de-icing question

[U-I pilot]

I know to de-ice the wing, planes use boots, deicing fluids or have heated leading edges. I was wondering how these heated leading edges are heated.... Is it hot air routed from engine exhaust? Its own heater? Is it electrical?
-Thanks...im sure its something simple

 

[DC9stick]

Most wing leading edges use hot air from the compressor section of the jet engine. The P&W JT8D uses 8th and 13th stage bleed air. Engine inlets of various Jet and Turbo-prop engines use all of the methods you described.

 

[sabreliner]

A/C with hot wings are typically jet aircraft. They use bleed air (before combustion) to heat the leading edges of the wings. This air hasn't yet been burned, but is very hot from the various stages of compression. It works pretty well, though it exacts a pretty heavy toll on performance as you rob the engine of that air they need to make thrust. There are a couple of exceptions to the hot surface. I know the older Lears use heated pads on the horizontal stab to deice that surface. I think the CitationJet may as well.

The next form of inflight deice/anti-ice is the inflatable boot. It is typically found on prop a/c including turboprops. The boot inflates, the ice cracks off. Pretty simple concept. We still do have some heated surfaces though, like the props, windshields, pitot static, etc. Those are electric.

The last common form is TKS deice/anti-ice. TKS fluid is pumped through a very fine mesh on the leading edge of the protected surface (like the wing) and removes any ice buildup while preventing further accretion. TKS fluid is unheated, and I believe is similar to the glycol we use to clean the a/c of snow and ice before taking off. It is relativly uncommon to find. The most common installations are on Hawker bizjets. You can also get Mooneys now with TKS systems. There are also several retrofits that add TKS systems to older a/c such as the Bonanza and Twin Commander 500's.

Ground deicing is conducted using heated glycol/water mix (usually 50/50.) This is known as type I fluid, and is used to remove accumulations of snow and ice. In conditions of falling frozen precip, usually a second fluid, either type II or IV are applied. These are applied full strength and cold. They help prevent futher accretion of snow and ice on the airframe until you can get airborne. They only work for a short period of time though, depending on the type of precip and the amount you are getting. This time is called a hold-over time and is established using charts we carry. Type IV generally has a longer hold-over time than Type II and is the most common used in air-carrier ops. All of thse fluids are VERY expensive, making their use by small a/c rare. Typical small operators (private stuff) choose to wait out the weather.

 

[mar]

A blast from the past

Just in case you're curious: The DC6 has heated wings but no bleed air (recip engines and all...).

Each wing and the tail have a 300,000 BTU heater that burns fuel from the #3 main fuel tank.

The heaters are equipped with dual ignition and a fuel crossfeed system (#2 main fuel).

Fire protection provided by two banks of CO2 for the wings and a seperate "peanut bottle" for the tail.

Works like a charm. Sort of.

 

[avbug]

A number of older piston airplanes also used an exhaust bleed from the turbo to do the same thing.

 

[rfeathe1]

Piston Convairs (R 2800s) have hot leading edges. The heat is taken off of the augmenter tubes & routed to the wings & tail. Not as effective as the combustion heaters on the DC 6 but they work when managed correctly.

 

[U-I pilot]

thanks to all the replys. this is what i was looking for and more.

 

[Illini Pilot]

hey bryan, its like we were just talking about this driving home or something...

 

[U-I pilot]

ya i know i needed an answer

 

[SkyWestCRJPilot]

The CRJ has heated wing leading edges and heated engine cowl inlets from the 14th stage engine bleed air. Interestingly though the horizontal and vertical stabilizers have no ice protection at all. The aerodynamics don't allow ice to accumulate very much and what ice does accumulate doesn't affect airflow enough to require ice protection. The F-14, many other fighters, the Sabreliner (and some other airplanes), don't have any ice protection whatsover. Their ice protection is to climb out of the iceing level. Also aerodynamics of jets at high speeds limits ice accumulation due compressibility of the air.

 

[skyking1976]

A PT-6 equipped turboprop (at least the KA-350 that I flew) that has heated engine inlets will use exhaust collected from scuppers installed in the exhaust stacks. The hot air goes in from one stack, through the heated intake lip, and out the other stack.

Speaking of Janitrols... Does anyone else have a problem with oily heater exhaust discharge on the cockpit floors. The Chieftains that I fly are darn near disgusting.

Skyking

 

[rfeathe1]

I think I would be careful about "oily heater exhaust" from any combustion heater inside the airplane--you can buy a cheap but effective carbon monoxide detector for under $5.00.

 

[skyking1976]

Carbon monoxide... hmmm... That would explain the light-headedness and being tired all the time. Wait a minute. Now I remember. I fly cargo at night. Those symptoms must be job-related and not heater-related.

Cheers,
Skyking

 

[TurboS7]

Tsa is going to love you when you show up with a vibrator, and pair of brushes, and a weird looking sparkplug in your flight case. Have you figured out how to reset the overheat switch in flight. I got so frustrated with ours I rewired it to the cockpit. It was an illegal installation but when the heater overheated all I had to do was reset the overheat switch an wooola. Do watch out for the carbon monoxide, Janitrols are famous for it. I used to keep carbon monoxide indicators in all our airplanes. BTW I was in Duluth yesterday, -9 F , and it is March. BRRRRRRRRRRRR

 

[skyking1976]

WOW...

I sure hope there aren't any Feds that read this board; telling that you had flown an A/C with a known illegal heater. Not a bad idea though. More than once I have had the ol' Junkitrol quit on me at FL190.

Skyking

 

[TurboS7]

In their deep dark past most Feds have done stuff a lot worse than running a wire from a Janitrol heater to the cockpit. It was so long ago I really don't care(22 years), come and get me. When I am a Fed look out though, that will be the first place I will look. cheers.