Anti Icing systems

[FL140]

Which one of the following system is the best for anti icing and what are the advantages compared to others ?
*Fluid based system
*Pneumatic de-ice boots
*Electrothermal de-ice system

[stevef]

Try posting this in the Tech Log or Engineers forums.
It's a vague question as it depends which part of the aircraft requires anti-icing (or de-icing, as the case may be).
Thermal de-icing (gas turbine bleed air) should be included as well.

[Northbeach]

Anti-ice systems are designed to prevent ice from forming. Bleed air routed to the engine cowl would be an example of an anti-icing system.

De-icing systems are designed to remove ice once it has formed. Pneumatic boots affixed to the leading edge of a wing would be an example of a de-icing system.

You asked which one is best? The answer is the best system is the system that works keeping ice from where it should not be. The lowly beat up and patched pneumatic boots of a Piper Seneca that worked as advertised on their last flight are better than the high priced pitot tube heaters (original equipment) that did not do their job well on Air France’s Airbus flight 447 on its last flight across the Atlantic.

As with many questions in aviation the answer depends. It depends; are you talking about a piston powered twin flying unpressurized usually below 14,000 (FL140), are you talking about a wide body transport category turbojet flying 14 hour legs and half way around the globe, or are you talking about the Shuttle mission? Is the system being evaluated original equipment or an aftermarket add on? Is the evaluation criteria based on effectiveness or cost of installation and maintenance. Are you operating out of Madagascar (your post), the South Pacific or the Middle East where your exposure to icing would be much different than Scandinavia, Siberia or Canada in January/February?

Smaller piston powered aircraft generally use pneumatic boots because they lack an adequate source of high temperature and pressure air. The weight associated with the necessary tubing and valves would be a limitation as well. The de-icing systems on smaller piston powered aircraft generally use small air pumps and associated tubing. Sometimes they use electricity to heat surfaces (props & windshields).

Turbojets often use high pressure/temperature bleed air for their anti-ice needs. The maintenance issues surrounding rubber or composite boots and high speed flight usually preclude their application [IA-Jet 1124 (Westwind) notable exception].

Anti-ice fluid and weeping surfaces have been used as well. Each system has its limitations and advantages.

To ask what the best anti-ice system is; is like asking what the best tool is. It depends on the nature of the job and the limitations one must consider.

The best anti-ice system is the system that works exactly as designed when you need it the most.

Each system had its reason for design and deployment. Every system needs to be properly installed, maintained and inspected. And every system needs to be understood and operated correctly within its design limitations to be effective. I will go with FlightSafey’s motto here: the best safety equipment in an airplane is a well trained pilot. What is the best anti-ice system? Besides the system that works correctly I would add a well trained, experienced pilot making good decisions is pretty important as well.


Which one of the following system is the best for anti icing and what are the advantages compared to others ?
*Fluid based system
*Pneumatic de-ice boots
*Electrothermal de-ice system


Fluid based systems. Advantages you do not have to deal with pneumatic pumps or the ongoing patching requirements of de-ice boots. But you have to locate a reliable source of the de-ice fluid and sufficient quantities must be stored.

Pneumatic de-ice boots well understood system widely used. Parts are usually available, but the system requires more ongoing inspection and maintenance efforts.

Electro thermal de-ice systems are generally lighter and do not have the ongoing maintenance and storage issues related with fluid based systems.

[Da-20 monkey]

Something relatively new is an Electro-Mechanical Expulsion Deicing System (EMEDS).

On page 16 of it's patent document there is a nice description of advantages/ disadvantages of other de- and anti ice sytems:

Electro (http://www.docstoc.com/docs/49618222/Electro-magnetic-Expulsion-De-icing-System---Patent-5782435#viewer-area)

Understanding how this works is not really easy :eek: From reading it appears that the deiced surfaces are semi rigid. (flexible?)

Here is the video. Can you tell?

EMEDS In Flight Video 2 - YouTube

[Piltdown Man]

*Fluid based system: Requires a tank, plumbing, pumps etc. The fluid is not cheap and not always available and you can't carry that much. I'd also suggest that it's best used to give you enough protection while you the leave icing conditions ASAP.

*Pneumatic de-ice boots: Is not an anti-icing system. It gets rid of the ice that has already formed. But you can run it with minimal penalty for a long periods.

*Electrothermal de-ice system: Normally used for small areas like turbo-prop intakes, propellers. It works but it does require the aircraft to have larger generators than would otherwise be the case, just to provide sufficient power.

However, my favourite has to be bleed air. It's quite lightweight, is effective and trades a certain amount of engine efficiency for ice protection. Its use can also bugger up your climb and descent performance - on some aircraft reducing both to something approaching zero.

However, as Northbeach says, it's horses for courses.

[FL140]

Thank you guys for your Inputs , actually I was going thrugh the Caravan C208B technical stuff where it was stated that the fluid type anti-icng system is the latest as compared to old systems like Pneumatic de-ice boots , Electrothermal de-ice system. So a question arised in my mind wether it is better compared to old systems.

Thank you once again for your valuable inputs.

[NutLoose]

Some aircraft use a mixture of types, the citation 2 if memory serves me correctly has deice boots on the tail and wing outboard, but the inboard wing has electrically heated anti ice panels, as device boots would direct the ice in that area down the engines! The intake lips are heated too, but. Annot remember if they are electric or bleed air.

[Northbeach]

Y'all be careful out there. The Cessna caravan would not be my first choice for flying around for any real length of time in known icing. I have zero time in the caravan but the accident investigator sitting in my jump seat headed up to investigate a fatal caravan accident in the frozen north was not impressed with the type's safety record in ice.

It would be interesting to hear from others who have actually flown the C208 regarding its capability in known ice.

[FL140]

Thats a new fact I am hearing about the Caravans , If possible can you give more inputs about Caravans flying in Icing condition.

thanx Northbeach

[Northbeach]

I have 0 time in the Cessna 208. I'm in the middle of a trip now. But I did a quick search on the Caravan+icing and got numerous "hits".

The C208 is a great work horse. There is some concern about its history in ice. In the mean time go ahead and search Cessna Caravan+icing and see what you come up with.

I am not here to bash the Caravan or Cessna.

Any regular C208 drivers care to comment??????????

[FL140]

Got some stuff , which states the icing problem of Caravans , with the new changes I guess the safety of Caravans in Icing condition has increased.

Aviation Safety - Saving The Cessna Caravan (http://www.aviationsafetymagazine.com/airplane/Cessna-Caravan-Safety-in-Icing-Conditions.html)