What was found
AIRCRAFT GROUNDED - EMERGENCY DECLARED - DESCENDING, EXPERIENCED SUDDEN LOSS OF PRESSURIZATION, ALL MASKS DEPLOYED AT FL380 WHEN CABIN ALT LIGHT CAME ON FOLLOWED BY ALT HORN SOUNDING AND BOTH BLEED TRIP-OFF LIGHTS ILLUMINATED. FLIGHT CREW FOLLOWED BLEED TRIP-OFF IN QRH (QUICK REFERENCE HANDBOOK) AND PRESSURIZATION WAS RESTORED. ENGINE ANTI-ICE WAS ON. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT LANDED AT DENVER SAFELY WITHOUT FURTHER INCIDENT. ***SUPPLEMENTAL REPORT: ACCOMPLISHED HEALTH CHECKS FOR LEFT ENGINE PER WORKCARD 4414, AND RIGHT ENGINE PER WORKCARD 4415; REPLACED THE FOLLOWING COMPONENTS, PER APPLICABLE WORKCARD: LEFT ENGINE BLEED AIR REGULATOR (AALA202007139003), LEFT ENGINE 390 DEGREE/PRECOOLER CONTROL VALVE SENSOR (AALA202007279015), LEFT ENGINE 450 DEGREE/BLEED AIR OVERTEMP SENSOR (AALA202007279016), RIGHT ENGINE 390 DEGREE/PRECOOLER CONTROL VALVE SENSOR (AALA202007279018), AND RIGHT ENGINE 450 DEGREE/BLEED AIR OVERTEMP SENSOR (AALA202007279019). (CLOSED)