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Newton locking fuel caps installation

Flange install

Maybe not the correct install procedure but here's how I did mine.
The flange fits inside centered on the hole.
Position it by hand and mark the skin and flange where it nestles against the skin nice and flush.
Next you need to clamp it in place somehow.
The trick is finding a clamp that will reach the flange.
I bought two big plastic plier type hand clamps.
Put one on the forward side and one aft. Tighten the clamps enough so the flange won't fall off but not so tight you can't move it.
Make small adjustments till the flange is centered in the skin hole and our marks line up.
Clamp them tight. Double check and adjust till it's perfect.
Start match drilling carefully. Add clekos as you drill till the clamps can be removed.
They're harder than the skin aluminum so rough them up with 220 or 150 so the Proseal will have a good grip.
There's a photo on my blog "Tanks" page.
 
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Thanks Larry. Two questions. I realize my 9 wing is different then your 7 wing, but did you have to alter the curvature on the top of the flange to match your wing configuration? Also, due to the fact that the top and bottom surfaces of the flange are different curvature, is there a problem setting the rivet since it will not protrude through the bottom of the flange perpendicularly?
 
Curve

diamond said:
Thanks Larry. Two questions. I realize my 9 wing is different then your 7 wing, but did you have to alter the curvature on the top of the flange to match your wing configuration? Also, due to the fact that the top and bottom surfaces of the flange are different curvature, is there a problem setting the rivet since it will not protrude through the bottom of the flange perpendicularly?
Click to expand...

Alter, no. It fit perfectly.
No problem setting rivets.
Dimple the skin and countersink the flange.
Build on
 
Draw a center line on the cap flange. This will help you align to the tank ribs.

IMG_7932-M.jpg


Center it on the hole and match drill. Clamp and cleco as needed to hold it steady. You'll need to countersink the flange and dimple the tank skin.

You will need to use varying length rivets around the cap, since the top of the flange is curved to match the tank skin and the back side is flat.

Scuff up the underlying areas, clean with acetone, and lay down the pro-seal.

IMG_8016-M.jpg


Rivet in place and then cover the rivet heads with a blob of pro-seal.
 
Remove cap before drilling

I was able to buy my caps direct from Robin Voice at his "factory" in the Cotswold's, England. His only advice was to ensure the cap is removed from the flange prior to drilling. Apparently Aluminum chips do the locking mechanism no good at all :D

Having the cap in place does help to get it centred initially though.
 
I'm at the same step. Tried to load all the rivets in and backrivet all at once. Did not set the rivets well, they kind of backed into the holes. Had to drill them out and clean off all the proseal.

What's the best way to rivet these? I was going to cleco all but one hole from the back side, so that the curved flange is flush with the skin. Then backrivet one rivet at a time using the backrivet plate on the bench (skin resting on the corner of the plate, in order to clear the clecos). Bucking looks tricky since the skin is floppy (ribs not installed yet).
 
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