# How do electric anti-icing systems work?

How do they work for GA propeller planes? More specifically, how is it implemented on the leading edge of the wing and propeller blades? I'm more interested in the mechanics of electric heating, not the theory or where it gets power from (alternator or batteries).

What are the pros and cons of electric anti-icing compared to other systems?

• If they weren't viable they wouldn't be used @JoshFang – GdD Nov 22 '17 at 8:35
• This is a very broad question. Aircraft electric anti-icing systems including air data sensor (temperature and pressure probes, e.g. pitot probe), windscreens, propellers, and wings. Each system has a different design and implementation. The direct answer to the question as asked is: by using DC or AC current resistance to heat a material; each system is implemented according to the design requirements of that system; and they are viable. This question should be narrowed to a specific design or subset of designs. – J Walters Nov 22 '17 at 14:14
• Thanks for the response. Edited to narrow down the question. – Josh Fang Nov 22 '17 at 17:21

How do they work?

An electric current is passed through a heating element built into the device needed to be heated. For example, 115 VAC may be applied to a heating element of anywhere between 5-300 ohms (resistance values vary widely depending on the heating application). The voltage applied may be dependent on a controller that will dictate how much voltage is applied.

Using basic Ohm's Law, we can deduce that the current draw of 115 VAC across an example 60 ohms coil, would be approximately 1.9 A, and the power 220W. Keep in mind, this isn't a strict calculation as phase angle and other variables might be involved in an AC circuit - but close enough... That 220W is dissipated as heat which thus heats the device.

This is virtually the same in most GA and commercial applications.

Are they viable?

If by viable you mean "They work, but do have occasional failures that falls within a reasonable rate of expectation," then yes, they are viable.

Small GA aircraft have made use of electric anti-ice systems on the wing and tailplanes. The most common one being ThermaWing, which consists of electrically heated laminate adhered to the leading edges of the wings and tailplane. They are powered by a separate alternator driven by the engine. They have an advantage over chemical deicing methods like TKS in that they are not time limited by the quantity of deicing chemical which can be carried at the cost of a lowered useful load due to the weight of the additional alternator plus the wing cuffs and other equipment. As to the best of my knowledge ThermaWing is an STC aftermarket kit and does not provide certified Flight Into Known Icing (FIKI) unlike some TKS applications. Columbia aircraft used to offer ThermaWing as optional on their 350 and 400 series aircraft prior to their bankruptcy and acquisition by Cessna.

Electric propeller deicing - hot props - consist of a rubber sleeve applied to the inboard most sections of the propller blade leading edge, each one containing an electric heating element underneath which could melt accumulated ice. Again it competes directly with chemical deicing systems which sling deicing fluid over the length of the propeller blade to melt ice and has similar benefits and drawbacks to the ThermaWing system.

Windshield deicing and defogging is usually done with cabin heat air coming from either outside air passed over the exhaust manifold then vented into the cabin or from a dedicated fuel burning cabin heater, common on twins. Still some light aircraft eg the BE58 Baron make use of electriccally heated windshield sections consisting of a finely woven heating element mesh applied in the transparency laminate and can be powered by the airplane’s electrical system.

Pitot-static ports, stall warning vanes, and fuel vents also often make use of electric heating elements to prevent accretion of ice which could block these ports and cause primary flight instruments to malfunction or cause fuel starvation of the engines.