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Thread: OAT issues

  1. #1

    OAT issues

    Have 5600 and 5500 Dual screens with separate OAT's in my Evolution. The lowest temperature that is displayed on the screens is -30 deg. C. On many of my flights, I know that the true outside temp at FL 280 is into the -40's, but the units will display no lower than -30 C. Is this a software issue or a limit of the probes themselves? Because of this temp error, the displayed TAS will be incorrect. Can this be fixed through a software or hardware upgrade?
    Also, on a recent flight at FL240 determining performance at increasing power levels, the indicated OAT dropped 1 degree C. for every 12-15 knot increase in TAS. For example, at TAS of 237Kts, the OAT indicated -22 C. At 262 kts, it was -21 C., 286 kts it was -20 C; at 306 kts it indicated -19 C, at 312 kts it indicated -18 C. I then slowed back down to 237 kts and the OAT returned to -22 C. Does the algorithm for the OAT display take into account the warming of the probe due to friction with increasing speed?

  2. #2
    Advanced Flight Systems Shawn McGinnis's Avatar
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    Dynon's manual specifies the SV-OAT-340 to reach -40 but the software is limiting to -30C.

    I'll check with their engineering to see if anything can be done.
    Shawn McGinnis

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

  3. #3
    Thanks, I look forward to your reply

  4. #4
    Any progress on this? I am trying to build detailed performance numbers using the data logging on my AFS 5600, but with the lower limit of -30C, I don't get accurate TAS information in the flight levels. The ISA temp reaches -30C at 23,000 feet and I usually fly in the upper 20s where the ISA temp is about -40C. Thanks.

  5. #5
    Advanced Flight Systems Shawn McGinnis's Avatar
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    It appears this is in the testing phase at Dynon. I would imaging -40
    Shawn McGinnis

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

  6. #6
    Thanks. Let us know when this is upgraded.

  7. #7
    I noticed on a flight yesterday that the OAT minimum temp must have been reduced on the last software change. It looks like it's now -40C rather than -30C. Thank you, thank you. I didn't see that listed on the description of changes for the new software, so it was a pleasant surprise.

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