Cowling Hinge/Engine Mount?

I am installing the engine mount and want to know if most people are riveting the cowling hinge to the fuse. before bolting on the engine mount or can it be riveted on later? Also should all of the rivets for firewall to fuse. skin be installed prior to hanging the engine (for strength)?


Thanks,

Sorry, building a 7.

Hi John,

I'm installing an alt engine, but the mount at the firewall didn't change. I left all the firewall rivets out; just clecos down the sides & across the bottom. Installed the mount, hung the engine, did all the plumbing/wiring, etc. Then pulled the engine & mount to rivet the firewall edges. You *might* be able to do the bottom after the mount is installed, if you have a no-hole yoke for your squeezer, but it would be tough. Not sure you could get to all of them, even with the special yoke. IIRC, some of the ones on the sides will require the mount to be out of the way.

I didn't see any evidence of stuff moving with the engine hanging on the mount & only clecos holding the skin. Remember, the firewall itself is non-structural. All the loads (at least in the 1G static load situation we're talking about) should flow through the aluminum angles to the top & bottom longerons. I fit my cowl with clecos in the firewall perimeter, & saw no difference in fit after riveting.

Having said all that, you might not need to wait on riveting. Biggest variable for you would be how much shim you need to get a perfect transition from cowl to fuselage skin. I waited because of the alt engine; I was delaying everything I could, as long as I could, just in case I needed to modify something.

FWIW,

Charlie

rv7charlie said:

....

Having said all that, you might not need to wait on riveting. Biggest variable for you would be how much shim you need to get a perfect transition from cowl to fuselage skin. I waited because of the alt engine; I was delaying everything I could, as long as I could, just in case I needed to modify something.

FWIW,

Charlie

Click to expand...

Rivet the cowl side now before the engine mount is finally fitted.

Just slightly over-estimate the shim thickness needed and add a little to the cowl when it is finally fitted. Better to add a little to the cowl edge thickness than to sand away the cowl to make it flush.

Thanks Charlie for the info. Looks like the top four on the sides do not have a hinge so looks like its safe to rivet those in. Also there are some on the bottom that may not have the hinge either. I will put the mount on and see if there are any that looks like they can't be riveted with the mount.

Thanks again.

az_gila said:

Rivet the cowl side now before the engine mount is finally fitted.

Just slightly over-estimate the shim thickness needed and add a little to the cowl when it is finally fitted. Better to add a little to the cowl edge thickness than to sand away the cowl to make it flush.

Click to expand...

This is the right answer. Some of those rivets along the firewall sides and bottom become much more difficult once the engine mount is in place.