"Shock cooling"

[WebMaster]

Not a problem with Turbines.
If you are cooking along at FL040, it's not a problem. If you are cooking along at FL180, it can be.
Here's what happens.
The engine is at a temp, say 350. Then you descend quickly, and the temp RAPIDLY decreases, to say 180. That sudden decrease in temp to the cylinder head causes thermodynamic stresses, and frequently ends up in a crack.
That's why it's a bad thing.
If you come to Dayton, Dr. Brian Von Herzon will discuss shock cooling at length. It's really a problem for the 520's (which he happens to own) which normally operate at altitude, and then are subjected to slam dunk approaches by ATC.