I know the core split when the oil was hot, but I suspect the major (repeated) stress is when the oil is cold.

Finn

 

In addition to whatever vibrational factors; we know that it is getting a major cycle every time we start and stop the engine; every time the oil pressure goes up and down.  The oil cooler can see pressures up to 100 psi.  That’s a bunch. 

 

I have a custom cooler made by Griffin Radiators to my dimensions and specs.  The specs included; working pressure – 125 psi.  Take a look at the attached photos; and note the tube sheet to tank weld, the heavy wall 6061 end tank, and the heavy side plate to keep the stress off the tube-to-tubesheet joints.  The tubes themselves are flat extruded material with internal channels about a ¼” wide with ribs in-between to carry the pressure loads.  These guys build coolers for the Winston up racers, and this unit was designed to do the job.

 

Now compare that to the evaporator cores.  Which would you trust in your airplane?

 

Looking at my cooler, I could see that it was robust. But I also pressure tested through a number of cycles to 150 psi.  Why did I do this?  Because I don’t EVER want to be in the situation that Rusty just went through; especially if I ever plan on carrying a passenger.  I believe in innovating, adapting, and keeping down the cost. But on a flight critical item like an oil cooler, I think the $475 for a unit designed and built for the job is not even a consideration if it can avoid putting ourselves and others at risk.

 

Proper installation of an evaporator core on a 15 psi cooling system?  I could go with that.

 

O.K.; I’ll get off the soap box now.

 

Al