# SDR P5CA0200694

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 5, 2002
- Submitted: August 8, 2002
- Operation: Air carrier
- Aircraft: [N354MC](https://openairdocs.org/aircraft/N354MC), registered now
- Make and model: Boeing 747-300 SERIES
- Registry model: [Boeing 747-300 SERIES](https://openairdocs.org/model/boeing-747-300-series) (OpenAirDocs)
- Aircraft serial: 23394
- Aircraft time: 515,833 hours, 9,907 cycles
- System (JASC): [3417 · Air Data Computer](https://openairdocs.org/jasc/3417)
- Part: Adc
- Part number: 78031055
- Condition: Failed
- Location: Nr 1
- Stage of operation: CR
- How discovered: O
- Nature of condition: G
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/P5CA0200694

## Discrepancy

DUAL CADC FAILURE CAUSING FAILURE IN TRANSPONDER ALTITUDE REPORTING & INACCURATE ALTIMETER & AIRSPEED INDICATIONS.  NR 1 & NR 3 INS WOULD NOT UPDATE.  REMOVED AND REPLACED NR 1 CADC.  CHECKED ALL DRAINS FOR MOISTURE; NONE FOUND.  PURGED PITOT/STATIC LINES AND FITTINGS WITH DRY NITROGEN ON BOTH SYSTEMS.  RERACKED NR 2 CADC.  PERFORMED FULL PITOT STATIC CHECK FOR ALL ASSOCIATED AIR DATA INSTRUMENTS AND LEAKS IN THE SYSTEM.  NO LEAKS NOTED.

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