# SDR A8JA201111260010

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 26, 2011
- Submitted: November 29, 2011
- Operation: Air carrier
- Aircraft: [N123FF](https://openairdocs.org/aircraft/N123FF), registered now
- Make and model: Cessna S550
- Registry model: [Cessna S550](https://openairdocs.org/model/cessna-s550) (OpenAirDocs)
- Aircraft serial: S5500005
- Aircraft time: 4,123 hours, 3,682 cycles
- System (JASC): [2497 · Electrical Power System Wiring](https://openairdocs.org/jasc/2497)
- Part: Connector
- Condition: Corroded
- Location: Inverter
- Stage of operation: CL
- How discovered: O
- Nature of condition: G, J
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/A8JA201111260010

## Discrepancy

DURING CLIMB,  AT 5000 FT IN IMC CONDITIONS, CREW NOTICED RED 'AC FAIL' LIGHT & A FLASHING "MASTER CAUTION" LIGHT.  CREW NOTICED AUTOPILOT DISENGAGE, ALTITUDE PRE-SELECT WENT BLANK, FLIGHT DIRECTOR "DISAPPEARED", & NR 1 ADI "TUMBLED".  "NR 1 INVERTER FAIL" AMBER LIGHT ILLUMINATED.  WHILE REVIEWING ABNORMAL PROCEDURES CHECKLIST, NR 1 ADI ERECTED FOR APPROX 15 SECONDS.  CREW CLEARED "MASTER CAUTION" & LEVELED OFF AT ASSIGNED ALTITUDE OF 5000 FT.  CREW GIVEN SECOND CLIMB TO 16000 FT WHEN NR 1 ADI TUMBLED AGAIN.  PILOT ELECTED TO RETURN TO DEPARTURE.  DID NOT DECLARE AN EMERGENCY, ATC ELECTED TO DECLARE AN EMERGENCY.  ACFT LANDED & TAXIED WITHOUT INCIDENT.  MX TROUBLESHOT SYS, INCLUDING A BENCH TEST OF NR 1 INVERTER.  NO OBVIOUS DEFECTS NOTED, MECHS DID CLEAN OXIDATION FROM THE INVERTER CONNECTORS & SWAPPED POSITIONS ON NR 1 AND 2 INVERTERS.  ACFT RELEASED FOR SERVICE.

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