Chieftain Icing

[AppleOTP]

I've recently read that the boots on the 'ho are the 'old style', where you want to wait and pick up ice before blowing them, as opposed to 'constantly'.

How Capable is the chieftain at handling ice? (Real world appreciated, not just 'book' answers).

Thanks.

[confusedalot]

Man, I am surprised that these planes are still in operation.

To answer your question from an old guy who last flew the plane somewhere around 1984, I would assert that the boots are of the old style where you need to wait awhile before popping them. It makes a total mess if you use them before you have a good amount of ice to shed. The leading edge just seems to accumulate even more ice if you use them too fast.

My 2 cents.

[C-GGGQ]

Likely depends on the age of the Navajo. The one i shared a hangar with flight training was one of the lock and key panthers and it (if i remember correctly) had the newer style boots. Stock chieftain though I'm not sure. However, never remember any of the ho pilots i know mentioning anything special about icing for it.

[mbav8r]

I don’t know about “new” boots, I always figured a boot was a boot, the premise being if you blow the boots to soon you could in theory not break the ice and actually form it to the shape of the inflated boot making any further attempts to remove the ice futile.(Bridging theory debunked)
I was trained to wait until between 1/4” and 1/2” ice before blowing the boots, generally seemed to work pretty good on all types that I flew with rubber boots.

[Ki-ll]

https://www.tc.gc.ca/eng/civilaviation/ ... 7-1615.htm

[Big Pistons Forever]

My personal experience is if (and it is a big if) the boots are inflating properly and they are in decent condition with a regular scrub down with boot conditioner, then they will shed even small build ups and there is no need or good reason to wait until ice has built up to cycle them.

[bobcaygeon]

The “Old” boots theory and ice bridging applied to the DC3 era aircraft with low pressure air and had a small number of large “bladders”.

The chieftain, new boots or older just generally doesn’t perform well in ice and an immediate exit strategy is required most of the time. Climb while you can because it won’t once you picked up ice. It’s not a particularly spectacular performer with a full load without ice, especially with the increased MTOW because of the VG kit.
I can’t remember if was only the straight ‘ho that could have the non-certified de-icing equipment or if the chieftain had that problem too.

[PostmasterGeneral]

I haven’t flown the Navajo in over 15 years, but I remember it being pretty solid in any kind of icing, much like a King Air. Let a bit build up before you blow it off and you’ll still be fine. That’s of course assuming all your boots are in working order. That’s one of those things you wanna test on the ground before a flight.

[leftoftrack]

well NASA says that Bridging dont happen but yoy seem to think you're smarter than NASA. WTF

[valleyboy]

I have never had an issue with "bridging" but boots will not completely shed trace amounts of less than about 1/2 inch - having said that it does depend on so many factors, type of icing, catch rate and of course condition of boots. So like many other things in aviation you can't have a set rule. You still need to use your head, keep it on your shoulders and adapt to the situation.

Example: Herc has a hot wing but loaded in a climb it robs so much power/performance that most herc drivers used the wing system as a deice instead of anti-ice in the climb.

[mbav8r]

Thanks ki-ll, I remember that article from way back and completely forgot about it, thank goodness I’ve had a hot wing for the last decade or so. I also seem to recall on the Dash that the boots were on immediately upon entering ice and something about ensuring 4 cycles prior to landing but that could’ve been a technique used by pilots, not necessarily directed by the AFM.
Either way, it was good advice about climbing right away if able, the Chieftain is not a great performer in icing and I remember a time that one was descending at 400’ per minute with full power and just made it to the runway, this pilot couldn’t climb and didn’t have the fuel to divert. There was at least 4” of ice on all the unprotected surfaces, I remember him being quit shook up.
Big pistons, I used to condition the boots weekly in the winter, they shined like brand new but there was still residual ice if you blew them right away, I still feel that waiting for at least 1/4” is the best method however if you’re trying to climb out of ice, the cleaner the better..

[nine sixteenths]

If you are having trouble with the boots, clean them and have a really good look at them with a strong flashlight. Look for tiny little crack/hole lines, if you get too many the boots will look like they are inflating when they are on the ground and tested, but they don’t retain enough air to blow up and become firm when there’s airspeed and resistance against them, they won’t keep enough pressure inside to push and actually shed the ice.

[atphat]

If the manual says to start cycling the boots upon entering icing conditions. Start cycling the boots upon entering icing conditions.

Easy peasy.

[mbav8r]

If the manual says to start cycling the boots upon entering icing conditions. Start cycling the boots upon entering icing conditions.

Easy peasy.

The OP asked for real world, that being said going from memory which I’ve already established isn’t terribly reliable but the Chieftain is not certified for known icing, approved yes but not certified. The difference being it wasn’t tested, it was approved because it had similar equipment to a certified aircraft. Anyhow, I believe the POH just simply tells you how to operate the de-ice equipment not when, again going from memory so if someone who currently flies one would chime in, that would be better.

Edited, so I downloaded a FAA approved Chieftain POH, normal operation of pneumatic de-ice boots it says;
Icing- turn surface deice switch ON. Boots will cycle once each time the switch is activated. Most effective deicing is obtained if a thickness of 1/4” to 1/2” of ice is collected before the deicers are operated.

[Rowdy]

Its been over three years.. but their is no 'difference'. Start running the boots when you start encountering accumulation. Anything else is old wives tales.

The chieftain handles ice fairly well for being a light piston twin. I never seemed to have any issues shedding accumulation under normal conditions.

[HiFlyChick]

https://www.tc.gc.ca/eng/civilaviation/ ... 7-1615.htm

The most important part of this AC is the date! I just watched a Mayday episode a few days ago where the cause of the crash was ice and a subsequent stall (tail stall? can't remember) One of the TSB discussions was that the whole ice bridging theory was an old wives tail that originated from the early days of flying in ice when the boots didn't work very well, but it had somehow gotten carried forward for decades.

I've never flown a Chieftain, but I can tell you that the Navajo handles ice pretty well, so long as you keep an eye on the rate of catch and have experience with how much it will handle. I'm no longer flying the ho, but had a fair bit of experience in it in some hard IMC, including frequent icing, and as soon as I saw any ice, the boots went on and stayed on, and they did just fine. Ice bridging may have had its roots in reality, but hasn't existed for many decades - put your boots on!

(And I forgot to say, that boots do best with a bit of TLC, so use conditioner to keep them subtle, and then apply a thin layer of Icex before going flying to help that ice slide right off)

[C-GGGQ]

I think we are confusing the poor guy. Half say the Navajo sucks in ice, half say it was good

[AppleOTP]

Clearly the left side of the aircraft does well, the right side catches faster than a peterbilt in ice fog, I hear what you're sayin'.

But seriously, it'll be interesting, fortunately we're going into the warm season, but with that comes the "I can't see out" due to bugs.

[AppleOTP]

https://www.tc.gc.ca/eng/civilaviation/ ... 7-1615.htm

The most important part of this AC is the date! I just watched a Mayday episode a few days ago where the cause of the crash was ice and a subsequent stall (tail stall? can't remember) One of the TSB discussions was that the whole ice bridging theory was an old wives tail that originated from the early days of flying in ice when the boots didn't work very well, but it had somehow gotten carried forward for decades.

I've never flown a Chieftain, but I can tell you that the Navajo handles ice pretty well, so long as you keep an eye on the rate of catch and have experience with how much it will handle. I'm no longer flying the ho, but had a fair bit of experience in it in some hard IMC, including frequent icing, and as soon as I saw any ice, the boots went on and stayed on, and they did just fine. Ice bridging may have had its roots in reality, but hasn't existed for many decades - put your boots on!

(And I forgot to say, that boots do best with a bit of TLC, so use conditioner to keep them subtle, and then apply a thin layer of Icex before going flying to help that ice slide right off)

Well, this'll be the first job with boots on an aircraft, so.... learning curve!

Would IceX on the boots have adverse affects (long term - degradation of the boots themselves?) I think I know what Mayday episode you're talking about. They interviewed a bunch of pilots from the same company, and got told "Wait. Company SOPs"?

[C-GGGQ]

Clearly the left side of the aircraft does well, the right side catches faster than a peterbilt in ice fog, I hear what you're sayin'.

But seriously, it'll be interesting, fortunately we're going into the warm season, but with that comes the "I can't see out" due to bugs.

I'll never forget hitting my first June bug at 3-4000 feet thinking "how the f$%& did you get up here?!"

[goingnowherefast]

It's not as bad as the Caravan, but it's no King Air either. However your icing strategy should be an exit strategy.
Know where the tops are and climb through.
The only time I'd stay in icing conditions is if the freezing level is reasonably higher than the MOCA/MEA. AKA, you can descend safely and melt it off. Make that decision early too, descend before the ice makes that decision for you
If turbine airplanes are giving pireps for moderate ice, it's probably bordering on severe.
Once you have your first few icing encounters, try blowing the boots at different accumulations. Trace ice isn't going to blow off, but it doesn't hurt to try either. See what amount of accumulations break off well, but be a chicken too, try often.
IceX is good for the boots, the more the merrier. Keeps them from drying out in the summer too. (although some companies use a different product in summer for UV protection)

[AppleOTP]

Nowherefast, only turbines around are 1900s, and PC12s... and an occasional 748.

Are they going to be more adept at icing encounters than the chieftain? (Comparison - I know they're larger/heavier, but for my future reference, are they better/worse than the ho?)

[HiFlyChick]

Well, this'll be the first job with boots on an aircraft, so.... learning curve!

Would IceX on the boots have adverse affects (long term - degradation of the boots themselves?) I think I know what Mayday episode you're talking about. They interviewed a bunch of pilots from the same company, and got told "Wait. Company SOPs"?

If it's your first job in icing, then approach it with caution. I recall flying with a very new F/O in icing conditions - he looked out, sawthe ice and was somewhat agitated, so I looked out, told him that we had boots and all heats turned on and were doing fine. He replied "How can you tell?" And the only answer I could give him was experience. I'm sorry if that sounds like a cop out, but ultimately, there's no real way to accurately quantify what you're seeing other than to get used to seeing it (always with a way out!) and knowing what your aircraft can handle. On that particular flight, the rate of catch was such that the boots and heat were handling it (i.e. kept everything clear), but after a while, we got into an area of heavier ice, and I pointed out to the new F/O that things had changed and that while we were okay for a while, we couldn't stay where we were for the hour remaining. So we asked for a block of airspace and climbed up until we found a spot between the layers.

I mentioned the conditioner - that is a cream to keep the boots supple, but we found it only needed to be applied once a year (we did it in the fall before the start of heavy ice season). We applied the Icex on a regular basis, but it's really expensive and it takes very little to cover the boots, so don't just slather it on, a small dampening of the rag will suffice. We actually used the same rag over and over again and kept it in a jar between uses. We're talking seriously expensive for a very small bottle (i.e. you could easily use half a bottle on the aircraft if you were careless). Being sparing with its application accomplishes the job, and also shows your company that you care about their bottom line while ensuring you have a supply left over for next time.

I don't know why people would say that the Navajo doesn't handle ice well, unless the boots on the aircraft they flew weren't kept in shape. The company I flew for was good at reluarly inspecting the boots, patching the small spots, and replacing the boot when there were too many patches. For the most part, other than freezing rain, I had very few flights that didn't go due to ice in the approx 18 yrs I flew Navajos. Having said that, there was one flight I recall where the ice built up crazy-fast and even though I took prompt action and ended up diverting to the nearest airport on my path, it looked like golf balls glued to the leading edge.

Above all else, don't waffle - make decisions early, act immediately and aggressively, and always think about your escape plan.

And FYI, don't be stingy about the windshield or prop heats either - if we were above the freezing level, I turned them on whenever we were in cloud. I've had the windshield heat fail before, and you want to find that out early on so you can go somewhere where you'll stay in the clear. If you can't see to land, even though your boots are working, you can still be in a world of hurt...

[mbav8r]

Nowherefast, only turbines around are 1900s, and PC12s... and an occasional 748.

Are they going to be more adept at icing encounters than the chieftain? (Comparison - I know they're larger/heavier, but for my future reference, are they better/worse than the ho?)

“The size of droplets affects the rate of catch. Small drops tend to follow the airflow and are carried around the wing. Large, heavy drops tend to strike the wing. When a small drop does hit, it will spread back over the wing only a small distance. The large drop spreads farther. As for airspeed, the number of droplets struck by the aircraft in a certain time increases as the airspeed increases. The curvature of the leading edge of the wing also has an effect on the rate of catch. Thin wings catch more droplets than do thick wings. The rate of catch is, therefore, greatest for an aircraft with thin wings flying at high speed through a cloud with large droplets and a high liquid water content”

AppleOTP, hidlychick gave some very good advice, regarding your question there are many variables to consider, comparing the aircraft you asked about, the Chieftain has a much thinner wing than all three of those at roughly the same speed so the rate of catch will be higher in the Ho in the same cloud. Another big variable is those aircraft will typically climb faster through the icing layer so in it a shorter time, a third factor would be additional power increasing your ability to carry the extra weight and keep climbing, those factors will play a big role in whether you’re picking up moderate or severe amounts of ice.

[valleyboy]

The total irony of all this discussion is that in reality boots are what pacifiers are made out of -- well ok similar materials. Boots are ancient technology and for most aircraft that have them, all they are good for is perhaps providing enough time to find an exit. The main issue with any piston aircraft is performance and the lack of ability to wave at ice on the way by. Even turbo props, especially 705 group are likely as dangerous an aircraft you want to find in icing. Until you reach the turbo jet class with lots of thrust and plenty of bleed air icing begins to become so much less of a factor, even operations in freezing rain is a non issue and ironically wing and empenauge likely isn't even turned on in the climb. Boeing classics didn't have tail anti-ice.

Back when DC-3 was the mainstay of NWO/Manitoba the game was to lighten up the aircraft as much as possible, this mean removing the boots all together. Didn't seem to effect operations much., although I think there was more rum drank back in those days Maybe there is a bonus when flying with no wx reporting,"it was always like a box of chocolates" Bottom line - just because you have boots doesn't mean they really will make that much difference. Percentage wise I would tend to believe that most flights where boots were cycled the flight could have been conducted without their use. They do give you a little bit of a edge but in reality it will be your brain that is the biggest asset.

For the SOP worshipers out there, what rules do you apply if the system fails at the critical time. Even with a great SOP you still have to think on your feet from time to time.