Scudrunners

Gents - It's been a long time since I have dealt with piston engines, let alone lycomings. A small company I do contract admin for is experiencing premature engine changes due to this issue. The engine shop is pointing fingers but there is a little more to it than that, thus the post here.


According to their definition and start with a cold engine (meaning an engine at or cooled to ambient temperature (cylinders) is considered a cold engine. They then state any start allowed to go above 1000 RPM is considered a runaway start and the engine is not getting proper lubrication to the front bearing area and there is wear happening due to forward play in crank shaft and the wear ring is eroding and heat cracks are showing up in the crankshaft. This apparently is know as a lycoming issue but to honest I never encountered it before but most of my piston experience is round and continentals.


Experiences??? Fixes ??? and starting techniques -- we are trying to educate but experience level is low and new faces monthly. Open to any suggestions  --- cheers

Lycoming Service Instruction 1505

Point 4:  Do not exceed idle RPM until oil pressure...

It has been a long time for me as well, but investing in a Tanis preheat system will resolve a great deal of your problems.  And a good engine blanket for holdovers.  With a full Tanis your engine temps will almost be in the green 30 Secs after start, and the crank is picking up nice warm oil.
Cheaper than engine repairs.  Much cheaper.

Sorry for the thread drift.



If your engines are properly preheated it makes a huge difference.  And less time sitting in a cold cabin if you only have manifold heat.  Which brings me to part 2.  A cabin warmer will make your instruments last longer as well.
Little buddy type heaters are cheap. ( maybe they do not make little buddys anymore).


If you are in reall cold weather, a battery blanket is good, particularily on those aircraft where the battery is located in the back.

[u]How To Start A Flat Piston Engine[/u]

Ok.  As previously mentioned, the colder it gets,
the harder it is, to start a flat piston engine.  And
the harder it is, on the engine.

Preheat is a wonderful thing.  I used to use it anytime
the temperature dropped below 32F or 0C.  Some
people immediately plug the engines in after landing
in the winter, and run the heater continuously, so it
never cools off.

What is bad about a cold engine?

1) fuel does not atomize.  And this is why it's hard
to start.  100L evaporates really slowly in the winter -
mogas is much, much easier to start in the winter.
But just because an engine will fire, doesn't mean
you won't hurt it.  You can get starter spray at
Canadian Tire which will start just about anything
in the winter.

2) oil is too thick.  Don't run straight-grade in the
winter.  Run that cat piss called multigrade, because
it flows better at start, and very importantly, won't
congeal in the oil cooler like straight grade.  Multi
grade is good to -40C.  Colder than that, fuck, go
to Key West, ok? 

Also, if an engine has sat for a long time - months! -
all the oil has run off, and you run dry for a while.
Truth be known, with a Lycoming, this actually
isn't a big a deal as you think it might be.  See
the handling notes for the AEIO-360 and AEIO-540
engines.

3) Clearances decrease.  Know what a bimetallic
thermometer is?  Probably not.  But your aluminum
crankcase halves expand and contract faster than
your steel crankshaft, and that means in the cold,
clearances go to zero.  You can hang off the prop,
when it's cold enough.  That prop is frozen.

So.  Mogas if you can, multigrade is a must, and
try to pre-heat.  At least stuff a blanket in the
inlets when you park it.  An engine/prop cover
is much better.

How to start?  Well:

a) you must prime more than you usually do.
I could write a book, just about priming, but
suffice to say, try not to catch the fucker on
fire, ok?

b) hopefully your battery is charged and warm.
Another story.  See battery tender mumblings.  If
it's cold, be sure you have a battery tender and
consider removing it and taking it inside.

c) when it starts, [b]minimum RPM for the first minute[/b].
It's ok if it quits.  In fact, it's a good thing if it does
when it's cold, because it gives the heat a chance to
conduct around your engine.  Better too slow than too fast.

d) after the first minute, you had better see
oil pressure on the gauge in the cabin.  If not,
shut it down.

e) lean the mixture after start to avoid fouled
plugs and valves.  This is more of a problem in
the summer, but ...

f) after one minute of limping and farting, you
can gently raise the RPM to 900-1000 which
should allow for smooth running.

g) DO NOT EXCEED 1200 RPM.  There is no
need to.  High RPM immediately after start
is not only hard on the bearings, it is hard
on the piston pins (below).

h) taxi out.  Don't fucking ride the brakes! 
Control the speed with the throttle.

j) sit on the ramp and let the engine warm
up at 1100-1200 RPM with the mixture lean.

k) wait until you have 200F on the CHT before
the runup.  After the CHT hits 200F you are
safe for 1700 RPM.

m) since you have multi-grade, you do not need
to wait for the oil temp.  Only if you have straight
grade in the winter (are you nuts) do you need to
worry about the oil temp.

n) get the CHT over 250F (closer to 300F is better)
for takeoff.  See, if you get the RPM up when the
CHT's are cold, the cold steel cylinder wrapped around
that hot, rapidly aluminum piston is going to put
aluminum shavings in the oil.  Very bad.

p) try not to look at the EGT after takeoff in the
cold.  You will be producing more than rated sea
level power in the cold air, with the negative density
altitude, and I hope your fuel system is set up rich
enough to keep the EGT's down, as your engine
goes incredibly lean at max power.  You won't
detonate or pre-ignite because of the wonders
of 100LL but you are going to shorten your
exhaust valve life with those extreme temperatures.

Try not to turn your engine into a frozen lump
in the descents.  I know several guys who have
stopped a prop on final.  Don't do that.  Lean
the mixture in the descent and keep a trickle
of power on, to try to keep the engine warm.

Remember a couple of things

i) you didn't pay me a fucking cent for this,
so try not to be such a whiny bitch

ii) I have given up on winter.  Half a century
was enough for me.  You can find me at the
beach, walking my dogs this winter.


[img width=375 height=500][/img]

--
Your not-so-local substandard ex-instructor

Our issue has nothing to do with winter ops. Aircraft are always plugged in or hangered. According to the engine shop this issue is year round and just as likely to happen in the summer as winter. It is a weakness in the lycoming engine and I'm at a lose on how to prevent the issue. All I can see is training and monitoring and hopefully reporting if there is a "hard" starting engine so maint can address the issue. I have a lycoming hand book here and will do a search to see if it's mentioned. Damn flat engines -- haha --

[i]Minimum RPM[/i] after start for the first minute to
allow oil to circulate, is a good idea year-round.

There are idiots that hit 1700 RPM immediately after
start.  They hate their engines, I guess, and want them
to fail at inopportune times so they can spend huge
amounts of money because they need to get rid of some.

Thanks Col for the detailed post -- training, knowledge and a big hammer to whip a little sense into my aviation virgins will be in order. They come out of the schools and colleges with habits that need to be fine tuned. Theory and rules up the ass but little to none of the know how of actually operating an aeroplane. Fuck according to spell checkers aeroplane is not a word --  >:D 

If I may paraphrase von Richthofen:

[size=14pt][b]Keep the metal happy.  All else is nonsense.[/b][/size]

All the silly paper in the world, is a feeble
attempt to simply keep the metal happy.

One important thing I forgot to mention:

Sooner or later you're going to catch the fucker
on fire, starting it in the cold.  Heck, some people
manage to do that in the summer.

When it catches on fire, please don't jump out of
the airplane and run away from it.

[size=14pt][b]KEEP CRANKING[/b][/size]

If you've over-primed, you have too much fuel
and probably a fire in the intake system.  And
the way to deal with that, is to suck it into the
engine.  And the way you do that, is to keep
cranking.  For now, don't worry about any 45
second limit on the starter.  Melt the windings
if necessary.  Lesser of two evils.

Once you're [i]really sure[/i] the fire is out, then
you can stop cranking, get out and inspect
the intake (air filter damage?) and nearby
cowling.

Something to pass on:

When you're cranking, and it won't fire, stop.
You're just heating up the starter and running
down the battery.

Stop and think for a moment.

You've got spark (see caveat below).  Assuming
that the moving parts of the engine are doing what
they're supposed to be doing, and there are no blockages
of the intake or exhaust stopping the air from moving
through the engine.

Your problem is fuel.  Do you have too little of it,
or too much of it?  Do you need to prime some more,
or do you need to crank with the fuel off and the
throttle open to purge excess fuel out of the engine?

re: spark.  If you have a lycoming, you probably have
spark when the engine is cold, albeit probably from
only one impulse coupled magneto on the left.

However, if you have a continental, they have a
distressing habit of frosting up the spark plugs
when you try to start them in the cold with no
preheat.

I had a TCM engine that would fire precisely six
times if you tried to start it below freezing, at
which time the spark plugs were frosted over
and it said, "Fuck you, I want to go back to Mobile
where it's warm".

100LL doesn't evaporate worth shit in the cold,
and remember, liquid fuel doesn't burn.

I shouldn't mention this, but that starter fluid
from Canadian Tire works wonders with many
different kinds of piston engines.  Keep a spray
can of it in your garage.