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So whats too cold for the plane


FlyboyKC

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On ‎1‎/‎2‎/‎2018 at 2:38 PM, neilpilot said:

I've been using "ISO-HEET Premium Fuel-Line Antifreeze", when appropriate, since I first started winter flying back in Niagara Falls.  As previously mentioned, buy 100% alcohol in the RED bottle.  Their other formulation in the yellow bottle is a solution of IPA and water.  It's particularly important to use IPA when you're tankering fuel from a warmer area of the country, since the water solubility in 100LL is much higher when the fuel is relatively warm

Just a follow-up since I originally posted and had the loss of power event. I received the order from Amazon and even ordered some Prist from Spruce. After a sudden power loss and you have had time to reflect you are willing to try any and ALL suggestions. To say I over ordered and took everyone's advice is a understatement.

Neil is fairly local and gave me a call the day I posted this and gave me his reasoning and background about the water in the fuel theory. I bought some of the ISO-HEET the next day and put a bottle in each tank. I also did a very thorough pre-flight fuel test and drain..much more than I normally do. Everything appeared good. I'm happy to report I've had about five  separate 1/2 hour to a full hour of flights with no engine issues and all gauges are reading correct. Hopefully that was a once a lifetime event, but at least I now know what that type of situation feels like and I feel slightly more confident knowing under a minor emergency I remembered procedure...for the most part anyway. :) The landing leaved a lot to be desired. I was just glad to be on the ground. 

Thanks for all the info and input.

 

-Tom

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1 hour ago, TWinter said:

...even ordered some Prist from Spruce....

Just remember Prist is prohibited from being used in our Mooney's; its not compatible with our sealant. (I don't know about bladders compatibility). I would only use it in an emergency and after very carefully diluting with avgas before adding it to the fuel tank. Its probably safe enough after diluting it if you really needed it and it was the only thing available. Only isopropyl Alcohol is approved.  

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1 hour ago, kortopates said:

Just remember Prist is prohibited from being used in our Mooney's; its not compatible with our sealant. (I don't know about bladders compatibility). I would only use it in an emergency and after very carefully diluting with avgas before adding it to the fuel tank. Its probably safe enough after diluting it if you really needed it and it was the only thing available. Only isopropyl Alcohol is approved.  

Isn’t the modern sealant (a recent reseal ) different from the original?

and avgas prist comes with a spray sky stem you are supposed to spray into the fuel nozzle stream as it flows rather than just dump it in.

at weepnomore they the,selves dumped some isoprop into my fuel for me 0f morning for my departure in Minnesota Jan... so I figured they are good with isoprop,

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35 minutes ago, aviatoreb said:

Isn’t the modern sealant (a recent reseal ) different from the original?

and avgas prist comes with a spray sky stem you are supposed to spray into the fuel nozzle stream as it flows rather than just dump it in.

at weepnomore they the,selves dumped some isoprop into my fuel for me 0f morning for my departure in Minnesota Jan... so I figured they are good with isoprop,

Foremost, because I am not an expert on the sealant, the prohibition on Prist pertains to the current production aircraft - so its just as applicable to modern sealant. My limited understanding is that the non-modern sealant is the dating back to the vintage Mooney's. I believe all the mid-body's such as our K's since the 80's were sealed with "modern" sealant or material  which is equivalent to todays but I can't factually say, except that is also about when the prohibition on Prist began by the factory as far as I know and continues in today's production aircraft.

I personally have never used it, and I've only very seldom used IPA, but I am also anal about keeping the cap o-rings in good shape and use the more modern longer lasting material. But I know I have gotten a little water into the fuel system every time I remove the caps when they are soaked despite trying to mop up the water first with a towel.  But I have never experienced the condensation issue flying in the flight levels for past 15+ years either. But through Savvy I see a lot of fuel contamination issues, so I am certainly not implying aircraft shouldn't need it. Many clearly do on occasion, especially since our fuel system is particularly vulnerable to it, but luckily I have managed to avoid any. 

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8 hours ago, kortopates said:

Foremost, because I am not an expert on the sealant, the prohibition on Prist pertains to the current production aircraft - so its just as applicable to modern sealant. 

I'm staying with IPA, but to confuse the Prist discussion even more the compound that is Prist was EGMME until 1994, and then was changed to DEGMMA.  So in addition to any changes in tank sealing components, the "new Prist" can have very different effects in your liner.  Or not.

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Since I brought Prist up into the discussion, I sent them an email asking specifically what limitations are in place for general aviation 100LL fuels. As Neil pointed out, they went from a mono-ethylene glycol ether formulation to a di-ethylene glycol ether. Presumably to make it for environmentally friendly.

Either formulations is an ether based compound. The fact they now specifically call out turbine certification (military DOD) and nothing on 100 LL usage may have more to do with legal concerns than function. I’ll let you know what I find out.

BTW - to Paul’s point. From the Aircraft Spruce Q&A:

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Sent from my iPhone using Tapatalk Pro

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13 minutes ago, larryb said:

I have wondered about the same thing.

One can get 99% quality at a good paint shop.

In the world of buying chemicals, 99%, 99.9%, 99.99%, etc ever more pure may be available and needed for some applications where impurity could be critical for the application,

but on the other hand as the quality improves logarithmically, generally the price increases exponentially.

So how good is good enough for this application?

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15 minutes ago, larryb said:

99% anhydrous is fine.  Maybe CA is different, as it is in so many ways, but why not just buy HEET in the red bottle?  One bottle is the perfect size for one tank, and that packaging is easy to manage and even carry in your hat rack if required on the road.  As an aside, when I was working I made byproduct IPA that we would burn as supplemental fuel in our steam boiler.  With a 20k gallon tank of IPA, it was always tempting to just take a few gallons.  But I never did; it was about 95% and laced with an acrylate monomer.:rolleyes:

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Concur that 99% is fine, since it will get ridiculously expensive beyond that. But the concern would be what is the remaining 1% in case its harmful. ISO-HEET is 99& alcohol and 1% proprietary. The 1% proprietary part is a bit scary if its not compatible with our fuel system. But whatever it may be, its pretty diluted in a fuel tank. Yet its pretty expensive compared to 99% isoproyl alcohol; just package conveniently which can make it worth while to many.

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27 minutes ago, kortopates said:

Concur that 99% is fine, since it will get ridiculously expensive beyond that. But the concern would be what is the remaining 1% in case its harmful. ISO-HEET is 99& alcohol and 1% proprietary. The 1% proprietary part is a bit scary if its not compatible with our fuel system. But whatever it may be, its pretty diluted in a fuel tank. Yet its pretty expensive compared to 99% isoproyl alcohol; just package conveniently which can make it worth while to many.

Pretty expensive is a relative term.  For 24 bottles, which should last a few years, it's $36, shipping included.  https://www.goldeagle.com/product/iso-heet-fuel-line-antifreeze-injector-cleaner/

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Expect the 1% will most likely be water... as the separation/distillation process gets very expensive to send this through multiple process steps to separate the common water from the alcohol....

alcohol with low% water is better for adsorbing the moisture in the fuel tank.

Rubbing alcohol is often closer to 50% water already.

Always read the label on consumer products...they will list the other stuff that may be in the container...

 

What we are looking for is...

1) an alcohol that adsorbs water, down at the molecular level...

2) doesn't come with a lot of water in it already...

3) doesn't dissolve tank sealant... or paint when spilled...

4) easily distributes itself in the fuel system...  good to add just prior to when filling the tank...

5) safe to handle... (alcohol has the ability to pull moisture from the skin as well, or be absorbed into the skin...)

 

There are two forms of moisture we are combatting....

1) visible moisture that has entered the tank and settled near the sump/drains.  The last drops of water can be absorbed into the fuel using the alcohol being discussed here...

2) small amounts of moisture, that at the molecular level, is floating around with the 100LL.  This is the stuff that falls out of solution as the temperature decreases... a few grams of crystals collecting in the wrong place has caused problems with fuel flow...

 

Apparently, when they say oil and water don't mix.... and water will sink to the bottom of a container filled with 100LL.... they didn't mean 100 percent, all the time...

 

Funky physics that describes it...

1) A tiny small amount of water is always absorbed into 100LL.  

2) It is at equilibrium, based on temperature.

3) The colder it gets, the less moisture can be absorbed in 100LL... the excess falls out of solution...

4) Warmer fuel that has been delivered by truck may have moisture in at equilibrium...

5) As the warmer fuel chills under the atmospheric conditions of the plane, this excess moisture falls out of solution, crystallizing on something... kind of like cloud seeding.  Or super cooled crystallization videos we have watched on MS....

6) The larger the temp drop, the more likely water and ice crystals becomes...

 

Also Keep in mind... an open container of this alcohol stuff will start absorbing moisture out of the air.  Expect the instructions for use may mention using the whole container once opened...

 

PP understanding of what I read on MS.  I may have studied some of this somewhere as well...

Best regards,

-a-

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39 minutes ago, carusoam said:

Expect the 1% will most likely be water... as the separation/distillation process gets very expensive to send this through multiple process steps to separate the common water from the alcohol....

The remaining impurities depend on the method of manufacture and purification.  I can say that there was less than 50ppm water in the >96% I made.

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IIRC, isopropyl alcohol cannot be distilled past 88%, so any higher grades have to be made by some other method of removing water (like passing over a dessicant).  That being the case, any IPA greater than 88% will actually slowly pick up water from any source (including humidity in the air).

It's not clear to me how much IPA s needed to dissolve how much water in gas  I found this reference online but did not fact check it:

Adding about 3% by volume of anhydrous iso propyl alcohol
will provide a water tolerance of about 0.35% at 15C and about
0.2% at 0C, thus it's ability as a cosolvent is superior on
a volume basis, and far less temperature sensitive than
methanol.

That suggests that at 0degC, if you put in something like 93% IPA, you won't help because you'll be putting as much water in as gasoline can tolerate.  Of course, we don't put in 3% by volume of IPA in our tanks, so I don't know how applicable that number is.

TLDR; I figure 99% IPA at about $20-25/gallon is probably reasonable.

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35 minutes ago, jaylw314 said:

IIRC, isopropyl alcohol cannot be distilled past 88%, so any higher grades have to be made by some other method of removing water (like passing over a dessicant).  That being the case, any IPA greater than 88% will actually slowly pick up water from any source (including humidity in the air).

Again, it depends on the method of manufacture.  There's no reason to assume that all IPA is made in an azeotropic distillation of an aqueous mixture.  In the process I ran, the IPA was a byproduct in a system that had essentially no water.  I could have easily distilled the IPA to =>99%, but since it was a byproduct that was going to be burned anyway we settled for 95%. 

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So the wife went to Walmart and told her to get some 99% Isopropal alcohol if the had it, but all she could find was 91% and she bought it anyway. Just ordered a case of 99% on amazon in 16oz bottles for convenience. 

Now I gotta either take the 91% back or find a use for it

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52 minutes ago, Bartman said:

So the wife went to Walmart and told her to get some 99% Isopropal alcohol if the had it, but all she could find was 91% and she bought it anyway. Just ordered a case of 99% on amazon in 16oz bottles for convenience. 

Now I gotta either take the 91% back or find a use for it

Mix it with with water down to about 30% and a few drops of dish soap and it makes a cheap kitchen countertop cleaner

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54 minutes ago, Bartman said:

So the wife went to Walmart and told her to get some 99% Isopropal alcohol if the had it, but all she could find was 91% and she bought it anyway. Just ordered a case of 99% on amazon in 16oz bottles for convenience. 

Now I gotta either take the 91% back or find a use for it

You could use it in a spritzer to de-ice your car windshield.

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I got a wild hair to exercise my plane last week. It was 13°F when I arrived Sunday morning. Had to torch the door pins just to get the hanger open. After a nice gentle preheat it fired right up. While taxiing I could feel where the tires had taken a set from sitting for a few weeks. Performance was out of sight as usual. Just shy of 0°F at 4500’. The thing that was bothersome was  that the absolutely highest CHT I could attain was 283°F. Mixture had little effect on CHT. Full rich yielded a hottest CHT of about 270°F. Anything leaner than peak hottest dropped below 250°F. I had to run pretty aggresiy to see 283. on approach, my coolest CHTS (1 and 4) dropped well below 200°F. 

Oil temp maxed at 155°F

Absolutely no problems keeping the cabin toasty. I had a lot more heat that I could have used.

Is this typical of what the rest of you see? I intentionally left the oil cooler clear to see how it would do. 

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14 hours ago, Marauder said:

 


It will dissolve oils. Good for getting oil marks off of the concrete in your hangar.



Sent from my iPhone using Tapatalk Pro

 

I've been toying with painting the whole hangar floor with oil. Why should the stain be restricted to the area around the nose gear... :wacko:

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  • 1 year later...

So, I was at FL 210 temp -27C when I experienced a primary alternator failure ( alt new 150 hrs ago). The back up alt worked fine. I had very little load on the alternator when it failed. No circuit breakers popped. I landed for fuel for about 1/2 hr, temp +5C. I was expecting the primary alt to remain non functional. However, after things presumably warmed up a bit, the primary alt started working just fine. No further issue past 75hrs in temps as low as -15C.

I believe the cold combined with very little load caused some sort of alt disfunction.  Could cold temps be an alt limitation? Or do you turn every thing on creating a heavy load when temps are low?

 

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My coldest departure was 8°F (-13°C), memorable because my wife stayed home that morning; I don't recall temps aloft. All I did was run Cabin Heat wide open for a few minutes before pushing it half closed and opening Cabin Air aboit halfway. And boy did I climb!

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A couple of things.

IPA will dissolve the tank sealant. Not as good as ethanol, but it is almost as good as MEK. I've tried them all while stripping tanks.

Way back when I was young and foolish I started the Mooney without a preheat (the plane was sitting for about 4 hours) at Casper WY when the temperature was -25F with the wind blowing about 50 MPH. I was parked right in front of the FSS. I couldn't get the bendix to engage (frozen) and was getting it to engage with a BIC pen when a man from the FAA came out and started reading me the riot act for moving the propeller without the plane tied down. I politely told him it would be an act of God if it fired at all with the starter turning it. It did start and I quit parking in front of the FSS.

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