Gulfstream IV / G350 / G450
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Diverted; General Declared Emergency
Aircraft
An hour and a half into the flight at FL430 we noticed the cabin was ascending and the pressure differential was dropping. We tried to stop the ascent by following the QRH procedure with no success. A few minutes later the 'Cabin Press Low' message illuminated on the CAS system. At this point we donned our oxygen masks; declared an emergency; dropped the masks in the cabin and initiated an emergency descent procedure and diverted. At approximately 10;000 feet MSL we cancelled the emergency and made an uneventful landing. Upon further investigation there was no indication of bleed air pressure from the L Engine and L Bleed air CB and 28V cabin press CB's had popped.
GLF4 Captain experiences slow loss of cabin pressurization at FL430. An emergency descent is initiated and the flight diverts to a suitable airport. On post flight it was discovered that the L Bleed air CB and 28V Cabin press CB's had tripped.