I’ve been working on the sump quite a bit. After getting the hardpoints installed, I’ve been sanding the inside and spreading epoxy to make a smooth surface. The inside was incredibly coarse. I probably put 3-4 coats of epoxy down (and sanding in between). But just as I think I’m ready to drill and tap for the fuel lines, I discover two “minor” problems.

The engine I’m installing would rather have 1/2″ fuel lines instead of 3/8″. The problem is the the 1/2″ fittings will interfere with the main gear when it retracts. so that means I’ll need to install two new hardpoints that won’t be in the way.

An even bigger problem is that the lower engine mounts are going to be in the same place as the tank.

Inside of firewall. The two squares with the “X” is where an engine mount bolt will be.

Same view but with the tank in place.

How do you get to the bolts if the tank is in the way? Or how do you mount the tank if the bolts are in the way?

A call in to the factory reveals the best way to work around the issue of where the fuel lines go in.

Instead of mounting the two feed lines on the top front of the tank, they’ll have to go on the side. Which means adding two more hardpoints for the fuel lines.

As for the engine mount bolt issue, a somewhat more… Neanderthal solution is called for… Check it out:

Before

After.

Elegant, huh?

Another view.

Won’t hold much fuel like that.

New corner installed.

The new corners are covered with 2x BID inside and out.

Now here’s where not having built one of these airplanes before can bite you.  I’m working on this because the “Flow Chart” has it listed as task 40. Well, I’ve done 1-39 so I’m doing this. But what I learned much later is that it doesn’t have to be done now. And if I had waited, I could have made smaller, rounded clearance corners that would match up to the engine mount bolts exactly and allowed more fuel. As it is, it’s a little tight where one of the enging mount bolts is.