# SDR ASAA2022042138081

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: April 21, 2022
- Submitted: April 25, 2022
- Operation: Air carrier
- Aircraft: [N428AS](https://openairdocs.org/aircraft/N428AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 36353
- Aircraft time: 22,464 hours, 7,086 cycles
- System (JASC): [3610 · Pneumatic Distribution System](https://openairdocs.org/jasc/3610)
- Part: Pressure Valve
- Part number: 32145526
- Part serial: 17122
- Condition: Stuck
- Location: #2 Engine
- Part time: 20,051 hours, 8,981 cycles
- Stage of operation: TO
- How discovered: V
- Nature of condition: O
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2022042138081

## Discrepancy

ON DEPARTURE DURING AFTER T/O CHECKLIST WE NOTED A DUCT PRESSURE SPLIT OF 27PSI (LEFT PACK AT 54/ RIGHT PACK AT 28) PRESSURE SPLIT DECREASED WITH A/C DECREASE BUT WAS STILL GREATER THAN 25PSI. GROUNDED - YES. PERFORMED DEFERRED MAINTENANCE LIMITS AND ABBREVIATED T/S REF B737-900 AMM 36-00-00-860-807. FOUND AT TABLE 1 STEP 5B WHEN MANUALLY OPENING #2 ENG PRSOV WITH BLEED AIR ON THE VALVE DID NOT MOVE TO THE FULL OPEN POSITION. NO LEAKS NOTED AT ANY SENSE LINES. REPLACED PRSOV PER B737-900 AMM 36-11-04. OPS CHECK WITH APU BLEED NORMAL. PERFORMED ENGINE BLEED AIR CROSSOVER OPS TEST PER AMM 36-11-00-710-801. FOUND #1 ENGINE DUCT PRESSURE TO BE WITHIN LIMITS. #2 ENGINE DUCT PRESSURE REMAINED CONSTANT AT 8-9 PSIG. WHILE PERFORMING #2 ENG HEALTH CHECK REF TASK CARD NG-36WC-00001. FOUND BAR OUT OF LIMITS . REMOVED AND REPLACED #2 ENG BAR REF AMM 36-11-03.

---
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.