On Fri, 07 Oct 2005 06:44:27 -0700, Seth Masia wrote:

Cooling shock is, IMHO, an overblown issue in normally aspirated airplanes.
Coming east over the mountains, I regularly descend from 13,000 to land at
5300 -- and my cylinders are still tight 500 hours over TBO. It's a plain
vanilla O-540, severely understressed, and I baby it by running lower rpm
most of the time.

IIRC, Rod Machado also has the same sentiment about the subject. His take
is if shock cooling was a major factor, twins used for training should
constantly have a problem with once engine dying before the other....but
as he sees it, most training twins see TBO or better for both engines.

Greg