# SDR ASAA2021110836570

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 8, 2021
- Submitted: November 12, 2021
- Operation: Air carrier
- Aircraft: [N462AS](https://openairdocs.org/aircraft/N462AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 36362
- Aircraft time: 28,002 hours, 8,997 cycles
- System (JASC): [7320 · Fuel Controlling System](https://openairdocs.org/jasc/7320)
- Part: Hmu
- Part number: 442653
- Part serial: BECW3590
- Condition: Faulty
- Location: #1 Engine
- Part time: 58,830 hours, 19,864 cycles
- Stage of operation: DE
- How discovered: V
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2021110836570

## Discrepancy

TOP OF DESCENT N1'S MATCHED AS THROTTLES RETARDED THROUGH 60% THEN #1 N1 LAGGED BY UPTO 12% AND TOOK ADDITIONAL 20 SECONDS TO REACH IDLE #2 ENG. GROUNDED - YES. VERIFIED FADEC3 SOFTWARE PER B737-900 IPC 73-21-60-01A. FOUND FMV DATA TO BE UNUSUAL DEMAND AND POSITION READ JUST UNDER 6% ON #1 ENG #2 ENG DEMAND AND POSITION READ APPROX 8%. B737-900 FIM 73-05 TASK 816 STEP E 8 REQUIRES HMU REPLACEMENT. REMOVED HMU PER T/C N8473000 AND REINSTALLED HMU PER T/C N8473001. LEAK AND OPS CK GOOD ON #1 HMU. VERIFIED N1'S AT ACCEL AND DECEL WERE MATCHED, OK FOR CONT'D SERVICE.

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