Engines have vibration and resonances that vary with RPM. Running at a
constant RPM for long periods of time causes a certain wear pattern on
certain parts. Varying RPM over time induces different vibration an
part resonances and spreads the wear over different areas. This isn't a
bad, bad, bad thing.

True enough. It is good for your engine to vary RPMs gradually and
gently.

In my experience, every mechanical thing last longer when treated
gently. This is why I (and others) take a full 3 or 4 seconds to
apply full power at take off, rather than simply slapping the throttle
lever to the stops. (I confess that I never worried about such things
as a renter...)

Young people -- especially young men -- take a long time to learn
this. (I know I did.) To illustrate this phenomenon, we need only
look at my riding lawn mower. For four years it ran perfectly with
me on board. This summer, my 16 (now 17) year old son took over the
hotel mowing duties. Within two weeks, the mower needed to be
repaired. Rough, abrupt usage of ANY mechanical equipment will
shorten its lifespan.

At the core I think we're talking about a matter of degree and
technique here. In my experience of doing engine out practice with
CFIs, we would get down to within a few hundred feet of the ground
(this in the wide-open Midwest, remember) and then quickly apply full-
power when we knew we had made (or not made) the chosen field.

I am going to try to practice them with a gentler technique next time
I fly.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"