Oil Cooler Screws

When I got to the hangar together this lady was there to help:

Praying Mantis

I told her that her claws would probably scratch the aluminum, hence the look of indifference.


I realized that the oil cooler bolts weren’t going to work as I had planned. Since the left rear baffle sits right up against the cooling fins on the back of the number 4 cylinder, I would not have any room for bolt heads. I’d have to use something like flush screws instead, so here’s what I came up with. I’d not recommend that anyone else copy this idea based on my use of it, at least not until I’m able to fly for a couple hundred hours and be sure that nothing cracks. Note that the top bolts will still go through both oil cooler flanges. When the airplane is upright and flying normally, the top bolts are loaded in tension and the bottom are loaded in compression.
Dimpled Screw Holes

Dimpled Screw Holes


Dimpled Oil Cooler Flange

Dimpled Oil Cooler Flange


Flush Mounting Hardware

Flush Mounting Hardware


And from the back too.

And from the back too.


I know that I’m going to need to add some support to the back baffle. I have been researching what other folks have done, mostly on the Vans Air Force site. The problem is that unless the post is from someone who had a baffle crack, it’s hard to know what works or doesn’t. Even in the case of a crack, that tells more about what didn’t work than about what did. The consensus seems to be that extra support in the back left corner and a diagonal brace from the crankcase are both helpful, so we’ll use both of those options.