B737-800
Training / Qualification; Situational Awareness; Workload; Distraction
Aircraft Equipment Problem Critical
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Became Reoriented; Flight Crew Took Evasive Action; General Maintenance Action
Aircraft
Upon commencing our initial decent from FL400 to assigned FL340 the right BLEED TRIP OFF light illuminated and the right PAC failed. At this point we observed that the cabin altitude was increasing. I requested FL200 as we performed the QRH BLEED TRIP OFF procedure. We were cleared first to FL240 then FL200. The right BLEED TRIP OFF light reset per the QRH and the PAC was restored. About 10 seconds later the right BLEED TRIP OFF light again illuminated and the cabin altitude again began to climb. I then requested 10;000 feet and was cleared to 11;000 feet. When the right PAC switch was placed to the off position per QRH; the left PAC did not go to high flow and the cabin altitude continued to climb. As the cabin altitude reached 9;000 feet; we donned our oxygen masks; First Officer (FO) transitioned to a rapid decent (330kts; speed brakes to the flight detent) and we performed the first 4 items of the CABIN ALTITUDE WARNING or Rapid Depressurization checklist. We did momentarily receive a CABIN ALTITUDE WARNING during the decent; but the indicated cabin altitude never exceeded 10;000 feet during the evolution. I then requested 9;000 feet and was cleared to it. During the decent we never approached any of the intervening altitudes before being cleared lower.When we leveled at 9;000 feet and the power came off idle; the left PAC output increased sufficiently to return the pressurization to normal. We then proceeded to ZZZ for an uneventful landing an taxi in. The aircraft was subsequently removed from service.FO performance was excellent throughout the event and should be commended.I'm never reluctant to [state an emergency situation to ATC] inflight; however in this case due to the fact that the cabin altitude never exceeded 10;000 feet and that ATC never inhibited our decent; I didn't feel that our situation would be enhanced by doing so.
A B737-800 right BLEED TRIP OFF light illuminated followed by the A PACK Trip when thrust was reduced to begin a descent. Both reset but tripped again. With the cabin rising rapidly; the Rapid Depressurization Checklist was completed and the flight continued at 11;000 feet.