C560 crew was required to make an emergency descent because of a cabin door seal failure.

Attributes
ACN	551363
Time
Date	200206
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : gso.airport
State Reference	NC
Altitude	msl single value : 39000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl.artcc
Operator	general aviation : corporate
Make Model Name	Citation III, VI, VII
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute : direct
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 : 7700 flight time type : 1000
ASRS Report	551363
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : failed door seal annunciator light other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance controller : provided flight assist flight crew : declared emergency flight crew : diverted to another airport flight crew : landed in emergency condition other
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Flight from mdw-SOP. Had an annunciator light illuminate indicating a failed cabin door seal. About 1 min later (after completing checklist items), heard a loud 'pop' and the sound of air blowing at the door. Advised center that we had a door seal fail and that we needed to descend. Started a precautionary emergency descent to 15000 ft. Center gave us an altitude of FL350 and we again advised we needed to get down. They asked how low, we said 15000 ft. They cleared us down to 15000 ft and we opted to land at gso which was nearest suitable airport instead of continuing to SOP. Cabin did not lose pressure rapidly, no further services were requested from ATC or crash fire rescue equipment people on the ground. Landing uneventful. Plane was put into the service center for repair. Outcome unknown at this time. How problem arose: unknown (possibly inadequate seal. High humidity at departure 90 degrees F to -60 degrees C at altitude may have caused ice on seal). Corrective actions: checklist and precautionary emergency descent. Decision: took the most safe option of precautionary descent and landing at nearest suitable airport. Actions: pilots already were wearing oxygen due to checklist for 'door seal' annunciator. Opted to also drop the passenger masks as a precaution. Also kept passenger informed along the way to ease their anxiety. Factors affecting human performance: 1) inadequate checklists that leave lots of gray areas in dealing with potential emergencys. 2) difficulty in crew communication with oxygen masks on.

Original NASA ASRS Text

Title: C560 CREW WAS REQUIRED TO MAKE AN EMER DSCNT BECAUSE OF A CABIN DOOR SEAL FAILURE.

Narrative: FLT FROM MDW-SOP. HAD AN ANNUNCIATOR LIGHT ILLUMINATE INDICATING A FAILED CABIN DOOR SEAL. ABOUT 1 MIN LATER (AFTER COMPLETING CHKLIST ITEMS), HEARD A LOUD 'POP' AND THE SOUND OF AIR BLOWING AT THE DOOR. ADVISED CTR THAT WE HAD A DOOR SEAL FAIL AND THAT WE NEEDED TO DSND. STARTED A PRECAUTIONARY EMER DSCNT TO 15000 FT. CTR GAVE US AN ALT OF FL350 AND WE AGAIN ADVISED WE NEEDED TO GET DOWN. THEY ASKED HOW LOW, WE SAID 15000 FT. THEY CLRED US DOWN TO 15000 FT AND WE OPTED TO LAND AT GSO WHICH WAS NEAREST SUITABLE ARPT INSTEAD OF CONTINUING TO SOP. CABIN DID NOT LOSE PRESSURE RAPIDLY, NO FURTHER SVCS WERE REQUESTED FROM ATC OR CFR PEOPLE ON THE GND. LNDG UNEVENTFUL. PLANE WAS PUT INTO THE SVC CTR FOR REPAIR. OUTCOME UNKNOWN AT THIS TIME. HOW PROB AROSE: UNKNOWN (POSSIBLY INADEQUATE SEAL. HIGH HUMIDITY AT DEP 90 DEGS F TO -60 DEGS C AT ALT MAY HAVE CAUSED ICE ON SEAL). CORRECTIVE ACTIONS: CHKLIST AND PRECAUTIONARY EMER DSCNT. DECISION: TOOK THE MOST SAFE OPTION OF PRECAUTIONARY DSCNT AND LNDG AT NEAREST SUITABLE ARPT. ACTIONS: PLTS ALREADY WERE WEARING OXYGEN DUE TO CHKLIST FOR 'DOOR SEAL' ANNUNCIATOR. OPTED TO ALSO DROP THE PAX MASKS AS A PRECAUTION. ALSO KEPT PAX INFORMED ALONG THE WAY TO EASE THEIR ANXIETY. FACTORS AFFECTING HUMAN PERFORMANCE: 1) INADEQUATE CHKLISTS THAT LEAVE LOTS OF GRAY AREAS IN DEALING WITH POTENTIAL EMERS. 2) DIFFICULTY IN CREW COM WITH OXYGEN MASKS ON.

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.