aircraft de-icing?

In the US we have 4 different types of Deicing and Anti-Icing Fluids.

Type I Fluid: Applied hot to raise the temperature of the aircaft skin in addition to melting the accumulated ice/snow. It’s a thin fluid so it runs off quickly so its anti-icing capability is low. Mixture ratio (glycol to water) is adjusted to keep the freezing point of the fluid below the OAT (outside air temperature). I ususally see it offered at 50/50 but a few weeks ago it was applied at 25%. The maximum ratio is 80%. Type I is used as a deicer and offers little if no anti-icing protection.

Type II Fluid: I don’t know if this is even offered or used by anyone anymore. It’s a thick fluid intented for aircraft with high takeoff speeds.

Type III Fluid: A cross between Type I and Type IV. It can be applied heated and offers the deicing capability found in Type I as well as anti-icing protection found in Type IV (but not as much protection). It’s capable of being heated and applied using Type I application systems.

Type IV Fluid: A thick fluid used as an anti-icing protection. After an application of Type I to remove any accumulated ice/snow Type IV is applied to protect against any further accumulation. The time of protection is determined using charts and take into account the Outside Air Temperature, brand of fluid, mixture ratio, type of precipitation and rated strength of that precipitation. Type IV offers the longest Hold Over Times (precipitation protection) of the 4 fluid types.

The anti-icing fluids being thick fluids stick to the aircraft to extend their protection life but are designed to sheer from the aircraft skin before rotation and take any accumulated ice/snow with it.

Anti-Icing and Deicing fluids are either Ethylene Glycol or Propylene Glycol based.

We use type 2 fluid 50/50 fluid/water & it’s applied hot.

It doesn’t harm the aeroplane but it makes it a bit sticky to work on! Often after a transatlantic flight the fluid is still running out of panels on the airframe.

1stly..no such thing as a stupid question

2ndly the fluid has no efect on either metal or composite structure.

Rgds Cking

1stly…always possibility of a stupid answer though!:D:diablo:

2ndly…thanks for that, i assumed the de-icing fluid was acidic based!:o

Apologises for asking what is probably a few stupid questions, but…

I know its obviously got to be strong enough to get rid of the snow/ice, but won’t that have an issue on the structural integrity of the aircraft itself…:confused:

1stly..no such thing as a stupid question

2ndly the fluid has no efect on either metal or composite structure.

Rgds Cking

WHere i work we have ecowing26 Type II , 75% fluid, basically sugar and water, and 25% water.

ISO Type 1 Fluid (Unthickened) SAE AMS 1424B

This fluid has a high glycol content (50/50) and low viscosity. Deicing performance of the fluid is good. However, due to low viscosity, it provides limited anti-icing protection during freezing precipitation.

ISO Type II Fluid (Thickened) SAE AMS 1428C

This fluid has a lower glycol content than Type I fluid due to the inclusion of a pseudo plastic thickening agent. This means that when applied to the surface of an aeroplane the viscosity is high, thus allowing the fluid to remain on and protect against freezing precipitation for a period of time.

These are the main 2 used C9, type 1 is 50/50 glycol & water, I’m not sure of the content of type II as I’ve never had to use it yet. (there’s always a first). But I think it’s 50/50 as well (50% water, 50% the other 2)
Glycol is non-corrosive, for continued use in winter operations this would certainly have to be the case.

Hope this helps

Dean