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A BAE800XP flight crew received a cabin altitude warning horn in cruise at FL410. They declared an emergency; descended; and diverted to the nearest suitable airport; where maintenance found a loose clamp on a duct.
| Attributes | |
| ACN | 814498 |
| Time | |
| Date | 200812 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | msl single value : 41000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | general aviation : corporate |
| Make Model Name | BAe 125 Series 800 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : multi engine pilot : instrument pilot : atp pilot : cfi pilot : commercial |
| Experience | flight time last 90 days : 72 flight time total : 10000 flight time type : 810 |
| ASRS Report | 814498 |
| Events | |
| Anomaly | aircraft equipment problem : critical |
| Independent Detector | aircraft equipment other aircraft equipment : cabin altitude warning |
| Resolutory Action | flight crew : diverted to another airport flight crew : declared emergency |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
Flying northbound approximately 70 mi off the coast at FL410; the aircraft experienced a rise in cabin altitude which exceeded 10000 ft. Cabin altitude horn sounded and 'cabin altitude' master warning illuminated. Cabin altitude indicator showed in red somewhere between 10000 ft and 12000 ft. Donned oxygen masks; declared emergency with center controller; requested lower altitude and initiated descent. Informed center that we would be turning towards land and we were given routing direct to ZZZ. Requested and received a clearance to level off at 10000 ft. Center controller handed us off to ZZZ approach and we executed a visual approach to runway xx with an uneventful landing. On approach; the warning horn silenced and the master warning extinguished while descending through 8000 ft. On examination; maintenance found that the duct sleeve between the water separator and the turbine outlet duct had a loose clamp which allowed the sleeve to work itself open during flight. Aircraft was approximately 10 hours out of a 48 month inspection.
Original NASA ASRS Text
Title: A BAE800XP FLIGHT CREW RECEIVED A CABIN ALTITUDE WARNING HORN IN CRUISE AT FL410. THEY DECLARED AN EMERGENCY; DESCENDED; AND DIVERTED TO THE NEAREST SUITABLE AIRPORT; WHERE MAINTENANCE FOUND A LOOSE CLAMP ON A DUCT.
Narrative: FLYING NBOUND APPROX 70 MI OFF THE COAST AT FL410; THE ACFT EXPERIENCED A RISE IN CABIN ALT WHICH EXCEEDED 10000 FT. CABIN ALT HORN SOUNDED AND 'CABIN ALT' MASTER WARNING ILLUMINATED. CABIN ALT INDICATOR SHOWED IN RED SOMEWHERE BTWN 10000 FT AND 12000 FT. DONNED OXYGEN MASKS; DECLARED EMER WITH CTR CTLR; REQUESTED LOWER ALT AND INITIATED DSCNT. INFORMED CTR THAT WE WOULD BE TURNING TOWARDS LAND AND WE WERE GIVEN ROUTING DIRECT TO ZZZ. REQUESTED AND RECEIVED A CLRNC TO LEVEL OFF AT 10000 FT. CTR CTLR HANDED US OFF TO ZZZ APCH AND WE EXECUTED A VISUAL APCH TO RWY XX WITH AN UNEVENTFUL LNDG. ON APCH; THE WARNING HORN SILENCED AND THE MASTER WARNING EXTINGUISHED WHILE DSNDING THROUGH 8000 FT. ON EXAMINATION; MAINT FOUND THAT THE DUCT SLEEVE BTWN THE WATER SEPARATOR AND THE TURBINE OUTLET DUCT HAD A LOOSE CLAMP WHICH ALLOWED THE SLEEVE TO WORK ITSELF OPEN DURING FLT. ACFT WAS APPROX 10 HRS OUT OF A 48 MONTH INSPECTION.
Data retrieved from NASA's ASRS site as of May 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.