# SDR ASAA2022010737088

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: January 7, 2022
- Submitted: January 11, 2022
- Operation: Air carrier
- Aircraft: [N557AS](https://openairdocs.org/aircraft/N557AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35176
- Aircraft time: 57,187 hours, 16,605 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Modulating Valve
- Part number: 3989085
- Part serial: 13884
- Condition: Faulty
- Location: Left Ecs Bay
- Part time: 37,036 hours, 12,324 cycles
- Stage of operation: TX
- How discovered: V
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2022010737088

## Discrepancy

CONTROL CABIN ZONE TEMP LIGHT ILLUMINATED ON RECALL AFTER START. LIGHT OUT ON MASTER CAUTION RESET. GROUNDED - YES. CONFIRMED FAULT, #2 PACK/ZONE TEMP CONTROLLER BITE TEST SHOWS HARD FAIL "FLIGHT DECK" TCV (V143). REMOVED & REPLACED SAME PER B737-800 AMM 21-61-21, LK CK & GROUND FUNCTIONAL CK NML REF AMM 21-61-00-700-806-002.

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