# SDR ASAA2022060138538

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: June 1, 2022
- Submitted: June 3, 2022
- Operation: Air carrier
- Aircraft: [N428AS](https://openairdocs.org/aircraft/N428AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 36353
- Aircraft time: 22,879 hours, 7,187 cycles
- System (JASC): [2150 · Cabin Cooling System](https://openairdocs.org/jasc/2150)
- Part: Cabin Air Sys
- Part number: UNKNOWN
- Condition: Fluctuates
- Location: Unknown
- Stage of operation: CR
- How discovered: V
- Nature of condition: J
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2022060138538

## Discrepancy

WHILE LEVEL AT FL330 CABIN RATE INDICATOR CONTINUOUSLY FLUCTUATES BETWEEN +-200KPM. LH DUCT PRESSURE HOLD STEADY AT 40PSI. RH DUCT PRESSURE CONTINUOUSLY FLUCTUATES BETWEEN 42-46 PSI IN CONJUCTION WITH CABIN RATE INDICATOR. ALL OTHER PRESSURIZATION INDICATIONS STEADY AND INDICATING PROPERLY AND NORMAL. CABIN RATE FLUCTUATIONS GREATER WHEN CHANGING CABIN TEMPS. GROUNDED - YES. RAN B737-900 FIM 21-33 TASK 802, GVI OF RH PACK, NO LEAKS NOTED. RAN FIM 21-62 TASK 801 RH PFTC SHOWS EXISTING UNLATCHED FAULT 21-51253 FOR RH FCSOV, RAN FIM 21-62 TASK 857 RESET AND TEST OF RH PFTC, PASS TEST. OK FOR SERVICE.

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