I'm about half way through the first annual inspection of my Legacy and discovered that the aluminum oil cooler "box" is cracked.  The box I'm talking about is the aluminum part that comes with the IO-550 baffle kit from Lancair.  It fits on the forward side of the oil cooler, between the oil cooler and the left aft cylinder.  It directs airflow through the oil cooler and forces cooling air through the adjacent cylinder fins. 

 

Here's a photo of the oil cooler box, showing the crack:

 

 

 

The crack started at the bottom of the forward left corner of the box, where the aluminum is bent to form the corner.  It traveled up and is about 2" long.  I was watching for it because I saw the same crack on a friend's Legacy a couple of years ago.  Based on finding cracks on the only two engines I've looked at closely, I think this might be a common problem.

 

I hope I fixed it by riveting an aluminum 1" angle, 4" long, on the inside of the box to reinforce the corner.  I will also "stop drill" the crack, as soon as my finger heals from drilling into it while making holes for the rivets.  (I should know better, but I was in a hurry, yada, yada.) 

 

If you haven't installed the baffles yet, you might want to consider reinforcing this corner, when access to it is easy.  If you're already flying, you might want to inspect this area any time the cowling is off. 

 

Dennis Johnson

Legacy, first annual inspection