De-ice technology develops

De-ice Technology Develops New systems you can bet your boots on By Greg Napert October 1998 There are three basic types of ice prevention systems that have been in common use over the years: The rubber bladder type — typically...


The specs
According to ASandT, the outer skin of the TKS ice protection panels are manufactured with titanium, typically 0.7 to 0.9mm thick. Titanium provides excellent strength, durability, light weight, and corrosion resistance. The panel skin is perforated by laser drilling holes, 0.0025 inches in diameter, 800 per square inch. The porous area of the titanium panels is designed to cover the stagnation point travel on the appropriate leading edge over a normal operating environment. This range is typically from best rate of climb at the low end to VNO, maximum structural cruising speed. Conservative margins are added to this range.

The back plate of a typical panel is manufactured with stainless steel or titanium. It is formed to create a reservoir for the ice protection fluid, allowing fluid supply to the entire porous area. A porous membrane between the outer skin and the reservoir assure even flow and distribution through the entire porous area of the panel.

The porous panels can be bonded or attached as a cuff over a leading edge (typical in STC installations), or built in as the leading edge. Most high performance general aviation singles and twins utilize the cuff method. Panels are bonded to the airframe with a two-part, flexible adhesive.

Fluid is supplied to the panels and propeller by a positive displacement, constant volume metering pump. The two-speed pump provides two flow rates to the panels and propeller. The low speed supplies fluid for the design point of anti-icing during a maximum continuous icing condition. The high speed doubles the flow rate for removing accumulated ice or providing ice protection for more severe conditions. Flow rates are designed for this level of performance, regardless of the certification basis for the system.

For systems that are not certified for flight into known icing, one metering pump is provided. For systems certified for flight into known icing, two pumps are installed for redundancy. The pumps are individually selectable.

Fluid for the windshield spraybar system is provided by an on-demand gear pump. The spraybar may be activated as needed to clear forward vision through the windshield. Similar to the metering pump, one or two pumps are provided depending on the certification basis. The fluid passes through a microfilter prior to distribution to the porous panels and propeller(s). The filter assures all contaminants are removed from the fluid and prevents panel blockage. A system of nylon tubing carries the fluid to proportioning units typically located in the wings and tail of the aircraft. The proportioning units divide the flow into the volumetric requirements of each panel or device supplied through the unit. Each panel and device is fed again with nylon tubing. Each system is provided with a fluid reservoir that ensures a minimum ice protection endurance when filled. All systems are designed for a minimum anti-ice endurance of 2.5 hours. The endurance can be increased dependent upon available volume for the reservoir and weight constraints on the amount of carried fluid. For the high performance single, the design fluid quantity typically falls in a range of 6 to 7.8 gallons.

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The system is operated and monitored through a control panel in the cockpit. All modes of operation and selection for the metering and windshield pumps are controlled through the panel. Coupled to a float sensor in the reservoir, the remaining quantity of fluid is displayed. The operational state of the system may also be monitored with the panel.

One very important aspect of TKS ice protection is its inherent low power consumption, says the company. Little demand is placed on the aircraft electrical system by the TKS system. A 28-volt TKS system will typically draw 1.5 amps of current during normal operation. Complete airframe ice protection is provided for a fraction of the power consumption of a resistance heating device on the airframe.

The weight of a TKS ice protection system for a high performance, single engine aircraft will typically fall between 35 to 40 pounds without fluid. The final value is dependent upon the size of the aircraft, the coverage and size of the leading edge panels, and the configuration of the mechanical components. Systems with components individually mounted, tend to be lighter that pallet-based systems, because of the added weight of the pallet framework. The tradeoff is weight versus ease of installation of these components.

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