B737 flight crew reported a loss of cabin pressurization during descent when operating on one pack per MEL. Crew landed per MEL with bleeds off.
Synopsis
B737 flight crew reported a loss of cabin pressurization during descent when operating on one pack per MEL. Crew landed per MEL with bleeds off.
Narrative
Operating on MEL XXXXX. Prior to MEL; left pack was putting out 85 degree celsius air. Mx (Maintenance) tried to fix and yet it was worse. All duct temps were above 40 deg celsius. Mx figured out proper procedure and got duct temps down to 10 deg Celsius. We accepted jet at that point and started. Right pack only was weak but cold. Determined safe to continue. Took off and got to cruise uneventfully. Upon descent passing through approx 14;500 feet; cabin altitude warning horn sounded. Cabin alt showed approximately 10;500. Accomplished immediate action items. Opened speed windows and accelerated to 330. FO completed loss of cabin QRC and FM (Flight Manual) checklist. Requested priority handling. Utilized Captain's priority handling authority and exceeded 250 below 10k to minimize time with cabin altitude greater than 10k. Landed uneventfully at ZZZ on ILS XX. Set up for packs off landing IAW (In Accordance With) MEL below 2500'. Cabin O2 masks did not drop. Debriefed with Chief Pilot. Wrote up aircraft for loss of pressurization.
Second reporter narrative
We departed ZZZ1 uneventfully after an over 3 hour delay caused by the failure of the left pack. After MX (Maintenance) cleared the aircraft we noticed the right pack was weak but blowing cold air with both the APU or the engine running. We took off uneventfully per the MEL (bleeds off take off and landing) and had an uneventful flight until descending through approx 14;500 on the arrival into ZZZ. The cabin pressure alarm went off. We completed the memory items; broke out the checklist; and ran the loss of cabin pressurization through the end of the procedure. We configured per the MEL for a bleeds off landing once below 2500' AGL. We landed safely on runway XX via the ILS XX and taxied safely to the gate. The loss of pressurization was written up once in the chocks and passengers and crew safely and normally left the aircraft.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.