Differences between TKS and Known Ice

[VORTIME]

Hi there,

I picked up a very interesting point in the Cirrus debate.

What's the difference between an aircraft with TKS or Evade style ice protection system and an airframe certified for known ice.

The point made by IO540 is that the legislators allow a system essentially (legally) incapable of protecting the airframe from ice to be manufactured and sold as ice protection.

So what does it take to go from ice protection to known ice?

VT

[IO540]

I suppose the answer will be that one is allowed to sell a product which performs a function even though it does not perform that function to some certification requirement which could be applied to that function.

This is just as well, otherwise everything down to the door handles would need certification. There are enough blatent job creation schemes already in this business.

I fly with a TKS de-iced prop, which I can tell you is highly effective in terms of extending mission capability in typical European IFR scenarios, but no way could it be certified for anything whatsoever. And that is just as well because if it could be certified it would cost 5x the price.

Could also be that the manufacturer decided to not bother applying for certification.

The phrase "known ice" applies to FAA registered planes. It doesn't apply to G-reg for example; the system there is different. Maybe somebody can dig out an online reference to the exact requirements to get certification for various degrees of icing.

The whole subject is also wrapped up with legalities concerning whether you knew there would be ice before departure, and there is much debate on the subject especially in the USA where the law has been enforced in certain cases. I don't think there has been any enforcement in the UK. For example, in the USA, a PIREP of icing constitutes "known ice" but of course there are no PIREPs outside the USA (that I know of); anything you tell ATC might as well go down a black hole, unless another pilot just happens to overhear it.

[rustle]

...of course there are no PIREPs outside the USA (that I know of); anything you tell ATC might as well go down a black hole, unless another pilot just happens to overhear it.

Not true.

UK ATC relay information from pilots about windshear on final (how else would they know) as well as other flight-safety affecting matters.

UK FIS will also report windshear if it is reported by a previous aircraft on final.

There's even a formula for when a windshear warning can be revoked I believe :8

[bookworm]

The phrase "known ice" applies to FAA registered planes. It doesn't apply to G-reg for example; the system there is different.

Of course "known ice" applies to G-reg aircraft. The AFM is substantially the same as the FAA's POH.

The FAA's AC 23.1419-2C, AC 25.1419-1A deal with what the systems have to be capable of to get known icing certification.

[IO540]

Rustle - I know that you know exactly what I mean; there is no US-style national system for encoding and distributing PIREPs, generated enroute for example.

Bookworm - I was referring to the specific phrase "known ice" which has a well loaded meaning. Sure G-reg planes can and do have certifications for specified degrees of icing.

[FullyFlapped]

My single has boots, a hot prop and a heated windscreen - and it's still not certified for known icing. This doesn't bother me because other than climbing or descending through, I wouldn't conciously go flying into known icing conditions, but I must admit I've always wondered what else you'd have to have to become so certified ... I can think of a few things, but I'm sure the list is extensive (and have you noticed how, in aviation, the "t" in that word automagically becomes a "p" ? :ugh: )

FF :ok:

[drauk]

FF,

It has to meet certain power requirements - redundant alternators I think. Pricey for sure they if they went as far as fitting everything else and not those maybe it was just a certification issue?

[mm_flynn]

FF,
It has to meet certain power requirements - redundant alternators I think. Pricey for sure they if they went as far as fitting everything else and not those maybe it was just a certification issue?

Having scanned Bookworm's referenced doc, it looks like the real cost will be in the detailed analysis of potential icing accumulation and the flight tests in actual icing conditions. The dual power supplies, deiced static sources, ice light, ice measurement method, windshield plate, deiced fuel vents, etc. are probably 'relatively' low cost:rolleyes:

[PCentR]

The original KI package on my P210 consists of-
dual alternators w/ failure indicator lights
dual vacuum pumps w/ failure indicator lights
full height windshield hot plate
heated pitot and stall vane (larger heating elements than non KI)
heated prop with ammeter to check operation
boots on wings, hor stab and vert stab
ice detection light (illuminates wing leading edge)

A KI Cessna 210 TKS installation requires dual alternators and dual TKS fluid pumps. Price increases from 25.5k USD (non-KI) to 35k USD (KI).

[IO540]

Does anybody have a URL to the CAA equipment requirements for flight in icing?

[FullyFlapped]

PcentR :

The original KI package on my P210 consists of-
dual alternators w/ failure indicator lights
dual vacuum pumps w/ failure indicator lights
full height windshield hot plate
heated pitot and stall vane (larger heating elements than non KI)
heated prop with ammeter to check operation
boots on wings, hor stab and vert stab
ice detection light (illuminates wing leading edge)


Interesting (to me anyway, thanks). My non KI-certified T210 matches the above except the 2nd alternator and boot on the vertical stab.

I wonder what the additional cost would be to upgrade - not a question, I'll ask the engineering fraternity.

Thanks again,

FF :ok:

[IO540]

It's a wonder that the engine actually rotates, with all those accessories hanging off it :) But it does explain why a lot of manufacturers don't go for a certified installation. The non-certified system is probably just as good - especially if it is identical to the certified one minus the redundant power sources.

[possel]

I think the point to make clear here is that TKS is actually anti-icing, not de-icing equipment - that is, it prevents the formation of ice and does not get rid of it if it has already formed (as boots do).

There is a world of a difference between certifying an aircraft for flight where possible icing is forecast (and your SOP is to get out of it quickly) and for flight through known icing. I was involved with the certification of a certain military aircraft where this point had to be well understood, as otherwise the aircraft would have been prevented from flying if there was any icing forecast, even just a thin layer. In the trials it took ages to actually get some ice on the aircraft as most forecast icing wasn't! But when we did get some, it was horrendous.

As a PPL, I would not want to fly in known actual icing conditions, regardless of the kit ...

Going back to the original post, the answer is that the difference is a lot of money!

[IO540]

As a PPL, I would not want to fly in known actual icing conditions, regardless of the kit ...

Firstly, a plain PPL can't anyway because he is limited to VFR only ;)

Also I am not sure what a CPL/ATPL does when it comes to icing. Anybody can be told what to do in a given situation. The license type is nothing to do with this, as far as I can see. One needs to understand the aircraft capability which is what we are trying to debate here.

[scooter boy]

Anybody know what TKS stands for? Somebody once told me but it does not immediately spring to mind - I think it is the name of the company that first came up with the technology for this system which is pretty good at de-ice and is not just anti-ice.

I completely agree that ice is to be avoided if at all possible and that having a "get out" plan is essential if one gets too frozen up. Certification for flight into known ice simply implies a certain degree of systems redundancy has been achieved by the airframe manufacturer which is acceptable to the jurisdiction conferring the certification. It does not mean that all icing is now no problem.

My experience of significant rapid airframe icing has mainly been crossing cold fronts where there has been significant precipitation. Warm and occluded fronts tend to be more gentle in terms of the turbulence, precipitation intensity and rate of ice accretion.

Whichever the scenario the intense icing has been pretty short-lived (20-30 mins) depending on the breadth of the front and the TKS has taken care of it effectively.

Inability of the TKS to cope would demand a rapid descent (maintaining airspeed in order to avoid a tail stall) to below the freezing level but as a previous contributor has pointed out the freezing level is often at or not much above the MSA in the winter.

Wx radar or datalinked weather would help to avoid the most intense precip in the cold front crossing scenario - I can think of several occasions when I would dearly have liked to have it on board.

Maybe if I ask santa nicely...

SB

[IO540]

My experience of significant rapid airframe icing has mainly been crossing cold fronts where there has been significant precipitation. Warm and occluded fronts tend to be more gentle in terms of the turbulence, precipitation intensity and rate of ice accretion.

For this reason, I (TKS prop only) tend to avoid flying through any front unless I can be sure there won't be any "organised" IMC with tops anywhere near the operating ceiling (say 18k) so avoidance of any vertical nasties can be done visually. Otherwise, I would turn back. This strategy has so far worked for me 100%, although I have scrapped a few flights this summer - but on those flights one would have been in solid IMC, in very moist tops and probably severe icing, anywhere below 25k feet and that rules out even a lot of turboprops.

For inflight weather radar, look at

http://www.moving-terrain.de/en/index_en.htm

A very high entry cost, over £5000 I recall, followed by about £100/year, but their charging structure is complex and you need to phone them to not only get pricing but also to work out what you actually get...

We are never likely to see the US-style weather radar data.