What would you want in icing conditions?

What FIKI do you prefer?

  • Boots

    Votes: 15 36.6%

  • Weeping wings

    Votes: 10 24.4%

  • Other

    Votes: 16 39.0%
  • Total voters
    41
Leavitt

Leavitt

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Jan 27, 2010
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52
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Alaska
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Display name:
wanabe
I would think that weeping wings would provide the best protection, but I havn't ever had ice on my airplane, so what do those say that have been in some good ice.
 
My understanding is bleed air is the nicest, but that's not something that those of us with piston aircraft are likely to ever see.

I like my boots. While there is still the potential for issues, there is no bottle to run out like with weeping wings. No de-ice is perfect, and it's important to know the limitations for each.
 
What would you want in icing conditions?

An escape plan...


Trapper John
 
What would I want in icing conditions?

a) A seat at the bar
b) A seat in back of a large turbine powered aircraft - if I just have to be somewhere
c) A seat behind the wheel of a nice four wheel drive with studded tires if b) is not available and most of the underequipped nutzo's are off the road

So I selected "other." As always, YMWV
 
Having used neither, my expert opinion is that boots are superior.
 
Boots are deice equipment. When ice forms, the boots can be inflated to make it go away.

Weepers are anti-ice equipment. If they are turned on prior to ice forming, they will prevent it from sticking to the airframe.

Weepers must therefore be activated prior to the time ice starts to form, which involves some guesswork by the pilot. If the ice forms before the weepers are activated, the system has insufficient pressure to dislodge it. The inescapable result is that weeper fluid is used for some period of time before and after the actual icing conditions are encountered, since some residual fluid will continue to weep after the pump is turned off and the system pressure equalizes.

If you check the hangar floor under a Citation S-II with weepers and a Citation II (booted) that landed at the same time during forecast icing conditions, you'll typically find an outline of deice-fluid of the leading edges of the wing and tail. It's slicker than owl****, so be very careful as you walk around the airplane.
 
Trapper John said:
What would you want in icing conditions?

An escape plan...


Trapper John
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Yup. The C-182 I fly only has that as an option. Other than stay out of the icing conditions in the first place.

Clark1961 said:
What would I want in icing conditions?

a) A seat at the bar
b) A seat in back of a large turbine powered aircraft - if I just have to be somewhere
c) A seat behind the wheel of a nice four wheel drive with studded tires if b) is not available and most of the underequipped nutzo's are off the road

So I selected "other." As always, YMWV
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:thumbsup:

jesse said:
Having used neither, my expert opinion is that boots are superior.
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+1
 
Wayne, you outline my conceptual issues with TKS well. Having never used it, I can't speak to its effectiveness, but as with anything else, I'd suspect specifics of each installation would have a significant effect.
 
Leavitt said:
I would think that weeping wings would provide the best protection, but I havn't ever had ice on my airplane, so what do those say that have been in some good ice.
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I picked "Other" because "either one is fine" wasn't an option. What I want is one that's in good working order and fully "fueled" if it's liquid based. Either TKS or Boots works for me and each has pros and cons. Boots can't run out of fluid but don't need to be "primed" before entering ice (there's been a number of times when I've gotten hosed by a cloud I didn't expect to contain much unfrozen water). But unless you've got an all electric panel, activating the boots can kill the air supply to your gyros at a very unpleasant time. TKS usually does a better job of keeping ice off the entire airplane, especially in a single where the prop fluid can provide some protection for things like antennas.
 
wabower said:
Boots are deice equipment. When ice forms, the boots can be inflated to make it go away.

Weepers are anti-ice equipment. If they are turned on prior to ice forming, they will prevent it from sticking to the airframe.

Weepers must therefore be activated prior to the time ice starts to form, which involves some guesswork by the pilot. If the ice forms before the weepers are activated, the system has insufficient pressure to dislodge it. The inescapable result is that weeper fluid is used for some period of time before and after the actual icing conditions are encountered, since some residual fluid will continue to weep after the pump is turned off and the system pressure equalizes.

If you check the hangar floor under a Citation S-II with weepers and a Citation II (booted) that landed at the same time during forecast icing conditions, you'll typically find an outline of deice-fluid of the leading edges of the wing and tail. It's slicker than owl****, so be very careful as you walk around the airplane.
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My experience with TKS is limited and definitely doesn't involve any Citation time but it's my understanding that if you prime the system within an hour or so of an ice encounter, going to the high pressure mode will shed ice that's accumulated prior to activation.
 
I've heard that as well, but the pilots who fly them (more than I do, and we don't have that much ice around here anyway) say it takes a real man to sit there and wonder. There's no question about the fluid on the floor, however. You slip on it just before you think about looking to see if it's there.

gismo said:
My experience with TKS is limited and definitely doesn't involve any Citation time but it's my understanding that if you prime the system within an hour or so of an ice encounter, going to the high pressure mode will shed ice that's accumulated prior to activation.
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...to be somewhere else.

Seriously, I want turbine engines with hot lips and hot wings. Anything less is, well, less.
 
I have a Mooney with weeping wings. The system works very well. Previous, to the Mooney I had a T210 and before it a Baron which had boots. Weeping wing works best but boots will do the job. Either system requires a lot of maintenance. Since most pilots do not get into much ice they tend to under maintain the deice/anti-ice system. When they need it sometimes they find it does not work. The best thing you can have on board when the ice starts to form is an experienced pilot.
 
I have used both and think the pros and cons of each system almost are a push as high wing vs low wing....I do like TKS on a single(currently flying a tks be-36) but I like boots on a twin. TKS is purely preventative but it does an outstanding job of keeping ice off the plane when used correctly.
 
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Well, I put other because I'd want more than just boots to be K-ice and for my plane to be certified as K-ice there were several other requirements: pitot heat; heated fuel vents, heated stall warning, hot plate, 90 degree antennas to shed ice, boots, dual static inlets, dual vacuum pumps, hot props and a couple other things like an ice light.

I've not have issues with boots, but don't get into heavy icing. I have had the plane slow markedly when the boots were working fine and the wing was clean on top where I could see. So, there must have been a bunch of ice where I couldn't see it. When I got out of icing conditions, it slowly regained airspeed and about 20 minutes later was up to normal cruise.

From what I've read and the folks I know using TKS, it works well. The pros and cons have been covered well, but there is much more to a good system than just TKS.

Best,

Dave
 
What would you want in icing conditions?
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The initial cost outlay for TKS is higher, but maintenance is essentially nil- just run the pumps once in a while. No need to maintain the brushes on a hot prop or replace a hot plate on a windshield that's burnt out.

For an aftermarket installation, TKS will get KI certification for some planes, like Barons. Most systems will give around 3 hours of continuous use, which is a long time to be droning around in icing conditions, especially with a plane that is going fast enough to have either system installed. TKS also protects the entire surface, not just the leading edges. However, it is expensive and does make a slimy mess on the hangar floor. Since some planes rely on a hot plate and/or alcohol slinger for the props in addition to boots, the differential in cost for maintenance between boots and TKS gets less.

A lot of users will prime the system, then turn pumps on when encountering ice, and off when in the clear, so the actual functional time is a lot longer.
 
Trapper John said:
What would you want in icing conditions?

An escape plan...


Trapper John
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Right, Trapper, and that is all that boots/weepy wings/etc are meant to provide....a measure of protection while you are exiting the icing area. No de-ice system is intended to protect an airplane that remains in icing conditions.

At the risk of repeating myself, and working off the top of my head, Appendix C to FAR 25 (which covers Part 23 airplanes by reference), says that in testing, the de-ice system has protected a wing in a stratus layer for 17 miles. Stay in the ice any greater distance and you are a test pilot. In convective conditions the distance shrinks to 3.8 miles. It also says that the maximum droplet size used in testing is 40 microns, which is hardly large enough to see.

Be careful out there....all that money might not be buying you as much protection as you hoped for.

Bob Gardner
 
bobmrg said:
At the risk of repeating myself, and working off the top of my head, Appendix C to FAR 25 (which covers Part 23 airplanes by reference), says that in testing, the de-ice system has protected a wing in a stratus layer for 17 miles. Stay in the ice any greater distance and you are a test pilot. In convective conditions the distance shrinks to 3.8 miles. It also says that the maximum droplet size used in testing is 40 microns, which is hardly large enough to see.
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Wow - I'd never seen that before. What kind of ice accretion rate does that 3.8 mile distance translate to?


Trapper John
 
Ted DuPuis said:
I'd suspect specifics of each installation would have a significant effect.
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I think this is true for all types of anti-ice/deice systems. A certain method may work better on one airplane than another. My personal choices based on the airplanes I've flown are:

1. Bleed air
2. Boots
3. TKS
 
I like TKS for the reason Scott states, but given that I only need anti-ice for the time it takes me to get out of it, the aggro of TKS exceeds its usefulness for me. I'll go with boots.

Yes, I know ice can accumulate in the blink of an eye, but I try to stay away from such situations, and the boots will get the job done if it happens. All that TKS mess, and getting the refills, etc? Too much hassle for this pilot. YMMV.
 
Trapper John said:
Wow - I'd never seen that before. What kind of ice accretion rate does that 3.8 mile distance translate to?


Trapper John
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I'm not sure that accretion rate is part of the process. Why don't you go to the FAA web site and take a look at FAR Part 25. Appendix C?

Bob Gardner
 
scottd said:
Bob,

Here's the paragraphs from Appendix C. Note that figures/charts referenced below stops at 40 microns for stratiform clouds and 50 microns for cumuliform clouds. 50 microns is about half the diameter of a human hair. So, there's no requirement per se to test the aircraft in conditions where the median volumetric diameter of the drop size exceeds 50 microns (or SLD size).

(a) Continuous maximum icing. The maximum continuous intensity of atmospheric icing conditions (continuous maximum icing) is defined by the variables of the cloud liquid water content, the mean effective diameter of the cloud droplets, the ambient air temperature, and the interrelationship of these three variables as shown in figure 1 of this appendix. The limiting icing envelope in terms of altitude and temperature is given in figure 2 of this appendix. The interrelationship of cloud liquid water content with drop diameter and altitude is determined from figures 1 and 2. The cloud liquid water content for continuous maximum icing conditions of a horizontal extent, other than 17.4 nautical miles, is determined by the value of liquid water content of figure 1, multiplied by the appropriate factor from figure 3 of this appendix.

(b) Intermittent maximum icing. The intermittent maximum intensity of atmospheric icing conditions (intermittent maximum icing) is defined by the variables of the cloud liquid water content, the mean effective diameter of the cloud droplets, the ambient air temperature, and the interrelationship of these three variables as shown in figure 4 of this appendix. The limiting icing envelope in terms of altitude and temperature is given in figure 5 of this appendix. The interrelationship of cloud liquid water content with drop diameter and altitude is determined from figures 4 and 5. The cloud liquid water content for intermittent maximum icing conditions of a horizontal extent, other than 2.6 nautical miles, is determined by the value of cloud liquid water content of figure 4 multiplied by the appropriate factor in figure 6 of this appendix.
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I should never work from memory. The takeaway message, though, is that flying a FIKI doesn't buy the user a lot other than escape time. Too many pilots assume that FIKI certification indemnifies them against icing problems.

Bob
 
Ron Levy said:
...to be somewhere else.

Seriously, I want turbine engines with hot lips and hot wings. Anything less is, well, less.
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I agree that hot wings are the best solution, but you don't necessarily need turbines to get it. The Douglas DC-6/7 actually had avgas-fired heaters that blew hot air through the leading edge of the wings/tail. It worked very well! (Interestingly, the heaters were the *exact* same type that were used for cabin heat!)
 
Scott Skylane said:
I agree that hot wings are the best solution, but you don't necessarily need turbines to get it. The Douglas DC-6/7 actually had avgas-fired heaters that blew hot air through the leading edge of the wings/tail. It worked very well! (Interestingly, the heaters were the *exact* same type that were used for cabin heat!)
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From my history with those sorts of cabin heaters, I can't imagine their reliability to be the sort I'd want for flight in icing...
 
Bleed Air is the best (speaking from my own experience). I like it over boots because it can keep the wing hot, unlike Boots, which you need to keep blowing (inflating) to knock the ice off. Although it doesn't sound like a big deal, think about when you are in the situation, and you have ten other tasks building up on you. Its nice to have one thing constantly running to help you. (But keep looking out the window to make sure its doing its job anyway). Bleed Air (in my opinion) also beats out the wheeping wing design because it won't run out of fluid.
 
Ron Levy said:
...to be somewhere else.

Seriously, I want turbine engines with hot lips and hot wings. Anything less is, well, less.
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What Ron said. But of the choices, I'd prefer TKS. I've flown Mooney's with it and it does a fine job. The Mooney wing is quite sensitive to ice accumulation, and the TKS kept the ice off.

I tend to trust electrical things more than pneumatic things.
 
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