How to remove ice from fuel lines in the field

[pdb]

I got a bad batch of fuel recently and when I went to fly yesterday, both fuel drains in the wing tanks were frozen solid. (Its 19 F this morning, aren't you boys jealous.)

Careful application of hot air from my electric car heater that I use under my engine cover got the quick drains unfrozen and I drained a lot of fuel with lots of visible ice crystals and thought I had it all as eventually the sampling gas cleared up and I went flying.

It soon became clear however that I still had a problem as no fuel was draining from my left tank so I made a beeline for home. So, I have two questions.

1) What's the best fix for a field solution? I don't have access to a warm hangar and its likely to be below freezing for a while.

2) Does anyone have a copy of Cessna Service Information Letter SE79-30 dtd 6/18/79 ? This addresses the use of isopropanol for fuel deicing at a ration of 100:1. For 37gal, that equates to 1.5 pts/wing or 3 cups/wing or .7 L/wing mixed well

I would like to get a copy and persuade George to file it in the TIC170 MX Library so I don't have to thrash about trying to find it every winter.

[mit]

Get a herman and warm them up. If it is real bad drain it all out threw the line to the carb. Do not drain from the wing drains!

[pdb]

Thanks Tim.

Draining from the carb makes sense but what is the problem with the wing drains if fuel is flowing freely?

[mit]

I meant if you have to drain all the fuel out, don't try to do it from the wing drains. Turn the fuel off at the selector, disconnect the fuel line at the carb, put the end into the container you are using 5 gal jugs or what ever, just don't have the fuel falling, then select the tank you want to drain first, use the selector to shut it off. How do you know you where not getting fuel from a wing tank? did you switch to it and the Eng quit?

[pdb]

How do you know you where not getting fuel from a wing tank? did you switch to it and the Eng quit?

While flying with both tanks selected, I got no visible indication of fuel,consumption in one tank and the other appeared to drain normally but at faster rate. The engine functioned perfectly at all times but I cut the flight short to sort the problem out on the ground. My assumption is that I have an ice blockage in one tank even though it seemed to drain clean before I took off.

[GAHorn]

The rubbing alcohol you have at home....IS NOT WHAT you use!
FAA Advisory Circulars at the FAA.GOV web will describe how to use
100% isopropyl.
But
I dont advise it.
It will not defrost existing ice very well....it is primarily for anti-ice.

[blueldr]

I had a similar problem with my Stinson L-5 when I was at Weeks Field up in Fairbanks about sixty years ago. I found the best and safest way was to get a Herman Nelson out and heat up both tanks and drain them dry. Then start over from scratch. Isopropyl alcohol was fine to prevent water from freezing, but not effective for melting accumulated ice in fuel.

[jrenwick]

To verify fuel flow during preflight, you could open the gascolator with the fuel valve off, then turn each tank on in turn and verify that fuel is falling on the ground. But that's certainly no guarantee that ice crystals still present in the tank won't clog the lines later during flight. This sounds like a real sticky wicket, and it gives me a lot of respect for people who fly year-round up there!

[GAHorn]

At the risk of seemingly promoting an automotive product for aircraft use....(I don't like this stuff one bit in airplanes!)....
there is anecdotal evidence that brand-names "HEET" and "ISO-HEET" purport to solve this problem.

Most automotive "octane" enhancers and fuel additives contain methanol...a type of alcohol which is effective for external de-icing of aircraft and , in JET FUEL can be used to prevent/remove ice in fuel lines and filters.

This stuff is corrosive and will swell rubber seals/gaskets and if left standing will actually attract humidity into the fuel. (Have you priced a carb overhaul lately?) But if ice is already frozen your drain valves and there is no other way to heat the system up with a Hermann-Nelson or warm hangar...it may be the only way. Problem is...it's BAD...read BAD for your airplane fuel system.

The other alcohol product sometimes approved in 5% or less concentrations is ISOPROPYL alcohol. (This is the same stuff found in PRE-mixed with water and sold in drug stores for "rubbing alcohol" It will also contribute to corrosion. You DON"T want rubbing alcohol in your aircraft fuel system because it contains water and sometimes mineral or "baby" oil and glycerin. Again, DO NOT USE "rubbing alcohol" except for massages and anti-bacterial/medical useage.)

100% Isopropyl is sometimes sold in paint stores. I have searched high/low for what I seem to recall an Advisory Circular which deals with the subject, and cannot find it...but in any case, ISOPROPYL will mix/absorb water and remain in suspension, as opposed to methanol which will sink to the bottom of the tank, mix with ice or water, to be drained out.

I wish to remain on record as opposed to using "HEET" (Methanol) or "ISO-HEET" (Isopropyl) for aircraft operations, but understand that some folks disagree with me, and claim it helped their problem.

Here's what one of their distributors post as FAQ:
http://www.goldeagle.com/brands/heet/faq.aspx

[pdb]

These bits were a hard to find but, for what it's worth,

Lycoming Service Instruction 1070Q dated July 16, 2010 contains the following note :

"Isopropyl alcohol in amounts not to exceed 1% by volume may be added to the aviation fuel (not automotive fuel) to prevent ice formation in fuel lines and tanks. Although approved for use in Lycoming engines, do not use isopropyl alcohol in the aircraft fuel systems unless recommended by the aircraft manufacturer."

Continental Service Information Letter SIL 99-2B Dtd 10/17/05 also contains the following note.

"Under certain ambient conditions of temperature/humidity, water can be supported in the fuel in sufficient quantities to create restrictive ice formation along various segments of fuel system. To alleviate the possibility of this occurring, it is permissible to add Isopropyl Alcohol to the fuel supply in quantities not to exceed 3 percent of the total. "

[n2582d]

SNL 79-30 refers to ME 73-25. Copies of those bulletins are in the MX Library.

[marathonrunner]

ONe other reason to not use the frozen quick drains is that an ice crystal can get between the seat and seal and keep the drain draining. When not anywhere near power or a hangar I one time used my hot coffee to unstick a frozen drain just by holding it up to the drain. I think I would drain the whole batch and filter it and start over.

Just because it appears that one tank is not draining does not mean that is the case. You can select one tank and the other and open your gascolator quick drain and see if it continues to flow or stops, slows down, whatever...just a thought.

[pdb]

Boys... Thanks for the helpful suggestions and references.

[jrenwick]

A British friend of mine once told me that to remove water from fuel, put a chamois in a funnel and pass the fuel through it. The chamois will absorb the water and hold it. I've done this, but without finding any water, so I don't personally know how it works with water in the fuel.

[jrenwick]

Also -- if 170 tanks are anything like the Cessna 150 tanks in http://sumpthis.com/, you won't get all the water out through the drain valve. There may still be ice crystals in the tank after you've drained it from the sump.