Do You Want Your Piston Engine To Last?

[Colonel]

It's really pretty simple.

First, realize that the worst enemy of a private
aircraft engine is lack of use.  This results in
condensation and corrosion inside the engine.

Lycomings are famous for cam lobe, lifter and
cylinder wall corrosion.

To deal with this, the best way is to frequently
fly the engine, to burn the water out of the
crankcase.  You want to see at least 150F on
the oil temp, and after landing, immediately
pop open the oil access door, open the dipstick
or filler tube cover, and make a little convection
chimney, carrying the moisture out the top of
the engine.

Operating Tips

Preheat below +10C.  Yes, +10C.  Cold starts
are terribly hard on the engine.  Don't do that.
There is no oil, and the aluminum contracts
faster than the steel, decreasing the main
bearing clearance to ZERO.

During winter ops, run multigrade.  Yes, it's
shit oil compared to straight grade but it's
the choice of the lesser of two evils.  See
pour point.  You don't want it congealing
in the oil cooler.

Minimum RPM after start to reduce metal on
metal damage and allow oil to circulate.  If
the engine occasionally stalls because your
RPM is too low, you are doing it right.

After the first minute or so (depending on
preheat and temps), LEAN THE MIXTURE
and idle at 1100 RPM to reduce spark plug
and valve fouling.  Always lean the mixture
on the ground!

No higher than 1100-1200 RPM until CHT 200.
Remember, aluminum piston is heating up
and expanding faster than the steel cylinder,
and it's easy to stuff.

After CHT 200, you can safely runup to 1700
or 1800 RPM and cycle the prop, check the
mags, etc.

For full power for takeoff, it's nice to see the
CHT's climb well into 200F's.

In flight, CHT always above 300F and never
above 400F.  Lean the mixture in the climb at
high density altitude with your eye on the CHT.

Lean mixture in cruise.  Always.

Lean the mixture in descent and landing.  Always.

Lean the mixture on the ground after landing.  Always!

CHT is the key to engine longevity.  Don't go above
400F in a climb, and don't go below 300F in a descent.

With multi-grade oil, we are not as concerned with
warming the oil after the first start because it flows
very well, cold.

However if your oil temps are abnormally high (250F)
consider changing your oil more often, and looking
at your baffling.

[Colonel]

minimum RPM without it stalling (900-1100, lean)

After start, I'm looking for 600 RPM.

Easier with a metal blade prop, than
composite - more rotating mass, more
flywheel effect.

Any danger in leaning earlier than a minute after starting?

Nope - the engine will just quit if you lean
it too early / too much on the ground.  As
I said before, no harm done and you should
occasionally experience this (engine quitting
after start) because that tells you that you
are running minimum RPM and leanest mixture.

[Colonel]

Any input to 380F vs 400F?

No.  Your gauges are more accurate than mine!!

What about cowl flaps in cruise flight, fully closed or temp dependent?

Ok, this really is one time that you CAN shock
cool, but the "inch a minute" lemmings ignore.

You are climbing slowly, full power, the engine
is as hot as hell.  Cowl flaps open.  You level
off and start to accelerate and pour cold air
at altitude into that extremely hot engine.

Now you're shock cooling (with air)!

Always close the cowl flaps immediately
after leveling off to try to minimize this,
and let that hot-as-hell engine cool down
gradually.

I read in an article somewhere that the author flew with the cowl flaps closed regardless.

All the time?  Even in climb, he has the cowl flaps
closed?  That's retarded.  I know it's not a normal
use case, but I don't ever close the cowl flaps on
the Pitts.  Wide open, all the time for max airflow
through that engine, to keep it cool.  Costs me a
couple MPH in cruise but I have so much junk
hanging out, who cares?

[Colonel]

HPC:  Your 337 is notorious for cooking the
rear TCM IO-360.  Keep the CHT below 400F
in the climb, ok?

[Colonel]

Especially with the fuel-injected TCM's ...

DO NOT PULL THROTTLE BACK AFTER TAKEOFF!

This is especially important during the winter.

The first inch or so of throttle reduction will
probably not change the MP much, but it will
drastically reduce the fuel flow - look at the
meter!

If your CHT's are 400F (my redline), you want
to cool them with as much air and fuel as you
possibly can!

Read your engine manufacturer's operating
manual carefully.  Green (continuous) arcs
are nice on the gauges, but TCM is big into
"2 minute" operating limits.

[Rookie Pilot]

Especially with the fuel-injected TCM's ...

DO NOT PULL THROTTLE BACK AFTER TAKEOFF!

This is especially important during the winter.

The first inch or so of throttle reduction will
probably not change the MP much, but it will
drastically reduce the fuel flow - look at the
meter!

If your CHT's are 400F (my redline), you want
to cool them with as much air and fuel as you
possibly can!

Read your engine manufacturer's operating
manual carefully.  Green (continuous) arcs
are nice on the gauges, but TCM is big into
"2 minute" operating limits.

I used to use climb power, pull back to 25 ".  Not anymore. 2 reasons, cooling, and more importantly messing with a setting that's working. Theory is touching throttle low to the ground maybe isn't a great idea if it quits.  Wait till higher altitude and speed.

[Colonel]

I used to use climb power, pull back to 25 ".  Not anymore.

You have a Lyc 540, right?  I know a little about that
engine  ;D



It runs just fine with all the knobs in.  All you have
to do is keep the CHT below 400F.  And it would be
nice to keep the oil temp below 250F (I like 200F)
otherwise you should be changing it every 10 hours.

Contrary to what people say, it does not hurt an
engine to produce rated torque at rated RPM.  You
know, rated power.  That is not a condition to be
frightened of, and to try to avoid at low altitude
with fast hand movements in the cockpit.

Keep the temps down and the metal in your
engine will last longer.