Riveting the cowl split hinges

I'm getting ready to do the cowl split hinges. Van's instruction don't appear to be that explicit. I understand how the bottom hinge is riveted on, but when it comes to riveting the top hinge in place I'm a little lost. I have the dark gray cowl so a bright light will not penetrate the fiberglass. My thought was to layout the rivet patterning the upper hinge and then still them and I could hopefully see the holes in the hinge half to drill from the outside of the cowl. When I called Van's they weren't much help in making me understand the process. If anyone has suggestions or pics I'd be extremely greatful

Thanks

Tom Clark
N646LC ready to take flight soon
The Villages, FL 32162

The cowl was one of the most frustrating parts of the entire build for me. It turned out pretty good in the end, but it took a lot to get there. In general we're on our own to make it work - whatever it takes.

I also have the gray cowl and couldn't see through to follow the plans. I measured from the bottom cowl edge to the point I would drill and drew a line on my top cowl. Then I measured off the rivet pattern on that line. In other words, you have the bottom hinge in place. You know how far up from the edge of the bottom cowl you need the holes to be on the top cowl. Put them there.

Follow the plans for drilling. Stick your arm in the air inlet and drill the holes working aft, cleco in each hole. (Avoid drilling your hand!!). Once you get a few clecos in and can no longer reach through the air inlet, just go easy on the drill pressure and it should work out fine.

Before riveting the hinges to the cowl, I smeared thickened epoxy on the hinges and stuck them to the cowl with clecos and let the epoxy cure. Then I was sure to insert the hinge pins when riveting. This prevents the hinge from deforming from the riveting process. I did this with all the hinges and have no trouble whatsoever inserting any of the pins. Even the aft cowl pins go in and out without trouble. I read this process here on VAF somewhere but don't know where or I would credit who deserves it.

For what it's worth, here's a link to my log.
http://airplane.athomeinthewilburness.com/2017/01/03/cowling/

Thanks Joe I appreciate the help

Near Finishing my Cowling

I too have had a terrible time completing this cowling.

To begin the process the cowling flange behind the spinner backplate is supposed to be clamped to the spinner backplate at 1/4 inch accepting 3/8, well what happens when the flange is not square?

I can tell you that the cowling top and bottom go on cockeyed. Not nice

Many, many hours on this and for sure it was far more annoying than the canopy.

As for the posters question, i did a variety of locate, backlight and guess to get my hinge done, it turned out ok but wish i could offer more.

Good luck
Dave

Drilling cowl

Here's what I did. Got it perfect then drilled from the inside. Turned out ok.

Don't do what I did, and get so worried about ruining clecos that you start riveting before the epoxy bed between hinge & fiberglass sets up. If you just cleco the epoxied hinge & let it cure, when you rivet it won't distort the hinge into the irregularities of the 'glass.

Thanks

Charlie I send you a
Private message

ClarkieSr said:

Charlie I send you a
Private message

Click to expand...

If that was to me, it hasn't arrived yet.

I bedded the cowling hinges on my RV-10 in Pro-Seal instead of an epoxy/flox mix. Same for the aluminum rivet backing strips for the cabin cover. Even if you sand the mating surfaces of the aluminum and fiberglass with course grit sandpaper, you can strip the aluminum off after cure with very little effort before riveting. The Pro-Seal not only gives a more structurally sound bond of the hinge to the cowling, it can absorb some of the vibration and the rivets remain tight. After fitting the cowling to my satisfaction, I drilled and cleco'd the cowling and hinges from forward to aft. Took it all apart and prepped the surfaces for bonding. A thin smear of Pro-Seal on the hinges then reinstalled the cowling and hinges putting a cleco in every hole and running the hinge pin through. After a couple days cure I disassembled, cleaned up the rivet holes and squeeze riveted each rivet with a dab of fresh Pro-Seal and cleaned up the squeeze out.

rivet with at least hinge pin in place

Something I have found in my builds is that having the hinge pin in place during riveting, and ideally a scrap hinge-half in place, are very helpful in retaining the hinge shape as the rivets are squeezed. This is true from my experience regardless of what the hinge is being riveted to (i.e. aluminum, fiberglass with cure resin, soft resin, soft tank sealant, cured tank sealant, etc......). This is also a place that less squeezing is better than over doing it, at least from my perspective, this is the time and place to be maybe a little less than the 1.5 dia of the ideal finished rivet.