# SDR ASAA2021062835193

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: June 28, 2021
- Submitted: June 29, 2021
- Operation: Air carrier
- Aircraft: [N918AK](https://openairdocs.org/aircraft/N918AK), registered now
- Make and model: Boeing 737-9
- Registry model: [Boeing 737-9](https://openairdocs.org/model/boeing-737-9) (OpenAirDocs)
- Aircraft serial: 44083
- Aircraft time: 589 hours, 289 cycles
- Engine: Cfmint LEAP1A23
- System (JASC): [7710 · Power Indicating System](https://openairdocs.org/jasc/7710)
- Part: Status Message
- Condition: Illuminated
- Location: Fan Speed
- Stage of operation: IN
- How discovered: 9
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2021062835193

## Discrepancy

WHILE PERFORMING T/C 05-020-01, FOUND PRESENT LEG FAULT MAINTENANCE MESSAGE 73-44632 FAN SPEED (N1) SENSOR LOW TOOTH SIGNAL IS INVALID. DETECTED BY ENG 1 EEC CHANNEL-B FAULT IS NOT ACTIVE AND UNCORRELATED. GROUNDED - YES. MAINTENANCE MESSAGE IS UNCORRELATED AND FAULT IS NOT ACTIVE AT THIS TIME A/C IS ACCEPTABLE FOR DISPATCH REF 737-9 IFIM GENERAL INFO AND STANDARD FAULT ISOLATION PRACTICES STEP 3 A (1) (C).

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