I don't remember if I showed this before but if I did, my bad.
One of the things about this project or any for that matter, are the little things that need attention, that many times get over looked or there's just not enough time to get them done. As Gary showed many times, there are several steps to a process of completing a repair. In this series of pictures, I'll show you what a single cowl flap needed to complete a repair. There's 12 of them on each cowling. We removed them all so they could be cleaned, inspected, repaired and repainted. This ones from the #4 cowling.
This first picture shows what it looked like before I started. At the bottom of the flap, you'll notice the rub strip is partcially broken and missing in some areas. The top one is completely gone, meaning the rivets that held it on are rubbing directly on the cowl flap next to it, causing more damage.

The first step is to drill out all the rivets that hold the strips on.

Next step is to fabricate a new set of rub strips. These strips are made of a product called phenolic. It's a material that has been used in aviation for years and really does hold up to alot of abuse. This application calls for 1/16" sheet and can be cut very easily on the metal shear. Rough cut two pieces and hold them in place with cleco clamps.

Next, you flip it over and drill thru the exsisting holes and thru the phenolic. add clecos.

Mark the strips, trim to fit and countersink the holes for flush rivets. This tool on the end of my drill is a countersink that can be set for a specific depth, so all you have to do is drill too it's stop depth and go to the next hole. Makes life alot easier and all the holes are uniform.


Now before you go and cleco that back on and rivet the new strip on, you want to prep the surface where you removed the old one. Take some ScotchBrite and clean the old paint and grime off. If you're down to bare aluminium, you'll alodine, then prime with a good zinc chromate primer.

Now you can go ahead and cleco it back on and get ready to rivet.

This tool is called a rivet squeezer. Real handy when it's just you in the shop.

Just load a rivet and put the squeezer in place and pull the trigger. It too does a real nice job and all your rivets come out looking great.

Last thing to do is prime, number and paint the flap.


Next I'll show what Mark and I are doing on the interior of the cowl to close up the holes.
Dave