Winter Kits

This oil cooler cover says to install below 40 degrees. How cold until you guys start blocking air over the cylinders? How low of temps does this configuration work?


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I never covered any part of the cylinder air intake. Operated regularly down to close to -40. Never felt a need to cover those inlets. And, those engines seemed to last just fine. The oil cooler cover is the “essential” piece in my experience.

I am concerned about creating turbulence over the cylinders with any “homemade” block offs installed in front of those cylinders.

Anyway, we spent MANY, many hours dragging around at relatively low power settings counting critters, in VERY cold temps, and with no mods to the air inlets, except the oil cooler.

MTV

Agree!!
Denny

In those sub zero temps what things do you give particular attention to that may not be a factor when it is warmer? Do you add anything to a checklist or change flying behaviors in any way?


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Dress warmer!

Unless you have a 4-cylinder engine monitor you should leave cylinder airflow alone. If you had a monitor you'd come to that conclusion like the rest of us. Oil temp management isn't limited to winter. Duct tape is a useful tool year-round.

Sub-freezing temp management for me includes using isopropyl fuel additives. And don't sump fuel if the plane parks out in cold weather. Sumps don't drain ice but they do jam open from ice. Moisture precipitates out of fuel as ice crystals and makes slush that ultimately becomes hard ice. Pull a fuel screen in cold temps and it likely has some slush in it. Isopropyl eliminates it. Maybe not necessary in every tank but it doesn't hurt.

Use the red bottle alcohol, not the yellow bottle.
Use extra care not to cold shock your engine.
Preheat.
Be prepared for frosted windows.
Inspect your breather tube to make sure there's a way for pressure to escape when the slobber in the bottom end of the tube freezes up.
If you can do so safely, consider pushing in your mixture control so if the cable freezes up, it isn't frozen shut off. Probably not a problem if adequately preheated.

Jim

All Good advice above! The alcohol these guys is referring to is the red bottle HEET product, found in auto parts supply. It’s iso propyl alcohol, which is an approved fuel additive.

good wing covers and engine covers are essential. If you stop for a break, cover the engine to keep it warm. Wing covers are for over night, and double as shelter if stuck out.

In severe cold, it’s typically much colder close to the ground than up a ways. That’s an “inversion”, and can be severe. First winter I was in Fairbanks, I installed the full winter kit on my 185 and launched to the north, with surface temps close to -30. Climbed up and watched CHT climb as I crawled up out of that really cold air into air at 2000 agl that was thirty degrees warmer.
And wound up driving around below 1000 in the cold all day. Duh! Got home and took the winter fronts off the cowl inlets, leaving the oil cooler covered and the induction block off in place. Never looked back.

Be a little conservative with power application in extreme cold. That very cold air is also very dense, and your engine is actually capable of making more than rated power there. So, unless you’re bad stuck on skis, or???, don’t use max throttle in extreme cold.

MTV

Don't go by bottle color. Read the label. NAPA isopropyl is in a yellow bottle and is half the price of HEET brand. Isopropyl is the only approved fuel dryer for our airplanes and it's usually approved at 1% concentration, which translates to one 12oz bottle per 10 gallons.

Some guys with constant speed props will use a wood clothes pin on the prop control shaft to limit full RPM. Me? Full throttle, flat prop, and below zero temps will shake the neighborhood, so let 'er rip!

Thanks for the advice! Much appreciated!


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RookieCubPilot said:

Thanks for the advice! Much appreciated!


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I don’t know where you are, but if you’re in REALLY cold country, understand that when the local village is reporting -40, thr temperature on that lake you might choose as a landing site after engine trouble could easily be at -60.

I was monitoring a seismic operation once in winter, based at a man camp on lake ice about 25 mile from Fort Yukon (look it up). I flew from FAI to the camp, since Ft. Yukon was reporting -19. I looked at the LZs the crew was working, and nobody there, so I flew to the camp lake. Sure enough, the planes and helicopters were parked there.

So, I swung around and landed. As I descended below the trees, the airplane decelerated, and it got really cold fast.

The “Official National Weather Service” weather station thermometer read -58.

The point being, IF you’re going to fly in cold, first you need to have some good training and skills in cold weather survival.

Second, you need to have a few tools, and know how to use them. Oh, yeah, a gun.....most useless thing there is at -58. No, I’m talking about real survival tools. And you must be dressed to survive.

Finally, it’s almost always colder at night than in daylight. And it’s almost always colder on the surface than in the air.

Properly prepared, winter flying can be some of the best flights ever.

MTV