Type 1 de ice fluid

[flyboynight]

Can type 1, 50/50, be used to de ice wings that have Non Environmental Ice if the fuel tank temp is below 0 and outside temp above 0 with no other threat of snow etc.? Is this operator specific ?
I think the mix should be stronger 75/25, or just use type 11 any ideas ?:confused:

[Kirks gusset]

You can use water if you like, it depends if you are de-icing and then anti-icing, i.e a two stage process. The holdover time starts at the second application of anti-ice type XX fluid.

[Swedish Steve]

You are wasting money using more than 50pc mixture of type 1 fluid. It doesn't do any more at higher concentrations. At zero deg, the mix should be lower than that, say around 30pc fluid.
Look in your hold over table. There is just one line for Type 1. The strength is not specified.

[TolTol]

What if the aircaft has been left idle over night and its snowing? i.e. what mix should be used for the first step?

Reason I ask is because I recently arrived at aircraft and it had been de-iced with 10% fluid and it frozed straight away.

[A and C]

Type 1 is a very good de-icer but it has a low hold over time so the best plan is to de-ice with type 1 and them anti-ice with 100% type 2 due to the much longer hold over time.

[No_Speed_Restriction]

normally if holdover time has expired, a 2-step process is recommended. Not ideal to put anti-ice over anti-ice.:=

[A and C]

This link should clear up a few misconseptions.

http://vendors.airtransport.cc/WebDataFiles/Pubs/OPS/Deice.pdf

[flyboynight]

Thanks all for the information.Type 1 on cold soaked wings alone not a good idea !:ok:

[homerj]

How did you come to that conclusion Flyboy

[flyboynight]

Check out this link from A and C, clear ice def. pg 12.


http://vendors.airtransport.cc/WebDa.../OPS/Deice.pdf

[Mansfield]

FAA AC 120-58 provides guidance on this, with discussion of North American and European practices. If this link fails, simply go to the FAA.gov website and look up AC 120-58.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%20120-58/$FILE/120-58.pdf

The principal purpose of the Type I glycol/water mixture is to depress the freezing point as much as possible. More glycol does not mean a lower freezing point, so the mix ratio is optimized. In addition, more glycol may lead to an unacceptable viscosity of the surface film.

If properly prepared, a temperature buffer of approximately 20 degrees is targeted to prevent refreezing. The manual referenced above by A and C contains a statement to the effect that Type I on a cold soaked wing may refreeze, but seems to place this statement out of context. Deicers know about this, and should be using procedures designed to insure an adequate temperature buffer. If the temperature is so cold that a Type I mix cannot provide the minimum temperature buffer between freeze point and existing conditions, then another fluid type should be used. On the other hand, if the conditions are such that a Type I mix provides the buffer, then there is nothing wrong with using it.

[safewing]

Just a query/doubt about the Type I concentration.

I believe Type I has eutectic properties. That is when mixed with water to a certain concentration it performs better than by itself.

It's eutectic properties mean that when it is mixed with water to an optimum mix ratio as given by the manufacturer for the ambient conditions then it can lower the freezing temperature down as low as -40 to -50 degrees celsius, which with a LOUT buffer would mean ambient temperatures as low as -30 to -40 degrees.

Are there specific fluids available that refute this belief?

In our companies guidelines it states that Type I fluid should not be used undiluted.

[FEHERTO]

Safewing: You are wrong with the freezing point. A T1 in concentrated form normally contains more than 80% glycol (acc. SAE AMS 1424). This means, if it is Proylene Glycol or Ethylene Glycol, it will basically not freeze at all. The major problem with a 100% T1 is that it would aerodynamically not pass and maybe stick to the wings. Therefore during certification the optimum concentratio to reach the lowest operational use temperature is defined by two parameters: the aerodynamic aceptance and the 10° anti-icing buffer. A typcial T1 with propylene Glycol has the best performance at around 70:30 mixture ratio (around -32° C). The same product with Ethylene Glycol would go down till around -42° C.

Swedish Steve: Using ahigher mixture than 50:50 is not a waste of money. It is maybe sometimes necessary. If I have an OAT of -30° C, not a single T2, T3 or T4 in the world is useable. But a T1 in around 70:30 will work and must be used.

[safewing]

Feherto

Have you a link to this information?

Above 80 percent concentration does it alter its Newtonian fluid properties i.e. its low shear characteristics?

I was aware of the aerodynamic acceptance tests but I figured they related to the Non Newtonian fluids II and IV because of their high viscosity.

I was led to believe Type I was a low viscosity fluid and considered "unthickened".

If you read some of the web links above I'm sure I reading information about Type I that can be used in concentrations up to and including 100 percent.
I also know that rigs in EDDF state Type I up to 100 percent.

If it presents such issues above the 80 percent you quote why offer 100 percent? Is it stored in the rig at 100 percent and diluted at the nozzle to the figures you quote?

Also beyond the nominal figure of -25 degrees celsius if you do a LOUT and aerodynamic test are you stating that the margin of improvement is minimal or is it more to do with the industries ability not to do it in the field?

Any advice would be appreciated.

Thanks

[FEHERTO]

If it is a Newtonian Fluid or Non-netonian Fluid has nothing todo with the glycol type or amount. It is solely related to a chemical component in the SAE Type II/III/IV Fluids, called vulgo "Thickener" (that is the reason why some people call them "Thickened Fluids". It is a polymer creating the higher viscosity and changing the shear behavior.

Aerodynamic Test: A SAE Type II/III/IV Fluid must üass the High Ramp Speed Test, a SAE Type I Fluid additionally the Low Ramp Speed Test (simulating an aircraft with rotation speeds of less than 100 knots).

SAE Type I Fluids are not thickened, correct. But as lower the temperature, the glycol becomes "thicker", meaning more sticking onto the aircraft surfaces. So, unthickened fluid may also fail from an aerodynamic point of view.

You can use a SAE Type I Fluid in 100%, when:
1. It is a so called pre-diluted or factory diluted fluid. This means that the glycol content in the original, concentrated product isless than 80%. Such fluids shall never be diluted in the field and therefore must be used concentrated.
2. You can use any other Type I also in 100%, but must observe that the Lowest Operational Use Temperature (LOUT) is higher as with a mixture of lets say 70:30. A lot of people do not know this and may misuse the product in a dangerous way.

EDDF: The trucks have three tanks: Water, Concentrated T1 and Concentarted T4. The mixtures are done in the truck, either by an automatic system (measuring teh OAT and adjusting the mixture properly) or by manual selection. So showing 100% T1 is correct, but mixunderstanding for not well trained pilots.

Each single T1 Fluid has a different LOUT, some have -20°C only, some go down to -45° C. It is not the place here to make more details, these are detailed and long tables to know.

I am not sure what profession you are, I assume pilot. My suggestion is that you talk with your company about more detailed training. Your questions show me taht they have not spent a lot of effort to let you know the things, which are important. Do not misunderstand me, his is not against you as a person.

I am training every year hundreds of engineers, pilots and ground handling staff. Sometimes it is a horrow, what low level of knowledge they have. The industry ignores an area, which is the cause for more than 100 accidents in commercial aviation in the last 40 years.

[Capot]

Some more background information, for the less technical, was in a recent CAA FODCOM (posted before on pprune but I can't recall where!)

UK CAA FODCOM - Winter Operations (http://www.caa.co.uk/docs/33/FOD200931.pdf)

[FEHERTO]

Hi Capot, this document is mainly addressing the problem of residues created by "thickened fluids", but unfortunately does notproper specify the risks, when using a SAE Type I Fluid wrong.

[safewing]

Thankyou for the reply.

In your last paragraph you state that Type I fluid can be used in 100 percent concentration. However from what I have read I can see no benefit in using TYPE I undiluted if as you correctly point out the optimum mix ratio is around the 70:30 figure. I have read some of those tables you mention today regarding concentrates and performance.

I accept what your saying is technically feasable but if the optimum mix provides the best LOUT and by extension the optimum quantity of Glycol for the OAT or skin temperature why would you want to make the fluid under-perform?

From a economic and environmental view is using maximum concentrate also more expensive and harmful than a diluted mix?

[FEHERTO]

Hi, I mentioned the usage of 100% just to make clear that it is possible to use, but absolutely useless. From a technical, environmental and financial point of view. Unfortunately a lot of people involved, pilots, engineers and gorund staff, do not know.