On Oct 2, 12:27 am, Jay Honeck wrote:

The average privately owned GA aircraft is flown AT MOST once a week.
As a result, rust (from inactivity) is the #1 killer of the average,
privately owned GA engine. Many don't make TBO because of
inactivity.

Touch & goes are the #1 worst thing you can do to your engine. Flight
school planes do them all day long, but it's because they are flown
daily, sometimes 8 hours per day, and they therefore NEVER experience
the ravages of inactivity. Therefore, although it's STILL the worst
thing you can do, the engines often make it to TBO simply because they
are flown all day, every day.

Are the engines designed to take this kind of abuse? Sure. But they
were designed to be run daily, not weekly, too. And when you are
paying something in the range of $20,000 for an overhaul (as we did
for our O-540) we don't generally make a practice of stressing the
engine any more than necessary.
--

Interesting points you bring up here Jay. I've had similar
conversations with the maintenance mgr at the flight school I taught
at a few years back. As the consumate gearhead, I'm always picking up
data points from mechanics & operators/pilots and attempting to
separate real usable advice from the old wives' tales (and outright
BS) which seem to be prevalent in aviation.

Letting a plane sit idle is bad as it invites corrosion & seals drying
out etc. Starting the engine and letting it run for a 10 minutes
(thinking you're helping by circulating oil) and shutting it down is
even worse, as all that does is introduce more moisture into the
engine. You can't get an engine up to operating temp without flying
it, which will evaporate moisture in the crankcase. Flying is the only
way to properly excercise all the plane's systems IMHO.

Touch & go landings are probably harder on an engine than cruise
flight because of the short cycle heat/cool effect from full power/low
airspeed flight followed by reduced/idle power (repeat ad nauseum) I
think this is much less an issue in a low HP engine like the 160/180HP
O-320/O-360 or even the 200hp IO-360. I'd never do T&G with a high HP
plane like a Saratoga/C210/Bonanza because those engines generate more
heat (I'm told) because of their higher power output, and air cooled
engines can only dissipate so much heat effectively. I have talked to
one pilot who did T&G landings somewhat regularly in a Turbo Bonanza,
which made me cringe. I doubt that engine made it to TBO with its
original cylinders. For those planes, full stop & taxi back landings
are preferred. They also eliminate the possibility of grabbing the
gear handle instead of the flaps when cleaning up the plane on the go.
(seen this happen a few times with predictable results)

After hearing all the stories and warnings about shock cooling, I've
come to understand it's an issue mainly with turbo'd high HP engines
(Duke, 421, P-Navajo) that operate in the flight levels where the
cooling effect is not great. A "chop n drop" approach without careful
CHT monitoring can cost big $$$ if cylinders cool too fast and warp.
This just isn't a problem in a low HP, non-turbo'd aircraft IMO. It
doesn't mean you can be ham-fisted when operating your engine, just
that there's a bigger margin for error with a lower performance acft.

BTW, did your 540 overhaul only cost $20k? That sounds like a steal!

Will