Propeller De-Icing

Harnessing the latest solid-state switching, digital processing and communication technologies, we offer to experimental aviation a propeller anti-icing / de-icing system that is advanced yet straightforward in nature.

Our PDC unit applies de-icing to an aircraft's propeller blade heating boots in the prescribed way, while monitoring the correct or otherwise application thereof and keeping the pilot informed.

We employ the latest solid-state technology to gain both high power switching and built-in current monitoring. In this way we avoid the use of relays to achieve a system with no moving parts. We combine this with a processor that provides precise yet adjustable timing and operation, to end up with a durable and versatile solution in a compact form factor.

So far, our propeller de-icing system has been deployed on many Epic LT and Lancair IV aircraft, while also addressing various special applications. It easily interfaces with either EFIS annunciation, like the Garmin 900 series, or with traditional lights.

Features

• Applies electrical power to blade heating elements in exact cycles
• Monitors electrical current and voltage applied to heating elements
• Indicates failure should current go out of the specified range
• Able to send measured information to displays, laptops, etc.
• Employs adaptive switching to limit heating boot duty-cycles
• Adaptable to suit various applications

Basic Interfacing

Our propeller de-icing system composes of a single propeller de-ice controller unit, the PDC. The diagram below illustrates the basic interfacing to the operator and the propeller heating boots.

Operator Interface

The pilot has one switch to control and two annunciation lights to monitor:

1. The PROP-HEAT switch will turn de-icing ON or turn it OFF. A three position switch may alternatively be employed to provide two levels of heating, either HIGH or LOW when not turned OFF.
2. The HEAT-ON light will light-up when de-icing is turned ON. In case of de-icing failure while turned ON, this light will blink continuously. Otherwise, when PROP-HEAT is turned OFF, the HEAT-ON light will go out.
3. The HEAT-FAIL light will light-up when a failure has been detected while de-icing is turned ON. Failure results when the electrical current flowing to the heating boots falls out of the configured bounds.

Propeller Heating Boots

The PDC is normally installed within the engine compartment (in front of the firewall) and receives its power locally. This minimizes the wire-count through the firewall and increases efficiency by reducing the distance the de-icing current have to flow to get to the propeller blade heating boots. The PDC applies power to the boots directly (without the need for extra power relays) via the slip-ring assembly at the back of the propeller hub. We combine pins in parallel on the PDC connector to facilitate the switching of relatively high electrical currents through the unit.

Operational Scenario

You switch the aircraft MASTER switch ON and both HEAT-ON and HEAT-FAIL lights up for about 2 seconds while the PDC performs a system self-check. The lights go out to show it is ready for use.

As part of your pre-flight or during flight you decide to turn PROP-HEAT ON and notice that the HEAT-ON light lights up while the HEAT-FAIL stays dark.

As the heating cycle continues the system moves from energizing phase A to energizing phase B and you notice the HEAT-ON light blink once or twice to mark this transition. These blinks continues every so often informing you of the phase transitions and correct operation, giving you added peace of mind.

Suddenly there is a problem with either the heating boots, the slip-rings or the electrical wiring and the HEAT-FAIL light immediately lights up while the HEAT-ON light starts flashing continuously. You realize that the system is still cycling through the phases, but that propeller de-icing is not working properly and you start taking appropriate action.

Maintenance Operations

From time to time a Laptop PC and USB-to-Serial Converter may be connected to the PDC, as depicted below, in order to perform maintenance operations on an installed system.

Maintenance operations allow you to confirm (troubleshoot) your installation, make adjustments, view operational information and record a certain operation. All these tasks are done through the VR System Link software running on the laptop.

System Link enables making adjustments to set-points, calibration values and other configuration settings, such as setting the working current minimum and maximum limits.

More Information

Additional information is contained in our PDC manual, wiring diagrams, etc. listed in the colum on the right side of the web page. You'll also find PDC firmware updates here that we provide free of charge to all customers. This firmware will be updated from time to time to provide additional features and improvements. Also, please feel free to contact us with any query you may have regarding any of our products.