# SDR ASOA04346

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 13, 2004
- Submitted: June 17, 2004
- Operation: Air carrier
- Aircraft: [N632AS](https://openairdocs.org/aircraft/N632AS), registered now
- Make and model: Aerosp ATR 72-212
- Registry model: [Aerosp ATR 72-212](https://openairdocs.org/model/aerospatiale-atr-72-212) (OpenAirDocs)
- Aircraft serial: 338
- Engine: Pwa PW127
- System (JASC): [3452 · ATC Transponder System](https://openairdocs.org/jasc/3452)
- Part: Control Head
- Part number: 6226523207
- Condition: Inoperative
- Location: Atc
- Part time: 4,393 hours
- Stage of operation: CR
- How discovered: O
- Nature of condition: B, J
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASOA04346

## Discrepancy

ENROUTE, DURING CRUISE FLIGHT, CREW NOTICED AN OILY/WATERY SUBSTANCE ON THE TRANSPONDER RADIO HEAD.  SHORTLY FOLLOWING THE DIGITS DISAPPEARED AND ATC REPORTED TO THE CREW THAT THEY HAD LOST BOTH NR 1 AND NR 2 TRANSPONDERS.  THEN SMOKE WAS NOTICED IN COCKPIT BETWEEN THE CONDITION LEVERS FOR APPROXIMATELY 15-20 SECONDS.  ALL NON-ESSENTIAL EQUIPMENT WAS TURNED OFF, AND THE SMOKE DISSIPATED.  AN EMERGENCY WAS DECLARED AND AIRCRAFT DIVERTED, WHERE A SAFE LANDING WAS ACCOMPLISHED.  MAINTENANCE REMOVED AND REPLACED THE ATC CONTROL HEAD AND RESET THE TCAS CIRCUIT BREAKER.  OPERATIONAL CHECKS FOR BOTH ATC NR 1 AND NR 2 TRANSPONDERS GOOD.  AC RETURNED TO SERVICE.

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