Gulfstream IV / G350 / G450
Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 153; Flight Crew Total 1460; Flight Crew Type 650
Physiological - Other
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed As Precaution
Aircraft
Flying an IFR flight plan from ZZZ to ZZZ1; I was PIC; pilot flying. Dual crew; flying the XXX departure VIA radar vectors. In contact with center we were 'stepped up' to flight level 260. Once reaching 260; the 'cab press' (cabin pressure) CAWS illuminated. I gave controls to the SIC while I donned my O2 mask and took controls back and requested a descent and turn back to ZZZ mean while the SIC could read from the Emergency Checklist. Once I determined that the cabin pressure was maintaining pressure correctly according to the pressure gauge; I determined that an emergency descent was not imminent; but had the SIC and passengers don O2 masks while we completed a precautionary descent. We were not able to get to an acceptable lower altitude below 15k feet for O2 requirements for terrain on an IFR flight plan; so I requested VFR and continued my descent. The CAB PRESS CAWS went away between 18 and 16k feet. Once getting to an acceptable altitude; we removed and instructed passengers to remove O2 while we contacted ZZZ Approach; did a pop up IFR Flight plan into ZZZ and landed safely. Somewhere between 14 and 10k feet our pressure spiked and hurt the passengers and SICs ear drums. Again upon landing in ZZZ; we did a normal landing with full reverse input where the pressure again spiked. Multiple passengers complained about their ears upon landing and the SIC went to urgent care for complaining about pain in her ears; a 'liquid feeling' in her ears; and later determining that she had blood in her ear canals.Although; I did not feel that this situation did not require declaring an emergency; this plane has been written up MELed for both of these issues multiple times in the past and 'OPS CHECKED GOOD'.
Gulfstream IV Captain reported multiple malfunctions of the pressurization system; which caused physical discomfort to passengers and crew and resulted in return to the departure airport.