Vent Tubes

[ryan602]

I am new to this 170 thing but am enjoying it so far. I bought the ventubes for cabin air. When I started installing them I found what would appear to be a radiator hose in the left wing instead of the aluminum tube that is supposed to be there. The only parts book I have was downloaded from microtools, and I can't make out what parts I need to order. I have a '48 170.

Any help would be appreciated.

Ryan

[4583C]

Ryan
Welcome to the board. I looked thru all the wing pages and couldn't find what I think you are looking for either. Finally found it in Figure 56 if you can find that in what you have. There is an elbow in each wing (0413233 ) which attaches to the tube the vent slides into (0413163-8 LH and 0413163-9 RH) Hope this helps. Paul

[n2582d]

Ryan,
The fig. 56 Paul mentions is in the 170B parts manual. In looking at the 170 parts manual, (fig. 15, pg. 28) and the 170A parts manual, (fig. 17, pg. 28) the straight "tube assy." that the vent slides in is the same p/n as for the 170B. http://www.Iwantcessnaparts.com say the tube assy. is also used on the C-152, 172, 182 and 200 series Cessnas.

I'm on a layover in Minneapolis now so just returned from a parts scrounging run at Wentworth for my 170B project. They had a whole box full of those vent assemblies there. The guy I talked to said they go for $35-40. http://www.wentworthaircraft.com/ I'm sure any other salvage yard would have them as well.

The 170 parts manual listed the elbow, or what they call the "scoop assy - cabin ventilator" as p/n 0413234. Fig. 4-22 on pg. 8 doesn't show it very clearly but it is the same p/n in the right wing. See fig. 8-20 for a slightly better picture. Any of you others with straight 170s know if this elbow is the same as the elbow, p/n 0413233, in later models?

[PilotMikeTX]

I have a couple of questions about the vent tube parts as well.

What is the part# for the part that is supposed to keep the vent from coming out of the vent tube? I believe it is called the "retainer". It seems to be part snap ring, part gasket. Is it an AN part, or do I need to source one through a Cessna parts dealer. I'm sure it's the same part in almost all the 100 series.

What is the correct size felt material that is supposed to seal the vent in the vent tube and where do I find it? Spruce only has 1.25" x 1/16 or 3/32. It seems like it should be at least 1/8" thick, if not more.

And is there supposed to be any sort of gasket material between the "head" (the dome shaped outer part of the vent) and the vent tube? Mine had what appeared to be some old crusty RTV type residue. A few used ones that I've seen online look like they've either had RTV or some foam insulation in there to seal it when it's closed. I'm of the opinion that the way they are designed, the vent should simply snap closed over the vent tube with no material at all between them. Of course, they might whistle a little, but with mine missing the felt and all the crusty crap on mine, they BLOW cold air on my leg when they're closed.

Any help is appreciated. Thanks.

[Robert Eilers]

I rebuilt my airvents using felt purchased at the local hardware store. Once rebuilt the vents worked well and did not leak. No foam or other type of sealer was needed for the dome cap. There was a good example of how to rebuild the air vents on this forum, unfortunately I have not been able to relocated it for you.

[PilotMikeTX]

I rebuilt my airvents using felt purchased at the local hardware store. Once rebuilt the vents worked well and did not leak. No foam or other type of sealer was needed for the dome cap. There was a good example of how to rebuild the air vents on this forum, unfortunately I have not been able to relocated it for you.

Thanks! Did you go to the "Big Orange" place for your felt, or do you have a real hardware store with useful hard-to-find stuff where you live? I've looked at the HD and Lowes for something similar.

[3958v]

Guys quit looking at the hardware store and send your wife to the fabric store. Then use contact cement to secure the fabic inside the tube. Then cover your insert with saran and insert it to keep the fabric pressed tightly to the outside surface until the adhesive cures. Bill K

[flat country pilot]

Guys quit looking at the hardware store and send your wife to the fabric store.

Ditto that, The big hardware stores have synthetic felt and the fabric/quilting stores have genuine wool felt.
There is a difference.

The other Bill K

[GAHorn]

To repair your original Cessna cabin vents is easy. (And a whole lot cheaper than buying those ugly aftermarket add-ons). Simply go to the local hardware store and ask for felt weather-stripping. It comes in various widths and lengths coiled up in plastic bags. Disassemble the vent. First, simply pull it out completely into the cockpit by hand. (Notice that it has two spring-loaded plungers at its base. When it comes time to reinstall them, one must depress these plunger-balls before inserting the vent into its tube.) Unscrew the small-knob on the vent or the temperature gauge and remove the cup shaped end. Clean off all the old felt.
This is a good time to clean up the aluminum tube and cup. One way to do this is with a bench grinder and a linen wheel to polish it bright. I used a bit of jeweler’s rouge to load the wheel first, but one might also simply use a rag and some metal polish. When finished, be sure to clean the metal with alcohol to afford a clean surface for adhesive.
Tip: Hardware or plumbing supply houses handle large flat rubber washers. These are very useful when replacing/re-sealing the thermometer thru-mountings, if your vent is so equipped.
Cut new felt to measure. The lower seal will simply be cut about 1” wide by about 7 inches long. Shorten it as necessary when you wrap it around the tube. Make certain it completely surrounds the tube in order to make a complete seal. Then glue it in place with 3M brand 1300L adhesive or suitable substitute. The upper cup-seal will require you to cut one in an appropriately sized circle, and then snip out the center in order to allow you to form it into the “bowl” formed by the cup. (This will have a finished appearance of a hollowed-out circle, with it’s center having a “pentagon” shaped hole in it or, if you’re especially talented with scissors it’ll look like a flat doughnut. I suppose an Exacto-knife or gasket-cutter might also work well in this job.) Be especially careful to get the felt inside the cup area in correct position as that is critical to creating an effective seal when the vent is pushed all the way into its tube. After the adhesive is thoroughly dry hold the vent up to it’s receptacle tube and compare the felt thickness to the inside diameter of the receiving tube. You will probably have to remove some material to “thin” it down slightly, in order to get it to slide into the wing-root tube. This is easy to do with a wire wheel but can also be done with a hand-held wire brush. Don’t remove any more than absolutely necessary or the vent will not work properly. You want a fairly tight fit so the vent will remain closed by friction in flight against air pressure. It should be tight enough to require “wiggling” it into the wing-root tube. Remember to slightly depress the plungers to assist inserting the vent back into place.

When I did mine, I actually did the felt around the base first, and then the felt in the cups last, so that the felt in the cup would still be not quite dry when I reinserted it. That allowed the cup-felt to take a “set” against the receptacle tube and affect a better seal.

Now my vents are still original and work perfectly and stay exactly in whatever position I place them. It’s a very satisfying repair you can do yourself and costs less than $5. Compare that to the $90 or so for Soros or whatever and it’ll put a smile on your face.

[170C]

I followed George's suggestion and my vent tubes work OK. Don't remember where I located the felt, but once glued to the vent tube & dried, it stays stuck. I don't believe I have much if any leaks when they are closed and if I pull them out for just a little air or somewhere else short of full open, the felt keeps the tubes where I want them. As an aside, I get a lot of air around the piece that the vent tubes are in where it mates to the windshield. Seems the only way to stop that air leak is to put a lot of fiberglass in that area and I am not sure fiberglass is a good material to use in that area. Maybe there is some other material that is safer for our lungs ??

By the way George, I had to use GREEN felt

[GAHorn]

I followed George's suggestion and my vent tubes work OK. Don't remember where I located the felt, but once glued to the vent tube & dried, it stays stuck. I don't believe I have much if any leaks when they are closed and if I pull them out for just a little air or somewhere else short of full open, the felt keeps the tubes where I want them. As an aside, I get a lot of air around the piece that the vent tubes are in where it mates to the windshield. Seems the only way to stop that air leak is to put a lot of fiberglass in that area and I am not sure fiberglass is a good material to use in that area. Maybe there is some other material that is safer for our lungs ??

By the way George, I had to use GREEN felt

If you look closely you'll see my felt has red threads within it.

The most likely source of air leaking past the windshield area is from high-pressure behind the leading-edge fairing. Remove the wing-root fairing strip and bridge the gap between the windshield and the wing root with duct tape, then reclose the fairing strip.
(I hate fibreglas because I don't like to think about breathing it.)

[PilotMikeTX]

One could, in theory, seal the wing root/windshield area from the inside using aluminum foil tape from the insulation or HVAC section at the hardware store. It would look a little less ghetto than duct tape (even I can't see it, I know it's there!)

I found some wool at the fabric store. I took my wife so the old ladies there wouldn't think I was a fruit. They only had 100% wool in an ugly cream color, so I bought some 80% wool in a nice grey. The old lady at the counter asked me what I was making. I told her socks for my dog. I figured that was easier than trying to explain what it was really for.

[GAHorn]

One could, in theory, seal the wing root/windshield area from the inside using aluminum foil tape from the insulation or HVAC section at the hardware store. It would look a little less ghetto than duct tape (even I can't see it, I know it's there!) ....

Great minds think alike. I felt exactly the same and that's exactly what I first attempted.

Unfortunately, it was a complete failure. The aluminum foil tape completely self-destructed in the breeze that flows in that area.

So I recommend duct tape.

[blueldr]

Not only that, but the very soft aluminum will tear all to hell if you have to try to remove it after the adhesive has dried and hardened. The aluminum tape ,however,is great for use with a ball point pen when making an airplane type and serial number sticker to install on the fuselage or the "Drug dummies".

[170C]

PilotMikeTX, your post is a classic I am laughing so hard I can hardly type this message I can just imagine how you would have explained what you actually purchased the wool for. Thanks for the good laugh. After a day like today I needed it.