*Using Rubber O-Rings On Cowling*

*Using Rubber O-Rings On Cowling*
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*Using Rubber O-Rings On Cowling* - 11/27/2005 5:16:24 PM

Zippi

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From: Evansville, IN, USA
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The cowling on my Edge 540 is showing signs of wear and its only had a dozen flights. The four screws that hold the cowling on has metal washers, I was told to use rubber O-Rings and it would help stop the cracking and excessive wear. I intially smeared epoxy on the inside of all the holes I made in the cowl. My question is, If I use the rubber O-Rings, would you put the metal washer on top of the O-Ring or not use the metal washer at all?

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 5:30:30 PM

RCKen

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You can use o-rings, or even a small piece of fuel tubing will accomplish the same thing. They isolate the cowl from vibrations which help protect the cowl. See the attached diagram.

Hope this helps

Ken

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 6:40:47 PM

Don M.

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The best thing I've found are round servo grommets and servo screws or screws & metal washers - works great.

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 7:35:52 PM

Zippi

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Thanks for the info guys. This is for a 120 application and seems a little big as far as drilling a big enough hole to put fuel tubing or a round servo grommet. Have any pics of an actual installation?

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 7:58:52 PM

BillS

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With fuel tubing over a servo screw the hole only needs to be .090 to .100” diameter and would work fine on a 40-size airplane.

Bill

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 8:08:29 PM

da Rock

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From: western, NC, USA
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I punched out some small circles from a punctured inner tube. Then punched a small hole in the middle of each. Put your hold down screw through the cowl and then through one of the rubber circles. If the screw hole in the rubber is tight on the screw the rubber will stay with the screw when it's unscrewed and it holds the screw in the cowl and that helps you keep up with them and has them ready to go when you replace the cowl.

You can also use two rubber circles per cowl hole, one inside the cowl and one outside.

A small set of punches isn't too expensive and you'd be surprised how often you use them around the house much less with this hobby.

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 8:13:36 PM

Zippi

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Thanks Bills, I just measured the standard fuel tubing that I use and the OD is .250. I found some that was smaller that came with an old kit and it was a little smaller at .187 OD. Thats why I was saying that I thought it might be a pretty good size hole. Just what kind of fuel tubing are you talking about that will fit into a .090 to .100 hole?

quote:

ORIGINAL: BillS

With fuel tubing over a servo screw the hole only needs to be .090 to .100” diameter and would work fine on a 40-size airplane.

Bill

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 8:39:50 PM

mimhoff

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Here are some commercially available cowl binders -- seem to be based on the same idea as O-rings or fuel tubing. I purchased these but have yet to use them.

http://www.pspmfg.com/CowlBinders.html

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 8:47:01 PM

jlkonn

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From: Planet Earth, IA, USA
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Mimhoff,
I have the cowl binders on my UCD 60 with Saito 100.
About 6 gallons now and no problem.
They really hold up great!
I will use them in the future whenever I can.
JLK

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 8:50:54 PM

Zippi

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That's what I'm talking about. Nice find mimhoff.

quote:

ORIGINAL: mimhoff

Here are some commercially available cowl binders -- seem to be based on the same idea as O-rings or fuel tubing. I purchased these but have yet to use them.

http://www.pspmfg.com/CowlBinders.html

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 10:24:25 PM

Steve Campbell

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RCKen's method is a good fix.

Try this: before you do anything else, glue a CA hinge over each of the holes, on the inside of the cowl, with medium CA. Ensure that the entire hinge is saturated and adheres to the cowl. When dry, open up the screw hole to the same i.d. as your pieces of tubing o.d. Use a washer under the screw head, and you've got a quick, easy vibration isolator.

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 11:16:51 PM

Zippi

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From: Evansville, IN, USA
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Steve, yours looks like a good idea also. With RCKen's idea it looks like the fuel tubing gets smashed out at the bottom so do you think there is a need for the CA hinge to be glued to the inside of the cowl?

quote:

ORIGINAL: Steve Campbell

RCKen's method is a good fix.

Try this: before you do anything else, glue a CA hinge over each of the holes, on the inside of the cowl, with medium CA. Ensure that the entire hinge is saturated and adheres to the cowl. When dry, open up the screw hole to the same i.d. as your pieces of tubing o.d. Use a washer under the screw head, and you've got a quick, easy vibration isolator.

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 11:18:37 PM

blikseme300

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From: Mission, TX, USA
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What I do on all my 25% and larger planes is to use #10 nylon screws/bolts. I tap the wooden blocks, harden with CA, retap and voila! The holes in the composite never enlarge and the cowl never loosens. IMHO using metal screws/bolts and blind nuts - is nuts. I use nylon screws/bolts to hold the canopy frame as well. Never lost a bolt this way. I have done this ever since I lost a canopy frame off a 42% Giles during a snap roll. The flight & landing was a real adrenaline pumper!

Safe Flying!

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RE: *Using Rubber O-Rings On Cowling* - 11/27/2005 11:23:15 PM

Zippi

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From: Evansville, IN, USA
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That's cool to. Where can a guy buy these nylon bolts or screws? I don't think I've ever saw nylon bolts or screws at the LHS except wing hold down bolts.

quote:

ORIGINAL: blikseme300

What I do on all my 25% and larger planes is to use #10 nylon screws/bolts. I tap the wooden blocks, harden with CA, retap and voila! The holes in the composite never enlarge and the cowl never loosens. IMHO using metal screws/bolts and blind nuts - is nuts. I use nylon screws/bolts to hold the canopy frame as well. Never lost a bolt this way. I have done this ever since I lost a canopy frame off a 42% Giles during a snap roll. The flight & landing was a real adrenaline pumper!

Safe Flying!

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