Repair Firewall Holes

I purchased a used RV9 and am putting a new engine / engine monitor, etc in. There are extra holes in the firewall. I am going to use fire-sleeves to protect the penetrations I have that have wires going through, but how do i patch the holes and keep the fire protection of the firewall? Rivet small stainless steel plates over the holes, and seal with the 3M firewall caulk? thanks, david shevick 415.794.2084

Size?

For small holes I use two nester tinnerman washers and a stainless screw and nut. One goes on the front side of the firewall with the dimple going through the hole, the other is nested from the back side...works great and looks great too...

Picture as example?

Hi Bob,
Do you have a picture to illustrate what you've done?
I have to do the same on my 9A (coincidence?)
Appreciate the help. - Thank you.

Steel press-in hole plugs from the local hardware store plus some sealant. Variety of sizes available, usually including stainless. Simple and cheap, but not as elegant as the nested tinnermans.

photos

Anyone have a good sight to use for pictures here? Photobucket isn't working for me for some reason...

If the hole is larger I will fab a square patch using galvanized or stainless sheet. Use a break to bend all four edges up with a nice radius so the patch is quite rigid. Install on the hot side of the firewall with high-temp RTV around the outside of the firewall hole and wipe up the squeeze-out to make a neat job. Install using four stainless screws, washers and high-temp lock nuts with the screw heads on the hot side, fay sealed with high-temp RTV.

The nice part of doing it this way is that you now have four nice mounting holes to use when you install the "pipe and flange" style firewall feedthroughs so highly recommended by the esteemed Dan Horton.

Your comment about using fire sleeve on your other penetrations has my curiosity piqued. Please elaborate on your method.