C550 crew lost cabin pressurization twice after adjusting the pack temperature control. The aircraft...

Attributes
ACN	594757
Time
Date	200309
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mgm.airport
State Reference	AL
Altitude	msl bound lower : 10000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : ztl.artcc tracon : mgm.tracon
Operator	general aviation : corporate
Make Model Name	Citation II S2/Bravo
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude cruise : level descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : instrument pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 120 flight time total : 2875 flight time type : 950
ASRS Report	594757
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance
Independent Detector	aircraft equipment other aircraft equipment : cabin altimeter rate of clb other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : declared emergency flight crew : diverted to another airport other
Consequence	other
Factors
Maintenance	performance deficiency : fault isolation performance deficiency : training performance deficiency : testing performance deficiency : repair
Supplementary
Problem Areas	Aircraft FAA Maintenance Human Performance
Primary Problem	Aircraft

Narrative:

We departed destin, fl (dts) for pontiac, mi (ptk). As we were climbing through FL275 we started losing pressurization after adjusting the temperature control lever. We stopped our climb at FL280 and referred to the emergency checklist. Despite using checklist procedures we were unable to control cabin pressure. As a result we requested and began our descent to 10000 ft. The first officer was flying and the captain was doing checklists, radios and assuming passenger safety. We received vectors for a visual approach and landing at mgm. On the ground, the FBO maintenance, in accordance with our company's maintenance department, inspected for the overweight landing, svced the oxygen, inspected and repacked the passenger oxygen masks and inspected and svced the pressurization. Ground pressurization checks were completed and maintenance returned the aircraft to service in an airworthy condition. We departed mgm for ptk. We leveled off at a cruise altitude of FL290. Pressurization was holding well until the cabin temperature knob was adjusted to a warmer setting. Immediately, the cabin began to depressurize. We went through the emergency checklist, but were still unable to control cabin pressure. As a result we requested and began our descent to 10000 ft. The captain was flying and the first officer did checklists, radios and assured passenger safety. At 10000 ft we noticed our pressurization had been restored. We discussed the option of continuing the flight to ptk noting fuel and oxygen requirements. We agreed that the flight could continue safely at 10000 ft and discussed it with our passenger. As the flight continued, we maintained normal pressurization and agreed to climb to 14000 ft to get a better fuel burn. The pressurization remained normal for the remainder of the flight. The crew maintained proper coordination and communication throughout the entire trip. ATC responded to us efficiently and they were attentive to all requests.

Original NASA ASRS Text

Title: C550 CREW LOST CABIN PRESSURIZATION TWICE AFTER ADJUSTING THE PACK TEMP CTL. THE ACFT ONLY HAS A SINGLE PACK. WHEN IT TRIPS OFF THE ACFT HAS NO PRESSURIZATION SOURCE.

Narrative: WE DEPARTED DESTIN, FL (DTS) FOR PONTIAC, MI (PTK). AS WE WERE CLBING THROUGH FL275 WE STARTED LOSING PRESSURIZATION AFTER ADJUSTING THE TEMP CTL LEVER. WE STOPPED OUR CLB AT FL280 AND REFERRED TO THE EMER CHKLIST. DESPITE USING CHKLIST PROCS WE WERE UNABLE TO CTL CABIN PRESSURE. AS A RESULT WE REQUESTED AND BEGAN OUR DSCNT TO 10000 FT. THE FO WAS FLYING AND THE CAPT WAS DOING CHKLISTS, RADIOS AND ASSUMING PAX SAFETY. WE RECEIVED VECTORS FOR A VISUAL APCH AND LNDG AT MGM. ON THE GND, THE FBO MAINT, IN ACCORDANCE WITH OUR COMPANY'S MAINT DEPT, INSPECTED FOR THE OVERWT LNDG, SVCED THE OXYGEN, INSPECTED AND REPACKED THE PAX OXYGEN MASKS AND INSPECTED AND SVCED THE PRESSURIZATION. GND PRESSURIZATION CHKS WERE COMPLETED AND MAINT RETURNED THE ACFT TO SVC IN AN AIRWORTHY CONDITION. WE DEPARTED MGM FOR PTK. WE LEVELED OFF AT A CRUISE ALT OF FL290. PRESSURIZATION WAS HOLDING WELL UNTIL THE CABIN TEMP KNOB WAS ADJUSTED TO A WARMER SETTING. IMMEDIATELY, THE CABIN BEGAN TO DEPRESSURIZE. WE WENT THROUGH THE EMER CHKLIST, BUT WERE STILL UNABLE TO CTL CABIN PRESSURE. AS A RESULT WE REQUESTED AND BEGAN OUR DSCNT TO 10000 FT. THE CAPT WAS FLYING AND THE FO DID CHKLISTS, RADIOS AND ASSURED PAX SAFETY. AT 10000 FT WE NOTICED OUR PRESSURIZATION HAD BEEN RESTORED. WE DISCUSSED THE OPTION OF CONTINUING THE FLT TO PTK NOTING FUEL AND OXYGEN REQUIREMENTS. WE AGREED THAT THE FLT COULD CONTINUE SAFELY AT 10000 FT AND DISCUSSED IT WITH OUR PAX. AS THE FLT CONTINUED, WE MAINTAINED NORMAL PRESSURIZATION AND AGREED TO CLB TO 14000 FT TO GET A BETTER FUEL BURN. THE PRESSURIZATION REMAINED NORMAL FOR THE REMAINDER OF THE FLT. THE CREW MAINTAINED PROPER COORD AND COM THROUGHOUT THE ENTIRE TRIP. ATC RESPONDED TO US EFFICIENTLY AND THEY WERE ATTENTIVE TO ALL REQUESTS.

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.

C550 crew lost cabin pressurization twice after adjusting the pack temperature control. The aircraft only has a single pack. When it trips off the aircraft has no pressurization source.