edgersh

hi guys i need help with my fiberglass cowl the ho;d down screws are elongeing the holes in the cowl i am using a brission 2.4 engine in a cg extra 300 i have tryied using a piece of fuel tubing and a flat washer to hold the cowling on but it didnt work thanks eddie

Bass1

The best solution I've found for securing "gas engine' cowls is to replace your metal screws with nylon screws and blind nuts. I believe Sullivan carries nylon screws they use as wing attachment screws. The 6/32 size works perfectly. When the nylon screw is tightened down the threads slightly distort and act as a thread lock so to speak. They are not prone to vibrating loose and elongating the holes in your cowl like the metal ones. I change out all my metal cowl screws in my gas planes with these and have never had the old "loose cowl" problem since converting. I carry some spares in case I get heavy handed and over tighten and strip one.

Don M.

My Feedback: (5)

The plastic screws & blind nuts are a good idea. Another is to make the holes in the cowl just large enough to install servo gromments, this also helps a lot

Zippi

My Feedback: (10)

edgersh,

Take a look at these [link=http://www.pspmfg.com/CowlBinders.html]cowl binders[/link].

Zeeb

My Feedback: (41)

This problem seems to be model dependant since I've only had it with one, the others have not given me grief with the cowl mounting screws.

On the one I kept fighting, the solution for me was to use just the small nylon washers with metal 4/40 socket head screws going into blind nuts. Then I got a little green Permatex thread locker (pay attention to the uses for any thread locker you select as different brands have different numbering and coloring) which is the removeable, penetrating type. Just put a tiny, and I do mean tiny drop on the threads with a toothpick or something when you install them and the problem goes away. When you remove them, there's just enough locker left on the threads to act like a locknut would and you can re-install them multiple times without re-applying the thread locker each time. As it wears off, and you can tell when that happens, just put another tiny drop on them. If you do happen to get too much locker on them and the screws are really tight, you can loosen them by applying a little heat to the head with your soldering iron that will cause removeable type thread lockers to release.

I'm sure some of the other solutions offered might work, but I chased this problem through several repairs and one new cowling on a GP Patty Wagstaff Extra with a 50cc gasser in it before I came up with this idea...

edgersh

thanks guys you all gave me some good ideas eddie

gravlrd

Use bonded washers. The cowls for my CA 2.6 and 2.3 are held on with #4x 3/8 sheet metal screws and bonded washers into #4 All Threads from GP. 200 flights w/o a problem.

pettit

My Feedback: (23)

Here's what I sometimes do:

Drill a hole in the cowl that's the exact diameter of a piece of medium glow fuel tubing.

Cut a piece of glow fuel tubing about 1/8" to 1/4" long and slip it in the hole, and center it.

Put a flat washer over the attachment screw, thread it through the tubing and tighten it to the fuselage.

Make sure the tubing stays somewhat "centered" on the cowl.

When the tubing expands due to the tightening, you're done.

The cowl will now be floating in silicone rubber.