 ft.) we requested lower altitude with ATC and were given FL380. I began a descent on autoplt with a vertical speed of approximately 2000 FPM. At about FL420 and descending; a loud audible squeal was heard from the main cabin door. The squeal became very loud followed by a whooshing sound and physical rush of air. I looked at the cabin pressurization indicator. Cabin altitude vertical speed/vsi was pegged at +6000 FPM; the airplane was depressurizing very rapidly. The red 'cabin altitude' light illuminated on the annunciator panel; meaning cabin altitude was above 10000 ft MSL. We initiated a rapid descent to a safe altitude and declared an emergency. Once stabilized and level; we assessed the situation and determined the aircraft had no structural problems. We diverted to ZZZ. The cabin oxygen masks dropped. The cabin altitude reached a maximum of approximately 25000 ft.

Original NASA ASRS Text

Title: CABIN DOOR OR DOOR SEAL FAILURE ON ASTRA SPX RESULTS IN EMER DSCNT AND DIVERSION.

Narrative: THE ACFT WAS ON AUTOPLT AT FL430. ABOUT 45 MINS INTO THE FLT; THE 'CABIN DOOR' CAUTION LIGHT ILLUMINATED ON THE ANNUNCIATOR PANEL. THE PNF READ THE CHKLIST FOR THAT ITEM. THE CHKLIST SAID TO REMAIN BELOW FL390 IF NO PRESSURIZATION PROBS WERE PRESENT. (NONE WERE AT THE TIME AND THE ACFT WAS HOLDING PRESSURIZATION WITH A CABIN ALT OF 7500 FT.) WE REQUESTED LOWER ALT WITH ATC AND WERE GIVEN FL380. I BEGAN A DSCNT ON AUTOPLT WITH A VERT SPD OF APPROX 2000 FPM. AT ABOUT FL420 AND DSNDING; A LOUD AUDIBLE SQUEAL WAS HEARD FROM THE MAIN CABIN DOOR. THE SQUEAL BECAME VERY LOUD FOLLOWED BY A WHOOSHING SOUND AND PHYSICAL RUSH OF AIR. I LOOKED AT THE CABIN PRESSURIZATION INDICATOR. CABIN ALT VERT SPD/VSI WAS PEGGED AT +6000 FPM; THE AIRPLANE WAS DEPRESSURIZING VERY RAPIDLY. THE RED 'CABIN ALT' LIGHT ILLUMINATED ON THE ANNUNCIATOR PANEL; MEANING CABIN ALT WAS ABOVE 10000 FT MSL. WE INITIATED A RAPID DSCNT TO A SAFE ALT AND DECLARED AN EMER. ONCE STABILIZED AND LEVEL; WE ASSESSED THE SIT AND DETERMINED THE ACFT HAD NO STRUCTURAL PROBS. WE DIVERTED TO ZZZ. THE CABIN OXYGEN MASKS DROPPED. THE CABIN ALT REACHED A MAX OF APPROX 25000 FT.

Data retrieved from NASA's ASRS site as of January 2009 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.