On 2007-10-13 06:57:56 -0700, Jay Honeck said:

As previously noted (in the thread about Paul's wife getting scared),
Mary and I had virtually stopped doing this kind of flying for fear of
harming our (very expensive) engine. A lively debate ensued as to
whether or not repeated high-to-low-to-high power applications would
wear out your engine any faster than would normal operations.

Most flight schools practice engine out emergencies frequently, even on
high performance aircraft. The engines typically make it to TBO.

The things that seem to shorten engine life have little to do with
shock cooling. The biggest factor seems to be how much the engine is
used.

If the engine is flown in accordance with the manual, you should not
have any problems with shock cooling.



--
Waddling Eagle
World Famous Flight Instructor