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Thread: erratic OAT readings

  1. #1
    Junior Member
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    Jul 2015
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    Palo Alto, CA
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    erratic OAT readings

    My 5600 has started reporting erratic OATs.

    On a flight yesterday from Oregon to California, the OAT on the EFIS indicated +18C, which seemed correct. Later the OAT showed -3C, then back to +17C, then -24C, then back to +17C. About ten minutes later it showed -64C, then -42C, then +18C. These indicators all occurred at the same altitude.

    The 5600 is in a Glasair Sportsman (if that matters) and has reliably reported OAT for two years, until lately.

    I would appreciate any suggestions for how to troubleshoot the problem.

    thanks,
    Bob

  2. #2
    Advanced Flight Systems Shawn McGinnis's Avatar
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    Sep 2012
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    Canby, OR
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    We have added some filtering to alleviate com transmission interference with the OAT in the recent releases of AF-5000 software. What version are you currently running. Did the error show up after a transmission? One way that has helped several customers is to disconnect the shield connection (black wire) of the three wire OAT sensor.
    Shawn McGinnis

    Advanced Flight Systems
    support@advanced-flight-systems.com

  3. #3
    Junior Member
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    Sean,
    I didn't notice whether the erratic readings coincided with radio transmissions. I don't think so, because I seem to recall it happening even when I wasn't on flight following (and therefore wasn't transmitting).
    A couple days ago I cleaned the OAT sensor and the contacts on its connector in the wing. Today I flew again and still got one OAT reading at -41C even though the actual OAT was +22C.
    My 5600 is running:
    SW X10.02.03 MV16 9/11/2014
    OS 1 12/2/2011
    FS 1.0
    BB 3
    NXP 1.9
    NET 6.3
    ARINC V4.0
    XPDR 2.04

    thanks,
    Bob

  4. #4
    Advanced Flight Systems Shawn McGinnis's Avatar
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    Sep 2012
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    Canby, OR
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    I emailed the software over to add the OAT delta monitoring. This should avoid the dips in temperature. If it continues after disconnect the shield connection (black wire) of the three wire OAT sensor.
    Shawn McGinnis

    Advanced Flight Systems
    support@advanced-flight-systems.com

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