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This question is related to small single/twin engine general aviation airplanes with aluminium construction. I understand that it is generally not recommended to use windshield washer liquid to deice an airplane.Based on your personal experience can someone validate this eitherways? I am looking for answers like:

  1. Used it once and my wing fell off

or

  1. Been doing this for 15 years with no side effects whatsoever.

As far as I know there is nothing in the POH for the planes that I'm currently flying ( C152 and Piper Dakota ). Also there is a significant price difference in the price of common windshield washer fluid and stuff like TKS. Also the question is limited to deicing the metal parts like the wings and the stabilator, not the plexiglass.

Jimy
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Prashant Saraswat
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  • Warm water is far cheaper. I've used that very successfully to deice 1/4 inch of frozen rain. Caveats include no holdover time and should not be used prior to operation in freezing conditions. – J W Dec 18 '17 at 11:08
  • Although it is not clear from the question, I'm interpreting this to question to be about removing minor ice and snow accumulation during a pre-flight from a plane that has been sitting on the ground, and not about FIKI. – abelenky Jan 29 '18 at 23:29

2 Answers2

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The short answer is, you should not use windshield wiper fluid.

TKS fluid and Windshield wiper fluid are very different things first and most importantly windshield wiper fluid has no FAA approval for this kind of operation (hence the price difference). You can find a full list of de-ice fluid for ground deicing of small aircraft in table 1 of AC 135-17. AC 135-17 also provides the FAA's suggestions on small craft ground de-icing in general.

TKS fluid is not for deicing aircraft on the ground it is for in-flight fluid based FIKI systems and is pumped out of various ports and flows over the wings/surfaces. It prevents the build up of ice in flight. For ground deicing, you use FPD/ADF fluid which is a thick viscus fluid that is often sprayed on the aircraft. Ground based deicing is intended to last from the aircraft from the gate (or other static position) until airborne and thus the FIKI system can be used. it also may prevent the build up of things like snow and ice while taxing.

The reason your POH says little if anything about de-icing is because neither the Dakota or the Cessna you mention are certified for flight into known icing, thus if icing conditions prevail on the ground they more than likely prevail in the air and you are not going anywhere anyway. The typical use case of de-icing a small aircraft is getting it out for the day after outdoor storage over night during snow, freezing rain, or enough frost build up to be an issue. If the temp is warming and icing no longer prevails the aircraft may still be contaminated. In this case you would use FDS liquid to clear the surface (and possibly a brush for any heavy snow build up). Many airports will have this on hand at the FBO.

You should avoid warm water as it can freeze again if the temperature is low enough.

This question is worth reading over as well.

Dave
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  • This is a great answer, however I suspect that the OP was asking about cleaning the surfaces before attempting the flight when there is no risk of further icing (I hope). As I said below, if you have to worry about things like 'holdover time' or cleaning an inch of ice from the wings of a C152, you are better off staying put. Judicious use of warm water (and carefully wiping it) is ok to speed up the cleaning, and the ww fluid would not hurt in this case, either. – alexsh Jan 30 '18 at 00:49
  • @alexsh one can only hope but either way the advice the FAA puts forward in AC 135-17 is fairly clear and should be followed if practical. Even if icing conditions dont prevail wet wings can still build up ice. – Dave Jan 30 '18 at 00:58
  • To clarify, I only meant to deice the plane on the ground when airborne icing is not a factor. – Prashant Saraswat Jan 30 '18 at 22:44
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A short answer it is relatively safe, since aluminum and steel are quite immune to interactions with various organics in the windshield washer fluid. Make sure you use the 'winter grade' fluids (they have enough iso alcohol to prevent them from freezing). I do think hot water is more effective and cheaper though so probably it is hard to find people who used the ww fluid long enough to provide reliable experimental data.

On the other hand it makes me cringe when 'deicing' (or 'holdover time') is applied to aircraft like C152 or P28A. Cleaning off ice using the ww fluid (or hot water as has been suggested) is fine if entering known icing conditions is not attempted afterwards. If your airplane has deicing boots, however, I would definitely spring for approved fluids for cleaning and treating the boots: they are quite fragile (chemically speaking) and very expensive to replace.

alexsh
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