Cowling fitting giving me a fit

[Rick_A]

After many frustrating hours I thought I finally had the cowling fitting very well. Here's a picture of the cowling cleco'd to the camloc support strips

and here's a shot of side and lower camloc strips riveted in place.

So I installed the camloc's for the lower cowling and the fit went to **** (your choice of expletive). At first I could not get the hinge on the left to mate, there was a gap of almost 1/2". I removed the upper "corner strips" for the camlocs which let me get the hinges together but you can see how poorly it fits now.

Last night I removed the bottom camloc strip on the left which let the cowl shift up but when I do that the upper corner of the fiberglass extends above the skin.

I'm using .063 strips for the camloc mounts. I'm thinking about redoing the upper strips in .040 or .050 (the .063 doesn't bend at all, maybe the thinner stock would give just enough flexibility to make things work).

My other thought is to use shims between the camloc strips and the firewall flange to make the strips lower relative to the skin.

Any other idea's? I think the cowling may be even worse then doing the canopy.

 

[Jekyll]

Rick:

Does the camlock strip impinge upon the cowling core? I fit my cowl and and didn't notice the camlock strip was hitting the core edge and not sitting flush untill I drilled locating holes for the fasteners. If your strip hits the rise of the core, it won't sit flush and may self adjust once drilled. The core was too close to the edge for my comfort vis-a-vis edge distance so I decided to switch to hinges for the bottom cowl to F/W (sides and bottom).

Jekyll

Same engine and airframe as yours.

 

[Rick_A]

Yes, had core interference

The strips were hitting the core in a couple of spots. I sanded the core back about about 1/4" to provide clearance. I may end up using hinges along the bottom if it helps to solve this problem.

 

[Jekyll]

Rick:

After doing both camlocks and hinges, I find the hinges much easier to build and use for the bottom cowling. The hinges for the lower cowling sides and botton seem to be be a better method than camlocks. The hinges will move into place and grab the cowling while you position it and insert the pins. I'll keep the camlocks for the top cowl as gravity does that for me.

Jekyll

 

[Norman CYYJ]

If the top flange that is holding cowl down is not done in several pieces, it is extremely hard to make it work. Take the cowl off and lay a straight edge on the boot cowl parallel to the center line of the airframe. If the straight edge touches the flange that holds the fasteners then you will need to divide the flange up into pieces and put a twist in the pieces that are near the corners. There must be a gap between the straight edge and the flange all the way around equal to the thickness of the cowling. It will take some work.

 

[bkc3921]

Camloc Strips vs. Cowl Core

...Had everything done and drilled, I thought..when I went to install the cowl, the receptacle mounting strips are up against the cowl honeycomb core..and it will not sit flush..My Question..Someone said they "sanded" the cowl core back....Exactly how do you do that, and does it interfere with the cowl strength...? Also, at the edge of the soon to be sanded core, do you need to "glass in" some type of edge and/or apply some epoxy to seal it? Another problem I did not expect! Any thoughts appreciated...

 

[CNEJR]

I recently fitted the cowl on my 6. It can be very trying, but ultimately it came out very well. Please take what I have to say constructively.

It appears to me the cowl must be under extreme stress in order to make it distort in the front that way if it was fitting well previously. You have to get the cowl to fit without stress. One thing I noted that will work to your advantage in fixing it is the cowl appears to be to "high" in relation the spinner backplate. On the intial fitting the top of the cowl should be approximately even with the spinner backplate. As a little time goes on you will find the engine will "sag" on its mount and will turn out about right if you fit it this way.

I used hinges up the sides on the firewall, hinges on joining the top and bottom together, hinges on the bottom and skybolt fasterners on the top. It worked out really well. Now as you refit the cowl top down to be even with the back plate, it gives you an opportunity to take a little off from the bottom and the bottom of the sides. You need to treat the top where the sides of the fuse and top covering of the fuse meet as a pivot point in this fit.
Take a 2' or 3' level and 3M 60 grit sandpaper on the side and work this down the sides to get the right line. Do not use power tools for trimming in any of this. Just use the level as a sanding bar. Take your time and your efforts will be rewarded. After you get the cowl to "line up". Your going to find you have a fair crack at the top. "work all edges down evenly until this closes.

You are on the right track about using a little lighter mounting material, I used a single band on the top and just shrunk it some on the leading edge to fit the contour of the cowl. One other thing I learned is not to drill the side hinges into the cowl until last. If you use hinges on the side to join the cowl halfes and skybolt on the top near the firewall, it is practically impossible to mount the side hinges on the cowl , then drill the top without some sort of buldge occurring, better after everything lines up to drill top fasterners to get top to lay flush, tape the &&%%$$ out the sides of the cowl with duct tape, remove the top then drill the side hinges in the cowl that attach to firewall sides.

I hope these ramblings help a little, I know how frustrating this can be. Good Luck.

 

[Rick_A]

Regardng sanding down the core. I just used 80 grit adhesive backed sandpaper on a small wood block. It was slow going at first but I eventually sanded it down to be flush with the solid glass.

I have not sealed it yet but I will coat it with something, probably epoxy resin mixed with something like West 407.

Regarding the orginal problem. I added an .063 shim between the upper cowl camloc strip and the firewall flange. This lowered the upper cowl a fraction. I also removed one of the bottom mounting strips which was keeping the bottom cowl to low. Between the 2 changes, I was able to get the sides to mate up again.

 

[Finley Atherton]

Regardng sanding down the core. I just used 80 grit adhesive backed sandpaper on a small wood block. It was slow going at first but I eventually sanded it down to be flush with the solid glass.

I have not sealed it yet but I will coat it with something, probably epoxy resin mixed with something like West 407.

Rick,
If I understand you correctly, starting from the inside surface of the cowl, you have sanded through the glass then the foam core down to glass, leaving the edge of the foam exposed. I suggest you think about laying a couple of plies of glass over the foam and over-lapping all around on to the surrounding glass by an inch or so to restore the original strength and stiffness of the glass/foam sandwich construction.

Finley Atherton
9A
Vari-Eze