While your number one tools for navigating icing conditions are gray matter and a good mental map of the weather, deicing equipment opens up a world of options. Flights that would be preemptively cancelled can be attempted and situations that would be emergencies turn into calm requests for a new altitude. Deicing options are largely set by the airframe, with only a few models having certification for both boots and the TKS weeping wing. In November 2008, we picked TKS as the better choice. We still think so, and in our recent survey, most owners agree. While not without drawbacks, most pilots are happy with the system and accept its tradeoffs. We heard primarily from Cirrus and Mooney owners, but also from pilots of Hawker jets, Cessna 210s and even a de Havilland Dove. Most fly well in excess of 100 hours a year. About half bought a plane with TKS already installed and for many that was a selling feature.
While your number one tools for navigating icing conditions are gray matter and a good mental map of the weather, deicing equipment opens up a world of options. Flights that would be preemptively cancelled can be attempted and situations that would be emergencies turn into calm requests for a new altitude.
Deicing options are largely set by the airframe, with only a few models having certification for both boots and the TKS weeping wing. In November 2008, we picked TKS as the better choice. We still think so, and in our recent survey, most owners agree. While not without drawbacks, most pilots are happy with the system and accept its tradeoffs.
We heard primarily from Cirrus and Mooney owners, but also from pilots of Hawker jets, Cessna 210s and even a de Havilland Dove. Most fly well in excess of 100 hours a year. About half bought a plane with TKS already installed and for many that was a selling feature.
Why Fly TKS?
The primary motivation for pilots purchasing planes with TKS or adding it is dispatch reliability. One pilot gave us his math: “For about 15 percent of the value of the airframe, I was able to take an aircraft that had transportation utility for eight months a year and turn it into a 12-month aircraft-an increase of 50 percent in utility.” Another pilot put a regional twist on this: “In the New York City vicinity, where I fly, GA aircraft dont get to choose altitudes. That severely limits the utility of the airplane when icing is an issue.”
These comments outweighed ones about getting out of inadvertent icing conditions by a respectable margin (although ice scares were dealmakers for some pilots). The bottom line was that pilots with TKS are confident launching knowing they may encounter ice before the wheels touch back down. How much icing and under what circumstances pilots were up for varied quite a bit. Hold that thought for a moment.
We also heard from two pilots who installed TKS after hail damage in flight. No, the
TKS wasnt to prevent against future hail. The TKS install was covered by insurance rather than just repair the leading edge. Not that wed recommend seeking out a hailstorm to score a discount TKS system. Some other pilots had pneumatic boots that needed replacement and chose to switch to TKS for a small cost delta.
It Works, Mostly
Pilots with experience using boots told us the system was equal to or better than boots. “I fly across the Great Lakes regularly in the winter and the piece of mind is priceless. The system works much better than boots on my twins.” Another told us: “I became a believer after flying Commanders for Central Air Southwest. I landed at Cincinnati one night behind a King Air who had an inch or more of ridge ice behind the boots, and my wings were slick as slime with TKS.”
Pilots with turbine time and hot wing experience were split. Some felt TKS was acceptable in jets. Others did not: “In flying the Hawker 700, 800 and 800XP for over seven years, the system is minimally protective at best. If priming is completed every 60 minutes (when temps permit) then, and only then, will the system work 40 percent as advertised. It will never maintain a clean leading edge.” Other Hawker pilots pointed out how critical flying the published speed was with TKS running.
Sifting through the comments, it seems clear the system works best for the under-200-knot crowd and in light icing. Pilots told us that in moderate icing or freezing rain, the wings often carry slushy areas or spots of ice that may or may not pop off in flight. However, the airplane keeps flying with only a small apparent hit to performance. Icing can definitely get beyond the capability of the TKS, but with
fluid flowing, there is time to make an immediate move to get out.
We looked specifically at how well TKS protected specific areas, but saw no red flags by area or airframe. Non-FIKI Cirrus pilots reported issues with wingtips and elevator balance horns at a higher percentage than average across all respondents. But thats no surprise as those parts are unprotected. Systems on the Cessna 210, Mooney and Diamond DA42 scored above average on effectiveness, both FIKI and non-FIKI.
One advantage of TKS is that in systems with TKS to the propeller(s), fluid gets sprayed over many unprotected areas of the airframe, such as antennas or engine cowls, reducing buildup if not eliminating it. Wingtips still build ice on all airframes.
The number one operational takeaway from our survey was that TKS must be running for five to 10 minutes before encountering the ice. This is actually required per the POH for certified systems. Depending on your system, that could use half a gallon of fluid at $20-$40/gallon only to enter a cloud and find it wasnt needed. But as one owner put it, “thats the price of peace of mind.” If ice builds before the fluid flows, it might not come off at all. TKS is best thought of as anti-ice, not de-ice.
The wise advice was not to count on a low (normal) setting keeping off the ice. Non-certified systems often only carry a few gallons of fluid. A non-FIKI Cirrus SR22 might only have 30 minutes of protection at the high setting. Yet few pilots reported ever having run out of fluid in flight, as its most often used for a climb or descent through icing. Those that did run out got caught unexpectedly lingering in
holds or on long vectors for an approach.
Thoughts on FIKI
The fact that TKS comes in FIKI and non-FIKI flavors has incited endless debates as to how much certification matters, and if non-FIKI systems motivate pilots to take on conditions they shouldnt. Surveyed pilots were split. About half the pilots had FIKI systems and half didnt. About half felt that FIKI was essential for anything beyond emergency use.
Pilots who felt FIKI was a nice ticket-protecting CYA, or simply didnt care about certification so long as it kept ice off, were numbered about 26 percent across the board, but numbered more like 50 percent if you just look at non-FIKI aircraft owners. Given that a FIKI system is $10,000 -$15,000 more for a given airframe, this makes sense: Those who dont care buy only what they feel they need.
That leaves 24 percent who say the FIKI answer is not that simple, and we agree. The physical difference between FIKI and non-FIKI on some airframes may be as slight as an ice light and a backup fluid pump. But a single pump is a still a point failure if youre regularly flying in icing. The difference could also be much wider airframe protection, more fluid capacity and a cockpit display of the TKS fluid level.
We saw multiple comments similar to this non-FIKI Cirrus pilot: “A winter day with ground temp +2 degrees C, solid overcast at 2000 with tops reported as 5000, clear above. I will often launch into that. If ice is worse or accumulates even with TKS, my out is to RTB where its above freezing. Would I do that without TKS? Probably not … I think TKS is a great system. I just wish I could buy a FIKI Cirrus to enjoy the even better protection that offers. But, like anything, we need to use our minds and think through each circumstance.”
The system isnt cheap. On a new Cirrus SR22, the non-FIKI TKS option adds $20,000. The FIKI system adds $40,000. Retrofits costs are similar, ranging from the mid-20s to the mid-40s for piston singles. Note that retrofits often have additional modification costs, so every job is a custom quote. Expect to lose between 40-50 pounds of useful load just for the hardware. Costs and weight go up slightly for twins.
TKS fluid is a consumable. Just like gas, it eats into useful load and you can run out. The fluid weighs nine pounds per gallon. Looking at the Mooney system, thats 54 pounds of fluid if the tank is full. You need to keep some fluid in the system even in the summer to run it monthly-required to keep the pads wet and the pores open. You may also need to take extra fluid in jugs with you on trips.
Few FBOs stock TKS fluid, and those that do may charge upwards of $50 gallon for it. You can find it online for $20/gallon or less, including shipping. The best prices we saw were from Skygeek (www.skygeek.com) or directly from Kilfrost (www.kilfrost.com). Be aware that theres a hazmat charge with TKS shipments, so check the final cost closely before clicking “complete order.”
The fluid is toxic if ingested, and attractively sweet tasting to animals. This is an issue with storage and spillage. Its also quite slippery. It tends to weep out of the wings for some time after use. If conditions permit turning it off several minutes prior to landing, that helps, but still expect to clean the fluid off your hangar floor with absorbent rags and warn line service folks about the dripping fluid. Pre-G3 SR22s have the tank filler on the side of the fuselage, so spillage is an issue.
Kilfrost has a low-toxicity, more bio-friendly product called TKS Sustain thats approved for the Quest Kodiac. Other approvals are in the works. We werent able to find any for sale in the U.S. for this report, but Kilfrost says it will be selling it directly as more approvals occur.
A few owners reported corrosion, both on metal wings and metal control surfaces of composite aircraft. Kevin Hawley, President of CAV Aerospace that sells the system told us they havent seen reports of this recently, but it has been an issue in the past. The culprit isnt the TKS fluid-its not corrosive-but water getting between dissimilar metals. The TKS panels must not be in contact with the metal of the wing. Poor installation (as was the villain with well-known corrosion problems on some Hawkers) or stripper from repainting are strong candidates.
Weve seen corrosion on some Cirrus elevators that might be TKS related. Hawley says that its possible the fluid is carrying water into tight spaces and could be a factor, but with on proper installs, CAV isnt seeing this issue. TKS fluid is hydrophilic and it is operating in a wet environment, however, and CAV is investigating getting anti-corrosives added to TKS fluid formulations.
There is a speed penalty for simply having the TKS system installed on the wings without the fluid running. It seems most significant on long-body Mooneys, where anywhere from five to 10 knots is reported. For the Cirrus, its only three to five knots and for draggier airframes, like the Cessna 206 or 210, it seems undetectable.
Other than regularly running the system, we saw few complaints about hardware failures. Most problems were from pores getting clogged on the wings either from disuse or general grime. Water can also freeze overnight on the leading edge blocking pores. Making sure its fully working is another good reason to turn it on before hitting the ice.
Worth the Mess
No system that requires handling toxic liquids or preemptive activation can be called ideal, and no system can handle any ice Ma Nature could dish out. But TKS delivers on its promise of keeping the airfoils clear enough for long enough for that gray matter of yours to find some ice-free air or a runway.