Narrative:

Shortly after departing the captain (pm) selected ecs [environmental control system] to hi-flow due to a warm cockpit; which is fairly normal for hot weather. At FL180; climb checks were completed with normal pressurization. Just prior to entering oceanic airspace; at approximately FL270; the captain deselected ecs hi-flow to allow for a normal in-flight airflow to cockpit and cabin. Very shortly after this deselecting; the crew noticed that ecs airflow was nill and that the cabin was climbing above a normal schedule. A very brief discussion was had about the abnormal cabin pressure and rate of climb; which was approximately 1;000 to 1;300 fpm with the cabin now climbing through 8;000 feet and the cabin altitude display in amber. ATC was contacted and advised that we had lost our cabin. They promptly cleared us for an immediate descent and turn us towards our planned depressurization alternate. The aircraft reached approximately FL300 prior to initiating the descent. The cabin continued to climb; peaking at slightly over 14;000 feet as we descended to 7;000 MSL. The rate of cabin climb was somewhat erratic; but not excessive at about 1;000 to 1;300 fpm. When level at 7;000 we discussed about burning fuel prior to landing since the situation was stabilized and no urgency was felt to land immediately. The first officer maintained the radios and flew while I contacted the company to advise them of the situation. They asked if we could safely divert to another nearby station since they were working another G-200 at that location. The crew agreed and we changed our destination with ATC; proceeded directly there and landed without incident.maintenance found a clamp on the ecs line was not installed as required. I suggest we inspect other G200 aircraft which have had ecs maintenance at that facility as well as other G200s with suspect airflow.

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Original NASA ASRS Text

Title: A GLF-2 flight crew suffered loss of pressurization as they approached cruise altitude. They descended promptly and diverted to a nearby airport where maintenance crews were available. Maintenance determined an ECS clamp had been improperly installed.

Narrative: Shortly after departing the Captain (PM) selected ECS [Environmental Control System] to Hi-Flow due to a warm cockpit; which is fairly normal for hot weather. At FL180; climb checks were completed with normal pressurization. Just prior to entering Oceanic Airspace; at approximately FL270; the Captain deselected ECS Hi-Flow to allow for a normal in-flight airflow to cockpit and cabin. Very shortly after this deselecting; the crew noticed that ECS airflow was nill and that the cabin was climbing above a normal schedule. A very brief discussion was had about the abnormal cabin pressure and rate of climb; which was approximately 1;000 to 1;300 fpm with the cabin now climbing through 8;000 feet and the cabin altitude display in amber. ATC was contacted and advised that we had lost our cabin. They promptly cleared us for an immediate descent and turn us towards our planned Depressurization Alternate. The aircraft reached approximately FL300 prior to initiating the descent. The cabin continued to climb; peaking at slightly over 14;000 feet as we descended to 7;000 MSL. The rate of cabin climb was somewhat erratic; but not excessive at about 1;000 to 1;300 fpm. When level at 7;000 we discussed about burning fuel prior to landing since the situation was stabilized and no urgency was felt to land immediately. The First Officer maintained the radios and flew while I contacted the company to advise them of the situation. They asked if we could safely divert to another nearby station since they were working another G-200 at that location. The crew agreed and we changed our destination with ATC; proceeded directly there and landed without incident.Maintenance found a clamp on the ECS line was NOT installed as required. I suggest we inspect other G200 aircraft which have had ECS maintenance at that facility as well as other G200s with suspect airflow.

Data retrieved from NASA's ASRS site as of July 2013 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.