Extreme cold temperature winterization

[exM20K]

@dkkim73 does your plane have the cabin heater mod? M20|308A
it works wonders in extreme cold. 
not a lot else to share, except that I’m currently in the same pickle, only worse. Brand new top o/h with Phillips XC 15W50 Type M, and half a tank of Florida fuel. I’m trying to get from Illinois back to Florida but will pass on flying till Thursday most likely.  I presume t(e Type M oil is more prone to congealing than A/D oil and don’t want to risk it.  
 

I will put 0.5G per side of the 99.9% IPA when I go

 

good lck

-dan

[Schllc]

@dkkim73

sorry, I don’t really have enough extreme cold weather experience to be helpful. 
my winters seldom get to 45deg 

[hais]

Funny story: you need to know your systems. I didn't know that the overhead vents don't pass through the heat exchanger. That ignorance was rewarded with a memorable flight

[dkkim73]

1 hour ago, exM20K said:

@dkkim73 does your plane have the cabin heater mod? M20|308A
it works wonders in extreme cold. 
not a lot else to share, except that I’m currently in the same pickle, only worse. Brand new top o/h with Phillips XC 15W50 Type M, and half a tank of Florida fuel. I’m trying to get from Illinois back to Florida but will pass on flying till Thursday most likely.  I presume t(e Type M oil is more prone to congealing than A/D oil and don’t want to risk it.  
 

I will put 0.5G per side of the 99.9% IPA when I go

 

good lck

-dan

Does that work out to about 1% IPA?  (thinking 44.5 gal per, bottom of collar) I'm going by volume. I recall at least one person suggesting 0.5%, and the POH mentions up to 3%. I've gone almost as cold with nothing, so thinking lower values are better. 

I'm running 20W-50 but not type M. Hence the concern about blocking the oil cooler. Has anyone here done this on the TSIO-550G? 

Checked on that mod. While he didn't mention it by name (the SB you noted), the MFSC directory did tell me my plane "had the upgraded heater system". Should have clarified, but  think that is what's in SBM20-308A/B.

Thx

D

SBM20-308A.pdf

[exM20K]

7 minutes ago, dkkim73 said:

Does that work out to about 1% IPA?  (thinking 44.5 gal per, bottom of collar) I'm going by volume. I recall at least one person suggesting 0.5%, and the POH mentions up to 3%. I've gone almost as cold with nothing, so thinking lower values are better. 

I carry 100 gallons of our cheap fuel out of here, so that’s a 1% solution.  Or, I’m a one percenter lol.

-dan

[dkkim73]

11 minutes ago, exM20K said:

... Or, I’m a one percenter lol.

-dan

Shhhh! They'll hit you with airport fees...

[dkkim73]

Went out tonight and taped the front side of the cooler with metallic tape. I would guess about 30% coverage. I am thinking with the airflow direction I don't have to worry too much about a lot of reinforcement. 

Savvy suggested taping below 190F oil temp. I've been seeing 170's in the last couple weeks, temps about 20F higher, so I'll see how it goes tomorrow. 

Bringing more tape with me...

Edited January 19 by dkkim73

[exM20K]

23 minutes ago, dkkim73 said:

Bringing more tape with me...

Keep it in the plane for when a TKS stall strip breaks loose.  NB: “When,” not “If.”

Enjoy your trip.

-dan

[Fly Boomer]

9 hours ago, exM20K said:

Keep it in the plane for when a TKS stall strip breaks loose.  NB: “When,” not “If.”

Enjoy your trip.

-dan

Haven't lost one yet, but they do seem to want to fall off periodically.  Do you do any kind of pre-flight inspection (yank, wiggle, visual observation)?

[GeeBee]

I regularly run below 190 in my Ovation even in the summer.

[exM20K]

1 hour ago, Fly Boomer said:

Haven't lost one yet, but they do seem to want to fall off periodically.  Do you do any kind of pre-flight inspection (yank, wiggle, visual observation)?

Wiggle lightly. I caught one loose on my 231 and was able to save it and the panel it sits on.

-dan

[Slick Nick]

@dkkim73 yes, you’ll want to run it hard and ROP to keep the temps up. I posted a thread awhile back where I ran lean of peak at altitude and couldn’t get the CHT’s above 200. 

My hang up with the IPA is that it can be hard on tank sealants, so I only use it if I’m going to go through a couple full tanks right away. If my destination is such that I will leave the plane sitting for a few days with the IPA in the wings, I usually go without. Something to keep in mind. 

Flying when it’s this cold out is awesome, the air is often still and crisp. 

[dkkim73]

Gentlemen,

Thank you for all the timely advice and help! 

Yeah, the IPA seems like a damned-if-you-and-damned-if-you-don't. I tanker fuel to that location, for both price and convenience,  89 gal and landing a bit under MLDW with baggage. Usually return and land with north of 24-28 gal depending on wind and power settings. So it would sit for a couple days and that was exactly what was running through my mind. I would probably try to run the tanks lower after the return leg for the reasons you note (e.g. local flights to burn them down). 

TKS stall strips: 

One was loose when I evaluated the plane for purchase, so the initial pre-purchase/annual/greenup involved re-bonding all of them at the MFSC. I haven't noticed any issues yet. I touch each of them on every pre-flight, though I'll be honest I don't push hard. I always check the little tubes which I understand, if they break, cause a lot of work and cost (as well as not functioning in the meantime). 

The broker who sold me the plane put clear repair tape over the loose strip for our test flight, after warning me about the little tube. He said "this looks crazy, but the fluid will seep under the tape and it protects the tube". Sure enough it actually worked well. 

After all that fuss, I punted the flight until tomorrow. The wx forecast got worse, lower ceilings at destination (followed by 180 degree wind shifts and gusts), IFR over a broad region with extreme cold wx warning, etc. Tops well into FLs, theoretically too cold for icing but I've seen the clouds not read the forecasts b4 in Feb . Things were starting to stack, and tomorrow should be clearer high pressure. I'll still get to deal with the cold, though, will report back if I get any good insights (how much to tape). 

At least the 2nd flight I've canceled or meaningfully postponed due to winter wx. I suppose I'm actually more surprised how often I've been able to dispatch. 

 

 

 

[dkkim73]

4 hours ago, GeeBee said:

I regularly run below 190 in my Ovation even in the summer.

Yeah, it's funny but my temps are never really high except CHTs breaking in new cylinders ROP (expected and still only "high" using Mike Busch's 380F working limit). 

So it might be a bit conservative (if that's the right word). I was calculating -40F at cruising altitude had I gone today, so more heat is probably better. 

On the plus side, I found these guys to do my annual: 

 

[dkkim73]

Flight went well today. Much better choice than the widespread IFR and changing lowering ceilings yesterday. Oil warmed up and stayed pretty warm. No hiccups. Did have to run ROP to keep in the green (went around 29"/2500/lean then switched to rich as expected).

Temps in cruise around 180F at OAT -22C at lowest, warming up going west, actually all warmer than forecast.

(I am told there is an oil cooler winterization kit with a bracket... I wonder if that's it in my earlier picture, and if there's a specific "block" that's supposed to slide in there).

Quite pretty:

 

Edited January 21 by dkkim73

[Yooper Rocketman]

On 1/18/2025 at 10:17 PM, exM20K said:

Keep it in the plane for when a TKS stall strip breaks loose.  NB: “When,” not “If.”

Enjoy your trip.

-dan

I've rebonded 2 and had to replace one, at $1200 from CAV.  Best to find them loose before they fall off!!

[Yooper Rocketman]

I flew to Appleton, WI yesterday, -13 below on the ground, and with my oil cooler 1/2 blocked off I was seeing 120 degree oil temp.  Blocked off the cooler the rest of the way (100%) and my second flight yesterday I was just under 160 degrees.  I find the Rocket really challenging to keep oil temps up in the winter.  And, yes, I have removed the oil temp sensor and tested it, finding it's right on temp.

On Isopropyl I have always used it in the winter on my Rocket (on my monthly trips to Florida, always up in the flight levels, I routinely see OAT's at -30F to -40F+).  The one time I didn't, many years ago, I had a freeze up of the fuel spider on top the engine and coasted at an ugly idle from FL210 to 14k before it thawed enough to allow fuel flow to the engine again.  I've never forgotten to add it again.  Cheap insurance.

Tom

[dkkim73]

1 hour ago, Yooper Rocketman said:

On Isopropyl I have always used it in the winter on my Rocket (on my monthly trips to Florida, always up in the flight levels, I routinely see OAT's at -30F to -40F+).  The one time I didn't, many years ago, I had a freeze up of the fuel spider on top the engine and coasted at an ugly idle from FL210 to 14k before it thawed enough to allow fuel flow to the engine again.  I've never forgotten to add it again.  Cheap insurance.

Thank you for that anecdote. I've had a lot of people say "you don't need that" locally (at least if I sump religiously, which I do, and include the gascolator in the winter), and the board is skeptical due to sealant issues. But then again we read about these weird fuel icing issues.

I would probably be more worried coming North from FL due to the change.

D

[GeeBee]

13 minutes ago, dkkim73 said:

Thank you for that anecdote. I've had a lot of people say "you don't need that" locally (at least if I sump religiously, which I do, and include the gascolator in the winter), and the board is skeptical due to sealant issues. But then again we read about these weird fuel icing issues.

I would probably be more worried coming North from FL due to the change.

D

Sumping is not enough. It only drains free water. All fuel contains entrained water to some degree or another. In cold weather your only choice is isopropyl alcohol. Used sparingly it should not be a problem.

 

[carusoam]

The chemical dot CO detector is great…

your next of kin will know immediately what happened to you… 

 

 

That cold outside…

getting started… requires the entire engine to be pre-heated long enough to warm the oil, cylinders, and case… don’t forget to warm the oil cooler…  if cold enough the cooler will be by-passed automatically… recovery of oil flow and temp control in flight may never happen…

warming just the cylinders can get it started, but without normal oil flow…. You risk serious engine damage…

 

in flight…

too much surface area open in front of the oil cooler will show low oil temperature, that you can’t get up into the green zone…

 

write yourself a check list…

What engine are you flying behind?

Some continental engines have an oil cooler blocking kit… specific to winter ops… comes with some ops details…

 

as far as getting heat in the cabin really depends on the engine you have…

turbos usually don’t get heater muffs… and operating in the flight levels can get pretty cold…

Get a lot of practice flights in before launching in -40 air…

be sure to have many layers of clothing…

be ready to find all the leaky seals your cabin has to offer…

on the coldest days…. My M20C could not generate enough heat in the cabin…

cold soaking in the cabin for a two hour flight was a bad idea….  
 

 

Best regards,

-a-

[dkkim73]

3 hours ago, GeeBee said:

Sumping is not enough. It only drains free water. All fuel contains entrained water to some degree or another. In cold weather your only choice is isopropyl alcohol. Used sparingly it should not be a problem.

That is exactly the analysis I ended up using. Went with 0.5% anhydrous(ish) IPA. I think that was your ratio?

@carusoam Warm clothes, yes. I was a bit of a nerd about it. I wore an underlayer and boots fleece and core survival stuff in a vest (thanks @Rick Junkin) in case I had to ditch quickly. Had an A bag with the rest of it in the back seat.

The Acclaim does have a heater muff on the hot-side crossover pipe, and also a feed from sonic nozzles on the high pressure side. It actually all worked pretty well.

I did both hangar storage (heated) and Reiff XP overnight. Taped oil cooler as above. Do you know where I can get that oil cooler blocking panel (that fits in the shelf)?

Thx

D

[Pinecone]

19 hours ago, carusoam said:

The chemical dot CO detector is great…

your next of kin will know immediately what happened to you… 

 

 

as far as getting heat in the cabin really depends on the engine you have…

turbos usually don’t get heater muffs… and operating in the flight levels can get pretty cold…

Agreed, get a good CO monitor.

Turbos have heat muffs.  They don't have mufflers (sound).

[carusoam]

On 1/21/2025 at 10:26 PM, dkkim73 said:

That is exactly the analysis I ended up using. Went with 0.5% anhydrous(ish) IPA. I think that was your ratio?

@carusoam Warm clothes, yes. I was a bit of a nerd about it. I wore an underlayer and boots fleece and core survival stuff in a vest (thanks @Rick Junkin) in case I had to ditch quickly. Had an A bag with the rest of it in the back seat.

The Acclaim does have a heater muff on the hot-side crossover pipe, and also a feed from sonic nozzles on the high pressure side. It actually all worked pretty well.

I did both hangar storage (heated) and Reiff XP overnight. Taped oil cooler as above. Do you know where I can get that oil cooler blocking panel (that fits in the shelf)?

Thx

D

The oil cooler has a slide in piece of aluminum that matches the oil cooler…

it probably has a Mooney part number for it…

 

the POH may actually reference it for cold weather ops…

it most likely is a continental part number… as the oil cooler is mounted directly to the engine…

best regards,

-a-

[jlunseth]

I live in Minnesota so experience pretty much the same temps as you, although I am in the Twin Cities area so a little warmer but I get up to International Falls in the winter once in awhile. I have a 231, which is turbocharged, and the consequence of that is that I need to be very mindful that the Oil Temp does not fall below 100 dF, which it can do in cold conditions. The turbo bearing needs oil and the space for oil passage is very thin, so the oil must be thin enough to lube the turbo.

I always preheat if the temp is below 40 dF. I call my FBO the night before and have them plug the plane in (engine heater). I can start it down to about 20 dF without preheat, but am told that creates unwelcome wear. Below 20 it is pretty hard to get the engine to start and there is a risk of wearing down the battery.

I never open the cowl flaps for any purpose in cold temps. Sometimes the East Coast people will jump in and say, oh heavens, what about hot spots! Cold for them is anything below 40. I will take all the hot spots I can get, whether during starting, runup, taxi, or in the air. The problem we both have is that we are around sea level in elevation and the air in winter, especially below about 5,000, is very dense and very cold, making it superior for cooling, which is not ideal for an air cooled engine.

I have my A&P install an oil cooler block when it starts to get cold. They have made me a couple, they are just thick foam bound with duct tape that is stuffed into the cooler. Definitely helps with the OT, although it is still possible to get an OT that is too cold. If necessary I will run ROP and as close to the red box as I dare. I attended the GAMI live seminar several years ago. The whole point of LOP operation is to flatten out the power curve during the combustion cycle to avoid a high peak ICT, which is what happens when operating in the red box and what causes high CHT's. They warned that CHT alone is not a good measure of peak pressure in very cold temps, in other words, you can still get the high peak ICTs you don't want even if the CHTs look ok. My normal ROP operation is 125 ROP, I will go as low as 100 in cold temps. I ran my last engine out to several hundred hours past TBO so apparently did not hurt it much if at all with this method.

One thing not mentioned is that during cold temp ops it is very important to warm not just the engine itself, but the entire engine compartment. I learned this the hard was practicing fast approaches and landings for an anticipated trip to our local Class B airport. The air/oil separator generates moisture. The moisture all froze, blocking the breather. I got unusual temp readings during a takeoff, returned immediately for landing, and had oil streaks about 18" wide running down both sides of the aircraft. The fix for this is to dawdle before first takeoff, keep the cowl flaps closed, spend about 10 minutes on your checklist and runup. Have not had a problem since that episode many years ago now.

I have operated in extremely cold temps because in the 231 I can fly in the flight levels. It is almost always below zero up there. I made a very fast trip from Williston ND to Minneapolis once at 21k with the temp at -54 dF (great tailwind). It was so cold that with the heater and defroster full open, all the windows were frosted and I was operating on instruments. However, I kept the engine amply warm and had no problem other than the cold in the cockpit.

I have not used ISO in the fuel for many years, but it is probably a good idea. We have had several discussions on the board about the problem of fuel line freezing at high altitudes. It appears to happen when a plane is fueled on the ground in higher temps and humidity and then is flown in the flight levels in below zero temps, because the fuel at ground level can carry moisture. I have not had any problem fueling around here in MN in the winter and then going up high. That said, there have been a couple of incidents where others have experienced fuel line freeze so I am going back to putting a bottle of HEET in each tank during the winter if a high altitude flight is planned. 1-3% is ok, or so I have been told by the experts.

Lastly, if I am flying up to International Falls or some other place that is foolishly cold I always plan ahead. I carry at least a 100' extension cord and call ahead to find out if there is a way to plug in. On occasion I have run a cord from the tarmac through the door or window of a rural airport building to plug in, but many in MN have outdoor plug-ins the same as cars. Need to do this if you want to get back home before spring thaws the plane out.

[GeeBee]

11 minutes ago, jlunseth said:

One thing not mentioned is that during cold temp ops it is very important to warm not just the engine itself, but the entire engine compartment.

The bomb. Guys in AK say the same thing.