# SDR ASAA2020102833446

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 28, 2020
- Submitted: November 3, 2020
- Operation: Air carrier
- Aircraft: [N534AS](https://openairdocs.org/aircraft/N534AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35202
- Aircraft time: 37,343 hours, 10,766 cycles
- Engine: Cfmint CFM567B27
- System (JASC): [3610 · Pneumatic Distribution System](https://openairdocs.org/jasc/3610)
- Part: Regulator
- Part number: 1074847
- Part serial: 3116C
- Condition: Failed
- Location: Pnematic Sys
- Part time: 74,590 hours, 35,669 cycles
- Stage of operation: CR
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2020102833446

## Discrepancy

FOLLOW-UP TO REPORT OF LOW LEFT DUCT PRESS IN FLIGHT, ACCOMPLISH NR 1 ENGINE PNEUMATIC SYSTEM HEALTH CHECK, PER TASK CARD NG-36WC-00002-1.  GROUNDED-YES.  ACCOMPLISHED T/C NG-36WC-00002-1 NR 1 ENGINE BLEED AIR SYSTEM HEALTH CHECK.  NR 1 PRECOOLER CONTROL VALVE FAILS TO OPEN & OVER PRESSURE ON CONTROL SIDE.  NR 1 HSR FAILS TO SHUTOFF.  REPLACED NR 1 PRECOOLER CONTROL VALVE, REF B737-800 AMM 36-12-02-000-801 & 36-12-02-400-801.  REPLACED NR 1 HSR, REF AMM 36-11-07-000-801 & 36-11-07-400-801.  OPERATIONS & LEAK CHECK GOOD.  NO DEFECTS NOTED ON ANY OTHER SENSE LINES.  ACCOMPLISHED ENGINE BLEED AIR CROSSOVER OPERATIONAL TEST, REF AMM 36-11-00-710-801.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.