N603AC

ATA 2131

AT FL 400, APPROX 2 HOURS INTO FLIGHT WE EXPERIENCED SOME PRESSURE CHANGES ON OUR EARS. CREW LOOKED AT THE CABIN RATE INDICATOR WHICH WAS INDICATING AN 800 FOOT CLIMB PER MINUTE. WE THEN OBSERVED THE DIFFERENTIAL PRESSURE DECREASING. (WAS AT 8.9 IN CRUISE). WE THEN NOTICED THE CABIN ALTITUDE RISING FROM THE CRUISE ALTITUDE OF 6800 FEET TO 10500 FEET IN APPROXIMATELY 4 TO 5 MINUTES. AT 10000 WE STARTED THE EMERGENCY DESCENT. ALL ASSOCIATED SYSTEMS WERE INSPECTED FOR DEFECTS, LEAKS AND FUNCTIONALITY. NO LEAKS WERE DISCOVERED, OUTFLOW VALVES FUNCTIONED AS INTENDED. CABIN PRESSURIZATION SYSTEM FUNCTIONAL CHECK PERFORMED NORMALLY. EMERGENCY PRESSURIZATION SYSTEM FUNCTIONED AS INTENDED. NO FAULTS WERE DETECTED BY THE CABIN PRESSURIZATION CONTROLLER FAULT INDICATOR. AIRCRAFT FLEW TO HOME BASE KDVT FROM KALS ON 8/21/2024 AFTER BEING RELEASED FROM MAINTENANCE WITH NO ISSUE OR ERRATIC INDICATION DURING FLIGHT. UPON RETURNING TO HOME BASE, WE BEGAN TO PERFORM MORE THROUGH INSPECTIONS WITH THE ASSISTANCE OF DUNCAN AVIATION AND IDENTIFIED A FAULT WITH THE CABIN PRESSURIZATION INDICATOR. THE CABIN PRESSURIZATION INDICATOR WAS REPLACED, AND ALL CABIN PRESSURIZATION VERIFICATIONS PASSED. AIRCRAFT WAS RETURNED TO SERVICE.

ATA 3150

APPROXIMATELY 20 MINS FROM PAE VOR, AT FL 430 (DESTINATIONCYVR) WE EXPERIENCED DUAL L & R BLEED AIR ANNUNCIATIONS. THE PIC ELECTED TO TRY & EXTINGUISH THE LIGHTS BY REDUCING THE THRUST LEVERS.AFTER APPROX 2 MINS, ASKED ATC FOR A DESCENT TO FL 400TO ASSIST IN MAINTAINING AIRSPEED WITH A REDUCED THRUST LEVER SETTING.AT FL 400 THE FLIGHT CREW INITIATED THE DUAL BLEED AIR CHECKLIST FROM THEQRH. AFTER INITIATING THE CHECKLIST, AND WAITING APPROXIMATELY 2-3MINS FOR THE PROCEDURE TO TAKE AFFECT, AND WITH THE BLEED AIR LIGHTSSTILL ON, THE CREW INITIATED THE MEMORY ITEM PROCEDURE (ONE BLEED AIROFF AND ONE BLEED AIR TO EMERGENCY). THE FLIGHT CREW THEN ALERTED ATC TO THE ISSUE, & DECLARED AN EMERGENCY REQUESTING A DIVERSION TOKBFI WHICH WAS APPROXIMATELY 10 MINUTES WEST OF OUR POSITION. ATC THEN GAVE US VECTORS TO KBFI AND WE CONTINUED OUR DESCENT. DURINGT HE DESCENT, AS WE RAN OUR NORMAL DESCENT & APPROACH CHECKLISTS,THE BLEED AIR LIGHTS EXTINGUISHED APPROXIMATELY FL 260.(APPROXIMATELY 15 MINUTES AFTER THE FIRST INITIAL ANNUNCIATION). WECONTINUED WITH A REDUCED THRUST LEVER SETTING TO MINIMIZE THEPOSSIBILITY OF RECEIVING THE ANNUNCIATIONS FOR A SECOND TIME ANDLANDED AT KBFI WITHOUT FURTHER INCIDENT. WHEN WE TAXIED INTO THEFBO, THE FIRE DEPARTMENT CHECKED THE AIRCRAFT FOR HEAT AND DAMAGE.THE FIRE DEPARTMENT MENTIONED HOT TEMPERATURES IN THE LAVATORY AREA, BUT NO OTHER PART OF THE AIRPLANE.