Winter & Piston Engines

[GyvAir]

I think what pelmet is referring to is blocking some of the cold air going through the cooler to prevent it from freezing or gelling up inside to the point where oil can't make its way through when the engine reaches normal operating temperature. When this happens, your cooler essentially is in permanent bypass mode, no matter the position of the vernatherm, resulting of course in elevated oil temperature and lower pressure.

The other fun one is the scavenge line from the turbocharger. On start up in extreme low temperatures, if this line isn't warm enough, the engine can force oil through to the turbo, but the scavenge pump can't overcome the clot of frozen oil in the return line, resulting in the oil taking the next path of least resistance, one way or another, onto the ramp.

[Expat]

It happened to me in a C-172. Slow flight in winter with CASARA. The windshield got smeared so bad, that I had to land almost IFR. Oil loss was not so bad. Fortunately, I found a cheap solution the next day in the form of a split seal replacement, that you can do yourself.

[GyvAir]

uh oh... someone's going to start beating you about the head with a copy of Standard 625 APPENDIX A, Expat. Hope you didn't chip any paint in the process of changing that seal out!

[GyvAir]

A good read for those that just tend not to fly between the equinoxes:

http://www.avweb.com/news/redundant/sto ... 881-1.html

[Colonel Sanders]

No one bothers to properly pickle their engine.

Free suggestion, if you're not going to bother to pickle:

- Drain the oil to get rid of the acids.

- Replace it with new oil and toss in a pint of camguard

- Pull the battery and bring it home. Put a $10 constant
current 1 amp charger on it for 12 hrs every 2 weeks.

[akoch]

Thank you CS!

[Colonel Sanders]

Forgot to mention: if you have a conventional
lead-acid battery, before you trickle charge it as
described above, unscrew each of the cell caps
and ensure that the plates are covered.

If they are not, go to the drugstore and get
some distilled water and top each cell up until
the plates are covered, plus a little.

If you let a battery's plates get exposed to air,
it will never be as strong as was before.

You take the battery home to not only keep
it periodically charged up, but also to make sure
that it doesn't freeze and crack and leak battery
acid all over the place. This happens amazingly
frequently to private aircraft that don't fly in the
winter, because the specific gravity of the acid
drops when a battery goes flat, and when that
happens, the freezing temperature increases.

I am not a big fan of lead-acid batteries. They
are cheap, but I prefer the sealed Concorde
RG/XC batteries. I really hate getting acid on
an airplane.

[CpnCrunch]

Much better (and easier in my opinion) to just fly the plane every week or two.

[Mohawk]

Yep run it!

[Colonel Sanders]

just fly the plane every week or two

Yeah, that's my mantra too, but you'd be surprised
how many privately-owned aircraft sit for months
in the winter.

Between work schedules, family obligations, low
temperatures, aircraft covered with snow, ramp
and taxiway and runway conditions, and nasty
weather (either it's snowing or viciously cold and
blowing violently out of the north) ... and it's easy
to see why.

Flying a light aircraft in the winter is a bit like riding
a motorcycle in the winter. It's theoretically possible
but physically painful and pretty sporty at times.

[black hole]

Good points here. Not a fan of the Tanis system. Not a great system for preheating a stone cold engine. I like the little Buddy heater from CTC. The PA-12 I had with a tight fitting engine cover and the little Buddy; plugged in the night before gave me 100 oF oil temp the next morning at -35. That was the whole engine, oil, even the engine mount rubbers. Also not mentioned here, is the engine cooling inlets for extreme cold opperations. Sometimes a few strips of Duct tape will do the job; applied on the inside( next to the prop as to partially block the cyl barrels but leaving it open to cool the heads). Some cover the case vent tube with foam ( for home water pipes) which works well too.


BH

[pelmet]

Tanis worked well for me on IO-360's.

[Colonel Sanders]

Couple of comments about engine oil.

1) Look at your oil temp during flight. Shell says you
want to get it up at at least 150F, which means that
parts of the engine are hot enough to burn off the
water in it, which is really important. During the winter
with the cold air coming in, if you do not install a "winter
kit" from your manufacturer, which includes a restrictor
plate which goes over the oil cooler, you will have too
much cold air going through your oil cooler. Some
people with homebuilts just partially block them off.

2) Speaking of the oil cooler, I'd like to remind people
about the "pour point" of their engine oil. Below that
temp, it congeals and can plug up the oil cooler and
cause the oil pressure to soar. Not good in your constant
speed prop hub, either. W100 (sae 50w) has a pour
point of -20C. 15w50 has a pour point of -40C. Guess
which one is better for winter ops in Canada?

Last point which was brought up again: crankcase oil
breather tube - if it's solid, drill a couple of small holes
a long way up from the end. If it's flexible rubber, cut
a slit in it with a sharp knife. It will plug up in the winter
due to the water as a byproduct of combustion, and
if you do not have a relief as described above, will dump
out all the engine oil through the blown crankshaft seal.

Actually, it's worse than that. Look at the breather
tube of an R44 helicopter. Guess what happens
when you land in snow?

[oldtimer]

Back in ancient times I had a problem with the oil coolers congeling in the Cessna 180/182. I/we came up with two solutions. First was to run up the engine to bring oil temperature up and then shut down and cover the engine with an engine tent/blanket and let the engine heat soak which solved the problem most times. But if the oil pressure drops and oil temp starts to rise, close the cowl flaps, slow down, drop 20 flap and sit there at slower speeds until oil begins to flow. Reducd power helps to lower oil temperature and engine heat will help uncongele the oil cooler. Suddenly, oil pressure will rise, oil temperature will drop and you will be golden for the rest of the flight. During my flight training many moons ago, the club used a propane fueled large heater but it has been my experience that propane produced a large amount of moisture so heating has to continue until the engine is both warm and dry. In the bush in the early days, we always used a canvass tent and a plumbers blowpot to preheat engines. One for a Cessna 180/185, two for a Beaver and as many as 4 for a Norseman or Otter.
I wish I had one other option, called Arizona but!!! oh Well.

[cowboy]

Another thought, a cup of isopropel alcohol in the tanks to take care of any suspended ice crystals in the fuel tanks.

[pelmet]

It's getting cold again, and time to review some fundamentals
about operating piston aircraft engines in the cold weather.

The four-stroke, air-cooled internal combustion engine in your
aircraft has what is called a "crankcase breather vent tube"
which exits the engine, almost always down low on the belly
where you probably can't see it very easily.

Because the piston rings don't seal perfectly, the crankcase
is pressurized, and that air needs to escape. Hence the
breather tube. But not just air escapes - you've got an
emulsification of oil and water going out the breather tube,
too - which is how the belly of the aircraft gets greasy.

During the summer, the water in that greasy mixture is
harmless - it evaporates. However, during the winter,
the water in the greasy mixture can freeze and plug
the breather tube.

When the crankcase breather tube gets plugged like
this, the pressure increases inside the crankcase and
the next weakest link is the front seal around the
crankshaft, behind the prop. When that seal lets go,
the engine oil is pump out of the engine onto your
windshield (in a single) or over the nacelle of a twin,
like these guys who were flying across the North
Atlantic and made an unplanned stop at Greenland:

To avoid this, you need to drill a small hole or two
in the crankcase breather tube a few inches above
the end of the tube, to act as a pressure relief in
case water plugs the end of the tube up. Some
people like to put one wrap of electrical tape
around the holes, but I have mixed feelings about
that.

It can happen to your radial engine as well. I suspect that because agplanes don't do much cold weather flying, they don't have modified breather tubes.

Occurrence No. : A13C0170 Occurrence Type: INCIDENT VOLUNTARY
Class : CLASS 5 Reportable Type:
Date : 06-12-2013 Time : 14:41 CDT
Region of Responsibility : CENTRAL
Location : CYQV YORKTON MUNI, SASKATCHEWAN

Aircraft Information:
Registration : C-GBTK Operator : ACCUMARK AVIATION
Manufacturer : AIR TRACTOR Operator Type: COMMERCIAL
Model : AT-401 CARs Info: 702 - AERIAL WORK
Injuries: Fatal : 0 Serious : 0 Minor : 0 None : 1 Unknown : 0

Occurrence Summary :
A13C0170: The Air Tractor AT-401 aircraft, registration C-GBTK, was enroute from Nipawin, SK, to Yorkton, SK. Approximately 10 miles northwest of Yorkton, the pilot advised ATC that he had an oil leak and was losing oil pressure. The pilot elected not to shut the engine (Pratt & Whitney R-1340) down and continued on to Yorkton where the aircraft landed without futher incident. No assistance was required. It was reported that the engine breather tube had frozen.

[Colonel Sanders]

It can happen to your radial engine as well

Yup. Doesn't matter which way your pistons are pointed.

Funny how as the years and decades roll by, people keep
learning the same lessons over and over again.

[xchox]

This is a great thread.

[pelmet]

I remember a C337 that was flying out of Wabush to YFB a few years back. They had a double engine failure and it was suspected that the breathers had frozen over.

http://worldairops.com/NAT/docs/NAT_C33 ... ps.com.pdf

I got involved with ferrying a Cirrus aircraft overseas in the winter a few years back. There were four brand new aircraft that we picked up from the factory. We flew them to Penn Yan, New York for ferry tank installation sometime in January. That was the end of my participation as I had to head back to work among other things.

These were SR-20 aircraft and one of the pilots was quite experienced in ferrying these planes and said that it was important to make sure that the breather tube had a slot cut in it by us as this was not done at the factory. The breather tube starts at the forward upper portion of the engine on the SR-20. So slots were cut and insulation was purchased from a hardware store to cover the breather lines for our aircraft and provide protection from the icy blast of winter. No problems were encountered.

One of the fellows I flew with was an American who obviously like the ferrying thing as he got into it big time. He used to have a webpage with picture of his experiences.

A couple of years later, he was with a European guy and someone else ferrying three SR-20's from Goose Bay to Reykjavik in the winter for a delivery to Thailand. As they were getting close to Greenland, the European guy had all the classic oil fluctuation indications and eventually lost power an had to ditch(unfortunately he almost made land). He did not survive.

When I called my American friend to find out what happened, he said that the other pilot would not listen to him and did not cut a slot in the breather tube. As well, he flew much higher where it was colder. The breather tube froze, the oil was lost and he paid for it with his life.

You can read about the accident here...

http://www.hcl.dk/da/havarirapporter/~/ ... eport.ashx

[Colonel Sanders]

If you leave your battery in the airplane, and don't fly it often
(who does in the winter?) the charge drops on the battery,
and with it the specific gravity of the acid.

And as it does, the freezing temperature of the acid rises.

So on a chilly morning like this morning (-21C) the acid in
the weak battery can freeze. As it freezes, it expands and
cracks the case. When it thaws, acid leaks out of the battery
and can do serious damage to your airplane.

Take your battery out. Take it home. Put it on a trickle charger
in the basement every couple of weeks.

There are so many benefits:

- your battery will last longer because it won't go flat when
you are charging it at home

- your battery will be warm and fully charged and will crank
your engine over better for those winter starts

- your battery won't freeze and crack and damage your
aircraft with acid.

You simply won't believe the number of airplanes that
have been damaged by the acid from cracked batteries.

[Beefitarian]

You can get battery monitors now. They cycle the battery to not only trickle charge them but automatically allow them to discharge slightly then recharge them. Extends the battery life significantly on anything you're not operating often enough.

It is still optimum to remove the battery to an indoor warm place. Mostly because you will be keeping the connections clean and preventing venting of corrosive gasses during the format time.

[Jungle Jim]

I also bring the radio, transponder, encoder and ELT home when I bring the battery home. I have large zip lock bags and they stay dust free in the closet until spring.

Jim

[Colonel Sanders]

I also bring the radio, transponder, encoder and ELT home

I can see bringing the ELT home - it's quick-disconnect
and has a battery - but I wouldn't mess with the radio,
transponder or encoder. Not sure the cold is going to
bother them, and if the Legal Beagles here find out you
are touching the encoder without a Maintenance Release
signed by the Queen of England herself, you are going to
be in Deep Crap.

I know a guy, was silly enough to take his AME's advice
and pulled his radios for the winter. Buggered up the
connectors at the back of the tray when he tried to put
them back in. That cost a pretty penny to fix. Failed a
basis cost/benefit analysis miserably.

Unless you think someone is going to steal them, leave
the radios in for the winter. Probably a better idea to
take them home every time you fly in the summer, to
keep them out of the heat. I just couldn't be bothered.

Frankly I'd be more likely to pull the gyros out of the
panel and take them home, and spin them up periodically.

Not many moving parts in the radios.

[Beefitarian]

The battery in an ELT is a dry cell. It does not mind getting cold unless you're using it. Then it will not last as long as if it is warm. Banging it around taking it home and putting it back in the plane come spring time might jiggle the inertial switch.

Then you can tell us, "I didn't even land that hard." When it turns on and we come find it with the hand held homer.

[pelmet]

From TCM "Caution:Attempting to start your engine with a partially discharged aircraft battery may result
in damage to the starter relay, possible engine kick-back resulting in a broken starter
adapter clutch spring."

Could someone explain the details of why.

Thanks