What was found
DEPARTING FROM MMUM, THE CREW NOTICED A FAULT LIGHT ON THE PRESSURIZATION CONTROL PANEL ILLUMINATED AND THE AIRCRAFT WOULD NOT PRESSURIZE. THEY COMPLETED THEIR CHECKLIST FOR PRESSURIZATION FAULTS, FAULT LIGHT REMAINED ON. AFTER BURNING ENOUGH FUEL TO MEET LANDING REQUIREMENTS, THEY LANDED SAFELY BACK AT MMUM. ANOTHER ATI JET AIRCRAFT WAS DISPATCHED TO COMPLETE THE INTENDED TRIP. THE CREW SWAPPED TO EXPEDITE THE PASSENGERS DEPARTURE. THE SECOND CREW PERFORMED A PRESSURIZATION CHECK ACCORDING TO THE LEARJET M.M. ALL INDICATIONS WERE NORMAL AT THAT TIME. THE CREW DECIDED TO REFUEL AND ATTEMPT THE FLIGHT TO KELP, AFTER REFUELING, JUST BEFORE TAKE OFF, ANOTHER PRESSURIZATION CHECK WAS PERFORMED WITH NO DISCREPANCIES NOTED. THE AIRCRAFT COMPLETED THE INTENDED FLIGHT BACK TO KELP WITH NO ISSUES. ATI MAINTENANCE COMPLETED A DETAILED INSPECTION OF THE PRESSURIZATION SYSTEM WITH NO PROBABLE CAUSES DISCOVERED.