IFR in an older Cessna?

Discussion in 'Cleared for the Approach' started by DKirkpatrick, Jan 7, 2021.

  1. DKirkpatrick

    DKirkpatrick Pre-takeoff checklist

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    Hi. Can you legally fly IFR approaches in an older Cessna with external venturii for the attitude indicator and heading indicator? I think the airplane has a heated pitot, but not sure, and don't know if that's a requirement either... although I can't believe you'd wanna make a practice of coming down through the clouds on a cold day without it.
    Coaching is appreciated!
    thanks
     
  2. Country Flier

    Country Flier Pre-takeoff checklist

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    Legal? Yes. For training? You bet! In actual IFR? No thanks!
     
  3. RussR

    RussR Pattern Altitude

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    I trained a client for his instrument rating in exactly that setup. 1960 (?) Cessna 172. I was actually surprised how quickly the gyros were usable after takeoff. They really spun up pretty fast, to the point where by a couple hundred feet up, they seemed just fine.

    We actually only did the first 3/4 of his training in it, then he bought a Comanche and gained a good 60 knots or so!

    As far as actual IFR, once you're going fast enough, the venturi is far more reliable than a vacuum pump. Short of icing it up or hitting a bird, there's almost no way for it to break.
     
  4. DKirkpatrick

    DKirkpatrick Pre-takeoff checklist

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    thank you for the replies. This "fits the mission, then..." Buying a 172 for three folks in my family to learn to fly in... and this could take them even into some IFR training. I appreciate the help.
     
  5. bnt83

    bnt83 Final Approach

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    I wouldn't be surprised if a lot of the vitriol over venturi is caused by pilots that have never flown them before.
     
  6. GRG55

    GRG55 Final Approach

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    Vitriol? Can't recall hearing any of that about venturis. But I've heard lots of vitriol from friends who own airplanes when their vacuum pumps have failed. :D

    Personally, the mech eng in me subscribes to two philosophies when it comes to little airplanes; simpler is almost always better because it reduces or eliminates failure modes, and I prefer redundancy when the failure mode can't be eliminated and it's a critical component or function.

    Friend of mine just bought a very nice 1953 Cessna 170 with a Lycoming 180 hp STC. But they kept the dual venturis on that baby. :thumbsup:
     
  7. asicer

    asicer Final Approach

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    I wouldn't describe it as "vitriol", but I'm not a big fan of things hanging out in the wind. However, on a C172 it's merely yet another drop in a rather large bucket. :)
     
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  8. brcase

    brcase Pattern Altitude

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    Why not? Really not should be flying most cessna singles IMC in below freezing conditions anyway. In non freezing conditions, as mentioned, it is probably more reliable than a vacuum pump system.

    Brian
    CFIIG/ASEL
     
  9. chemgeek

    chemgeek Pattern Altitude

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    Of course, it's entirely possible to remove the vacuum system if you have the appropriate instrumentation. My vacuum system is gone and the aircraft is 10 pounds lighter to boot.
     
  10. GRG55

    GRG55 Final Approach

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    For really little airplanes I have gotten rid of the instrumentation. Vacuum pump failed on the way back from Oshkosh in my first airplane, a Cherokee 160. I ended up removing the vacuum system and the two gyro instruments. It was always a VFR plane.

    I'm thinking seriously about doing the same with my Husky now. Simpler. Lighter. Fewer failure modes.
     
  11. Dan Thomas

    Dan Thomas Final Approach

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    That right there. If your venturi ices up you have much bigger trouble developing.
     
  12. Country Flier

    Country Flier Pre-takeoff checklist

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    I do whatever I can to avoid ice, but in 25 years of flying, ice has found me twice. Getting immediately out of icing is enough of a distraction, without worrying that the gyro instruments will quit too. I have also had a pump failure, but the thought of having a pump failure at the same time as encountering ice does not sound like my cup of tea.
     
  13. Maxnr

    Maxnr Pre-takeoff checklist

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    Yeah, you can do approaches with a venturi driven instrument. Departures? That's another story. I got my first hood time in a venturi equipped airplane. It was well, well known around the airfield that it takes at least five minutes at cruise to spin up a gyro. Now icing? Stay away from Ice.
     
  14. texasclouds

    texasclouds Cleared for Takeoff

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    Legal, of course. Reliable? Less moving parts than a vacuum pump. Would I do it? Sure, with proper training and proficiency. Low IFR in a older single engine with limited equipment? Let’s stay home that day.
     
  15. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    The fear I have with venturis is that is how long after takeoff I'd have to fly before i worried about the gyros being stable. It's one thing to sit around on the ground with the engine running while they spin up, its another to have to wait until you're rolling down the runway.
     
  16. IK04

    IK04 Pattern Altitude

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    I did some IFR flights in an airplane that didn't have provisions for a vacuum pump. Those venturis would produce plenty of suck just from the propeller...
     
  17. AeroLudite

    AeroLudite Pre-Flight

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    Replace one or both gyros with a Uavionix AV30. add a Garmin 175 or 355.

    I was strongly considering a 1956 Cessna 172 with dual nav/coms, g/s, audio panel. STC’d in ‘60’s to an O300D engine w/vacumn pumps. Venturis were removed.
    Until a Piper Cherokee 140 with a Garmin 430WAAS, dual g/s, etc fell in my lap. Added a BendixKing AeroCruze 100 autopilot. Uavionix Tailbeacon ADS-b. It’s all I can stand to keep up with demand for IFR training.
    I avoid icing like the plague...regardless of a/c flown.

    a C182 I flew had a shuttle valve allowing a mounted Venturi to function as a standby vacumn source... Good economical alternative.
     
  18. MBDiagMan

    MBDiagMan En-Route

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    No! Surely not! That only happens when it comes to those who claim that there isn’t enough room in a Mooney but they have admittedly never been inside one before.
     
    Last edited: Apr 18, 2021 at 7:39 AM