True Airspeed Indicator - Temp Trim?

Discussion in 'Maintenance Bay' started by 455 Bravo Uniform, Jul 10, 2017.

  1. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    On my 182P ASI, I have the manual rotating ring that has the true speed and pressure altitude, but there is no temperature marking to line the pressure altitude up with. Was it a decal or trim ring that had those markings on em? How do I get one?
     
  2. arnoha

    arnoha Line Up and Wait

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    Do you know what model ASI you have? Got a pic?
     
  3. AggieMike88

    AggieMike88 Touchdown! Greaser!

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    Now offering reverse discounts.
    This image is copied from a Google Search, and it's similar to 55WB's (1975 C182P)

    [​IMG]

    One thing to check on your aircraft is that the upper band on the outside of the rotating ring isn't covered up by the instrument panel overlay.
     
  4. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    That's a close enough pic with the plastic ring (mine ASI is in knots, no mph). Looking for the markings at 11 to 1 o'clock.

    About to head to the airport to see if it is indeed covered up.

    You guys are quick. Thank you.
     
  5. eetrojan

    eetrojan Pattern Altitude

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    Can you more experienced pilots elaborate a bit on how and why to use this TAS ring in real life?

    As to how, is it correct that you take these four steps?
    1. Get the pressure altitude (PA) by briefly setting your altimeter to 29.98”
    2. Get the Outside Air Temperature (OAT) by looking at the thermometer
    3. Move the ring to line up the PA with the OAT
    4. Read TAS next to indicated air speed

    As to why, I'm stumped.
    What do you routinely do with TAS in flight?
     
  6. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    How: I think that's right (29.92).

    Guess as to why: pre-GPS days for inflight fuel planning (prior to Step 5 of taking wind speed and direction into account with the e6b calculator to get ground speed...in conjunction with stopwatch and sectional to double check).
     
  7. eetrojan

    eetrojan Pattern Altitude

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    Thanks! I always seem to mis-remember that number instead of 29.92 for some reason.
     
  8. dmspilot

    dmspilot En-Route

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    Never used it "routinely" even when I had one. Most people probably just ignore it most of the time.
     
  9. mondtster

    mondtster Pattern Altitude

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    Do you look at cruise performance tables when you're flight planning? Wouldn't it be nice to know how your actual in flight performance stacks up against the book numbers for a given configuration? ;)

    Now, when I've been flying an airplane for a while and have made several cross country trips with it using the same configuration each time I generally don't continue to check the true airspeed. But you have check it often enough to know that your performance is repeatable before assuming that you're always going to get the same numbers every time.

    The need to know true airspeed hasn't gone away with the advent of GPS.
     
  10. mkosmo

    mkosmo Pattern Altitude

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    Or if you have a digital transponder that displays PA, use it :)
     
  11. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    There's actually a small cutout in the panel cover where the numbers should be.

    Is there a sticker or a bezel that's missing? If so, where can I find one? Low Googl saavy...
     
  12. RussR

    RussR Line Up and Wait

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    [QUOTE="register@teamandras.com, post: 2327143, member: 10823]Get the pressure altitude (PA) by briefly setting your altimeter to 29.98?[/QUOTE]

    (29.92) But in practice, getting your actual pressure altitude doesn't matter much. Maximum typical deviation from standard is only a few hundred feet, and given the scale of the instrument that's not going to make much of a difference. Typically I'll just set it to my current indicated altitude and know that my accuracy is probably only within a knot...
     
  13. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    Reviving this. So no one knows about a sticker, decal, or bezel for the temperature on an ASI?
     
  14. bnt83

    bnt83 Final Approach

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    I've never seen a replacement sticker for one. Mine is not a sticker but silkscreened painted on text on the bezel. You will either need to buy salvage or create youre own seems like about the only two options.
     

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  15. Bell206

    Bell206 Line Up and Wait

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    455:
    Call an instrument shop that repairs your P/N ASI. Inquire if it is a separate decal/plate/bezel. Doubtful that item will be procurable/repairable anywhere except a certified shop. For reference get a quote to install the temp ring. However, if it is a separate decal/plate might call the larger salvage ops and see if you can get a cheap unserviceable ASI with the decal/plate/bezel.
     
  16. Pilawt

    Pilawt Final Approach

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    Here's the ASI in my 172N. The temps look like they're printed (not just a decal) on an outer metal ring.

    Screen Shot 2017-12-06 at 7.28.51 AM.png