GLF2 on a maintenance test flight lost pressurization; declared an emergency and descended safely.

Attributes
ACN	844349
Time
Date	200907
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Gulfstream G200 (IAI 1126 Galaxy)
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 125 Flight Crew Total 8000 Flight Crew Type 400
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 65 Flight Crew Total 6900 Flight Crew Type 200
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

Our mission was to complete a post maintenance flight and to test the systems that were giving previous problems. The main system that was worked on was the environmental control system (ecs). After reaching our altitude of FL390; I exercised the temperature controller where the origin of our previous problems were detected. After about a minute the cabin altitude began to climb. After noticing that we were losing pressurization; we put on our masks and asked for a descent to 10;000 ft. We were given FL380 due to traffic. The cabin was rising quickly; so at that point we declared an emergency. ATC gave us a vector; then a descent to 11;000 ft. Once we leveled at 8000; we called off the emergency and requested a return to our home base. On the ground; we called the center and thanked them for their help and professionalism.

Original NASA ASRS Text

Title: GLF2 on a maintenance test flight lost pressurization; declared an emergency and descended safely.

Narrative: Our mission was to complete a post maintenance flight and to test the systems that were giving previous problems. The main system that was worked on was the environmental control system (ECS). After reaching our altitude of FL390; I exercised the temperature controller where the origin of our previous problems were detected. After about a minute the cabin altitude began to climb. After noticing that we were losing pressurization; we put on our masks and asked for a descent to 10;000 FT. We were given FL380 due to traffic. The cabin was rising quickly; so at that point we declared an emergency. ATC gave us a vector; then a descent to 11;000 FT. Once we leveled at 8000; we called off the emergency and requested a return to our home base. On the ground; we called the Center and thanked them for their help and professionalism.

Data retrieved from NASA's ASRS site as of April 2012 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.