# SDR 2009FA0000501

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 14, 2009
- Submitted: June 8, 2009
- Operation: General aviation
- Aircraft: [N2648X](https://openairdocs.org/aircraft/N2648X), registered now
- Make and model: Cessna 501
- Registry model: [Cessna 501](https://openairdocs.org/model/cessna-501) (OpenAirDocs)
- Aircraft serial: 5010105
- System (JASC): [3417 · Air Data Computer](https://openairdocs.org/jasc/3417)
- Part: Adc
- Part number: 24471
- Condition: Failed
- Stage of operation: DE
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2009FA0000501

## Discrepancy

AT APPROX 7:30 PM WE BEGAN A DESCENT OUT OF FL420 FOR OUR ARRIVAL.  OUTSIDE AIR TEMP WAS AS LOW AS -46 C AT ALTITUDE FOR 2 HOURS.  AT FL340 WE GOT THE YELOW AMBER ENUCIATOR LIGHT JUST ABOVE THE PFD ILLUMINATING "AIU FAIL".  OUTSIDE AIR TEMP WAS -31 C.  IMMEDIATELY WE LOST THE IAS AND ALT DATA OF THE PFD.  THE AUTO PILOT DID NOT DISCONNECT.  THIS OUTAGE LASTED APPROX 2 MINUTES AS  WE CONTINUED DESCENDING.  THE AIU FAIL LIGHT FINALLY EXTINGUISHED.  AT 3 HOURS AND 2 MINUTES INTO THE FLIGHT THE PFD FAILED AGAIN FOR APPROX 20 SECONDS.  OUTSIDE AIR TEMP WAS +3 C.  SAME SCENARIO.  AP DID NOT DISCONNECT  ALTHOUGH BELIEVE WE LOST THE ALT CAP ARMED MODE AND HAD TO RE-ARM ALT CAPTURE BOTH TIMES.  (K)

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