# SDR 99ZZZX1812

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 18, 1999
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: [N734ST](https://openairdocs.org/aircraft/N734ST), registered now
- Make and model: Cessna 172N
- Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (OpenAirDocs)
- Aircraft serial: 17269083
- Engine: Lyc O320H2AD
- System (JASC): [3416 · Altimeter, Barometric/Encoder](https://openairdocs.org/jasc/3416)
- Part: Transponder
- Condition: Failed
- Location: Encoder
- Component: Narco, AT50A
- Stage of operation: NR
- Nature of condition: O
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/99ZZZX1812

## Discrepancy

FOUND TRANSPONDER TRANSMITTING A CONSTANT A2 CODE IN MODE C.  REPLACED DEFECTIVE INTEGRATED CIRCUIT U106 (PN 740190001).  NO RECOMMENDATIONS TO PREVENT RECURRENCE.

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