It would be interesting to see a trace of these pulses, and they may be important; but I am skeptical about them being the primary cause unless your cooler is near the engine outlet, and you have rigid (solid metal) lines.   

 

Hi Al,

 

If I thought a standard pressure sensor could catch the pulses, I'd be tempted to put a scope on it. I just don't think it would be a conclusive test though.  Leon has told me some interesting stories that lead me to believe in the pressure pulse theory.  I also can't think of a better explanation.  I don't quite buy the cycling pressure theory, because I'm only running about 80 psi at the cooler.  I think the evap core probably sees close to an 80 psi cycle between static, and operating pressure.  Also, I believe the leak started after a good 20 minutes of flight, not on initial pressure at startup, which wouldn't indicate that it failed on the pressure cycle.  

 

Fortunately, I think the only point we need to prove is that evap cores are a bad idea for oil coolers.

 

Cheers,

Rusty