Cooler weather flying

[Kyle Wolfe]

It was -4 tonight while I was sitting on deer stand. Too cold to fly, so guess I had to do something.

Here are a couple of good articles relating to pre-heating and how cold weather affects engines.

http://www.reiffpreheat.com/Article-Busch.htm

http://www.tanisaircraft.com/article4.html

Both are from reliable vendors who sell heating units.

[N419A]

Just got back from a weekend Moose hunt flew out friday landed on a nice little lake up at 4200' (thought we'd be above the cold weather) set up camp then the temp dropped to -30F. Not as much fun at that temp but survivable. Any way this is how I operate in the cold, mostly stuff picked up from other 170 owners in AK.

Duct tape, duct tape, and more duct tape.
Oil 15w-50 year round.
As temps drop in the fall
1st. Blast tubes on rear baffle taped up.
2nd. Oil cooler hole on from nose bowl (this is progressive)
3rd. Front cowl openings this also progressive starting on the inside and moving out. Not much past the cylinder barrels about half way is as far as I go.

Flying back the other day my temp were as follows:
OAT Oil Temp
10F 185
0F 165
-10to-20F 140 to 145 this was while desending and doing low level scouting.

Then dress warm, I've tried a bunch of little tricks for increaseing cabin heat with no luck. But, I have a few more ideas to try.

Oh, you can also use the duct tape to tape your pant cuffs to your boots and you sleaves to your gloves, keeps the cold air out.

I also have a cold weather kit I don't use if someone wants it, don't know what it worth.
Paul

[AR Dave]

Hey Bruce! I really miss the flying part! Lot's of moose on the flats?

The temp down in AR/TX, for example today in Dallas, will run 58/34. Unlike Palmer today, 12/9. The sun comes out down there in the day so there is a big temp swing. With that said, to be on the safe side, I just called and woke Traci up (midnight) and ask her to turn the swimming pool pump on. Russellville is supposed to hit 26 tonight. She'll turn it off in the morning. I mentioned the pool to make a point. The temp does not stay cold long enough to form ice on the open water in our pool & pump, I doubt the engine is getting cold soaked. With that said, I have nothing against preheating at 50 degs, if one wants too. Certainly can't hurt! I'm just amazed at the diff perspective. Our FBO has been plugging the fuel truck engine heaters in for a month now, no matter if it's 60 degs. Seems folks have discovered those orange electric heater pads and they're sticking em on every oil pan n the south. Guess I should teach them about using a cigarette lighter to heat their key up when the door lock freezes.

The question Craig had was about getting his oil temp up to 180 degs while flying. I'm more concerned with the temp at start up than after the engine has been running. Well by George, what's the official Cessna 170 minimum oil temp when flying?

[jrenwick]

For what it's worth, Jim Montague, the "Answer Man" on the Swift web site, told me last weekend that he never preheated his Swifts until the temperature got below 20 degrees F. This from a mechanic who knows as much about the small Continentals as anyone I know; decades of experience with them. He's owned 31 Swifts over the years, most of them with C85, C125, C145 or O300 engines.

Best Regards,

John

[alaskan99669]

I recommend everyone read the article Kyle Wolfe linked to:
http://www.reiffpreheat.com/Article-Busch.htm

or at least read below what I got from it:
Busch recommends the following:
The newer the engine, the closer the tolerances, so it’s that much more important that you pre-heat when temperatures are 32 or colder, but all engines regardless of time should use pre-heat when temperatures drop below 20 degrees Fahrenheit. This is because of the aluminum crank case surrounding the steel crankshaft and the aluminum pistons inside steel cylinder walls. Aluminum expands and contracts twice that of steel so tolerances can change substantially at different temperatures. Busch further explains that it is important the engine is preheated long enough to have a uniform temperature throughout the entire engine that feels warm to the touch.

He also explains how cylinders are tapered with a smaller I.D. at the top which helps explain why my POH recommendation on avoiding engine damage (page 25) “on your initial take-off, use maximum power only when and as necessary for safe operation of the airplane, reducing power as quickly as possible.” Busch explains this is because on initial warm up to operating temperatures your aluminum piston is getting hotter faster than the cylinder and since aluminum expands more than steel this is a double whammy. But don’t take my word for it... read the article.

[doug8082a]

Here in New England, we really don't start preheating until it gets down below freezing. Heck, if it's in the 40's here we still have t-shirts on

Regarding interior heat, I’m going to approach this from a different angle. One of my other pastimes is long distance motorcycle touring. Has anyone ever tried using electrically heated motorcycle gear in the cockpit? Companies like Gerbing or Widder make things like electric jacket liners, pants liners, socks, etc that all plug into each other and then have a single plug to the power source. Common practice is to wire the receiving plug straight to the battery on the bike, but I believe some have the provision for a cigarette light adapter. Anyone ever tried this?

Assuming your electrical system had sufficient power to drive it, was wired appropriately, and had it’s own CB per the AD for the cigarette lighter, is there any reason NOT to try this? Just thinking out of the box for a minute here…

Standing by for incoming...

[jrenwick]

A friend of mine in Minnesota was trying out a new pair of heated gloves and a heated jacket liner from the local Harley store in his L4, which happens to have a battery and starter, but no generator. He said they worked great -- he only had to turn the heaters on intermittently to get the benefit. Go for it!

John

[GAHorn]

I... “on your initial take-off, use maximum power only when and as necessary for safe operation of the airplane, reducing power as quickly as possible.” Busch explains this is because on initial warm up to operating temperatures your aluminum piston is getting hotter faster than the cylinder and since aluminum expands more than steel this is a double whammy.

How does Busch deal with the fact that his technique is a direct violation of the manufacturer's and airplane's operating manuals?
I suggest warming the engine up to operating temps and then using the mfr's recommendations. (Full throttle for takeoff.)

[4-Shipp]

Reference the small straps, PN 0552106-2, shown in Corey's picture on the first page of this thread: If you dip these in that liquid plastic tool handle coating that you can get at the hardware store, they are much less likely to scratch the center peice of the cowl during installation and operation. Worked great for me.

Bruce

[alaskan99669]

I suggest warming the engine up to operating temps and then using the mfr's recommendations. (Full throttle for takeoff.)

Both the "Airplane Operating Manual" and the "Operator's Manual for Aircraft Engines" say to use full power only long enough to clear obstacles. Neither explain exactly why that is, but Busch's explanation of the tapered cylinder at temperatures lower than normal operating temperatures makes a good point. And since no operator manual recommends running an engine any longer than necessary for checks above 1700 RPM (on the ground), then your take-off run is going to be the initial time to bring the engine up to normal temps during winter operations.

[HA]

considering the cyl heads and barrels are the items that warm up to operating temperature the quickest on an engine, cylinder choke shouldn't present a real problem unless you literally took off as soon as the prop was turning, kind of like when my grandma went to the store in her car

one big reason to preheat is that the bearings and crankshaft can contract differently enough when cold to become an interference fit - meaning no clearance. CREAK of metal transfer when trying to start then.

plus if the plugs are frosted you're out of luck starting the thing anyway. and it doesn't hurt to warm up the oil some so it will actually flow when things turn

I use the 20F rule, sure I've managed to start planes colder than that but they weren't mine

[GAHorn]

I'm not familiar with the manuals/titles to which you are referrring.
In any case, Mr. Busch was writing "generically" I'm sure and with regard in general to all airplanes. I consider him an excellent writer, and well versed in such matters, but in this regard I think he's wrong. I believe most if not all mfr's will also disagree with him.
All the fixed pitch, reciprocating engines I've ever flown (and most of the constant-speed prop equipped ones) specify that full throttle be used for takeoff and that a static rpm at full throttle be confirmed to determine correct developed power prior to takeoff. Our own "owners manual" is ambiguous on the subject, but in the Operational Data sections states, "Data are based upon a gross weight of 2200 Ibs. with McCauley propeller installed, and full throttle for take-off and climb."
The TCM C-145/O-300 engine Operator's Manual allows full throttle continuously, as does the type certificate data. My only point is that if the engine is insufficiently warmed up to allow full power, then it's insufficiently warmed up for flight. IMHO.

[alaskan99669]

I'm not familiar with the manuals/titles to which you are referrring.

Here are some snap shots with references:

My only point is that if the engine is insufficiently warmed up to allow full power, then it's insufficiently warmed up for flight. IMHO.

That is exactly what I believe the manuals are telling us. It is impossible for the engine to reach "normal" cruising operating temperatures on the ground, so on your "initial" take-off of the day, ease off on that throttle when practical, but if your doing touch-n-go's then the next take-off should be with a sufficiently warmed and equalized engine, so it's not as important to reduce the throttle.

[cessna170bdriver]

FWIW, the cylinder barrels in the C-145/O-300 were originally designed with little if any taper. The new part limits are .000 to .001 (no spec on direction). Taper or out-of-round of more than .002 is cause for grinding to .015 oversize. (According to the Table of Limits, .005 oversize rings are only used to get the ring gaps to service limits.) The piston, however is substantially smaller at the top than the bottom. The mid point between max and min clearances in the cylinder bore goes from .040 at the top land to just over .010 at the bottom of the skirt. This makes sense, as there is most likely always a large temperature difference from the top to the bottom of the piston. It might be an interesting exercise to obtain the temp coefficients for the piston and cylinder and figure out what the difference in temperature between the piston and cylinder wall would have to be to cause an interference fit, and could the piston heat up fast enough for that to be a problem on a cold day. (The clearances are larger on a cold day.)


Keep in mind that this info is from the overhaul manual last updated in 1982. I haven't yet searched through the stack of service bulletins to see if the Table of Limits has been updated. The numbers may also be different for Millenium or ECI cylinders.

Also FWIW, Service Information Letter SIL-03-1, issued Jan. 28, 2003, applicable to all TCM engines states:

Preheating is required whenever the engine has been exposed to temperatures at or below 20° Fahrenheit / -7 degrees Centigrade (wind chill factor) for a period of two hours or more. Refer to the Pilot’s Operating Handbook/Airplane Flight Manual for specific instructions that apply to your aircraft.

The service bulletin goes on to say that "lack of lubrication due to the congealed oil blocking proper oil flow through the engine" is the primary cause of damage when starting an inadequately preheated engine.

I think it would be a good idea to treat the 20 F as a MINIMUM for starting without preheat. Certainly couldn't hurt to preheat at 40, if it's available.

As far as when the engine is ready for takeoff, The SIL describes several methods of preheat, but regardless of method, cautions, "Do not operate the engine at speeds above 1700 RPM unless oil temperature is 75° Fahrenheit or higher and oil pressure is within specified limits of 30-60 PSI". It also states: "When oil temperature has reached 100 degrees Fahrenheit and oil pressure does not exceed 60 PSI at 2500 RPM, the engine has been warmed sufficiently to accept full rated power."

Miles

[Kyle Wolfe]

Our local FBO restores WACOs. They did the AOPA sweeps airplane a couple years ago. I know they swear by the motorcyle suits that run on 12 volt. Not sure what brand or type they use. Do know that they're all BMW guys so would guess it's probably made by them.

Know how cold it can be in our 170s - can't imagine flying an open cockpit bird when it's winter in MN