Avionics Fans

The avionics fans system provides area cooling to the Garmin Display Units (GDU), It is controlled by the indicating/recording system. It consists of the avionics fans 1 and 2, and the avionics fans relay.

Avionics fans 1 and 2

The avionics fans push cooling air at the back of the Primary Flight Display (PFD) and the Multi-Function Display (MFD). The avionics fans are mounted on the bottom of the instrument panel shroud, on each side of the pedestal, behind the PFD and the MFD. The avionics fans will turn ON when the temperature reaches 125° F (51.6° C) and turn OFF when the temperature decreases below 110° F (43.3° C).

Avionics fans relay

The avionics fans relay supplies electrical current to the avionics fans. The integrated avionics unit (GIA) controls the relay. It is located on the relay panel.

Operation

The main bus provides the 28 VDC electrical power to the avionics fans through the FANS circuit breaker, which is applied to the avionics fans relay.

Activation of the fans is controlled automatically through a discrete output from the integrated avionics unit (GIA) and the avionics fans relay.

When the internal temperature of either display unit reaches 125° F (51.6° C), the integrated avionics unit (GIA) will remove a discrete ground output to the avionics fans relay which will de-energize the relay and apply 28 VDC electrical power to the avionics fans 1 and 2.

Electrical power return to ground is through the avionics fans 1 and 2.

When the internal temperature of both displays decreases below 110° F (43.3° C), the integrated avionics unit (GIA) reapplies the discrete output to the avionics fans relay which energizes the relay and deactivates both of the cooling fans.

Each of the fans are tested for operation during the Audio Alert Test

A signal from the avionics fans 1 and 2, is provided to the integrated avionics unit (GIA) when active. In the event of a failure of one or both avionics fans, the AVIONICS FAN Crew Alerting System (CAS) message will illuminate.