Ice Protection Design

CAV Ice Protection has over 50 years’ experience in the design, certification and manufacture of the TKS® Ice Protection systems for commercial, general aviation, corporate and military aircraft.

Whether your aircraft requires a TKS® FIKI or TKS® No-Hazard system, our ice protection programmes are tailored to your aircraft’s specific design, flight envelope and mission profile.

Panel

CAV’s leading edge micro-perforated titanium panels are created using laser drilling to create eight-hundred, 0.0025in diameter holes per square inch.

The system provides freezing point depression over the FAA Continuous Maximum Icing envelope for the protected surfaces and anti-icing capability for all flight conditions within the envelope at the design flow. It is also capable of providing de-ice capability during and after encounters with ice defined by the intermittent maximum envelope.

Flow Balance

Impingement and flow rate analysis are performed to determine the quantity and rate of fluid provided to the panels and propeller. Internally, the fluid is divided and volumetrically controlled by proportioning units, which deliver it to the panels via a network of carefully calibrated (sized) capillary tubes, ensuring they receive the correct fluid requirements.

Analysing all system components, such as tees, elbows, solenoid valves, and tubing sizes and lengths, inhouse software delivers a flow analysis of your aircraft’s system.

Whilst a combination of the desired flow rate for each panel, a pump curve for fluid delivery versus pressure and an evaluation of the design temperature is used by the software to appropriately size the proportioning unit capillary tubes. In the case of the propeller blade, fluid is distributed using a slinger ring and individual blade nozzles, and a boot is placed over the area requiring protection to properly distribute the fluid.

Finally, the pressure and flow rate characteristics of the system are determined for the entire icing envelope temperature range.

Windshield

CAV Ice Protection provides a standard hardware design for windshield ice protection and determines spray nozzle location and quantity via flight test. Designed for intermittent operation, when activated, a solenoid valve opens and the windshield pump runs for four seconds, clearing the windshield of ice, before the solenoid valve closes.

Hardware

Our hardware components are customised for your system and installation is defined to ensure their correct placement.

  • Reservoir: stores the fluid required.
  • Constant volume metering pumps: deliver the fluid via positive displacement.
  • Cracking check valves: prevent flowback to the tank as a part of the pump assembly.
  • Micro-filter: removes contaminants prior to distribution to prevent blockage.
  • Nylon tubing: supplies the fluid to the proportioning units and onto the panels.
  • On demand gear pump: supplies fluid to windshield ice protection.
  • Solenoid valve: is closed to ensure fluid does not flow to spray nozzle unless the gear pump is activated.

Monitoring

A combination of pressure switches and pressure transducers are used to monitor for high pressures in the case blockages or low pressures in the case of a line failure. In many installations an ultrasonic flow transducer downstream of the filters ensures that the overall flow rate, which the pump is providing to the arterial system, is monitored for indication of low flow conditions.

Operation

Typically, control of the system is performed by a series of switches from which the pilot will select the desired mode of operation. This feeds the selection to a timer box, controlling the pumps to provide the selected mode of operation.

In modern system designs for FIKI aircraft a timer box provides three different types of operation for the main metering pump.

Normal Mode

Icing: Typical icing encounters.

Pumps: Both pumps operate simultaneously for a time cycle of 30 seconds on and 90 seconds off.

Flow: 50% of design flow rate.

High Mode

Icing: Heavier, more prolonged icing encounters.

Pumps: One pump operates continuously.

Flow: 100% of design flow rate.

Maximum Mode

Icing: Severe icing encounters.

Pumps: Both pumps operate simultaneously for two minutes.

Flow: 200% of design flow rate.

Backup Mode

Many systems also contain a Backup Mode which bypasses the timer box. Identical to High Mode, it uses the opposite pump and is designed to be electrically isolated from the remainder of the system to provide an independent means of pumping fluid in the event of a main system failure.