79. The spring-loaded TEST position of the ON/OFF/TEST switch on the NAV VOR/ILS control unit provides a BIT capability. The self-test requires a signal from a VOR Station.

NOTE

This BIT does not test the ILS circuitry.

80. Carry out the test as follows:

a. Ensure the aircraft is positioned to receive ground signals for VOR.

b. Ensure the AIC-14 intercom system is ON.

c. Select receiver selector panel NAVS switch to ON position.

d. Ensure GHARS system is ON and serviceable.

e. Select (push) pilot, co-pilot and TACCO NAV SELECT switch to VOR/LOC position and ensure VOR/LOC segment illuminates in all positions.

f. Set CDI to a course of 315 degrees (both indicators) using SET knob.

g. On the VOR control unit select the local VOR frequency.

h. Select and hold OFF/PWR/TEST switch to TEST position and observe;

(1) All BDHI No.2 needles read 315 ±4 degrees.

(2) CDI vertical needles are centred ±4 degrees.

(3) OFF flags for vertical needles are out of view.

(4) TO/FROM indicators show TO.

NOTE

Any indications on CDI horizontal needle or associated flag are to be disregarded during this test.